A current control circuit

Abstract

The application discloses a current control circuit, comprising a first sampling resistor, a first amplifier, a comparator group, a control circuit, a selector, a threshold adjusting module, a first error amplifier, a current distribution module and a charging loop. The current control circuit provided by the application can determine three different current thresholds by the output of the threshold adjusting module and the first sampling resistor, that is, three current thresholds, and then realize the control of the current by combining the control circuit. The application can maximize the power demand of the system under the condition of ensuring the charging speed, and achieve the purpose of maximizing the power supply capacity of the adapter.

Description

Technical Field

[0001] This invention relates to the field of power management technology, and in particular to a current control circuit. Background Technology

[0002] Common electronic devices typically employ a power management scheme where the adapter simultaneously charges the battery and supplies power to the system (the electronic device). During charging and power supply, the adapter current, charging current, and system operating current must be monitored and controlled to prevent excessively large or small deviations from the normal range, which could lead to malfunctions and equipment damage.

[0003] To ensure the charging adapter operates within its normal range and with a certain margin, the current rating of the charging adapter is often defined to be less than the charger's maximum output capacity. When the system operating current changes, the charging adapter's current also changes within the current-limiting range.

[0004] Existing technologies typically use a single current threshold to limit the charger current. For example... Figure 1 As shown, when the adapter current Iin is less than Ith (single current threshold), Iin increases with the increase of the system operating current Isys; when Iin increases to the current limiting threshold Ith, the current limiting logic is triggered, and the current no longer increases. The single-threshold current structure is simple and easy to implement, but it cannot maximize the power supply capacity of the adapter while meeting the high-performance power requirements of electronic devices. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a current control circuit.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A current control circuit includes: a first sampling resistor, a first amplifier, a comparator group, a control circuit, a selector, a threshold adjustment module, a first error amplifier, a current distribution module, and a charging loop;

[0008] The input to one end of the first sampling resistor is the input voltage, and the other end of the first sampling resistor is connected to the second input terminal of the first amplifier and the input terminal of the current distribution module, respectively. The input to the first input terminal of the first amplifier is the input voltage, and the output terminal of the first amplifier is connected to the inverting input terminal of the comparator group and the inverting input terminal of the first error amplifier, respectively. The non-inverting input terminal of the comparator group is connected to the output terminal of the threshold adjustment module, and the output terminal of the comparator group is connected to the input terminal of the control circuit, respectively. The output terminal of the control circuit is connected to the input terminal of the threshold adjustment module and the input terminal of the selector, respectively. The input terminal of the threshold adjustment module is also connected to the output voltage of the preceding bandgap reference. The output terminal of the selector is connected to the non-inverting input terminal of the first error amplifier. The output terminal of the first error amplifier is connected to the input terminal of the current distribution module, and the current distribution module outputs the system operating current. The input of the charging loop is the charging current, and the input terminal of the charging loop is also connected to the output terminal of the threshold adjustment module, and the output of the charging loop is connected to the input terminal of the current distribution module.

[0009] Optionally, the comparator group includes: a first comparator, a second comparator, and a third comparator; the inverting input terminals of the first comparator, the second comparator, and the third comparator are all connected to the output terminal of the first amplifier; the non-inverting input terminals of the first comparator, the second comparator, and the third comparator are all connected to the output terminal of the threshold adjustment module; the output terminals of the first comparator, the second comparator, and the third comparator are all connected to the input terminal of the control circuit.

[0010] Optionally, the charging loop includes a second sampling resistor, a second amplifier, a second error amplifier, and a charging circuit; one end of the second sampling resistor is connected to the battery voltage, and the other end of the second sampling resistor is connected to the second input terminal of the second amplifier and the input terminal of the charging circuit; the first input terminal of the second amplifier is the battery voltage, and the output terminal of the second amplifier is connected to the inverting input terminal of the second error amplifier; the non-inverting input terminal of the second error amplifier is connected to the output terminal of the threshold adjustment module, and the output terminal of the second error amplifier is connected to the input terminal of the charging circuit; the output terminal of the charging circuit is connected to the input terminal of the current distribution module.

[0011] Optionally, the output terminal of the threshold adjustment module outputs a first threshold voltage, a second threshold voltage, a third threshold voltage and a fourth threshold voltage; the first threshold voltage is input to the non-inverting input terminal of the first comparator, the second threshold voltage is input to the non-inverting input terminal of the second comparator, the third threshold voltage is input to the non-inverting input terminal of the third comparator, and the fourth threshold voltage is input to the non-inverting input terminal of the second error amplifier.

[0012] Optionally, a timer is provided in the control circuit.

[0013] Optionally, the current control circuit is provided with three current thresholds, which are respectively a first current threshold Ith1, a second current threshold Ith2 and a third current threshold Ith3; Vref1<Vref2<Vref3, and Ith1<Ith2<Ith3; where Vref1 is the first threshold voltage, Vref2 is the second threshold voltage, Vref3 is the third threshold voltage, and R1 is the first sampling resistor.

[0014] Optionally, when the adapter current is between Ith2 and Ith3 within a set time period, the output terminal of the control circuit outputs a power supply reduction signal.

[0015] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0016] With the current control circuit provided by the present invention, three current thresholds of different levels, that is, three current limits, can be determined through the output of the threshold adjustment module and the first sampling resistor, and then current control is realized in combination with the control circuit. The present invention can meet the power consumption demand of the system to the greatest extent while ensuring the charging speed, so as to achieve the purpose of maximizing the utilization of the power supply capacity of the adapter. Brief Description of the Drawings

[0017] To illustrate the technical solutions in the embodiments of the present invention or the prior art more clearly, the accompanying drawings required for the embodiments will be introduced briefly below. Obviously, the drawings described below show only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without any creative effort.

[0018] Figure 1 is a current relationship diagram of a single-threshold solution;

[0019] Figure 2 is a schematic diagram of the current control circuit provided by the present invention;

[0020] Figure 3 is a timing diagram of the current control circuit. Detailed Description of the Embodiments

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] The current demand of a system is a quantity with relatively large variation. When operating in a low power consumption mode, the system operating current may remain at a relatively low level for a long time; when operating in a high performance mode, the system operating current will stay at a relatively high level for a long time. The conventional single current threshold power supply scheme uses one current threshold to control the current. If this current threshold is designed to be too small, it may not be able to meet the power consumption demand of the system operating in the high performance mode at all; if the current threshold is set to be too large, it will cause difficulties in circuit design and waste of cost.

[0023] A certain margin is usually reserved in the design of the output current rating of a charging adapter. Exceeding the current rating to a certain extent in a short period will not cause damage to the adapter, nor affect the service life of the adapter, and the single-threshold current control scheme fails to consider and utilize this current margin.

[0024] To optimize power supply and maximize the current output capability of the charging adapter, the present invention adopts three current thresholds, which are denoted as Ith1, Ith2 and Ith3 respectively in the embodiments of the present invention, and satisfy Ith1<Ith2<Ith3, and realizes current control in combination with a timer in a controller circuit. The values of Ith1 and Ith2 mark the minimum value and the maximum value of an average range of the sum of the system operating current and the charging current. Ith3 corresponds to the current output margin reserved when the adapter is designed, and marks the limit of the current output capability of the adapter. When the system power consumption current increases, the adapter can be allowed to output current with Ith3 as the upper current limit, so as to meet the system demand to the greatest extent and improve the system performance.

[0025] In order to make the above objects, features and advantages of the present invention more clearly understandable, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] As shown in Figure 2 the figure, the current control circuit provided by the present invention includes: a first sampling resistor R1, a first amplifier A1, a comparator group, a control circuit (including a timer), a selector MUX, a threshold adjustment module, a first error amplifier EA1, a current distribution module, and a charging loop.

[0027] The input to one end of the first sampling resistor R1 is the input voltage Vin, and the other end of the first sampling resistor R1 is connected to the second input terminal of the first amplifier A1 and the input terminal of the current distribution module. The input to the first input terminal of the first amplifier A1 is the input voltage Vin, and the output terminal of the first amplifier A1 is connected to the inverting input terminal of the comparator group and the inverting input terminal of the first error amplifier EA1. The non-inverting input terminal of the comparator group is connected to the output terminal of the threshold adjustment module, and the output terminal of the comparator group is connected to the input terminal of the control circuit. The output terminal of the control circuit is connected to the input terminal of the threshold adjustment module and the input terminal of the selector MUX. The input terminal of the threshold adjustment module is also connected to the output voltage Vbg of the front-stage bandgap reference. The output terminal of the selector MUX is connected to the non-inverting input terminal of the first error amplifier EA1. The output terminal of the first error amplifier EA1 is connected to the input terminal of the current distribution module, and the current distribution module outputs the system operating current Isys. The input of the charging loop is the charging current Ibat, and the input terminal of the charging loop is also connected to the output terminal of the threshold adjustment module. The output of the charging loop is connected to the input terminal of the current distribution module.

[0028] The comparator group includes: a first comparator CMP1, a second comparator CMP2, and a third comparator CMP3; the inverting input terminals of the first comparator CMP1, the second comparator CMP2, and the third comparator CMP3 are all connected to the output terminal of the first amplifier A1; the non-inverting input terminals of the first comparator CMP1, the second comparator CMP2, and the third comparator CMP3 are all connected to the output terminal of the threshold adjustment module; the output terminals of the first comparator CMP1, the second comparator CMP2, and the third comparator CMP3 are all connected to the input terminal of the control circuit.

[0029] The charging loop includes a second sampling resistor R2, a second amplifier A2, a second differential amplifier EA2, and a charging circuit. One end of the second sampling resistor R2 receives the battery voltage Vbat as input, and the other end is connected to the second input terminal of the second amplifier A2 and the input terminal of the charging circuit. The first input terminal of the second amplifier A2 receives the battery voltage Vbat, and its output terminal is connected to the inverting input terminal of the second differential amplifier EA2. The non-inverting input terminal of the second differential amplifier EA2 is connected to the output terminal of the threshold adjustment module, and its output terminal is connected to the input terminal of the charging circuit. The output terminal of the charging circuit is connected to the input terminal of the current distribution module.

[0030] The threshold adjustment module outputs a first threshold voltage Vref1, a second threshold voltage Vref2, a third threshold voltage Vref3, and a fourth threshold voltage Vref4. The first threshold voltage Vref1 is input to the positive input of the first comparator CMP1, the second threshold voltage Vref2 is input to the positive input of the second comparator CMP2, the third threshold voltage Vref3 is input to the positive input of the third comparator CMP3, and the fourth threshold voltage Vref4 is input to the positive input of the second differential amplifier EA2.

[0031] The working principle of the above current control circuit is as follows:

[0032] The adapter current Iin flows through the first sampling resistor R1, converting the current information into voltage information. After being amplified by the first amplifier A1, it is compared with Vref1, Vref2, and Vref3 by three comparators CMP1, CMP2, and CMP3, respectively. The comparison result is then input to the control circuit. The threshold adjustment module receives the output voltage Vbg from the preceding bandgap reference and generates four different threshold voltages Vref1, Vref2, Vref3, and Vref4. The control circuit selects the corresponding threshold voltage based on the output results of the three comparators CMP1, CMP2, and CMP3 using a 3-to-1 selector MUX. The selector MUX outputs the selected threshold voltage to the positive terminal of the first error amplifier EA1. A loop formed by the first error amplifier EA1, the current distribution module, the first sampling resistor R1, and the first amplifier A1 stabilizes the system operating current Isys. Similarly, a charging loop formed by the second error amplifier EA2, the charging circuit, the second sampling resistor R2, and the second amplifier A2 stabilizes the charging current Ibat. C1 is the output capacitor, which provides voltage regulation. SOC represents the core system in electronic devices.

[0033] The correspondence between Vref1, Vref2, Vref3 and Ith1, Ith2, Ith3 is as follows:

[0034]

[0035] The above equation always satisfies Vref1 <Vref2<Vref3,Ith1<Ith2<Ith3。

[0036] The charging current Ibat flows through R2, is amplified by A2, and then input into EA2 for comparison with Vref4. Changing the value of Vref4 alters the magnitude of the charging current Ibat. At all times, the adapter current Iin, the charging current Ibat, and the system operating current satisfy: Iin = Ibat + Isys (Iin > Ibat; Iin > Isys).

[0037] CMP1, CMP2, and CMP3 output corresponding logic signals by detecting the adapter current Iin. The control circuit receives and processes the corresponding information, and outputs a control signal to control the selector MUX to output a specific threshold to EA1, so as to control the subsequent circuit to realize the limitation and adjustment of the adapter current Iin. Meanwhile, if the demand of the system operating current Isys is too large, causing the value of the adapter current Iin to stay between Ith2 and Ith3 for a long time, the control circuit outputs a power down signal PD (Power Down) to indicate abnormal operation.

[0038] The truth table of the corresponding relationship among the digital logic output signals of CMP1, CMP2 and CMP3, the magnitude of the adapter current Iin and the selection of the current threshold Ith is shown in Table 1.

[0039] Table 1 Truth table of the corresponding relationship among comparator output signals, adapter current and current threshold

[0040]

[0041] When the adapter current Iin < Ith1, at this time Iin increases as Isys increases, such as Figure 3 the area A in. When Ith1 < Iin < Ith2, the timer Timer1 (the timing value is also denoted as Timer1) built in the control circuit starts to work. If Iin drops below Ith1 within the time of Timer1, such as Figure 3 the area B in, T1 < Timer1, the control circuit determines that the system operating current only has a short-time spike for some reason that causes Iin to exceed the threshold briefly. The current threshold at this time is still Ith2. When Ith1 < Iin < Ith2 and Iin does not drop below Ith1 within the time of Timer1, the control circuit determines that the current demand of the system has increased beyond the current limit constituted by Ith1 and Ith2. At this time, the current limit needs to be raised to a higher Ith3 to better meet the power consumption demand of the system and ensure the high-performance operation of the system, such as Figure 3 the areas D and E in, T2 > Timer1. When Ith2 < Iin < Ith3, Timer2 (the timing value is also denoted as Timer2) starts to work. If Iin drops below Ith2 within the time of Timer2, the control logic resets the current limit to Ith2. When Ith2 < Iin < Ith3, if Iin does not drop below Ith2 within the time of Timer2, the control circuit determines that the system has been operating at high power for a long time. In order to prevent the system from overheating and avoid equipment failure caused by long-term overload of the adapter, the control logic will output a PD signal as a prompt, and simultaneously set the current limit to Ith1, such as Figure 3region F. At this time, Timer3 (the timer value is also denoted as Timer3) starts to operate. When T4 is greater than Timer3, the PD signal is cleared. After the PD signal is cleared, the control logic of Iin returns to the original definition.

[0042] To optimize power supply and maximize the current output capability of the charging adapter, the present invention adopts three current thresholds Ith1, Ith2, and Ith3 (satisfying Ith1<Ith2<Ith3) to realize current control in combination with a timer. The values of Ith1 and Ith2 mark an average range of the sum of the system power consumption current and the battery charging current. Ith3 corresponds to the sum of the reserved current output margin and the average range of the charging adapter during design, marking the limit of the current output capability of the adapter. When the system power consumption current increases, the adapter is allowed to output current with Ith3 as the upper current limit, so as to maximally meet the system requirements and improve the system performance.

[0043] The present invention realizes current control through three current thresholds and a timer, which can not only reasonably exert the maximum current output capability of the adapter, but also prevent the system from operating at high power for too long, causing overheating of the system and long-term overload of the adapter.

[0044] Specific examples are applied in this text to illustrate the principles and implementations of the present invention. The description of the above embodiments is only used to help understand the method and core idea of the present invention. Meanwhile, for those of ordinary skill in the art, based on the idea of the present invention, there will be modifications in the specific implementations and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A current-controlled circuit, characterized in that, include: The circuit includes a first sampling resistor, a first amplifier, a comparator group, a control circuit, a selector, a threshold adjustment module, a first error amplifier, a current distribution module, and a charging loop. The control circuit is equipped with a timer; The input to one end of the first sampling resistor is the input voltage, and the other end of the first sampling resistor is connected to the second input terminal of the first amplifier and the input terminal of the current distribution module, respectively. The input to the first input terminal of the first amplifier is the input voltage, and the output terminal of the first amplifier is connected to the inverting input terminal of the comparator group and the inverting input terminal of the first error amplifier, respectively. The non-inverting input terminal of the comparator group is connected to the output terminal of the threshold adjustment module, and the output terminal of the comparator group is connected to the input terminal of the control circuit, respectively. The output terminal of the control circuit is connected to the input terminal of the threshold adjustment module and the input terminal of the selector, respectively. The input terminal of the threshold adjustment module is also connected to the output voltage of the preceding bandgap reference. The output terminal of the selector is connected to the non-inverting input terminal of the first error amplifier. The output terminal of the first error amplifier is connected to the input terminal of the current distribution module, and the current distribution module outputs the system operating current. The input of the charging loop is the charging current, and the input terminal of the charging loop is also connected to the output terminal of the threshold adjustment module, and the output of the charging loop is connected to the input terminal of the current distribution module. The current control circuit is provided with three current thresholds, which are respectively a first current threshold Ith1, a first current threshold Ith2 and a first current threshold Ith3; , , ; Vref1<Vref2<Vref3, and Ith1<Ith2<Ith3; where Vref1 is a first threshold voltage, Vref2 is a second threshold voltage, Vref3 is a third threshold voltage, and R1 is a first sampling resistor; When the adapter current is between Ith2 and Ith3 within a set time period, the output terminal of the control circuit outputs a power reduction signal.

2. The current control circuit according to claim 1, characterized in that, The comparator group includes a first comparator, a second comparator, and a third comparator; the inverting input terminals of the first comparator, the second comparator, and the third comparator are all connected to the output terminal of the first amplifier; the non-inverting input terminals of the first comparator, the second comparator, and the third comparator are all connected to the output terminal of the threshold adjustment module; the output terminals of the first comparator, the second comparator, and the third comparator are all connected to the input terminal of the control circuit.

3. The current control circuit according to claim 2, characterized in that, The charging loop includes a second sampling resistor, a second amplifier, a second error amplifier, and a charging circuit. One end of the second sampling resistor receives the battery voltage as input, and the other end is connected to both the second input terminal of the second amplifier and the input terminal of the charging circuit. The first input terminal of the second amplifier receives the battery voltage, and its output terminal is connected to the inverting input terminal of the second error amplifier. The non-inverting input terminal of the second error amplifier is connected to the output terminal of the threshold adjustment module, and its output terminal is connected to the input terminal of the charging circuit. The output terminal of the charging circuit is connected to the input terminal of the current distribution module.

4. The current control circuit according to claim 3, characterized in that, The threshold adjustment module outputs a first threshold voltage, a second threshold voltage, a third threshold voltage, and a fourth threshold voltage. The first threshold voltage is input to the positive input of the first comparator, the second threshold voltage is input to the positive input of the second comparator, the third threshold voltage is input to the positive input of the third comparator, and the fourth threshold voltage is input to the positive input of the second error amplifier.

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