A multi-parallel current sharing circuit for a linear regulator

Abstract

This invention relates to a multi-parallel current sharing circuit and method for linear voltage regulators. The multi-parallel current sharing circuit includes a first resistor module and a second resistor module. Based on the connection structure of the first and second resistor modules, the current of either the first or second resistor module is correlated with the average value of all modules. Further, the current of either the first or second resistor module is used as the feedback current for current sharing adjustment of each linear voltage regulator. Based on this, parallel current sharing of two or more linear voltage regulators is achieved without generating excessive additional power loss.

Description

Technical Field

[0001] This invention relates to the field of voltage regulator technology, and in particular to a multi-channel parallel current sharing circuit for a linear voltage regulator. Background Technology

[0002] Currently, many high-power systems, with their increasing functionality and rapid growth in power consumption, are placing increasingly higher demands on the current capability of linear voltage regulators (LDOs). Due to limitations in power density and heat dissipation, it is becoming increasingly difficult to power many systems with a single LDO; therefore, using multiple LDOs in parallel has become a trend.

[0003] Figure 1 This is a circuit diagram of an existing directly parallel linear regulator. For example... Figure 1 As shown, using multiple LDOs in parallel involves connecting their input terminals and output terminals together. However, due to inherent manufacturing variations in each LDO, their output voltage settings are not entirely equal. Therefore, in practical applications, the LDO with the higher output voltage setting always prioritizes output current until full load, reaching a current-limiting state, before the LDO with the next higher output voltage setting begins operation. This results in some LDOs always being in a current-limiting state, affecting the main loop operation of the system and leading to poor load response and reduced interference immunity. It also causes uneven heat dissipation, impacts the lifespan of LDOs at full load, and affects system reliability.

[0004] Therefore, current sharing processing is required for the LDO output. Traditional processing methods mainly include two approaches: such as... Figure 2 As shown, one approach involves directly connecting a current-sharing resistor in series with both the independent output and the total output (VOUT) of each LDO. When the output branch current of a particular LDO is too high, the voltage drop across the corresponding current-sharing resistor will also increase. By detecting this voltage rise, the LDO's feedback control reduces the output current, thus achieving current sharing. However, this method results in significant efficiency loss due to the current-sharing resistor, especially noticeable under high output current conditions. Furthermore, due to the correlation between current balancing effects, LDO matching, and the value of the current-sharing resistor, the currents of each LDO can only be kept as equal as possible, making it impossible to prevent LDOs from entering current-limiting states sequentially.

[0005] Figure 3 This is a parallel circuit diagram of an existing linear voltage regulator using a two-way mutual control method. For example... Figure 3As shown, another method is used for two LDOs connected in parallel. The two LDOs transmit their current output values ​​to each other, instructing the other to adjust its own output current value accordingly. This method has good current sharing performance but is not suitable for three or more LDOs connected in parallel.

[0006] In summary, it is evident that the traditional LDO current sharing method still has the above-mentioned shortcomings. Summary of the Invention

[0007] The present invention aims to solve the problem of large power loss in existing parallel current sharing circuits of linear regulators when multiple circuits are connected in parallel.

[0008] Based on this, the present invention addresses the shortcomings of traditional LDO current sharing methods by providing a multi-parallel current sharing circuit for linear regulators. This circuit has a total input terminal and a total output terminal, and includes n parallel linear regulators. Each linear regulator includes an input pin, an output pin, a shunt pin, and a current sharing pin, where n is a natural number of 2 or greater. The shunt pins of each linear regulator are connected to the total input terminal via sensing resistors, and the resistance value of each sensing resistor is R. SNS The current-sharing pins of each linear regulator are connected in parallel and then connected to the total input terminal via a current-sharing resistor. The resistance of this current-sharing resistor is equal to the resistance R of the sensing resistor. SNS 1 / n.

[0009] According to a preferred embodiment of the present invention, each linear regulator can adjust its own output current according to the voltage value input on its shunt pin and current sharing pin, so that its individual output current is consistent with the average output current of all linear regulators.

[0010] According to a preferred embodiment of the present invention, the difference between the voltage value input to the shunt pin and the current sharing pin of each linear regulator and the voltage value of the total input terminal is linearly related to the individual output current and the average output current of all linear regulators.

[0011] According to a preferred embodiment of the present invention, the individual output circuit of each linear regulator satisfies the voltage value input to its shunt pin as I. OUT(x)= (V IN -V CSNS ) ×A / R SNS , among which, I OUT(x) V represents the current output by the x-th linear regulator alone. IN This represents the voltage at the total input terminal, V. CSNS The voltage across the shunt pin is represented by A, which is a positive constant, and the output current I of the linear regulator is represented by I. OUT(x) The ratio of the current to the input current of the shunt pin, R SNS The resistance value of the sensing resistor.

[0012] According to a preferred embodiment of the present invention, the average output current of all linear regulators satisfies I... OUT_total / n = (V IN -V CSUM ) ×A / R SNS , among which, I OUT_total / n represents the average output current of all linear regulators, V IN This represents the voltage at the total input terminal, V. CSUM This represents the voltage across the current sharing pin, where A is a positive constant, and I represents the output current of the linear regulator. OUT(x) The ratio of the current to the input current of the shunt pin, R SNS The resistance value of the sensing resistor.

[0013] The parallel current sharing circuit for linear regulators proposed in this invention achieves parallel current sharing of two or more linear regulators without generating excessive additional power loss. Attached Figure Description

[0014] Figure 1 This is a circuit diagram of an existing directly parallel linear regulator.

[0015] Figure 2 This is a parallel circuit diagram of an existing linear voltage regulator using current-sharing resistors.

[0016] Figure 3 This is a parallel circuit diagram of an existing linear regulator using a two-way mutual control method.

[0017] Figure 4 This is a circuit diagram of one embodiment of the linear regulator multi-channel parallel current sharing circuit of the present invention. Implementation

[0018] To better understand the purpose, technical solution, and technical effects of this invention, the invention will be further explained and described below in conjunction with the accompanying drawings and embodiments. It should also be stated that the embodiments described below are only for explaining this invention and are not intended to limit this invention.

[0019] Figure 4 This is a circuit diagram of a multi-parallel current sharing circuit for a linear regulator according to an embodiment of the present invention. Figure 4As shown, the circuit includes a total input terminal, a total output terminal, and n parallel linear regulators, namely the first linear regulator LDO1, the second linear regulator LDO2, ..., the nth linear regulator LDOn, where n is a natural number of 2 or greater. Each linear regulator, in addition to its input and output pins, also includes a shunt pin CSNS and a current sharing pin CSUM. The shunt pin CSNS of each linear regulator is connected to the total input terminal via the first sensing resistor R1, the second sensing resistor R2, ..., the nth sensing resistor Rn, respectively. The input voltage at the total input terminal is V. IN The resistance value of each sensing resistor is R. SNS The current-sharing pins CSUM of each linear regulator are connected in parallel and then connected to the total input terminal via a current-sharing resistor R0. The resistance of the current-sharing resistor R0 is equal to the resistance of the sensing resistor R. SNS 1 / n, that is, the resistance of R0 is R SNS / n.

[0020] It should be noted that each linear regulator in this invention can adjust its own output current according to the voltage values ​​input to its shunt pin CSNS and current sharing pin CSUM, so that its individual output current is consistent with the average output current of all linear regulators. The principle is explained in detail below.

[0021] First, for the x-th linear regulator LDOx, where x is a natural number between 2 and n, the current flowing into the current sharing pin CSUM and the current shunt pin CSNS is equal, and also equal to the output current I of the linear regulator LDOx. OUT(x) The ratio is 1:A, where A is a positive constant.

[0022] The shunt pins CSNS of each linear regulator are connected to the total input terminal through current-sharing resistors R1, R2, ..., Rn, respectively. The resistance of each current-sharing resistor is R. SNS Thus, for the x-th linear regulator LDOx, the voltage difference between its shunt pin CSNS and the total input VIN is R. SNS ×I OUT(x) / A=R SNS / A×I OUT(x) , is a voltage value that is positively correlated with the output current of the x-th linear regulator LDOx.

[0023] The current I flowing through the current sharing resistor R0 CSUM_total As shown in the following formula:

[0024]

[0025] Therefore, it can be seen that the current I flowing through the current-sharing resistor R0 CSUM_total The total output current I of all linear regulators OUT_total The ratio is 1:A.

[0026] Thus, for any linear regulator in the circuit, the voltage seen on the current sharing pin CSUM is: V IN -R SNS / n×I OUT_total / A=V IN -R SNS / A×I OUT_total / n, and the total output current I of all linear regulators OUT_total Related.

[0027] In summary, Table 1 below shows the correlation between node voltage and current. As shown in Table 1, for any linear regulator, the difference between the voltage values ​​at the shunt pin CSNS and the current sharing pin CSUM and the voltage value at the total input terminal can reflect the output current of the linear regulator and the average output current of all linear regulators (total current divided by the number of linear regulators n).

[0028] Table 1 Correlation between node voltage and current

[0029] node shunt pin CSNS CSUM pin for equalization Node voltage <![CDATA[V CSNS ]]> <![CDATA[V CSUM ]]> Node voltage calculation formula <![CDATA[V IN -R SNS / A×I OUT(x) ]]> <![CDATA[V IN -R SNS / A×I OUT_total / n]]> Related current <![CDATA[The output current I of this LDO OUT(x) > <![CDATA[Average output current I of all LDOs OUT_total / n]]> Related current calculation formula <![CDATA[I OUT(x)= (V IN -V CSNS )×A / R SNS ]]> <![CDATA[I OUT_total / n = (V IN -V CSUM )×A / R SNS ]]>

[0030] Therefore, it can be seen that each linear regulator can be adjusted based on the voltage value V of its current sharing pin CSUM. CSUM To obtain the average output current I of all LDOs OUT_total The value of / n, and based on the voltage V of its shunt pin CSNS. CSNS To obtain its output current I OUT(x) The magnitude of the value is used to adjust the output current, thereby achieving a current-sharing state for each linear regulator (LDO).

[0031] The parallel current sharing circuit of the linear regulator of the present invention realizes the parallel current sharing of two or more linear regulators without generating too much additional power loss.

[0032] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0033] The above embodiments are merely exemplary implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention should be determined by the appended claims.

Claims

1. A multi-channel parallel current sharing circuit for a linear voltage regulator, having a total input terminal and a total output terminal, characterized in that: It also includes n parallel linear regulators, each of which includes an input pin, an output pin, a shunt pin, and a current sharing pin, where n is a natural number of 2 or greater than 2; Each linear regulator's shunt pin is connected to the main input terminal via a sensing resistor, and the resistance of each sensing resistor is R. SNS ; The current-sharing pins of each linear regulator are connected in parallel and then connected to the total input terminal via a current-sharing resistor. The resistance of this current-sharing resistor is equal to the resistance R of the sensing resistor. SNS 1 / n; Each linear regulator can adjust its own output current according to the voltage value input on its shunt and current sharing pins, so that its individual output current is consistent with the average output current of all linear regulators. The voltage difference between the input voltage at the shunt and current sharing pins of each linear regulator and the voltage at the total input terminal is linearly related to the individual output current and the average output current of all linear regulators, respectively.

2. The linear regulator multi-channel parallel current sharing circuit according to claim 1, characterized in that, The individual output circuit of each linear regulator satisfies the voltage value input to its shunt pin I. OUT(x)＝ (V IN -V CSNS )×A / R SNS , among which, I OUT(x) V represents the current output by the x-th linear regulator alone. IN This represents the voltage at the total input terminal, V. CSNS The voltage across the shunt pin is represented by A, which is a positive constant, and the output current I of the linear regulator is represented by I. OUT(x) The ratio of the current to the input current of the shunt pin, R SNS The resistance value of the sensing resistor.

3. The linear regulator multi-channel parallel current sharing circuit according to claim 2, characterized in that, The average output current of all linear regulators satisfies the I value of the voltage input to its current sharing pin. OUT_total / n ＝ (V IN -V CSUM )×A / R SNS , among which, I OUT_total / n represents the average output current of all linear regulators, V IN This represents the voltage at the total input terminal, V. CSUM This represents the voltage across the current sharing pin, where A is a positive constant, and I represents the output current of the linear regulator. OUT(x) The ratio of the current to the input current of the shunt pin, R SNS The resistance value of the sensing resistor.

Images