CN102354243B - Integrated linear voltage stabilizer - Google Patents

Abstract

An integrated linear voltage regulator, the input end is electrically connected to the output end through an error amplification module and a transmission module in turn, the output end of the transmission module is further electrically connected to the input end of a feedback module, and the output end of the feedback module is electrically connected to the The input terminal of the error amplification module, the output terminal of the error amplification module is grounded through a first capacitor, a second capacitor is coupled between the input and output terminals of the transmission module, and the output terminal of the feedback module is connected through a third capacitor to ground. The advantage of the present invention is that the bypass capacitor is distributed to each module, the capacitance value of each capacitor does not need to be very large, and it can be completely manufactured inside the chip without being plugged on the PCB board, so the PCB can be saved The area of the chip can also be reduced, and the number of pins of the chip can also be reduced. Secondly, through the new frequency compensation mechanism, it can not only provide a fast transient response for the linear voltage regulator circuit, but also provide AC stability within a larger current load range.

Description

Integrated Linear Regulator

technical field

The invention relates to an integrated linear voltage stabilizer, in particular to an integrated linear voltage stabilizer with no external capacitor, fast transient response and wide-range AC stability.

Background technique

Linear regulators use transistors operating in their linear region to subtract excess voltage from the applied input voltage to produce a regulated output voltage. The so-called dropout voltage refers to the minimum value of the difference between the input voltage and the output voltage required by the regulator to maintain the output voltage within 100mV of its rated value. Positive output voltage regulators typically use power transistors that are allowed to saturate, so the regulator can have a very low dropout voltage, typically around 200mV; compared to traditional linear regulation of composite power transistors The voltage drop of the device is about 2V.

Newer developments use MOS power transistors, which provide the lowest dropout voltage. With power MOS, the only voltage drop across the regulator is due to the on-state resistance of the power device load current. If the load is small, the voltage drop produced in this way is only tens of millivolts.

As a kind of linear voltage regulator, the low-dropout (LDO) linear voltage regulator is characterized by low cost, low noise, and small quiescent current. These are its outstanding advantages. The main reason why the performance of the LDO linear regulator can reach this level is that the adjustment tube uses a P-channel MOSFET, while the ordinary linear regulator uses a PNP transistor. The P-channel MOSFET is driven by voltage and does not require current, so the current consumed by the device itself is greatly reduced; on the other hand, in a circuit using a PNP transistor, in order to prevent the PNP transistor from entering a saturated state and reduce the output capability, between input and output The voltage drop between them cannot be too low; and the voltage drop on the P-channel MOSFET is roughly equal to the product of the output current and the on-resistance. Due to the small on-resistance of the MOSFET, the voltage drop across it is very low.

The low-dropout linear regulator in the prior art usually requires one or two bypass capacitors as external components, which occupies the area and wiring of the PCB, and increases the number of pins of the chip, thereby increasing the packaging cost.

Contents of the invention

The technical problem to be solved by the present invention is to provide an integrated linear voltage regulator without an external capacitor, and has the characteristics of fast transient response and wide-range AC stability.

In order to solve the above problems, the present invention provides an integrated linear voltage regulator, the input terminal is electrically connected to the output terminal through an error amplification module and a transmission module in turn, and the output terminal of the transmission module is further electrically connected to the input terminal of a feedback module , the output terminal of the feedback module is electrically connected to the input terminal of the error amplification module, the output terminal of the error amplification module is grounded through a first capacitor, and a second capacitor is coupled between the input and output terminals of the transmission module, and the The output end of the feedback module is grounded through a third capacitor.

As an optional technical solution, the error amplification module further includes an amplifier, the first end of the first capacitor is electrically connected to the output end of the amplifier, and the second end of the first capacitor is grounded.

As an optional technical solution, the transmission module further includes a field effect transistor, the gate of the field effect transistor is the input terminal of the transmission module, the source is the output terminal of the transmission module, and the second capacitor is coupled to Between the gate and source of a field effect transistor.

As an optional technical solution, the feedback module includes a first feedback resistor and a second feedback resistor, the first pole of the first feedback resistor is electrically connected to the output terminal of the transmission module, and the second pole of the first feedback resistor is electrically connected to the The first pole of the second feedback resistor, the second stage of the second feedback resistor is grounded; the common point of the second pole of the first feedback resistor and the first pole of the second feedback resistor is used as the output terminal of the feedback module; the third The first terminal of the capacitor is electrically connected to the common point of the second pole of the first feedback resistor and the first pole of the second feedback resistor, and the second terminal of the third capacitor is grounded.

The advantage of the present invention is that the bypass capacitor is distributed to each module, and the capacitance value of each capacitor does not need to be very large, and it can be completely manufactured inside the chip instead of being hung on the PCB board, so that the PCB can be saved The area of the chip can also be reduced, and the number of pins of the chip can also be reduced. Secondly, through the new frequency compensation mechanism, it can not only provide a fast transient response for the linear voltage regulator circuit, but also provide AC stability within a larger current load range.

Description of drawings

Figure 1 is a schematic diagram of the modular structure of the integrated linear voltage regulator described in this specific embodiment.

Accompanying drawing 2 is an optional circuit diagram for realizing the schematic diagram of the modular structure shown in Fig. 1 .

Detailed ways

Next, a specific implementation manner of the integrated linear voltage regulator of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 is a schematic diagram of the modular structure of the integrated linear voltage regulator described in this specific embodiment, including an input terminal 11, an output terminal 12, an error amplification module H1, a transmission module H2, a feedback module H3 and a first capacitor C1 , the second capacitor C2 and the third capacitor C3. The input terminal 11 is electrically connected to the output terminal 12 through the error amplification module H1 and the transmission module H2 in sequence. The output end of the transmission module H2 is further electrically connected to the input end of the feedback module H3. The output terminal of the feedback module H3 is electrically connected to the input terminal of the error amplification module H1.

In the prior art, in order to avoid the high-frequency noise interference of the above-mentioned modules, it is usually necessary to connect one or two bypass capacitors externally for AC signal shielding, and the bypass capacitors occupy the PCB area and wiring, and increase the chip size. Pin count thus increases packaging cost. In this specific embodiment, each module is equipped with a capacitor to filter out the AC signal. Specifically, the output terminal of the error amplification module H1 is grounded through the first capacitor C1, and the input and output terminals of the transmission module H2 are coupled between the first capacitor C1 The second capacitor C2, and the output terminal of the feedback module H3 is grounded through the third capacitor C3. Since the bypass capacitors are allocated to each module, the values of the three capacitors do not need to be very large, usually between several pF to dozens of pF, so they can be made inside the chip instead of on the PCB. The board is externally hung, so it can not only save the area of the PCB, but also reduce the number of pins of the chip.

FIG. 2 is an optional circuit diagram for implementing the schematic diagram of the modular structure shown in FIG. 1 , and the input terminal 11 further includes a voltage source P1. The error amplification module H1 specifically includes an amplifier G1, a first capacitor C1 and a first resistor R1. The first end of the first capacitor C1 is electrically connected to the output end of the amplifier G1, and the second end of the first capacitor C1 is grounded; the first end of the first resistor R1 is electrically connected to the output end of the amplifier G1, and the second end of the first resistor R1 is electrically connected to the output end of the amplifier G1. Both ends are grounded. The first resistor R1 functions as a protection resistor, and the first capacitor C1 can filter the high-frequency noise at the output terminal of the error amplifier module H1 , usually tens of pF.

Continuing to refer to FIG. 2 , the transmission module H2 specifically includes a field effect transistor T1 and a second capacitor C2. The gate of the field effect transistor T1 is the input terminal of the transmission module H2, and the source is the output terminal of the transmission module H2. The second capacitor C2 is coupled between the gate and the source of the field effect transistor T1, and the input to The high-frequency noise of the transmission module H2 is filtered so that it does not affect the normal operation of the field effect transistor T1. The output terminal of the transmission module H2 is electrically connected to the output terminal 12 .

Continuing to refer to Figure 2, most traditional LDO linear regulators increase the transient response speed by reducing the source impedance of the field effect transistor T1, so a buffer with low output impedance is required to drive the large-scale field effect transistor T1; The present invention uses the second capacitor C2 to generate a main pole, and as a differentiator, quickly senses the voltage change of the source terminal and the gate terminal of the field effect transistor T1, thereby achieving the purpose of fast transient response. Secondly, the main pole generated by the introduction of the second capacitor C2 can enhance its AC stability, so that the circuit of the present invention has high stability in a wide range of current loads.

Continuing to refer to FIG. 2 , the feedback module H3 specifically includes a first feedback resistor RF1 , a second feedback resistor RF2 , a third capacitor C3 and a current source I1 . The first pole of the first feedback resistor RF1 is electrically connected to the output terminal of the transmission module H2, the second pole of the first feedback resistor RF1 is electrically connected to the first pole of the second feedback resistor RF2, and the second pole of the second feedback resistor RF2 grounded. The common point of the second pole of the first feedback resistor RF1 and the first pole of the second feedback resistor RF2 serves as the output terminal of the feedback module H3, and the output terminal is electrically connected to the positive input terminal of the amplifier G1. The feedback voltage fed back from the feedback module H3 to the amplifier G1 can be adjusted through the values of the first feedback resistor RF1 and the second feedback resistor RF2 to realize closed-loop control of the voltage regulator. The first end of the third capacitor C3 is electrically connected to the common point of the second pole of the first feedback resistor RF1 and the first pole of the second feedback resistor RF2, the second end of the third capacitor C3 is grounded, and the function of the third capacitor C3 The purpose is to filter the high-frequency noise at the output end of the feedback module H3. The design value ranges of the second capacitor C2 and the third capacitor C3 are several pF.

From the circuit diagram in Figure 2, it can be seen more clearly that since the bypass capacitors are allocated to each module, the values of the three capacitors C1, C2 and C3 do not need to be very large, usually in the range of several pF to dozens It is between pF, so it can be made inside the chip, without the need to hang it on the PCB board, so it can save the area of the PCB and reduce the number of pins of the chip. At the same time, the introduction of the new differentiator C2 not only provides fast transient response for the linear voltage regulator circuit, but also provides AC stability within a larger current load range.

In summary, although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Those with ordinary knowledge in the technical field of the present invention can, without departing from the spirit and scope of the present invention, Various changes and modifications are made, so the scope of protection of the present invention should be defined by the patent scope applied for in the claims.

Claims (2)

1. An integrated linear voltage regulator, the input terminal is electrically connected to the output terminal through an error amplification module and a transmission module in turn, the output terminal of the transmission module is further electrically connected to the input terminal of a feedback module, and the output terminal of the feedback module is electrically connected connected to the input of the error amplification module, wherein the output of the error amplification module is grounded through a first capacitor, a second capacitor is coupled between the input and output of the transmission module, and the feedback module The output terminal is grounded through a third capacitor; the transmission module further includes a field effect transistor, the gate of the field effect transistor is the input terminal of the transmission module, and the source is the output terminal of the transmission module, and the second capacitance coupling Connected between the gate and the source of the field effect transistor; the feedback module includes a first feedback resistor and a second feedback resistor, the first pole of the first feedback resistor is electrically connected to the output terminal of the transmission module, and the first feedback resistor The second pole of the second feedback resistor is electrically connected to the first pole of the second feedback resistor, and the second pole of the second feedback resistor is grounded; the common point of the second pole of the first feedback resistor and the first pole of the second feedback resistor serves as the feedback module Output end: the first end of the third capacitor is electrically connected to the common point of the second pole of the first feedback resistor and the first pole of the second feedback resistor, and the second end of the third capacitor is grounded. 2. The integrated linear voltage regulator according to claim 1, wherein the error amplification module further comprises an amplifier, the first end of the first capacitor is electrically connected to the output end of the amplifier, and the first capacitor The second end of the ground.

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