CN204905845U - Protective circuit for battery - Google Patents

Abstract

The utility model provides a protective circuit for battery, including battery package module and control chip, inside battery electricity core and the temperature sensitive resistance of containing of battery package module, control chip includes the protective film piece, the protective film piece includes specifically that battery voltage and battery temperature sensor, battery discharge control circuit, chip temperature sensor, discharge power manage the circuit, battery voltage and battery temperature sensor are used for detecting battery voltage and battery temperature information, and battery discharge control circuit is used for judging the size that whether satisfies battery discharge condition and control discharge current, and chip temperature sensor is used for detecting control chip's temperature information, and discharge power pipe circuit is used for big temperature sensor 0 bleed off, connects between the output and ground of battery electricity core. The utility model provides an unsafe factor under this environment is effectively avoidd to the battery protection scheme, the decay of effectual suppression battery capacity with prolonged battery life.

Description

Battery protecting circuit

Technical field

The utility model relates to technical field of integrated circuits, is specifically related to a kind of battery protecting circuit.

Background technology

Portable power source is a kind of portable electronic outfit integrating charging, discharging function, can anywhere or anytime to the mobile digital such as mobile phone, PAD product makeup energy.Generally be made up of electronic circuit board and lithium battery electric core.Electronic circuit board is made up of control chip, periphery components and parts, printed circuit board (PCB) etc.; pattern of mainly finishing the work switches the functions such as (as charge and discharge mode), input and output power conversion, abnormality display and protection; lithium battery electric core is energy storage units, is mainly used in storage and the release of energy.For portable power source, it uses the most important to be job security.

Usually, portable power source fail safe is embodied in the comprehensive of protective circuit and promptness, and protective circuit is completed jointly by battery protecting circuit on control chip and plate.Generally, the integrated multiple protective of control chip self, at input; have overvoltage, under-voltage, overcharge, cross put, the protection such as current limliting, at output, have the protections such as overvoltage, overcurrent, short circuit; in addition, the control chip also function such as integrated chip overheat protector, battery temperature protection.On plate, battery protecting circuit provides double protection, comprise over-charging of battery, cross put, overcurrent and short-circuit protection.But these are mostly is a kind of active protection mechanism, namely portable power source be in charging or the operating state such as electric discharge abnormal time a kind of protection mechanism, and when ideal case is abnormal, these protection mechanisms can not be opened, and portable power source is in unprotect state.Such as, the application scenarios often run in daily life: it is afternoon that The sun is shining fiercely, the portable power source of full charge is as in car, even if place a period of time under ideal case, touch is got up also, and some scalds one's hand, height more obvious than ambient temperature.This is determined by lithium battery chemical characteristic, under lithium battery is placed in hot environment when electricity is higher, its catalytic activity strengthens, corresponding secondary chemical reaction also aggravates, and discharges a large amount of oxygen and heat, and these heats have little time release, be gathered in portable power source inside, make portable power source temperature higher than ambient temperature, therefore, touch and get up to have hot sensation.Portable power source is put for a long time capacity and the useful life that can reduce battery in such circumstances greatly.More seriously, if battery quality does not pass a test, power brick there will be air-blowing, smolders, leakage, even burns and the dangerous phenomenon such as blast.

Above-mentioned analysis is known, and the protection mechanism of existing portable power source is incomplete, full charge is standby be placed in high ambient temperature under, easily produce unsafe factor.

Utility model content

The utility model is for existing portable power source protection mechanism imperfection, and propose a kind of battery protecting circuit when to be applicable under hot environment standby, safe and reliable and circuit is simple and easy to integrated.The purpose of this utility model is realized by following technical scheme:

A kind of battery protecting circuit, comprise cell packet module and control chip, cell packet module inside comprises battery battery core and thermo-sensitive resistor, control chip comprises protection module, and protection module specifically comprises cell voltage and battery temperature sensor, battery discharge control circuit, die temperature sensors, discharge power pipe circuit; Cell voltage and battery temperature sensor are for detecting cell voltage and battery temperature information, its voltage signal acquisition end connects the output of battery battery core, its temperature signal collection end connects thermo-sensitive resistor output, and its transducing signal output connects the first transducing signal input of battery discharge control circuit; Battery discharge control circuit is for judging whether the size meeting battery discharge condition and controlled discharge electric current, its the second transducing signal input connects the transducing signal output of die temperature sensors, and its control signal output connects the control signal input of discharge power pipe circuit; Die temperature sensors is used for the temperature information of detection control chip; Discharge power pipe circuit is used for big current path bleed off, is connected between the output of battery battery core and ground.

As concrete technical scheme, described cell voltage and battery temperature sensor are made up of comparator CMP1, comparator CMP2 and logical AND gate NAND1; Two inputs of comparator CMP1 access a battery battery core output end voltage VBAT and preset reference voltage Vset respectively; Two inputs of comparator CMP2 access a voltage signal VBAT_T and a reference source Vref0 of described thermo-sensitive resistor output respectively; The output of comparator CMP1 and comparator CMP2 all accesses the input of logical AND gate NAND1, and the output of logical AND gate NAND1 is as the output of cell voltage and battery temperature transducing signal EN_BATDISCHG.

As concrete technical scheme, described die temperature sensors is made up of PMOS PM3 ~ PM5, NMOS tube NM1 ~ NM2, resistance R3 ~ R4, transistor Q1 ~ Q2, comparator CMP3; PMOS PM3 ~ PM5 S pole separately meets power vd D, the G pole of PMOS PM3 connects the G pole of PMOS PM4 and the G pole of PMOS PM5, the D pole of PMOS PM3 connects the G pole of self and the D pole of NMOS tube NM3, the S pole of NMOS tube NM3 connects the e pole of transistor Q1, the b pole of transistor Q1 and c pole ground connection through resistance R3; The D pole of PMOS PM4 connects the D pole of NMOS tube NM4, and the G pole of NMOS tube NM4 connects the G pole of self D pole and NMOS tube NM3, and the S pole of NMOS tube NM4 connects the e pole of transistor Q2, the b pole of transistor Q2 and c pole ground connection; The D pole of PMOS PM5 is through resistance R4 ground connection, and the D pole of PMOS PM5 and the node of resistance R4 are as chip temperature detectable voltage signals Ref_DIET output; The positive input termination voltage signal Ref_DIET of comparator CMP3, negative input end access reference voltage signal Vref3, output detects as chip temperature and judges signal TSEN_EN output.

As concrete technical scheme, battery discharge control circuit is made up of operational amplifier A MP1 ~ AMP2, PMOS PM0 ~ PM2, NMOS tube NM1 ~ NM2, resistance R1 ~ R2, simulation alternative selector AMUX; PMOS PM0 ~ PM2 S pole separately meets power vd D, and the G pole of PMOS PM0 connects the output of described cell voltage and battery temperature transducing signal EN_BATDISCHG, and D pole connects the D pole of PMOS PM1 and the D pole of NMOS tube NM1; The G pole of PMOS PM1 connects the G pole of self D pole and PMOS PM2; The D pole of PMOS PM2 connects the D pole of NMOS tube NM2, and the node of the D pole of PMOS PM2 and the D pole of NMOS tube NM2 is as the output of discharge control signal I4; The positive input termination reference voltage Vref 1 of operational amplifier A MP1, negative input end is through resistance R1 ground connection, and the output of cell voltage described in power supply termination and battery temperature transducing signal EN_BATDISCHG, exports the G pole of termination NMOS tube NM1; The S pole of NMOS tube NM1 is through resistance R1 ground connection; Two inputs of simulation alternative selector AMUX connect reference voltage Vref 2 and described chip temperature detectable voltage signals Ref_DIET output respectively, control chip temperature detection described in termination and judge signal TSEN_EN output, export the positive input terminal of termination operational amplifier A MP2; The negative input end of operational amplifier A MP2 is through resistance R2 ground connection, and power supply termination connects the detection of described chip temperature and judges signal TSEN_EN output, exports the G pole of termination NMOS tube NM2.

As concrete technical scheme, described discharge power pipe circuit is made up of NMOS tube NM5 ~ NM6; The D pole access discharge control signal I4 of NMOS tube NM5, S pole ground connection, G pole connects the G pole of self D pole and NMOS tube NM6; The D pole of NMOS tube NM6 connects the output of battery battery core, S pole ground connection.

The utility model analyzes the unsafe factor that portable power source exists under full charge hot environment, completely fills this approach solve problem by avoiding battery electric quantity under hot environment.The beneficial effects of the utility model are: propose a kind ofly to be applicable to the standby battery protection schemes of hot environment; effectively evade unsafe factor under this environment; effective suppression battery capacity decays and extends battery, and circuit is simple and reliable, facilitates integrated.

Accompanying drawing explanation

The theory diagram of the battery protecting circuit that Fig. 1 provides for the utility model embodiment.

Fig. 2 is the logical flow chart of the battery protecting method based on theory diagram shown in Fig. 1.

Fig. 3 is a kind of physical circuit implementation of cell voltage and battery temperature sensor in Fig. 1.

Fig. 4 is a kind of physical circuit implementation of Fig. 1 chips temperature sensor module.

Fig. 5 is a kind of physical circuit implementation of battery discharge control module in Fig. 1.

Fig. 6 is a kind of physical circuit implementation of discharge power tube module in Fig. 1.

The oscillogram that the battery protecting circuit chips discharging current size that Fig. 7 shows the utility model embodiment to be provided rises with chip temperature.

Embodiment

As shown in Figure 1, the battery protecting circuit that the present embodiment provides, comprises cell packet module U100 and control chip, and control chip comprises protection module U200.Particularly, cell packet module U100 inside comprises battery battery core and thermo-sensitive resistor, and battery battery core is used for stored energy and supply, and it is information of voltage that thermo-sensitive resistor is used for battery temperature convert information.Protection module U200 self comprises again four submodules, is respectively cell voltage and battery temperature sensor U201, battery discharge control circuit U202, die temperature sensors U203, discharge power pipe circuit U 204.Wherein, cell voltage and battery temperature sensor U201 are for detecting battery voltage information VBAT and battery temperature information TBAT, its voltage signal acquisition end connects the output of battery battery core, its temperature signal collection end connects thermo-sensitive resistor output, and its transducing signal output connects the first transducing signal input of battery discharge control circuit U202.Battery discharge control circuit U202 is for judging whether the size meeting battery discharge condition and controlled discharge electric current, its the second transducing signal input connects the transducing signal output of die temperature sensors U203, and its control signal output connects the control signal input of discharge power pipe circuit U 204.Die temperature sensors U203 is used for detection chip temperature information, when chip temperature exceeds certain value, reduces discharging current gradually.Discharge power pipe circuit U 204, for big current path bleed off, is connected between the output of battery battery core and ground.

As shown in Figure 2; based on the battery protecting method of above-mentioned battery protecting circuit; it comprises: when portable power source is in standby; cell voltage and battery temperature sensor U201 continue to monitor cell voltage and battery temperature; when cell voltage more than 3.9V and battery temperature more than 60 DEG C time; battery discharge control circuit U202 star t-up discharge power transistor circuits U204, with the electric current of 150mA through control chip inner by battery electric quantity bleed off to.Because there is big current to flow continuously through from control chip inside, cause control chip self-heating.Now, die temperature sensors U203 opens and continues to monitor the temperature of control chip, and when more than 115 DEG C, battery discharge control circuit U202 controlled discharge power transistor circuits U204, reduces discharging current gradually.Still do not stop the temperature of control chip to rise if reduce discharging current, when more than 125 DEG C, battery discharge control circuit U202 controlled discharge power transistor circuits U204 stops electric discharge, waits for cooling itself, reenters discharge cycle.In addition, during chip discharge, cell voltage detected lower than 3.9V or battery temperature lower than 60 DEG C, chip exits discharge circuit immediately, and portable power source recovers holding state.

Physical circuit implementation based on each module of above-mentioned battery protecting circuit and operation principle are described in detail in detail below.

As shown in Figure 3, the cell voltage used of the present embodiment and battery temperature sensor U201 are made up of comparator CMP1, CMP2 and logical AND gate NAND1.Comparator CMP1 is used for cell voltage VBAT and compares with reference voltage 3.9V, works as VBAT>3.9V, the output VBAT_OVER=1 of comparator CMP1.Comparator CMP2 is used for the voltage signal VBAT_T of characterizing battery temperature information to compare with a reference source Vref0, choose reasonable battery thermo-sensitive resistor size and a reference source Vref0, make the output TBAT_OVER=1 as Tbat>60 DEG C, comparator CMP2.VBAT_OVER and TBAT_OVER through gate phase with, produce EN_BATDISCHG signal to battery discharge control circuit U202.

As shown in Figure 4, the die temperature sensors U203 used in the present embodiment is made up of PMOS PM3 ~ PM5, NMOS tube NM1 ~ NM2, resistance R3 ~ R4, transistor Q1 ~ Q2, comparator CMP3.PMOS PM3 ~ PM5 S pole separately meets power vd D, the G pole of PMOS PM3 connects the G pole of PMOS PM4 and the G pole of PMOS PM5, the D pole of PMOS PM3 connects the G pole of self and the D pole of NMOS tube NM3, the S pole of NMOS tube NM3 connects the e pole of transistor Q1, the b pole of transistor Q1 and c pole ground connection through resistance R3; The D pole of PMOS PM4 connects the D pole of NMOS tube NM4, and the G pole of NMOS tube NM4 connects the G pole of self D pole and NMOS tube NM3, and the S pole of NMOS tube NM4 connects the e pole of transistor Q2, the b pole of transistor Q2 and c pole ground connection; The D pole of PMOS PM5 is through resistance R4 ground connection, and the D pole of PMOS PM5 and the node of resistance R4 are as the output of chip temperature detectable voltage signals Ref_DIET; The positive input termination voltage signal Ref_DIET of comparator CMP3, negative input end access reference voltage signal Vref3, output detects the output judging signal TSEN_EN as chip temperature.

Wherein, PM3 ~ PM5, NM3 ~ NM4, R3, Q1 ~ Q2 forms PTAT (with PTAT) current generating circuit, and size of current is: wherein, k is Boltzmann constant, and q is electron charge, and j is the number ratio of transistor Q1 and Q2, and T is kelvin degree (also claiming absolute temperature), and R3 is resistance value, and except kelvin degree T, other parameter is constant.Above formula shows, electric current I is directly proportional to kelvin degree.This electric current I is injected on resistance R4 and produces voltage signal Ref_DIET, known, this voltage signal Ref_DIET is also directly proportional to kelvin degree.Ref_DIET compares with a reference signal Vref3 by comparator CMP3, rationally Vref3 is set, when chip temperature is more than 115 DEG C, send TSEN_EN signal, i.e. TSEN_EN=1, the partial circuit controlled by die temperature sensors U203 in battery discharge control circuit is started working (described below).

As shown in Figure 5, the battery discharge control circuit U202 that the present embodiment is used is made up of operational amplifier A MP1 ~ AMP2, PMOS PM0 ~ PM2, NMOS tube NM1 ~ NM2, resistance R1 ~ R2, simulation alternative selector AMUX.PMOS PM0 ~ PM2 S pole separately meets power vd D, and the G pole of PMOS PM0 connects the output of described cell voltage and battery temperature transducing signal EN_BATDISCHG, and D pole connects the D pole of PMOS PM1 and the D pole of NMOS tube NM1; The G pole of PMOS PM1 connects the G pole of self D pole and PMOS PM2; The D pole of PMOS PM2 connects the D pole of NMOS tube NM2, and the node of the D pole of PMOS PM2 and the D pole of NMOS tube NM2 is as the output of discharge control signal I4; The positive input termination reference voltage Vref 1 of operational amplifier A MP1, negative input end is through resistance R1 ground connection, and the output of cell voltage described in power supply termination and battery temperature transducing signal EN_BATDISCHG, exports the G pole of termination NMOS tube NM1; The S pole of NMOS tube NM1 is through resistance R1 ground connection; Two inputs of simulation alternative selector AMUX connect reference voltage Vref 2 and described chip temperature detectable voltage signals Ref_DIET output respectively, control chip temperature detection described in termination and judge signal TSEN_EN output, export the positive input terminal of termination operational amplifier A MP2; The negative input end of operational amplifier A MP2 is through resistance R2 ground connection, and power supply termination connects the detection of described chip temperature and judges signal TSEN_EN output, exports the G pole of termination NMOS tube NM2.

Wherein, AMP1, NM1, R1 form voltage signal and turn current signal circuit, and size of current is: aMP2, NM2, R2 form same circuit, and size of current is: pM1, PM2 form image current source circuit, and this circuit has output input current direct ratio device size specific characteristic, if W, L design parameter value is consistent, then exports input current ratio: wherein, m is the number ratio of PM2, PM1.PM0 is the enable pipe of pull-up of image current source circuit, and AMUX is simulation alternative selector, and TSEN_EN=0, exports and select Vref2, TSEN=1, exports and selects Ref_DIET.(TSEN_EN and Ref_DIET meaning will be introduced below)

The final output current signal I4 of this circuit, specific formula for calculation is:

Work as EN_BATDISCHG=.0, TSEN_EN=x (x represents free position),

I4＝0；

Work as EN_BATDISCHG=1, TSEN_EN=0,

$I4=I2-I3=m*I1-I3=m*\frac{Vref1}{R1}-\frac{Vref2}{R2};$

Work as EN_BATDISCHG=1, TSEN_EN=1,

$I4=I2-I3=m*I1-I3=m*\frac{Vref1}{R1}-\frac{\mathrm{Re}f\_DIET}{R2}.$

As shown in Figure 6, the discharge power pipe in the present embodiment is made up of NMOS tube NM3 ~ NM4, is a simple image current source circuit, and image current compares: n is the number ratio of N4, N3.NM4 is discharge power pipe, and discharging current flows to chip ground from VBAT through drain electrode and source electrode, and heating concentrates on this path, and its silicon area size is relatively large.

Composition graphs 3 to Fig. 6, when cell voltage more than 3.9V and battery temperature more than 60 DEG C time, EN_BATDISCHG=1, battery discharge control module open, control chip starts battery discharge, and discharging current size is $I8=n*I4=n*(I2-I3)=n*(m*\frac{Vref1}{R1}-\frac{Vref2}{R2}),$ The parameter such as appropriate design Vref1, Vref2, R1, R2, m, n, makes I5=150mA.Chip internal has big current to flow through, and self start heating, die temperature sensors module continues to monitor chip temperature, monitoring judgment formula: be out of shape: the value of appropriate design R3, R4, Vref3, j, makes as chip temperature T>115 DEG C, TSEN_EN=1.TSEN_EN signal participates in battery discharge control circuit, reduces chip discharge electric current gradually, to reduce the thermal pressure of chip.In this case, discharging current size is: $I8=n*I4=n*(I2-$ $I3)=n*(m*\frac{Vref1}{R1}-\frac{\mathrm{Re}f\_DIET}{R2})=n*\[m*\frac{Vref1}{R1}-\frac{KT}{q}*\frac{R4}{R3R2}*\ln \left(j\right)\],$ Can see, along with temperature T increases, electric current I 8 reduces gradually.Appropriate design Vref1, m, n, j, R1, R2, R3, R4 parameter value, when making T=125 DEG C, electric current I 8=0.Fig. 7 shows the oscillogram that the discharging current size based on foregoing description rises with chip temperature.

Need explanation, voltage-reference 3.9V, Vref0 involved in describing above ~ Vref4 is all called the module of band-gap reference from chip internal, acting as of this module exports the precision offset voltage source irrelevant with power supply and temperature and current source, and nearly all chip has integrated.

Above-described embodiment only have expressed a kind of exemplary embodiment of the present utility model, and it describes comparatively concrete and detailed, but therefore can not be interpreted as the restriction to the utility model the scope of the claims.To one skilled in the art, do not departing under concept thereof of the present utility model, the some distortion made or improvement, all belonging to exposure scope of the present utility model.

Claims (5)

1. a battery protecting circuit, it is characterized in that: comprise cell packet module and control chip, cell packet module inside comprises battery battery core and thermo-sensitive resistor, control chip comprises protection module, and protection module specifically comprises cell voltage and battery temperature sensor, battery discharge control circuit, die temperature sensors, discharge power pipe circuit; Cell voltage and battery temperature sensor are for detecting cell voltage and battery temperature information, its voltage signal acquisition end connects the output of battery battery core, its temperature signal collection end connects thermo-sensitive resistor output, and its transducing signal output connects the first transducing signal input of battery discharge control circuit; Battery discharge control circuit is for judging whether the size meeting battery discharge condition and controlled discharge electric current, its the second transducing signal input connects the transducing signal output of die temperature sensors, and its control signal output connects the control signal input of discharge power pipe circuit; Die temperature sensors is used for the temperature information of detection control chip; Discharge power pipe circuit is used for big current path bleed off, is connected between the output of battery battery core and ground.

2. battery protecting circuit according to claim 1, is characterized in that: described cell voltage and battery temperature sensor are made up of comparator CMP1, comparator CMP2 and logical AND gate NAND1; Two inputs of comparator CMP1 access a battery battery core output end voltage VBAT and preset reference voltage Vset respectively; Two inputs of comparator CMP2 access a voltage signal VBAT_T and a reference source Vref0 of described thermo-sensitive resistor output respectively; The output of comparator CMP1 and comparator CMP2 all accesses the input of logical AND gate NAND1, and the output of logical AND gate NAND1 is as the output of cell voltage and battery temperature transducing signal EN_BATDISCHG.

3. battery protecting circuit according to claim 2, is characterized in that: described die temperature sensors is made up of PMOS PM3 ~ PM5, NMOS tube NM1 ~ NM2, resistance R3 ~ R4, transistor Q1 ~ Q2, comparator CMP3; PMOS PM3 ~ PM5 S pole separately meets power vd D, the G pole of PMOS PM3 connects the G pole of PMOS PM4 and the G pole of PMOS PM5, the D pole of PMOS PM3 connects the G pole of self and the D pole of NMOS tube NM3, the S pole of NMOS tube NM3 connects the e pole of transistor Q1, the b pole of transistor Q1 and c pole ground connection through resistance R3; The D pole of PMOS PM4 connects the D pole of NMOS tube NM4, and the G pole of NMOS tube NM4 connects the G pole of self D pole and NMOS tube NM3, and the S pole of NMOS tube NM4 connects the e pole of transistor Q2, the b pole of transistor Q2 and c pole ground connection; The D pole of PMOS PM5 is through resistance R4 ground connection, and the D pole of PMOS PM5 and the node of resistance R4 are as chip temperature detectable voltage signals Ref_DIET output; The positive input termination voltage signal Ref_DIET of comparator CMP3, negative input end access reference voltage signal Vref3, output detects as chip temperature and judges signal TSEN_EN output.

4. battery protecting circuit according to claim 3, is characterized in that: battery discharge control circuit is made up of operational amplifier A MP1 ~ AMP2, PMOS PM0 ~ PM2, NMOS tube NM1 ~ NM2, resistance R1 ~ R2, simulation alternative selector AMUX; PMOS PM0 ~ PM2 S pole separately meets power vd D, and the G pole of PMOS PM0 connects the output of described cell voltage and battery temperature transducing signal EN_BATDISCHG, and D pole connects the D pole of PMOS PM1 and the D pole of NMOS tube NM1; The G pole of PMOS PM1 connects the G pole of self D pole and PMOS PM2; The D pole of PMOS PM2 connects the D pole of NMOS tube NM2, and the node of the D pole of PMOS PM2 and the D pole of NMOS tube NM2 is as the output of discharge control signal I4; The positive input termination reference voltage Vref 1 of operational amplifier A MP1, negative input end is through resistance R1 ground connection, and the output of cell voltage described in power supply termination and battery temperature transducing signal EN_BATDISCHG, exports the G pole of termination NMOS tube NM1; The S pole of NMOS tube NM1 is through resistance R1 ground connection; Two inputs of simulation alternative selector AMUX connect reference voltage Vref 2 and described chip temperature detectable voltage signals Ref_DIET output respectively, control chip temperature detection described in termination and judge signal TSEN_EN output, export the positive input terminal of termination operational amplifier A MP2; The negative input end of operational amplifier A MP2 is through resistance R2 ground connection, and power supply termination connects the detection of described chip temperature and judges signal TSEN_EN output, exports the G pole of termination NMOS tube NM2.

5. battery protecting circuit according to claim 4, is characterized in that: described discharge power pipe circuit is made up of NMOS tube NM5 ~ NM6; The D pole access discharge control signal I4 of NMOS tube NM5, S pole ground connection, G pole connects the G pole of self D pole and NMOS tube NM6; The D pole of NMOS tube NM6 connects the output of battery battery core, S pole ground connection.