CN102468839B

CN102468839B - Circuit and method for implementing multifunctional pins applied to integrated circuits

Info

Publication number: CN102468839B
Application number: CN201010552390.5A
Authority: CN
Inventors: 汪若瑜; 陈曜洲
Original assignee: Richtek Technology Corp
Current assignee: Richtek Technology Corp
Priority date: 2010-11-19
Filing date: 2010-11-19
Publication date: 2015-03-18
Anticipated expiration: 2030-11-19
Also published as: CN102468839A

Abstract

The invention provides a circuit and a method for realizing a multifunctional pin applied to an integrated circuit, wherein the circuit comprises a first switch connected with the multifunctional pin, when the integrated circuit is not prepared, the first switch is closed, the circuit detects the current of the first switch to determine whether to start the integrated circuit, when the integrated circuit is prepared, the first switch is open, and the circuit detects the voltage of the multifunctional pin to start or close the integrated circuit. When the voltage of the multi-functional pin is greater than a critical value, the multi-functional pin is determined to be in a good power state. The current Iok in the present invention is higher than the current Iok in the existing circuit, so more IC interfaces can be connected in series, and the response speed of the system can be increased.

Description

Be applied in circuit and method that integrated circuit realizes multi-function pin

Technical field

The present invention is the circuit that relevant one is applied in that integrated circuit (IC) realizes multi-function pin, particularly utilizes single pin position to realize the circuit of chip enable and good (power good) function of power supply about one.

Background technology

Along with the increase of circuit function, IC needs increasing pin position to realize these functions, in order to reduce the quantity of pin position, has proposed at present much to utilize single pin position to realize the technology of several functions.Power supply good signal is common output signal on IC, judge whether IC function is ready to complete for system, the power supply of general IC well exports and is mostly that the framework with opening drain electrode (open drain) or opener pole (open collector) realizes, and utilize wiring or lock (wire-or) to come to be interconnected with other IC, system end has the power supply that a pull-up resistor connects all IC and well exports, when the power supply of all IC well export be all open circuit time, then triggering voltage good signal is all ready to complete with all IC of reporting system, when the power supply of any one IC well exports as short circuit, then power supply good signal is not triggered, therefore system will learn that IC is not ready to complete in addition.

Fig. 1 shows existing power supply changeover device, and it comprises IC 10, in order to control the switching of power switch M1 and M2, input voltage vin is converted to output voltage Vout.This IC 10 utilizes multi-function pin POK/EN to realize chip enable and power supply good function.Fig. 2 shows in the IC 10 of Fig. 1 and utilizes multi-function pin POK/EN to realize the circuit of chip enable and power supply good function, wherein pull-up resistor Rpull is connected between power voltage terminal VCC and multi-function pin POK/EN, switch Q2 is connected between multi-function pin POK/EN and earth terminal GND, be controlled by chip enable signal EN, diode D2 and switch Q1 is connected between multi-function pin POK/EN and earth terminal GND, the voltage of multi-function pin POK/EN compares with critical value Vth1 and produces signal CE to start or to close IC 10 by comparator 12, comparator 14 compares voltage and the critical value Vth2 generation signal PG control switch Q1 of back coupling pin position FB.When chip enable signal EN makes switch Q2 be closed circuit, the voltage of multi-function pin POK/EN is pulled to GND, and the signal CE that therefore comparator 12 exports low level makes IC 10 close.When switch Q2 is for open circuit, earth terminal GND will be flowed to from multi-function pin POK/EN through diode D2 and switch Q1 by the electric current I ok of pull-up resistor Rpull, due to when switch Q1 is closed circuit on it cross-pressure very little, therefore need the forward bias voltage drop VF by diode D2 to make the voltage of multi-function pin POK/EN be greater than critical value Vth1, and then the signal CE making comparator 12 export high levle starts IC 10.After IC 10 starts, if the voltage of back coupling pin position FB is greater than critical value Vth2, represent that this IC 10 is ready to complete, comparator 14 will make switch Q1 for open circuit, after all IC are ready to complete, the voltage of multi-function pin POK/EN is driven high, and is all ready to complete with all IC of reporting system with triggering voltage good signal.

Chip enable and power supply well export respective specification, in general, when the voltage of multi-function pin POK/EN is greater than 0.3V, comparator 12 will be sent signal CE and start IC 10, and when the voltage of multi-function pin POK/EN is greater than 0.4 or 0.8V, be just judged to be power supply kilter.But 0.3V is very little to the interval between 0.4 or 0.8V, therefore probably makes the voltage of multi-function pin POK/EN be greater than 0.4 or 0.8V when IC 10 is not ready to complete because of technique, voltage and variations in temperature, and then causes system to be judged by accident.In addition, the size of pull-up resistor Rpull also has impact, less pull-up resistor Rpull will produce larger electric current I ok, according to the characteristic of diode, when larger by the electric current on it, its forward bias voltage drop VF is also larger, therefore, pull-up resistor Rpull can not be too little, otherwise will make the voltage of multi-function pin POK/EN triggering voltage good signal when IC 10 is not ready to complete.But when pull-up resistor Rpull is excessive, electric current I ok becomes very little, and this slowly rises making the voltage of multi-function pin POK/EN, thus needs the longer time could triggering voltage good signal, especially, when the IC quantity be connected in series is more, the reaction speed of system is slower.Moreover, in this framework, because electric current I ok is limited in less scope, such as 50uA, therefore, as diode D2 comparatively strong (stronger), the voltage of multi-function pin POK/EN may be made to be greater than critical value Vth1, IC 10 thus cannot be made to start, contrary, as diode D2 more weak (weaker), may when IC 10 is not ready to complete just triggering voltage good signal.As mentioned above, the existing circuit utilizing multi-function pin POK/EN to realize chip enable and power supply good function, has many restrictions, causes the difficulty designed.

Electric current I ok in the present invention is high compared with the electric current I ok in available circuit, therefore can be connected in series more IC interface, and can speed the reaction speed of system.

Summary of the invention

The present invention is about a kind of circuit and the method that utilize single pin position to realize chip enable and power supply good function.

According to the present invention, be a kind ofly applied in the circuit that integrated circuit realizes multi-function pin and comprise: the first switch connects the multi-function pin of this integrated circuit; Current detector detects the electric current of this first switch, and determines the first signal according to the size of this electric current; First comparator compares voltage and the first critical value generation secondary signal of this multi-function pin; Multiplexer selects one of them to start or to cut out this integrated circuit from this first and second signal; And second comparator when the voltage of this back coupling pin position is greater than the second critical value, produce the 3rd signal make this first switch for open circuit; Wherein, after this first switch is for open circuit, if the voltage of this multi-function pin is greater than the 3rd critical value, power supply kilter is judged to be.

According to the present invention, be a kind ofly applied in the method that integrated circuit realizes multi-function pin and comprise: the electric current detecting the first switch be connected with this multi-function pin, and determine the first signal according to the size of this electric current; The voltage and the first critical value that compare this multi-function pin produce secondary signal; When the voltage of the back coupling pin position of this integrated circuit is less than the second critical value, select this first signal to control startup or the closedown of this integrated circuit; When the voltage of this back coupling pin position is greater than the second critical value, controlling this first switch is open a way and select this secondary signal to control startup or the closedown of this integrated circuit; And after this first switch is for open circuit, if the voltage of this multi-function pin is greater than the 3rd critical value, be judged to be power supply kilter.

Accompanying drawing explanation

Fig. 1 shows existing power supply changeover device;

Fig. 2 display utilizes multi-function pin POK/EN to realize the circuit of chip enable and power supply good function;

Fig. 3 shows functional block diagram of the present invention; And

Fig. 4 shows the embodiment of Fig. 3 function block.

Drawing reference numeral:

10 integrated circuits

12 comparators

14 comparators

The good decision circuitry of 20 power supply

22 current detectors

24 first comparators

26 multiplexers

28 second comparators

30 current sources

32 inverters

34 nodes

Embodiment

Fig. 3 shows functional block diagram of the present invention, wherein pull-up resistor Rpull connects the multi-function pin POK/EN of IC 10, electric current I ok is provided as current source, second switch SW2 is connected between multi-function pin POK/EN and earth terminal GND, be controlled by chip enable signal EN, the good decision circuitry 20 of power supply determines power supply good signal APG according to the voltage of multi-function pin POK/EN, first interrupteur SW 1 connects multi-function pin and is controlled by signal PG, current detector 22 detects and produces signal S1 by the electric current of the first interrupteur SW 1, first comparator 24 determines signal S2 according to the voltage of multi-function pin POK/EN, multiplexer 26 selects one of them as signal CE to start or to cut out IC 10 according to signal PG from signal S1 and S2, second comparator 28 determines signal PG according to the voltage of the back coupling pin position FB of IC 10.

Fig. 4 shows the embodiment of Fig. 3 function block, wherein the first interrupteur SW 1 and second switch SW2 are all MOS transistor, the good decision circuitry 20 of power supply is that comparator is in order to compare voltage and the critical value Vth3 of multi-function pin POK/EN, when the voltage of multi-function pin POK/EN is greater than critical value Vth3, power supply good decision circuitry 20 out-put supply good signal APG.Current detector 22 comprises the current mirror, current source 30 and the inverter 32 that are made up of transistor M1 and M2, wherein current mirror connects the first interrupteur SW 1, produce mirrored current Im by the electric current of the first interrupteur SW 1 with the reference current IEN that current source 30 provides in order to mirror to compare, when mirrored current Im is less than reference current IEN, the voltage of node 34 is high levle, therefore inverter 32 exports the signal S1 of low level, when mirrored current Im is greater than reference current IEN, the voltage of node 34 is low level, therefore inverter 32 exports the signal S1 of high levle.

With reference to Fig. 4, when IC 10 does not start, second switch SW2 is closed circuit, the voltage of back coupling pin position FB is less than critical value Vth2 again, therefore comparator 28 sends the signal PG of low level to make the first interrupteur SW 1 be closed circuit and to make multiplexer 26 select to send signal S1, now electric current I ok is almost complete flows to earth terminal GND via second switch SW2, therefore the first interrupteur SW 1 does not almost have electric current, thus make mirrored current Im be less than reference current IEN, signal S1 is that low level cannot start IC 10.Then, when chip enable signal EN makes second switch SW2 for open circuit, electric current I ok flows to earth terminal GND via multi-function pin POK/EN, the first interrupteur SW 1 and transistor M1, now mirrored current Im is greater than reference current IEN, thus signal S1 is made to transfer high levle to start IC 10, in this embodiment, compare with reference current IEN again after the electric current by the first interrupteur SW 1 will being reduced N times, therefore can not be too little by the electric current I ok of pull-up resistor Rpull, hypothetical reference electric current I EN is 10uA, then electric current I ok is about 1mA ~ 10mA.After IC 10 is activated, the voltage of back coupling pin position FB starts to rise, and when it is greater than critical value Vth2, represents that this IC 10 is ready to complete, comparator 28 exports the signal PG of high levle to make the first interrupteur SW 1 for open circuit, and makes multiplexer 26 select to send signal S2.During first interrupteur SW 1 of IC 10 is open circuit, if also have other IC not to be ready to complete, the voltage of the multi-function pin POK/EN making IC 10 is greater than critical value Vth1 and is less than critical value Vth3 by the first interrupteur SW 1 in the IC be not then ready to complete and the cross-pressure of transistor M1, therefore the signal S2 that high levle sent by the first comparator 24 in IC 10 maintains starting state to make IC 10, in general, critical value Vth1 is about 0.3V, and critical value Vth3 is about 0.8V.If other IC are all ready to complete, then electric current I ok will make the voltage rise of multi-function pin POK/EN, and when it is greater than critical value Vth3, all IC of signal APG reporting system that the good decision circuitry of power supply 20 sends high levle are all ready to complete.Because the electric current I ok in the present invention is high compared with the electric current I ok in available circuit, therefore more IC interface can be connected in series, and the reaction speed of system can be speeded.

Object for illustrating for describing of doing of preferred embodiment of the present invention above, and to be not intended to limit the present invention be accurately disclosed form, learn and make an amendment or change to be possible based on above instruction or from embodiments of the invention, embodiment is that technological thought attempt of the present invention is decided by claim and equalization thereof in order to explain orally principle of the present invention and allow those skilled in the art utilize the present invention to select in practical application with various embodiment and describe.

Claims

1. A circuit that is applied in an integrated circuit to realize a multifunctional pin, is characterized in that, the circuit that is applied in an integrated circuit to realize a multifunctional pin includes:

The first switch is connected to the multi-function pin of the integrated circuit;

a current detector, connected to the first switch, detecting the current of the first switch, and determining a first signal according to the magnitude of the current;

The first comparator is connected to the multi-function pin, and compares the voltage of the multi-function pin with the first critical value to generate a second signal;

a multiplexer, connected to the first comparator and the current detector, selects one of the first and second signals to enable or disable the integrated circuit; and

The second comparator is connected to the first switch and the feedback pin of the integrated circuit, and generates a third signal to make the first switch open when the voltage of the feedback pin is greater than a second critical value ;

Wherein, after the first switch is open, if the voltage of the multi-function pin is greater than a third critical value, it is determined that the power supply is good.

2. the application in integrated circuit as claimed in claim 1 realizes the circuit of multifunctional pin position, is characterized in that, described application in integrated circuit realizes the circuit of multifunctional pin position further comprising:

a current source connected to the multi-function pin to supply current thereto; and

The second switch is connected between the multi-function pin and the ground terminal, and the second switch is controlled by a chip enable signal to change the current of the first switch.

3 . The circuit for implementing multi-function pins in integrated circuits according to claim 2 , wherein the current source includes a pull-up resistor connected between a power supply voltage and the multi-function pins.

4. application as claimed in claim 1 realizes the circuit of multifunctional pin in integrated circuit, it is characterized in that, described current detector comprises:

a current mirror, connected to the first switch, mirroring the current of the first switch to generate a mirror current; and

A current source, connected to the current mirror, provides a reference current for comparison with the mirror current to determine the first signal.

5 . The circuit for implementing multi-function pins in integrated circuits according to claim 1 , wherein the multiplexer selects and outputs the first signal or the second signal according to the third signal.

6. A method for implementing a circuit of a multifunctional pin in an integrated circuit as claimed in claim 1, wherein the method for implementing a circuit of a multifunctional pin in an integrated circuit comprises:

(A) detecting the current of the first switch connected to the multi-function pin, and determining the first signal according to the magnitude of the current;

(B) comparing the voltage of the multi-function pin with the first critical value to generate a second signal;

(C) When the voltage of the feedback pin of the integrated circuit is less than a second critical value, selecting the first signal to control the startup or shutdown of the integrated circuit;

(D) when the voltage of the feedback pin is greater than a second critical value, controlling the first switch to be open and selecting the second signal to control the startup or shutdown of the integrated circuit; and

(E) After the first switch is open, if the voltage of the multi-function pin is greater than a third critical value, it is determined that the power supply is good.

7. The application of claim 6 realizes the method for the circuit of the multi-function pin in an integrated circuit, wherein said step (A) comprises:

mirroring the current of the first switch to produce a mirrored current; and

The first signal is generated by comparing the mirrored current with a reference current.