Electronic device and method for determining input voltage to an electrical isolation point

Abstract

An electronic device (100) is provided, which is configured to determine an input voltage to an electrical isolation point of the electronic device (100). The electronic device (100) includes an isolation transformer (120), which is configured to conduct a primary current (Ip) provided by an input voltage source (110) and provide a secondary voltage (Vs), which is proportional to a primary voltage (Vp) induced by the primary current (Ip). The electronic device (100) also includes a peak detection circuit (130) coupled to the isolation transformer (120), which is configured to receive the secondary voltage (Vs) and provide a signal proportional to the primary voltage (Vp) based on the secondary voltage (Vs).

Description

Technical Field

[0001] The embodiments described below relate to electronic devices including galvanic isolation points, and more particularly, to determining input voltages to the galvanic isolation points. Background Art

[0002] In industrial control products, there is a need to communicate in potentially hazardous and electrically noisy environments while utilizing limited computing and / or power resources. Due to the potentially hazardous and / or electrically noisy environments in which industrial control products are employed, many products include electrical isolation between input / output (I / O) channels, sensor connections, and / or processing functions. In non-hazardous facilities, since I / O channels may point to different systems, this isolation is provided to eliminate possible ground loops and noise sources. In hazardous area facilities, isolation may be necessary to meet approval standards.

[0003] A transformer may be used to electrically isolate an input voltage from an output voltage. The transformer may be part of a DC / DC converter such as a flyback converter. Figure 1 An exemplary flyback converter 10 is shown. Figure 1 As shown, the flyback converter 10 includes an input voltage source 11 and an isolation transformer 12. The isolation transformer 12 is coupled to the input voltage source 11 and is configured to receive an input voltage Vin provided by the input voltage source 11. The isolation transformer 12 is also coupled to a rectifier circuit 13. The rectifier circuit 13 includes a rectifier diode D1 and an output capacitor Cout. The switch 15 is coupled to the isolation transformer 12 and is configured to enable current to flow from the input voltage source 11 through the isolation transformer 12.

[0004] The isolation transformer 12 serves as an electrical isolation point. That is, the output voltage provided by the flyback converter 10 may not include noise, transients, high voltages, etc. that may be caused by the current flow between the input portion and the output portion that may occur without the electrical isolation point. The flyback converter 10 may be included in an electronic device (e.g., an electronic device) that needs to determine the input voltage Vin to ensure that the input voltage Vin is within specifications. For example, in a loop-powered device, power may be consumed on the secondary side or electrically isolated side of the electronic device of the device including (one or more) measuring transducers and associated signal processing circuit systems. Power must be provided by a loop coupled to the input side or primary side of the device, which may not be sufficient for the measuring transducer and associated signal processing circuit system.

[0005] The electronic device may also need to determine the input voltage Vin using circuitry on the secondary side or electrically isolated side of the electronic device. However, adding an additional electrical isolation point (e.g., an additional transformer) to transmit the measured value of the input voltage Vin requires additional board space. In addition, significant costs may be incurred when modifying an existing electronic design to incorporate an additional electrical isolation point, which may be avoided if the existing electrical isolation point can be utilized. Therefore, it is necessary to determine the input voltage to the electrical isolation point without requiring an additional electrical isolation point. Summary of the invention

[0006] An electronic device is provided, which is configured to determine an input voltage to an electrical isolation point of the electronic device. According to an embodiment, the electronic device includes an isolation transformer, which is configured to conduct a primary current provided by an input voltage source and provide a secondary voltage, which is proportional to a primary voltage induced by the primary current. The electronic device also includes a peak detection circuit coupled to the isolation transformer, which is configured to receive the secondary voltage and, based on the secondary voltage, provide a signal proportional to the primary voltage.

[0007] A method for determining an input voltage to an electrical isolation point is provided. According to an embodiment, the method includes: conducting a primary current provided by an input voltage source through an isolation transformer; providing a secondary voltage using the isolation transformer, the secondary voltage being proportional to a primary voltage induced by the primary current; receiving the secondary voltage using a peak detection circuit; and providing a signal proportional to the primary voltage using the peak detection circuit based on the secondary voltage.

[0008] All aspects

[0009] According to one aspect, an electronic device 100 configured to determine an input voltage to an electrical isolation point of the electronic device 100 includes an isolation transformer 120 configured to conduct a primary current Ip provided by an input voltage source 110 and provide a secondary voltage Vs proportional to a primary voltage Vp induced by the primary current Ip. The electronic device 100 also includes a peak detection circuit 130 coupled to the isolation transformer 120, the peak detection circuit 130 configured to receive the secondary voltage Vs and provide a signal proportional to the primary voltage Vp based on the secondary voltage Vs.

[0010] Preferably, the electronic device 100 further includes a rectifier circuit 140 coupled to the isolation transformer 120, the rectifier circuit 140 being configured to receive the secondary voltage Vs and provide the capacitor voltage to the load L when the secondary voltage Vs is at a negative value, and to provide the secondary voltage Vs to the load L when the secondary voltage Vs is at a positive value.

[0011] Preferably, the rectifying circuit 140 includes a rectifying diode D1 which is electrically connected in series with the isolation transformer 120 and is configured to provide the secondary voltage Vs to the load L by conducting the secondary current Is provided by the isolation transformer 120 when the secondary voltage Vs is positive. The rectifying circuit 140 also includes an output capacitor Cout which is electrically connected in parallel with the isolation transformer 120 and is configured to receive the secondary voltage Vs when the rectifying diode D1 conducts the secondary current Is.

[0012] Preferably, the rectifying diode D1 is also configured to block current flow when the secondary voltage Vs is at a negative value.

[0013] Preferably, the peak detection circuit 130 is further configured to maintain the first voltage value of the secondary voltage Vs when the secondary voltage Vs is at a second voltage value greater than the first voltage value of the secondary voltage Vs.

[0014] Preferably, the peak detection circuit 130 includes a peak detection diode D2 electrically connected in series with the peak holding capacitor C1 , and the peak detection circuit 130 is electrically connected in parallel with the isolation transformer 120 .

[0015] Preferably, the peak holding capacitor C1 is configured to maintain the first voltage value of the secondary voltage Vs when the secondary voltage Vs is at a second voltage value greater than the first voltage value of the secondary voltage Vs, and the peak detection diode D2 is configured to conduct current when the second voltage value of the secondary voltage Vs is less than the first voltage value.

[0016] Preferably, the secondary voltage Vs is proportional to the primary voltage Vp at a secondary-primary turns ratio Ns / Np of the isolation transformer 120 .

[0017] A method for determining an input voltage to an electrical isolation point includes: conducting a primary current provided by an input voltage source through an isolation transformer; using the isolation transformer to provide a secondary voltage, which is proportional to a primary voltage induced by the primary current; receiving the secondary voltage using a peak detection circuit; and based on the secondary voltage, using the peak detection circuit to provide a signal proportional to the primary voltage.

[0018] Preferably, the method further comprises receiving the secondary voltage using a rectifying circuit, and providing the capacitor voltage to the load using the rectifying circuit when the secondary voltage is negative, and providing the secondary voltage to the load using the rectifying circuit when the secondary voltage is positive.

[0019] Preferably, when the secondary voltage is positive, providing the secondary voltage to the load using a rectifier circuit includes: using a rectifier diode in the rectifier circuit electrically connected in series with the isolation transformer to provide the secondary voltage by conducting the secondary current provided by the isolation transformer; and when the rectifier diode is conducting the secondary current, using an output capacitor electrically connected in parallel with the isolation transformer to receive the secondary voltage.

[0020] Preferably, the method further comprises preventing current flow using a rectifying diode when the secondary voltage is at a negative value.

[0021] Preferably, the method further comprises maintaining the first voltage value of the secondary voltage using a peak detection circuit when the secondary voltage is at a second voltage value greater than the first voltage value of the secondary voltage.

[0022] Preferably, the method further comprises providing a peak detection diode and a peak holding capacitor, and connecting the peak detection diode in series with the peak holding capacitor to comprise a peak detection circuit.

[0023] Preferably, the method further comprises maintaining the first voltage value with a peak holding capacitor when the secondary voltage is at a second voltage value greater than the first voltage value, and configuring the peak detection diode to conduct current when the second voltage value is less than the first voltage value.

[0024] Preferably, the secondary voltage is proportional to the primary voltage at a secondary-to-primary turns ratio of the isolation transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Like reference numerals represent like elements throughout the drawings. It should be understood that the drawings are not necessarily to scale.

[0026] Figure 1 An exemplary flyback converter 10 is shown.

[0027] Figure 2 An electronic device 100 configured to determine an input voltage to an electrical isolation point is shown.

[0028] Figure 3 A graph 300 is shown illustrating various electrical values ​​and conditions in an electronic device configured to determine an input voltage to an electrical isolation point of the electronic device.

[0029] Figure 4 A method 400 for determining an input voltage to an electrical isolation point is shown. DETAILED DESCRIPTION

[0030] Figures 2 to 4And the following description depicts specific examples to teach those skilled in the art how to make and use the best mode of implementation of the electronic device and method that can determine the input to the electrical isolation point. For the purpose of teaching the principles of the invention, some conventional aspects have been simplified or omitted. Those skilled in the art will recognize variations of these examples that fall within the scope of this specification. Those skilled in the art will recognize that the features described below can be combined in various ways to form an electronic device and method that can determine the input to the electrical isolation point. Therefore, the embodiments described below are not limited to the specific examples described below, but are only limited by the claims and their equivalents.

[0031] Figure 2 An electronic device 100 including an electrical isolation point is shown. Figure 2 As shown, the electronic device 100 includes an input voltage source 110 coupled to an isolation transformer 120. The isolation transformer 120 is an electrical isolation point for the electronic device 100. A peak detection circuit 130 is coupled to the isolation transformer 120. A switch 115 is coupled to the isolation transformer 120 and is configured to selectively conduct current based on a switch control signal SW_Cntl. A rectifier circuit 140 coupled to the isolation transformer 120 is also shown. The topology of the electronic device 100 is a flyback converter, but the peak detection circuit 130 and the rectifier circuit 140 can be used in other topologies such as an isolated buck converter.

[0032] The input voltage source 110 provides an input voltage Vin. The input voltage source 110 can provide a constant voltage, such as a direct current (DC) voltage, to the isolation transformer 120. The input voltage source 110 can be on the non-isolated side of the electrical isolation point. Therefore, the input voltage Vin may include noise, transients, high voltages, etc. The input voltage source 110 can be any suitable source, such as a two-wire bus, an external power supply, a battery or power supply in the electronic device 100, etc. The input voltage source 110 has a first input voltage source terminal 110a and a second input voltage source terminal 110b.

[0033] The switch 115 is shown as including a metal oxide semiconductor field effect transistor (MOSFET), but any suitable switch may be used. As shown, the MOSFET includes a gate G terminal, a drain D terminal, and a source S terminal. The switch 115 is connected to the second input voltage source terminal 110b. The switch 115 is configured to receive a switch control signal SW_Cntl. When the switch 115 includes Figure 2 In the case of the MOSFET shown in FIG. 1 , the source S is electrically connected to the second input voltage source terminal 110 b , and the gate G receives a switch control signal.

[0034] The isolation transformer 120 includes a primary coil 122 and a secondary coil 124. The isolation transformer 120 can be any suitable configuration and is not necessarily limited to a transformer. For example, the isolation transformer 120 can include a coupled inductor. As shown, the primary coil 122 includes an inductor having a first primary terminal 122a and a second primary terminal 122b. The first primary terminal 122a is electrically connected to the first input voltage source terminal 110a of the input voltage source 110. The second primary terminal 122b is electrically connected to the second input voltage source terminal 110b and the switch 115.

[0035] As shown, the primary coil 122 is represented as having a primary voltage Vp, and the secondary coil 124 is represented as having a secondary voltage Vs. The primary coil 122 is shown as having a number of turns Np, and the secondary coil 124 is shown as having a number of turns Ns. Therefore, the primary voltage Vp can be proportional to the secondary voltage Vs at the secondary-primary turns ratio (Ns / Np) of the isolation transformer 120. However, any suitable relationship can be used.

[0036] The isolation transformer 120 can conduct the primary current Ip provided by the input voltage source 110. That is, the input voltage source 110 can provide the input voltage Vin to the isolation transformer 120, and the switch 115 can selectively close the circuit between the first input voltage source terminal 110a and the second input voltage source terminal 110b. Therefore, the primary voltage Vp is equal to the input voltage Vin, so that the isolation transformer 120 conducts the primary current Ip. Due to inductive coupling, the primary current Ip can induce a secondary voltage Vs on the secondary coil 124. The secondary voltage Vs can be provided to the peak detection circuit 130.

[0037] The peak detection circuit 130 is configured to receive the secondary voltage Vs. Figure 2 As shown, the peak detection circuit 130 includes a first voltage determination terminal 130a and a second voltage determination terminal 130b. The first voltage determination terminal 130a is electrically connected to the first secondary terminal, and the second voltage determination terminal 130b is electrically connected to the second secondary terminal. Therefore, the secondary voltage Vs is applied to the first voltage determination terminal 130a and the second voltage determination terminal 130b of the peak detection circuit 130.

[0038] The peak detection circuit 130 may also be configured to provide a signal Vin_sense via a signal terminal 130c. The signal may be proportional to the primary voltage Vp. Figure 2As shown, for example, since the peak detection circuit 130 maintains the secondary voltage Vs, the signal Vin_sense is proportional to the primary voltage Vp. For example, the signal Vin_sense provided by the peak detection circuit 130 may be a voltage value of the secondary voltage Vs. The voltage value of the secondary voltage Vs may be proportional to the primary voltage Vp and the secondary-primary turns ratio of the isolation transformer 120.

[0039] like Figure 2 As shown, the peak detection circuit 130 includes a peak detection diode D2 connected in series with the peak holding capacitor C1. The peak detection diode D2 is electrically connected to the peak holding capacitor C1 at the signal terminal 130c. The peak detection diode D2 is arranged to enable current to be conducted from the peak holding capacitor C1 to the first voltage determination terminal 130a. The peak detection diode D2 is also arranged to prevent current from being conducted from the first voltage determination terminal 130a to the peak holding capacitor C1.

[0040] Therefore, when the secondary voltage Vs is negative, the peak detection diode D2 can enable current to flow from the peak holding capacitor C1 to the first voltage determination terminal 130a when the first voltage determination terminal 130a is a negative terminal and the second voltage determination terminal 130b is a positive terminal. This can enable the peak holding capacitor C1 to be charged to the voltage value of the secondary voltage Vs.

[0041] When the secondary voltage Vs is positive, in the case where the first voltage determination terminal 130a is a positive terminal and the second voltage determination terminal 130b is a negative terminal, the peak detection diode D2 blocks the current from flowing from the first voltage determination terminal 130a to the peak holding capacitor C1. This enables the peak holding capacitor C1 to maintain the voltage value of the secondary voltage Vs. That is, the peak holding capacitor C1 is not discharged. Therefore, the signal Vin_sense is still provided.

[0042] As discussed above, the topology of the electronic device 100 may be a flyback converter, but the peak detection circuit 130 and / or the rectification circuit 140 may be used in other topologies such as an isolated buck converter. In an isolated buck converter, it may be necessary to subtract the output voltage of the "buck" winding from the signal provided by the peak detection circuit to obtain the input voltage. The peak detection circuit 130 may be used in any topology in which the input voltage has a magnitude discernible at the output side winding of the isolation transformer.

[0043] The rectifier circuit 140 is configured to provide an output voltage Vout which may be, for example, a substantially constant DC value. Figure 2 As shown, the rectifier circuit 140 can receive the secondary voltage Vs from the isolation transformer 120 and provide an output voltage Vout. Figure 3Explained in more detail, the secondary voltage Vs may have a negative voltage value or a positive voltage value. When the secondary voltage Vs has a positive voltage value, the rectifier circuit 140 may provide the secondary voltage Vs as the output voltage Vout. When the secondary voltage Vs has a negative voltage value, the rectifier circuit 140 may not receive the secondary voltage Vs, but despite this, the rectifier circuit 140 may still provide the output voltage Vout. The output voltage Vout is provided to the load L.

[0044] like Figure 2 As shown, the rectifier circuit 140 includes a rectifier diode D1 and an output capacitor Cout. The rectifier diode D1 is also electrically connected to the output capacitor Cout. The rectifier diode D1 is arranged to conduct current from the first voltage determination terminal 130a to the output capacitor Cout. The output capacitor Cout has a first output terminal Cout1 and a second output terminal Cout2. The first output terminal Cout1 is electrically connected to the rectifier diode D1. The second output terminal Cout2 is electrically connected to the second voltage determination terminal 130b. The voltage difference between the first output terminal Cout1 and the second output terminal Cout2 is shown as the output voltage Vout.

[0045] The rectifying diode D1 can prevent current from flowing from the first output terminal Cout1 to the first voltage determining terminal 130a. Therefore, if the secondary voltage Vs has a voltage value less than the voltage value at the first output terminal Cout1, the rectifying diode D1 can prevent current from flowing from the output capacitor Cout to the isolation transformer 120. The rectifying diode D1 can also enable current to flow from the first voltage determining terminal 130a to the first output terminal Cout1 to charge the output capacitor Cout, for example. That is, if the secondary voltage Vs has a voltage value greater than the voltage value at the first output terminal Cout1, the rectifying diode D1 can enable current to flow to the first output terminal Cout1.

[0046] Therefore, the output voltage Vout can be substantially constant at a voltage value approximately equal to the voltage value of the secondary voltage Vs that enables the rectifier diode D1 to enable current to flow to the first output terminal Cout1. Even if the peak detection circuit 130 provides a signal proportional to the input voltage Vin at the signal terminal 130c, the output voltage Vout remains substantially constant. That is, various electrical values ​​and conditions in the electronic device enable the peak detection circuit 130 to determine the input voltage Vin while being isolated from the input voltage source 110. The electrical values ​​and conditions in the electronic device will be referred to below. Figure 3 for a more detailed discussion.

[0047] Figure 3Graph 300 is shown showing various electrical values ​​and conditions in an electronic device configured to determine an input voltage to an electrical isolation point of the electronic device. Figure 3 As shown, the graph 300 includes a first time axis 310a to a fifth time axis 310e and a state / value axis 320. The first time axis 310a to the fifth time axis 310e are in seconds, but any suitable units may be used. The state / value axis 320 is in volts, amperes, or bit states, depending on which of the first time axis 310a to the fifth time axis 310e is referenced. Figure 3 As shown, the graph 300 includes a switch control graph 330a, a primary voltage Vp graph 330b, a secondary voltage Vs graph 330c, a primary current Ip graph 330d, and a secondary current Is graph 330e.

[0048] The switch control diagram 330a is shown as including an "on" state or an "off" state. The switch control diagram 330a may represent a state provided to the reference Figure 2 115 described above. It can be appreciated that the switch control diagram 330a alternates between the "on" state and the "off" state in a periodic manner. The frequency of the switch control diagram 330a can be, for example, 100kHz to 200kHz, but any suitable frequency or multiple suitable frequencies can be used. In addition, the control diagram 330a can be used Figure 2 Any suitable cycle or other manner of switch 115 or primary current Ip shown in FIG.

[0049] The primary voltage Vp graph 330b is shown to include a first voltage value 330ba and a second voltage value 330bb. The first voltage value 330ba is shown to be equal to the value which can be obtained by Figure 2 The input voltage source 110 shown in FIG. 1 provides an input voltage Vin. It can be appreciated that, for example, in the case where there are additional components between the input voltage source and the isolation transformer, for example, an alternative first voltage value may be employed.

[0050] The secondary voltage Vs graph 330c is shown to include a first voltage value 330ca and a second voltage value 330cb. The first voltage value 330ca is shown to be equal to -Vin(Ns / Np). That is, the first voltage value 330ca is proportional to the input voltage Vin at -Ns / Np, but any suitable relationship may be used, such as a turns ratio associated with a multiple winding transformer, a center tap transformer, a ratio associated with a coupled inductor, etc. The second voltage value 330cb is shown to be equal to the output voltage Vout. That is, using Figure 2 As an example, since the rectifying diode D1 enables current to flow to the output capacitor Cout, the second voltage value 330cb is the output voltage Vout.

[0051] The primary current Ip graph 330d is shown to include a first current value 330da and a second current value 330db. The first current value 330da is shown to have a positive and increasing value. The second current value 330db is shown to be zero. The first current value 330da may be positive due to, for example, the switch 115 being closed, thereby closing the circuit to the input voltage source 110. This enables the primary current Ip to flow through the isolation transformer 120. Because the switch 115 is open, thereby preventing current from flowing out of the input voltage source 110, the second current value 330db may be zero.

[0052] The secondary current Is graph 330e is shown to include a first current value 330ea and a second current value 330eb. The first current value 330ea is shown to be zero. The second current value 330eb is shown to have a positive and decreasing value. Since the rectifier diode D1 prevents current from flowing from the first output terminal Cout1 to the isolation transformer 120, the first current value 330ea can be zero. Since the rectifier diode D1 enables current to flow from the isolation transformer 120 to the first output terminal Cout1, the second current value 330eb can be positive.

[0053] Turning to the peak detection circuit 130, when the secondary voltage Vs is at a voltage value less than the voltage value at the signal terminal 130c, the peak detection diode D2 enables current to flow out of the peak holding capacitor C1. That is, when the peak detection diode D2 is forward biased, current can flow to the first voltage determination terminal 130a. Therefore, the voltage value at the signal terminal 130c can be equal to the voltage value of the secondary voltage Vs.

[0054] When the secondary voltage Vs has a value greater than the voltage value at the signal terminal 130c, the peak detection diode D2 can block the current from flowing from the first voltage determination terminal 130a to the signal terminal 130c. That is, when the peak detection diode D2 is reverse biased, the current can be blocked from flowing, thereby blocking the peak holding capacitor C1 from discharging. Therefore, the peak holding capacitor C1 can maintain a voltage value, for example, a voltage value of the secondary voltage Vs that can charge the peak holding capacitor C1 when the peak detection diode D2 is forward biased.

[0055] Thus, when considering the secondary voltage Vs diagram 330c, it can be appreciated that when the peak detection diode D2 is forward biased, the peak holding capacitor C1 can have a voltage value equal to the voltage value of -Vin(Ns / Np). That is, when the switch control diagram 330a is "on" with the primary voltage Vp equal to Vin, the voltage value of the signal terminal 130c can be equal to Vs, which is equal to -Vin(Ns / Np). It can also be appreciated that when the peak detection diode D2 is reverse biased, the peak holding capacitor C1 will maintain a voltage value of -Vin(Ns / Np). In addition, there may be a load resistor across the peak holding capacitor C1 (similar to the load L across the output capacitor Cout) that provides a path for a relatively slow rate of discharge of the peak holding capacitor C1, so that the peak holding capacitor C1 may not indefinitely maintain the maximum negative voltage to which it has been exposed.

[0056] As can also be appreciated, as the input voltage Vin decreases over time, the magnitude of the voltage value of the voltage of the peak holding capacitor C1 can be reduced accordingly. As an example, during the first "on" state, the peak holding capacitor C1 can be charged to a first voltage value of -Vin1 (Ns / Np). If the voltage value of the input voltage Vin decreases over time, the secondary voltage Vs may be at a second voltage value of -Vin2 (Ns / Np), which is more positive or less negative than the first voltage value of -Vin1 (Ns / Np). Therefore, the voltage value of the signal terminal 130c can be at a second voltage value of -Vin2 (Ns / Np).

[0057] Thus, the signal provided by the signal terminal 130c can be proportional to the input voltage Vin over time. This enables, for example, the electronic device 100 to determine the input voltage Vin over time even if the signal terminal 130c is isolated from the input voltage source 110. In addition, a single electrical point is used to provide the signal rather than separate electrical points. This reduces board space requirements relative to the prior art. As can be appreciated, an electronic device such as the electronic device 100 described above can perform a method for providing a signal. Figure 4 Exemplary methods are described.

[0058] Figure 4 A method 400 for determining an input voltage to an electrical isolation point is shown. Figure 4As shown, in step 410, method 400 conducts a primary current provided by an input voltage source through an isolation transformer. In step 420, method 400 provides a secondary voltage using the isolation transformer. The secondary voltage may be proportional to the primary voltage induced by the primary current. In step 430, method 400 receives the secondary voltage using a peak detection circuit. In step 440, method 400 provides a signal proportional to the primary voltage based on the secondary voltage using the peak detection circuit.

[0059] The method 400 may also include receiving the secondary voltage using a rectifier circuit and providing the output voltage or the secondary voltage to the load using the rectifier circuit. The output voltage may be provided when the secondary voltage is negative, and the secondary voltage may be provided when the secondary voltage is positive. Providing the secondary voltage to the load using the rectifier circuit when the secondary voltage is positive may include: providing the secondary voltage by conducting the secondary current provided by the isolation transformer using a rectifier diode in the rectifier circuit electrically connected in series with the isolation transformer; and receiving the secondary voltage using an output capacitor electrically connected in parallel with the isolation transformer when the rectifier diode is conducting the secondary current.

[0060] The method 400 may also include preventing current flow using a rectifying diode when the secondary voltage is at a negative value. Figure 3 As described, the rectifying diode D1 can prevent current from flowing from the first output terminal Cout1 to the first voltage determining terminal 130a. Therefore, if the secondary voltage Vs has a voltage value less than the voltage value at the first output terminal Cout1, the rectifying diode D1 can prevent current from flowing from the output capacitor Cout to the isolation transformer 120.

[0061] The method 400 may also include maintaining the first voltage value of the secondary voltage using a peak detection circuit when the secondary voltage is at a second voltage value greater than the first voltage value of the secondary voltage. Figure 2 As described, when the secondary voltage Vs is negative, the peak detection diode D2 enables current to flow from the peak holding capacitor C1 to the first voltage determination terminal 130a when the first voltage determination terminal 130a is a negative terminal and the second voltage determination terminal 130b is a positive terminal. This enables the peak holding capacitor C1 to be charged to the voltage value of the secondary voltage Vs.

[0062] Therefore, method 400 may further include providing a peak detection diode and a peak holding capacitor, and connecting the peak detection diode in series with the peak holding capacitor to include a peak detection circuit. Method 400 may further include maintaining the first voltage value using the peak holding capacitor when the secondary voltage is at a second voltage value greater than the first voltage value, and configuring the peak detection diode to conduct current when the second voltage value is less than the first voltage value. The secondary voltage may be proportional to the primary voltage and the secondary-primary turns ratio of the isolation transformer.

[0063] The electronic device 100 and method 400 that can determine the input voltage Vin to the electrical isolation point are described above. As discussed above, when the secondary voltage Vs is proportional to the input voltage Vin, the peak detection circuit 130 can charge to the secondary voltage Vs and maintain the secondary voltage Vs. Therefore, the peak detection circuit 130 can provide a signal proportional to the input voltage Vin.

[0064] The peak detection circuit 130 is isolated because it is coupled to the secondary coil 124 and the input voltage source 110 is coupled to the primary coil 122. The peak detection circuit 130 is also isolated without using additional electrical isolation points other than those used to provide the output voltage Vout.

[0065] This technical solution solves the technical problem of measuring the input voltage Vin to the electrical isolation point while using a single electrical isolation point, which can reduce the board space required to determine the input voltage Vin. This technical solution also solves the technical problem of measuring the input voltage Vin without coupling noise, transients, high voltages, etc. to the secondary coil 124 that provides the output voltage Vout. Therefore, the output voltage Vout can be provided without noise, transients, high voltages, etc. that may exist in the input voltage Vin.

[0066] The detailed description of the above embodiments is not an exhaustive description of all embodiments within the scope of the present specification that the inventors contemplate. In fact, those skilled in the art will recognize that certain elements of the above embodiments may be combined or eliminated in various ways to create other embodiments, and such other embodiments fall within the scope and teachings of the present specification. It will be apparent to those of ordinary skill in the art that the above embodiments may be combined in whole or in part to create other embodiments within the scope and teachings of the present specification.

[0067] Therefore, although specific embodiments are described herein for illustrative purposes, various equivalent modifications within the scope of this specification are possible as will be appreciated by those skilled in the art. The teachings provided herein can be applied to other electronic devices and methods for determining the input voltage to the electrical isolation point, not just the embodiments described above and shown in the accompanying drawings. Therefore, the scope of the above embodiments should be determined by the appended claims.

Claims

1. An electronic device (100) configured to determine an input voltage to an electrical isolation point of the electronic device (100), the electronic device (100) comprising: An isolation transformer (120), the isolation transformer (120) being configured to: conducting a primary current (Ip) provided by an input voltage source (110); and providing a secondary voltage (Vs) proportional to a primary voltage (Vp) induced by the primary current (Ip); as well as A peak detection circuit (130) coupled to the isolation transformer (120) is configured to receive the secondary voltage (Vs) at a first secondary end of the secondary winding connected to a first terminal of a load (L) and at a second secondary end of the secondary winding connected to a second terminal of the load (L), and provide a signal proportional to the primary voltage (Vp) based on the secondary voltage (Vs) since the peak detection circuit (130) maintains the secondary voltage (Vs).

2. The electronic device (100) according to claim 1, further comprising a rectifier circuit (140) coupled to the isolation transformer (120), the rectifier circuit (140) being configured to receive the secondary voltage (Vs) and: supplying the capacitor voltage to the load (L) when the secondary voltage (Vs) is at a negative value; and When the secondary voltage (Vs) is a positive value, the secondary voltage (Vs) is provided to the load (L).

3. The electronic device (100) according to claim 2, wherein: The rectifier circuit (140) comprises: a rectifier diode (D1) electrically connected in series with the isolation transformer (120) and configured to provide the secondary voltage (Vs) to the load (L) by conducting a secondary current (Is) provided by the isolation transformer (120) when the secondary voltage (Vs) is positive; and An output capacitor (Cout) is electrically connected in parallel with the isolation transformer (120) and is configured to receive the secondary voltage (Vs) when the rectifier diode (D1) conducts the secondary current (Is).

4. The electronic device (100) according to claim 3, wherein: The rectifying diode (D1) is also configured to prevent current flow when the secondary voltage (Vs) is at a negative value.

5. The electronic device (100) according to any one of the preceding claims 1 to 4, wherein: The peak detection circuit (130) is also configured to maintain the first voltage value of the secondary voltage (Vs) when the secondary voltage (Vs) is at a second voltage value greater than the first voltage value of the secondary voltage (Vs).

6. The electronic device (100) according to claim 5, wherein: The peak detection circuit (130) includes a peak detection diode (D2) electrically connected in series with a peak holding capacitor (C1), and the peak detection circuit (130) is electrically connected in parallel with the isolation transformer (120).

7. The electronic device (100) according to claim 6, wherein: The peak holding capacitor (C1) is configured to hold the first voltage value of the secondary voltage (Vs) when the secondary voltage (Vs) is at the second voltage value greater than the first voltage value; and The peak detection diode (D2) is configured to conduct current when the second voltage value of the secondary voltage (Vs) is less than the first voltage value.

8. The electronic device (100) according to any one of the preceding claims 1 to 4, wherein: The secondary voltage (Vs) is proportional to the primary voltage (Vp) at a secondary-primary turns ratio (Ns / Np) of the isolation transformer (120).

9. A method for determining an input voltage to an electrical isolation point, the method comprising: conducting a primary current provided by an input voltage source through an isolation transformer; providing a secondary voltage using the isolation transformer, the secondary voltage being proportional to the primary voltage induced by the primary current; receiving the secondary voltage at a first secondary end of a secondary winding connected to a first terminal of a load and at a second secondary end of the secondary winding connected to a second terminal of the load using a peak detection circuit; as well as Since the peak detection circuit holds the secondary voltage, a signal proportional to the primary voltage is provided by the peak detection circuit based on the secondary voltage.

10. The method of claim 9, further comprising receiving the secondary voltage using a rectifier circuit, and: When the secondary voltage is negative, supplying the capacitor voltage to the load by using the rectifier circuit; and When the secondary voltage is positive, the secondary voltage is provided to the load by using the rectifier circuit.

11. The method according to claim 10, wherein: When the secondary voltage is positive, using the rectifier circuit to provide the secondary voltage to the load comprises: Providing the secondary voltage by conducting a secondary current provided by the isolation transformer using a rectifier diode in the rectifier circuit that is electrically connected in series with the isolation transformer; and The secondary voltage is received by an output capacitor electrically connected in parallel with the isolation transformer when the rectifying diode is conducting the secondary current.

12. The method of claim 11, further comprising preventing current flow using the rectifying diode when the secondary voltage is at a negative value.

13. The method of any one of the preceding claims 9 to 12, further comprising maintaining the first voltage value of the secondary voltage using the peak detection circuit when the secondary voltage is at a second voltage value greater than the first voltage value of the secondary voltage.

14. The method according to any one of the preceding claims 9 to 12, further comprising providing a peak detection diode and a peak holding capacitor, and connecting the peak detection diode in series with the peak holding capacitor to form the peak detection circuit.

15. The method of claim 13, further comprising providing a peak detection diode and a peak holding capacitor, and connecting the peak detection diode in series with the peak holding capacitor to form the peak detection circuit.

16. The method of claim 15, further comprising maintaining the first voltage value using the peak holding capacitor when the secondary voltage is at the second voltage value greater than the first voltage value, and configuring the peak detection diode to conduct current when the second voltage value is less than the first voltage value.

17. The method according to claim 16, wherein: The secondary voltage is proportional to the primary voltage at a secondary-to-primary turns ratio of the isolation transformer.

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