CN102778912A - Startup circuit and power supply system integrated with same - Google Patents

Abstract

The invention discloses a startup circuit and a power supply system integrated with the same. Low-voltage power supply is produced by the startup circuit to be supplied to a reference voltage source in the system when the system is powered up, thereby avoiding use of high-voltage devices by the reference voltage source. After the system works normally, the startup circuit can be turned off completely, and no additional power consumption is needed. After the power supply system integrated with the startup circuit is applied, the reference voltage source in a chip can always maintain low voltage, and only one high-accuracy low-voltage reference source needs to be constructed in the chip. Therefore, due to high-voltage application of the power supply system, the number of the applied high-voltage devices can be reduced, the area of the chip can be reduced, and the design cost can be decreased.

Description

A startup circuit and a power supply system integrating the circuit

technical field

The invention belongs to the technical field of power supplies, and in particular relates to the design of a self-starting internal power supply system suitable for high-voltage applications.

Background technique

All chips have a power-on process, so it is inevitable to design the power-on process of the chip in chip design. Proper design can improve the performance of the chip and reduce the cost of the chip. The traditional chip power-on process is that the external power supply voltage Vin directly supplies power to the reference module, and then the internal power supply of the chip is established after the reference is established, and finally the chip can operate normally. This power-on process has two serious defects in high-voltage applications: ①Because the reference power supply is an external power supply voltage, a large number of withstand voltage devices are used in the reference part, which increases the chip area; Therefore, the reference voltage of the high-voltage power supply has serious temperature drift, which will cause serious drift of the reference voltage inside the chip with temperature. Therefore, a high-voltage application chip using the traditional power-on process often needs to add an additional low-voltage high-precision reference source inside the chip to meet the needs of internal precise control, which will further increase the power consumption and area of the chip.

Contents of the invention

The purpose of the present invention is to solve the above-mentioned problems in the existing self-starting internal power supply system for high-voltage applications, and propose a starting circuit.

The technical solution of the present invention is: a start-up circuit, comprising: a first PMOS transistor, a second PMOS transistor, a third PMOS transistor, a fourth PMOS transistor, a fifth PMOS transistor, a first NMOS transistor, a second NMOS transistor, a Three NMOS transistors, an inverter, a capacitor unit, a resistor unit, and a voltage stabilizing unit, wherein the gate terminal of the second NMOS transistor is connected to the input terminal of the inverter and used as the input terminal of the start-up circuit, and the inverter The output terminal of the phase device is connected to the gate terminal of the first NMOS transistor, the source terminal and the substrate of the first NMOS transistor, the second NMOS transistor, and the third NMOS transistor are all connected to the ground, the gate terminal of the first PMOS transistor, the second The drain end of the PMOS transistor MOS transistor, the drain end of the second NMOS transistor, the first terminal of the capacitor unit, the gate end of the third NMOS transistor, and the gate end of the fourth PMOS transistor are connected together, and the second terminal of the capacitor unit is connected to the power supply The voltages are connected, the drain terminal of the first PMOS transistor and the gate terminal of the second PMOS transistor are connected to the drain terminal of the first NMOS transistor, and the source terminals of the first PMOS transistor, the second PMOS transistor, and the fourth PMOS transistor are connected to the substrate To the power supply voltage, the drain end of the fourth PMOS transistor and the drain end of the third NMOS transistor MN3, the gate end of the third PMOS transistor and the fifth PMOS transistor are connected together, the substrate of the third PMOS transistor and the substrate of the fifth PMOS transistor The bottom is connected to the power supply voltage, the resistance unit is connected between the source terminal of the third PMOS transistor and the power supply voltage, the drain terminal of the third PMOS transistor and the source terminal of the fifth PMOS transistor are connected to the first terminal of the voltage stabilizing unit, the voltage stabilizing unit The second terminal of the unit is connected to the ground, and the drain terminal of the fifth PMOS transistor is used as the output terminal of the start-up circuit.

Based on the above starting circuit, the present invention also proposes a self-starting internal power supply system suitable for high-voltage applications, which also includes: a reference voltage source, an LDO, a comparison circuit, a diode and a switching device, wherein the output terminal of the starting circuit is connected to the The starting input terminal of the reference voltage source is connected to the negative terminal of the diode, the reference voltage source provides the reference source for the LDO, the output terminal of the LDO is used as the output terminal of the power supply system, and the two input terminals of the comparison circuit are used to input the reference voltage source The generated reference source and the output voltage of the LDO, the output terminal of the comparison circuit is connected to the input terminal of the start-up circuit and the control terminal of the switch device, and the first terminal and the second terminal of the switch device are respectively connected to the forward terminal of the diode and the output of the LDO end.

Beneficial effects of the present invention: the start-up circuit of the present invention generates a low-voltage power supply to the reference voltage source inside the system when the system is powered on, thereby avoiding the use of high-voltage devices for the reference voltage source, and the biggest feature of the start-up circuit compared with the traditional start-up circuit is , after the system works normally, the start-up circuit can be completely closed without consuming extra power consumption; the power supply system integrating the start-up circuit of the present invention makes the reference voltage source supply voltage inside the chip always low voltage, so that only a High-precision low-voltage reference source, so the high-voltage application of the power supply system provided by the present invention can reduce the use of high-voltage devices, reduce the area of the chip, and further reduce the cost of the chip. In addition, due to the power supply system of the present invention, the power supply of the reference voltage source is finally switched to the internal power supply of the chip, which can greatly improve the PSRR of the reference.

Description of drawings

FIG. 1 is a schematic structural diagram of the starting circuit proposed by the present invention.

Fig. 2 is a schematic structural diagram of a self-starting internal power supply system suitable for high-voltage applications integrated with a start-up circuit.

FIG. 3 is a schematic diagram of the power-on process of the power supply system in the embodiment when the power supply voltage is 5V.

Fig. 4 is a schematic diagram of the power-on process of the power supply system in the embodiment when the power supply voltage is 16V.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

The start-up circuit of the present invention is shown in Figure 1, comprises PMOS tube MP1, MP2, MP3, MP4, MP5, NMOS tube MN1, MN2, MN3, an inverter INV1, a capacitance unit, a resistance unit R1, a voltage stabilizing unit, The specific connection relationship is as follows: the gate terminal of the NMOS transistor MN2 is connected to the input terminal of the inverter INV1 and used as the input terminal of the startup circuit, the output terminal of the inverter INV1 is connected to the gate terminal of the NMOS transistor MN1, the NMOS transistor MN1, The source terminals and substrates of MN2 and MN3 are connected to ground, the gate terminal of PMOS transistor MP1, the drain terminal of MOS transistor MP2, the drain terminal of NMOS transistor MN2, the first terminal of the capacitor unit, the gate terminal of MN3, and the gate terminal of MP4 The terminals are connected together, the second terminal of the capacitor unit is connected to the power supply voltage Vin, the drain terminal of the PMOS transistor MP1 and the gate terminal of the PMOS transistor MP2 are connected to the drain terminal of the NMOS transistor MN1, and the source terminals of the PMOS transistors MP1, MP2, and MP4 The substrate is connected to the power supply voltage Vin, the drain end of the PMOS transistor MP4 and the drain end of the NMOS transistor MN3, the gate ends of the PMOS transistor MP3, and the PMOS transistor MP5 are connected together, and the substrate of the PMOS transistor MP3 and the substrate of MP5 are connected to the power supply The voltage Vin and the resistance unit R1 are connected between the source end of the PMOS transistor MP3 and the power supply voltage Vin, and the drain end of the PMOS transistor MP3 and the source end of the PMOS transistor MP5 are connected to the first terminal of the voltage stabilizing unit and the second terminal of the voltage stabilizing unit. The terminal is connected to the ground, and the drain end of the PMOS transistor MP5 is used as the output end of the start-up circuit.

As shown in Figure 1, the capacitor unit here is specifically a MOS capacitor. In Figure 1, the MOS capacitor is specifically realized by a PMOS transistor MP6, wherein the gate terminal of MP6 is used as the first terminal of the capacitor unit, and the source terminal of MP6 and The drains are connected together as the second terminals of the capacitor units.

As shown in Figure 1, the voltage stabilizing unit here is specifically a Zener diode D1, the negative terminal of the Zener diode is used as the first terminal of the voltage stabilizing unit, and the positive terminal of the Zener diode is used as the first terminal of the voltage stabilizing unit. second terminal.

In the start-up circuit, when the system is powered on, this module generates a low-voltage power supply V _L71 and provides it to the reference module. Among them, NMOS transistors MN1, MN2, PMOS transistors MP1, MP2 and inverter INV1 form a Level Shift structure, and the input low-voltage The logic signal L70 is transformed into a high-voltage logic signal V _A to the power supply voltage Vin, that is, the voltage at point A in FIG. 1 , so that the startup circuit can be shut down normally after the chip starts up normally.

The functional block diagram of the self-starting internal power supply system suitable for high-voltage applications is shown in Figure 2, which also includes: a reference voltage source, LDO, a comparison circuit, a diode and a switching device, wherein the output terminal of the start-up circuit is connected to the reference voltage source The starting input terminal is connected to the negative terminal of the diode, the reference voltage source provides the reference source for the LDO, the output terminal of the LDO is used as the output terminal of the power supply system, and the two input terminals of the comparison circuit are used to input the reference source generated by the reference voltage source and the output voltage of the LDO, the output terminal of the comparison circuit is connected with the input terminal of the starting circuit and the control terminal of the switch device, and the first terminal and the second terminal of the switch device are respectively connected with the forward terminal of the diode and the output terminal of the LDO.

Here, the reference voltage source, LDO and comparison circuit can adopt a conventional structure, and the switching device can be realized by a MOS tube.

The power-on process of this power supply system is: when the power supply voltage Vin is powered on, a low-voltage power supply V _L71 is generated through the startup circuit to supply power to the reference voltage source. When the reference is established normally, the LDO module starts to build the internal power supply voltage VOUT again. When the comparison circuit monitors that the output VOUT of the LDO reaches a preset value, it generates an enable signal L70, which closes the start-up circuit and closes the switch SW1 at the same time, and the power supply of the reference voltage source is switched to VOUT minus a diode D2 voltage drop supply.

The following explains the working principle of the start-up circuit in Figure 1: when the power supply voltage Vin is powered on, since no internal signal is generated, the NMOS tubes MN1 and MN2 are both in the cut-off state, and the output node A of the Level Shift is in a high-impedance state. The output node A of the Level Shift is initialized through the MOS capacitor composed of the PMOS transistor MP6, and the node A is at a high level when the power is turned on. Through the inverter composed of the PMOS transistor MP4 and the NMOS transistor MN3, the node B is obtained as When the level is low, the PMOS transistors MP3 and MP5 are turned on, thereby forming a path composed of R1, MP3 and MP5 to generate a power supply voltage V _L71 . Since the internal signal L70 remains low until the output VOUT of the LDO rises to a preset value, that is, the reference value V _REF , and the voltage of the inverter INV1 is V _L71 , the NMOS transistor MN1 is turned on and MN2 is turned off, maintaining node A is a high level, so that the voltage of the node L71 can always be maintained. When the input power supply voltage Vin is relatively low, Zener diode D2 is not broken down, the level of node C is obtained by subtracting the voltage drop of resistor R1 from Vin and the source-drain voltage of PMOS transistor MP3, and then the node is obtained through PMOS transistor MP5 The voltage of L71; when the input power supply voltage Vin is relatively high, the Zener diode D2 breaks down to stabilize the voltage of node C at about 5V, which can ensure that the voltage of the output node L71 is always in the low voltage range. When the comparison circuit detects that the voltage value of the output VOUT of the LDO rises to the reference value V _REF , the output signal L70 of the comparison circuit is turned from low level to high level, then the NMOS transistor MN1 in the startup circuit is turned off, and MN2 is turned on, and the The level of node A is pulled to low level, the potential of node B is high level after passing through the first-stage inverter, and the path formed by R1, MP3 and MP5 is closed, and the voltage of L71 is switched to be reduced by the output VOUT of LDO. Go for a diode drop to get.

FIG. 3 and FIG. 4 respectively show the power-on process of the power supply system provided by the present invention when the input power supply voltage Vin is 5V and 16V. In Figure 3, since the input voltage Vin is relatively low, the Zener diode does not break down, so the low-voltage power supply L71 is directly obtained from the power supply voltage Vin through a resistor R1 and two PMOS transistors MP3 and MP5. When the output VOUT of the LDO rises to 3.2V , the output signal L70 of the comparison circuit is turned from low level to high level, and then the start-up circuit is turned off, and the low-voltage power supply L71 is switched to be provided by the internal LDO. In Figure 4, because the input voltage Vin is relatively high, the Zener diode breaks down and stabilizes the voltage at node C at about 5.2V. The low-voltage power supply L71 is obtained from the voltage V _C at the electrical node C through a PMOS transistor MP5. When the LDO When the output VOUT rises to 3.2V, the output signal L70 of the comparison circuit is turned from low level to high level, and then the startup circuit is turned off, and the low-voltage power supply L71 is switched to be provided by the internal LDO. Figure 3 and Figure 4 show that the startup circuit can be completely shut down after the system works normally without consuming extra power consumption.

From the above analysis and simulation, it can be seen that the start-up circuit of the present invention generates a low-voltage power supply to the reference module inside the system when the system is powered on, thereby avoiding the use of high-voltage devices in the reference module, and the start-up circuit has the biggest feature compared to the traditional start-up circuit Yes, after the system works normally, the start-up circuit can be completely closed without consuming additional power consumption; the power supply system integrating the start-up circuit of the present invention makes the reference voltage source power supply voltage inside the chip always low voltage, so that only need to build A high-precision low-voltage reference source, so the high-voltage application of the power supply system provided by the present invention can reduce the use of high-voltage devices, reduce the area of the chip, and then reduce the cost of the chip. In addition, due to the power supply system of the present invention, the power supply of the reference voltage source is finally switched to the internal power supply of the chip, which can greatly improve the PSRR of the reference.

Those skilled in the art will appreciate that the embodiments described here are to help readers understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical revelations disclosed in the present invention without departing from the essence of the present invention, and these modifications and combinations are still within the protection scope of the present invention.

Claims (5)

1. start-up circuit; Comprise: PMOS pipe, the 2nd PMOS pipe, the 3rd PMOS pipe, the 4th PMOS pipe, the 5th PMOS pipe, NMOS pipe, the 2nd NMOS pipe, the 3rd NMOS pipe, a phase inverter, a capacitor cell, a resistance unit, a voltage regulation unit; Wherein, The grid end of the 2nd NMOS pipe and the input end of phase inverter links to each other and as the input end of said start-up circuit; The output terminal of phase inverter is connected to the grid end of NMOS pipe; The source end and the substrate of the one NMOS pipe, the 2nd NMOS pipe, the 3rd NMOS pipe all are connected to ground; The first terminal of the drain terminal of the grid end of the one PMOS pipe, the 2nd PMOS pipe metal-oxide-semiconductor, the drain terminal of the 2nd NMOS pipe, capacitor cell, the grid end of the 3rd NMOS pipe, the grid end of the 4th PMOS pipe link together; Second terminal of capacitor cell is connected with supply voltage; The grid end of the drain terminal of the one PMOS pipe and the 2nd PMOS pipe is connected to the drain terminal of NMOS pipe; The source end and the substrate of the one PMOS pipe, the 2nd PMOS pipe, the 4th PMOS pipe are connected to supply voltage, and the grid end of the drain terminal of the 4th PMOS pipe drain terminal and the 3rd NMOS pipe MN3, the 3rd PMOS pipe, the 5th PMOS pipe links together, and the substrate of the substrate of the 3rd PMOS pipe and the 5th PMOS pipe is connected to supply voltage, resistance unit is connected between the source end and supply voltage of the 3rd PMOS pipe; The source end of the drain terminal of the 3rd PMOS pipe and the 5th PMOS pipe is connected to the first terminal of voltage regulation unit, second terminal of voltage regulation unit is connected to ground, and the drain terminal of the 5th PMOS pipe is as the output terminal of said start-up circuit.

2. start-up circuit according to claim 1; It is characterized in that; Described voltage regulation unit is specially a Zener diode, and the negative end of Zener diode is as the first terminal of said voltage regulation unit, and the forward end of Zener diode is as second terminal of said voltage regulation unit.

3. start-up circuit according to claim 1 is characterized in that described capacitor cell is specially mos capacitance.

4. start-up circuit according to claim 3; It is characterized in that; Described mos capacitance realizes through the 6th PMOS pipe that specifically wherein, the grid end of the 6th PMOS pipe is as the first terminal of said capacitor cell; The source end of the 6th PMOS pipe is connected together with the leakage disconnection, as second terminal of said capacitor cell.

5. integrated self-starting internal power supply system of the described start-up circuit of the arbitrary claim of claim 1 to 4; Also comprise: reference voltage source, LDO, comparator circuit, a diode and a switchgear; Wherein, The output terminal of start-up circuit links to each other with the startup input end of reference voltage source and the negative end of diode; Reference voltage source is that LDO provides reference source, and the output terminal of LDO is as the output terminal of said electric power system, and two input ends of comparator circuit are used for the reference source of input reference voltage source generation and the output voltage of LDO; The output terminal of comparator circuit links to each other with the control end of the input end of start-up circuit and switchgear, and the first terminal of switchgear and second terminal connect the forward end of diode and the output terminal of LDO respectively.

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