Lithium Power GaugeIC Conservative repeatable measurement availab

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Lithium Power GaugeIC Conservative repeatable measurement availab

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bq2050
Lithium Power GaugeIC
Conservative repeatable measurement available capacity Lithium rechargeable batteries Designed battery pack integration
General Description
bq2050 Lithium Power GaugeIC intended batterypack in-system installation maintain accurate record available battery capacity. monitors voltage drop across sense resistor connected series between negative battery terminal ground determine charge discharge activity battery. Compensations battery temperature rate charge discharge applied charge, discharge, self-discharge calculations provide available capacity information across wide range operating conditions. Battery capacity automatically recalibrated, "learned," course discharge cycle from full empty. Nominal available capacity directly indicated using five-segment display. These segments
used graphically indicate available capacity. bq2050 supports simple single-line bidirectional serial link external processor (common ground). bq2050 outputs battery information response external commands over serial link. bq2050 operate directly from cell (VBAT 3V). With output external transistor, simple, inexpensive regulator built systems with more than series cell. Internal registers include available capacity, temperature, scaled available energy, battery battery status, programming settings. support subassembly testing, outputs also controlled. external processor also overwrite some bq2050 power gauge data registers.
120µA typical operating current Small size enables implementations little square inch
Integrate within system stand-alone device
Display capacity singlewire serial communication port direct drive LEDs
Measurements compensated current temperature Self-discharge compensation using internal temperature sensor 16-pin narrow SOIC
Connections
Names
LCOM SEG1/PROG1 common output segment program input segment program input SEG3/PROG3 SEG4/PROG4 SEG5/PROG5
PN-93
Voltage reference output connect Serial communications input/output Register backup input Battery sense input Display control input Sense resistor input 3.0-6.5V System ground
LCOM SEG1/PROG SEG2/PROG SEG3/PROG SEG4/PROG SEG5/PROG PROG
DISP
SEG2/PROG2
segment program input segment program input segment program input Program input
DISP
16-Pin Narrow SOIC
PROG6
Sept. 1996
bq2050
Descriptions
LCOM common output Open-drain output switches source current LEDs. switch during initialization allow reading soft pull-up pull-down program resistors. LCOM also high impedance when display off. SEG1- SEG5 display segment outputs (dual function with PROG1-PROG6) Each output activate sink current sourced from LCOM. PROG1- PROG2 Programmed full count selection inputs (dual function with SEG1-SEG2) These three-level input pins define programmed full count (PFC) thresholds described Table PROG3- PROG4 Power gauge rate selection inputs (dual function with SEG3-SEG4) These three-level input pins define scale factor described Table PROG5 Self-discharge rate selection (dual function with SEG5) This three-level input defines selfdischarge battery compensation factors shown Table PROG6 Capacity initialization selection This three-level defines battery state charge reset shown Table connect DISP Sense resistor input voltage drop (VSR) across sense resistor monitored integrated over time interpret charge discharge activity. input tied between negative terminal battery sense resistor. indicates discharge, indicates charge. effective voltage drop, VSRO, seen bq2050 Display control input DISP high disables display. DISP tied allows PROGX connect directly instead through pull-up pull-down resistor. DISP floating allows display active during charge. DISP activates display. Table Secondary battery input This input monitors battery cell voltage potential through high-impedance resistive divider network end-of-discharge voltage (EDV) thresholds, battery removed. Register backup input This used provide backup potential bq2050 registers during periods when storage capacitor battery connected RBI. Serial This open-drain bidirectional pin. Voltage reference output regulator provides voltage reference output optional micro-regulator. Supply voltage input Ground
Sept. 1996
bq2050 Functional Description
General Operation
bq2050 determines battery capacity monitoring amount current input removed from rechargeable battery. bq2050 measures discharge charge currents, measures battery voltage, estimates self-discharge, monitors battery battery voltage thresholds, compensates temperature charge/discharge rates. current measurement made monitoring voltage across small-value series sense resistor between negative battery terminal ground. estimate scaled available energy made using remaining average battery voltage during discharge cycle remaining nominal available charge. scaled available energy measurement corrected environmental operating conditions. Figure shows typical battery pack application bq2050 using display capability chargestate indicator. bq2050 configured display capacity relative display mode. relative display mode uses last measured discharge capacity battery battery "full" reference. push-button display feature available momentarily enabling display. bq2050 monitors charge discharge currents voltage across sense resistor (see Figure filter between negative battery terminal required rate change battery current great.
Figure Battery Pack Application Diagram-LED Display
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bq2050
Voltage Thresholds
conjunction with monitoring charge/discharge currents, bq2050 monitors battery potential through pin. voltage determined through resistor-divider network following equation: (hex) Temperature Range -30°C -30°C -20°C -20°C -10°C -10°C 10°C 10°C 20°C 20°C 30°C 30°C 40°C 40°C 50°C 50°C 60°C 60°C 70°C 70°C 80°C 80°C
where number cells, connected positive battery terminal, connected negative battery terminal. single-cell battery voltage monitored end-of-discharge voltage (EDV). threshold levels used determine when battery reached "empty" state. thresholds bq2050 programmable with default values fixed EDV1 (early warning) 1.52V EDVF (empty) 1.47V below either thresholds, assoc iate flag latc remains latched, independent VSB, until next valid charge. value also available over serial port. During discharge charge, bq2050 monitors various thresholds used compensate charge discharge rates. Refer count compensation section details. monitoring disabled discharge rate greater than (typical) resumes second after rate falls below
Input
input intended used with storage capacitor external supply provide backup potential internal bq2050 registers when drops below 3.0V. output when above 3.0V. diode required isolate external supply.
Layout Considerations
bq2050 measures voltage differential between pins. (the offset voltage pin) greatly affected board layout. optimal results, board layout should follow strict rule single-point ground return. Sharing high-current ground with small signal ground causes undesirable noise small signal nodes. Additionally: capacitors should placed close possible pins, respectively, their paths should short possible. high-quality ceramic capacitor 0.1µf recommended VCC. sense resistor capacitor should placed close possible pin. sense resistor (RS) should close possible bq2050.
Reset
bq2050 reset either removing grounding seconds writing 0x80 register 0x39.
Temperature
bq2050 internally determines temperature 10°C steps centered from approximately -35°C +85°C. temperature steps used adapt charge discharge rate compensations, self-discharge counting, available charge display translation. temperature range available over serial port 10°C increments shown following table:
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bq2050
Gauge Operation
operational overview diagram Figure illustrates operation bq2050. bq2050 accumulates measure charge discharge currents, well estimation self-discharge. Charge discharge currents temperature rate compensated, whereas self-discharge only temperature compensated. main counter, Nominal Available Capacity (NAC), represents available battery capacity given time. Battery charging increments register, while battery discharging self-discharge decrement register increment (Discharge Count Register). Discharge Count Register (DCR) used update Last Measured Discharge (LMD) register only complete battery discharge from full empty occurs without partial battery charges. Therefore, bq2050 adapts capacity determination based actual conditions discharge. battery's initial capacity equal Programmed Full Count (PFC) shown Table Until updated, counts beyond this threshold during subsequent charges. This approach allows gauge charger-independent compatible with type charge regime. Last Measured Discharge (LMD) learned battery capacity: last measured discharge capacity battery. initialization (application battery replacement), PFC. During subsequent discharges, updated with latest measured capacity Discharge Count Register (DCR) representing discharge from full below EDV1. qualified discharge necessary capacity transfer from register. also serves 100% reference threshold used relative display mode.
Figure Operational Overview
Sept. 1996
bq2050
Programmed Full Count (PFC) initial battery capacity: initial gauge rate values programmed using PROG1-PROG4. bq2050 configured given application selecting value from Table correct determined multiplying rated battery capacity sense resistor value: Battery capacity (mAh) sense resistor (mVh) Selecting slightly less than rated capacity provides conservative capacity reference until bq2050 "learns" capacity reference. Example: Selecting Value Given: Sense resistor 0.05 Number cells Capacity 1000mAh, Li-Ion battery, coke-anode Current range 50mA Relative display mode Serial port only Self-discharge NAC/512 25°C Voltage drop over sense resistor 2.5mV 50mV Nominal discharge voltage 3.6V Therefore: 1000mAh 0.05 50mVh
Table bq2050 Programming
Connection Note: PROG5 Compensation/ Self-Discharge Table 4/Disabled Table Table
NAC/ NAC/
PROG6 Reset
DISP Display State LEDs disabled LEDs when charging LEDs sec.
PROG5 PROG6 states independent.
Table bq2050 Programmed Full Count Selections
Programmed Full Count (PFC) 49152 45056 40960 36864 33792 30720 27648 25600 22528
PROGx
PROG4 PROG3 SCALE 1/80
PROG4 Units mVh/ count
Sept. 1996
PROG3 PROG3 PROG3 PROG3 PROG3 SCALE 1/160 SCALE 1/320 96.0 86.4 80.0 70.4 22.5 SCALE 1/640 76.8 70.4 64.0 57.6 53.0 48.0 43.2 40.0 35.2 11.25 SCALE 1/1280 38.4 35.2 32.0 28.8 26.4 24.0 21.6 20.0 17.6 SCALE 1/2560 19.2 17.6 16.0 14.4 13.2 12.0 10.8 10.0
equivalent counts/sec. (nom.)
bq2050
Select: 30720 counts 48mVh PROG1 float PROG2 PROG3 high PROG4 float PROG5 float PROG6 float initial full battery capacity 48mVh (960mAh) until bq2050 "learns" capacity with qualified discharge from full EDV1. Nominal Available Capacity (NAC): counts during charge maximum value down during discharge self-discharge reset initialization first valid charge following discharge EDV1. prevent overstatement charge during periods overcharge, stops incrementing when LMD. Discharge Count Register (DCR): counts during discharge independent could continue increasing after decremented Prior (empty battery), both discharge self-discharge increment DCR. After only discharge increments DCR. resets when LMD. does roll over stops counting when reaches FFFFh. value becomes value first charge after valid discharge VEDV1 valid charge initiations (charges greater than counts, where VSRO VSRQ) occurred during period between EDV1 detected. self-discharge count more than 4096 counts PFC, specific percentage threshold determined PFC). temperature when EDV1 level reached during discharge. valid discharge flag (VDQ) indicates whether present discharge valid update. Scaled Available Energy (SAE): useful determining available energy within battery, provide more useful capacity reference battery chemistries with sloped voltage profiles during discharge. converted value using following formula: E(mWh) (SAEH SAEL)
Sept. 1996
SCALE (RB1 RB2) where RB1, resistor values ohms. SCALE selected scale from Table SAEH SAEL digital values read Compensated Available Capacity (CAC) counts similar NAC, contains available capacity compensated discharge rate temperature.
Charge Counting
Charge activity detected based positive voltage input. charge activity detected, bq2050 increments rate proportional and, enabled, activates display. Charge actions increment after compensation temperature. bq2050 determines charge activity sustained continuous rate equivalent VSRO VSRQ. valid charge equates sustained charge activity greater than counts. Once valid charge detected, charge counting continues until VSRO (VSR VOS) falls below SRQ. 210µV, described Digital Magnitude Filter section.
Discharge Counting
Discharge activity detected based negative voltage input. discharge counts where VSRO VSRD cause register decrement increment. VSRD -200 described Digital Magnitude Filter section.
Self-Discharge Estimation
bq2050 continuously decrements increments self-discharge based time temperature. self-discharge count rate programmed nominal 1/512 disabled. This rate battery whose temperature between 20°-30°C. register cannot decremented below
Count Compensations
Discharge Compensation
Corrections rate discharge, temperature, anode type made adjusting internal compensation factor. This factor based measured rate discharge battery. Tables outline correction factor typically used graphite anode Li-Ion batteries, Tables outline factors typically used coke anode Li-Ion batteries. compensation factor applied based discharge rate temperature.
bq2050
Charge Compensation Table Graphite Anode
Approximate Discharge Rate 0.5C 0.5C Discharge Compensation Factor 1.00 1.05 bq2050 applies following temperature compensation during charge: Temperature Compensation Factor 0.95 1.00
Efficiency 100%
Temperature 10°C 10°C
Efficiency 100%
This compensation applies both types Li-Ion cells.
Table
Temperature Compensation Factor 1.00 1.10 1.35 2.50
Self-Discharge Compensation
self-discharge compensation programmed nominal rate 1/512 day. This rate battery within 20-30°C temperature range. This rate varies across ranges from <10°C >70°C, changing with each higher temperature (approximately 10°C). Table below:
Temperature 10°C 10°C -10°C -10°C
Efficiency 100%
Table Self-Discharge Compensation
Typical Rate Temperature Range 10°C PROG5
NAC/ NAC/ 2048 1024
Table Coke Anode
Approximate Discharge Rate <0.5C 0.5C Discharge Compensation Factor 1.00 1.15
10-20°C 20-30°C 30-40°C
NAC/ NAC/ NAC/
Efficiency 100%
40-50°C 50-60°C 60-70°C 70°C
NAC/ NAC/ NAC/
Self-discharge disabled connecting PROG5
Table
Temperature Compensation Factor 1.00 1.25 2.00 8.00
Digital Magnitude Filter
bq2050 digital filter eliminate charge discharge counting below threshold. bq2050 setting 200µV VSRD 210µV VSRQ.
Temperature 10°C 10°C -10°C -10°C
Efficiency 100%
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bq2050
Table bq2050 Current-Sensing Errors
Symbol Parameter Offset referred Integrated non-linearity error Integrated nonrepeatability error Typical Maximum Units DISP VCC. 0.1% above below 25°C volt above below 4.25V. Measurement repeatability given similar operating conditions. Notes
Error Summary
Capacity Inaccurate
susceptible error initialization updates occur. initialization, value includes error between programmed full capacity actual capacity. This error present until valid discharge occurs updated (see description page other cause error battery wear-out. battery ages, measured capacity must adjusted account changes actual battery capacity. Capacity Inaccurate counter (CPI) maintained incremented each time valid charge occurs (qualified NAC; register description) reset whenever updated from DCR. counter does wrap around stops counting 255. capacity inaccurate flag (CI) been updated following valid charges.
communication protocol asynchronous return-toone. Command data bytes consist stream eight bits that have maximum transmission rate bits/sec. least-significant command data byte transmitted first. protocol simple enough that implemented most host processors using either polled interrupt processing. Data input from bq2050 sampled using pulse-width capture timers available some microcontrollers. communication error occurs, e.g. tCYCB 6ms, bq2050 should sent BREAK reinitiate serial interface. BREAK detected when driven logic-low state time, greater. should then returned normal ready-high logic state time, tBR. bq2050 ready receive command from host processor. return-to-one data frame consists three distinct sections. first section used start transmission either host bq2050 taking logic-low state period, tSTRH,B. next section actual data transmission, where data should valid period, tDSU, after negative edge used start communication. data should held period, tDV, allow host bq2050 sample data bit. final section used stop transmission returning logic-high state least period, tSSU, after negative edge used start communication. final logic-high state should held until period, tSV, allow time ensure that transmission stopped properly. timings data break communication given serial communication timing specification illustration sections. Communication with bq2050 always performed with least-significant being transmitted first. Figure shows example communication sequence read bq2050 register.
Current-Sensing Error
Table illustrates current-sensing error function VSRO. digital filter eliminates charge discharge counts register when VSRO between VSRQ VSRD.
Communicating With bq2050
bq2050 includes simple single-pin plus return) serial data interface. host processor uses interface access various bq2050 registers. Battery characteristics easily monitored adding single contact battery pack. open-drain bq2050 should pulled host system, left floating serial interface used. interface uses command-based protocol, where host processor sends command byte bq2050. command directs bq2050 either store next eight bits data received register specified command byte output eight bits data specified command byte.
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bq2050
Figure Typical Communication With bq2050
bq2050 Registers
bq2050 command status registers listed Table described below.
Primary Status Flags Register (FLGS1)
read-only FLGS1 register (address=01h) contains primary bq2050 flags. charge status flag (CHGS) asserted when valid charge rate detected. Charge rate deemed valid when VSRO VSRQ. VSRO less than VSRQ discharge activity clears CHGS. CHGS values are: FLGS1 Bits CHGS
Command Register (CMDR)
write-only CMDR register accessed when eight valid command bits have been received bq2050. CMDR register contains fields: Command address command register used select whether received command read write function. values are: CMDR Bits
Where CHGS Either discharge activity detected VSRO VSRQ VSRO VSRQ
Where bq2050 outputs requested register contents specified address portion CMDR. following eight bits should written register specified address portion CMDR.
battery replaced flag (BRP) asserted whenever bq2050 reset either application serial port command. reset when either valid charge action increments equal LMD, valid charge action detected after EDV1 flag asserted. signifies that device been reset. values are: FLGS1 Bits
lower seven-bit field CMDR contains address portion register accessed. Attempts write invalid addresses ignored. CMDR Bits (LSB)
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bq2050
Table bq2050 Command Status Registers
Symbol CMDR Register Name Loc. Read/ Control Field (hex) Write 7(MSB) Write Read Read CHGS TMP3 TMP2 TMP1 TMP0 EDV1 0(LSB) EDVF
Command register Primary status flags FLGS1 register Temperature register Nominal available NACH capacity high byte register Nominal available NACL capacity byte register Battery BATID identification register Last measured discharge register Secondary status flags FLGS2 register Program pullPPD down register Program pull-up register CACH CACL Capacity inaccurate count register Battery voltage register End-of-discharge threshold select register Compensated available capacity high byte register Compensated available capacity byte register Scaled available energy high byte register Scaled available energy byte register Reset register used
NACH7 NACH6 NACH5 NACH4 NACH3 NACH2 NACH1 NACH0
Read NACL7 NACL6 NACL5 NACL4 NACL3 NACL2 NACL1 NACL0
BATID7 BATID6 BATID5 BATID4 BATID3 BATID2BATID1 BATID0 Read Read Read Read Read LMD7 CPI7 VSB7 VTS7 LMD6 CPI6 VSB6 VTS6 LMD5 PPD6 PPU6 CPI5 VSB5 VTS5 LMD4 PPD5 PPU5 CPI4 VSB4 VTS4 LMD3 PPD4 PPU4 CPI3 VSB3 VTS3 LMD2 LMD1 PPD3 PPU3 CPI2 VSB2 VTS2 PPD2 PPU2 CPI1 VSB1 VTS1 LMD0 OVLD PPD1 PPU1 CPI0 VSB0 VTS0
Read CACH7 CACH6 CACH5 CACH4 CACH3 CACH2 CACH1 CACH0
Read CACL7 CACL6 CACL5 CACL4 CACL3 CACL2 CACL1 CACL0
SAEH SAEL Note:
Read SAEH7 SAEH6 SAEH5 SAEH4 SAEH3 SAEH2 SAEH1 SAEH0 Read SAEL7 SAEL6 SAEL5 SAEL4 SAEL3 SAEL2 SAEL1 SAEL0 Write
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bq2050
Where Battery charged until discharged until EDV1 flag asserted bq2050 reset warn user that loss battery power imminent. EDV1 flag latched until valid charge been detected. EDV1 threshold externally controlled register (see Voltage Threshold Register this page). EDV1 values are: FLGS1 Bits EDV1
capacity inaccurate flag (CI) used warn user that battery been charged substantial number times since been updated. flag asserted 64th charge after last update when bq2050 reset. flag cleared after update. values are: FLGS1 Bits
Where EDV1 Valid charge action detected, providing that discharge rate
Where When updated with valid full discharge After 64th valid charge action with updates bq2050 reset
valid discharge flag (VDQ) asserted when bq2050 discharged from NAC=LMD. flag remains until either updated three actions that clear occurs: self-discharge count register (SDCR) exceeded maximum acceptable value (4096 counts) update. valid charge action sustained VSRO VSRQ least counts. EDV1 flag temperature below values are: FLGS1 Bits
final end-of-discharge warning flag (EDVF) flag used warn that battery power failure condition. segment drivers turned off. EDVF flag latched until valid charge been detected. EMPTY also forced high-impedance state assertion EDVF. host system pull EMPTY high, which used disable circuitry prevent deep-discharge battery. EDVF threshold 50mV below EDV1 threshold. EDVF values are: FLGS1 Bits EDVF
Where EDVF Valid charge action detected, (VTS 50mV) (VTS 50mV) providing discharge rate
Temperature Register (TMP)
read-only register (address=02h) contains battery temperature. Temperature Bits
Where SDCR 4096, subsequent valid charge action detected, EDV1 asserted with temperature less than first discharge after
TMP4 TMP3 TMP2 TMP1
first end-of-discharge warning flag (EDV1) warns user that battery almost empty. first segment pin, SEG1, modulated rate display enabled once EDV1 asserted, which should
bq2050 contains internal temperature sensor. temperature used charge discharge efficiency factors well adjust self-discharge coefficient. temperature register contents translated shown Table
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bq2050
Table Temperature Register
TMP3 TMP2 TMP1 TMP0 Temperature -30°C -30°C -20°C -20°C -10°C -10°C 10°C 10°C 20°C 20°C 30°C 30°C 40°C 40°C 50°C 50°C 60°C 60°C 70°C 70°C 80°C 80°C They used determine current discharge regime follows: TMPGG Gauge Bits Discharge Rate DRATE 0.5C 0.5C DRATE
Last Measured Discharge Register (LMD)
read/write register (address=05h) that bq2050 uses measured full reference. bq2050 adjusts based measured discharge capacity battery from full empty. this bq2050 updates capacity battery. during bq2050 reset.
Secondary Status Flags Register (FLGS2)
read-only FLGS2 register (address=06h) contains secondary bq2050 flags. discharge rate flags, DR2-0, bits 6-4. FLGS2 Bits
bq2050 calculates gauge bits, GG3-GG0 function CACH LMD. results calculation give available capacity 1/16 increments from 15/16.
Nominal Available Charge Registers (NACH/NACL)
read/write NACH high-byte register (address=03h) read-only NACL low-byte register (address=17h) main gauging register bq2050. registers incremented during charge actions decremented during discharge self-discharge actions. correction factors charge/discharge efficiency applied automatically NAC. NACH NACL during bq2050 reset. Writing registers affects available charge counts and, therefore, affects bq2050 gauge operation. write registers value greater than LMD.
overload flag (OVLD) asserted when discharge rate excess detected. OVLD remains asserted long condition persists cleared seconds after rate drops below overload condition used stop sampling battery terminal characteristics end-of-discharge determination. FLGS2 Bits
OVLD
Program Pull-Down Register (PPD)
read-only register (address=07h) contains some programming information bq2050. segment drivers, SEG1-6, have corresponding register location, PPD1-6. given location pull-down resistor been detected corresponding segment driver. example, SEG1 SEG4 have pull-down resistors, contents xx001001.
Battery Identification Register (BATID)
ead/w rite BATID register (addr ess=04h) available system determine type battery pack. BATID contents retained long greater than contents BATID have effect operation bq2050. There default setting this register.
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Program Pull-Up Register (PPU)
read-only register (address=08h) contains rest programming information bq2050. segment drivers, SEG1-6, have corresponding register location, PPU1-6. given location pullup resistor been detected corresponding segment
bq2050
driver. example, SEG3 SEG6 have pull-up resistors, contents xx100100. PPD/PPU Bits Register Bits VTS7 VTS6 VTS5 VTS4 VTS3 VTS2 VTS1 VTS0
PPU6 PPU5 PPU4 PPU3 PPU2 PPU1 PPD6 PPD5 PPD4 PPD3 PPD2 PPD1
Compensated Available Charge Registers (CACH/CACL)
read-only CACH high-byte register (address 0Dh) read-only CACL low-byte register (address 0Eh) represent available charge compensated discharge rate temperature. CACH CACL piece-wise corrections outlined Tables will vary conditions change. registers affected discharge rate temperature.
Capacity Inaccurate Count Register (CPI)
read-only register (address=09h) used indicate number times battery been charged without update. Because capacity rechargeable battery varies with operating conditions, bq2050 adapts changing capacity over time. complete discharge from full (NAC=LMD) empty (EDV1=1) required perform update assuming there have been intervening valid charges, temperature greater than equal 0°C, self-discharge counter less than 4096 counts. register incremented every time valid charge detected. When 0.94 LMD, however, register increments first valid charge; does increment again valid charge until 0.94 LMC. This prevents continuous trickle charging from incrementing self-discharge decrements NAC. register increments without rolling over. When contents incremented capacity inaccurate flag, asserted FLGS1 register. register reset whenever update register performed, flag also cleared.
Scaled Available Energy Registers (SAEH/SAEL)
read-only SAEH high-byte register (address 0Fh) read only SAEL low-byte register (address 10h) used scale battery voltage value which translated watt-hours remaining under present conditions. SAEL SAEH converted using formula page
Reset Register (RST)
reset register (address 39h) enables softwarecontrolled reset device. writing register contents from 80h, bq2050 reset performed. Setting other than most-significant register allowed results improper operation bq2050. Resetting bq2050 sets following: CPI, VDQ, NACH, NACL Note: Self-discharge disabled when PROG5
Battery Voltage Register (VSB)
read-only battery voltage register used read single-cell battery voltage pin. register (address 0Bh) updated approximately once second with present value battery voltage. 2.4V (VSB/256). Register Bits
Display
bq2050 directly display capacity information using low-power LEDs. LEDs used, program pins should resistively tied program high program low, respectively. bq2050 displays battery charge state relative mode. relative mode, battery charge represented percentage LMD. Each segment represents LMD. capacity display also adjusted present battery temperature. temperature adjustment reflects
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VSB7 VSB6 VSB5 VSB4 VSB3 VSB2 VSB1 VSB0
Voltage Threshold Register (VTS)
end-of-discharge threshold voltages (EDV1 EDVF) using register (address 0Ch). read/write register sets EDV1 trip point. EDVF 50mV below EDV1. default value register A2h, representing EDV1 1.52V EDVF 1.47V. EDV1 2.4V (VTS/256).
bq2050
available capacity given temperature does affect register. temperature adjustments detailed CACH CACL register descriptions. When DISP tied VCC, SEG1-5 outputs inactive. When DISP left floating, display becomes active whenever bq2050 detects charge progress VSRO VSRQ When pulled low, segment outputs become active period four seconds, seconds. segment outputs modulated banks, with segments alternating with segments segment outputs modulated approximately 100Hz with each segment bank active period. SEG1 blinks rate whenever been detected below VEDV1 (EDV1 indicating lowbattery condition. below VEDVF (EDVF disables display output.
Microregulator
bq2050 operate directly from cell. micropower source bq2050 inexpensively built using external resistor accommodate greater number cells; Figure
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bq2050
Absolute Maximum Ratings
Symbol other pins Parameter Relative Relative Relative Minimum -0.3 -0.3 -0.3 Maximum +7.0 +7.0 +8.5 Unit Current limited (see Figure Minimum series resistor should used protect case shorted battery (see bq2050 application note details). Commercial Industrial Notes
Relative
-0.3
+7.0
TOPR
Operating temperature
Note:
Permanent device damage occur Absolute Maximum Ratings exceeded. Functional operation should limited Recommended Operating Conditions detailed this data sheet. Exposure conditions beyond operational limits extended periods time affect device reliability.
Voltage Thresholds TOPR; 6.5V)
Symbol VEDVF VEDV1 VSRO VSRQ VSRD VMCV Note: Parameter Final empty warning First empty warning sense range Valid charge Valid discharge Maximum single-cell voltage Minimum 1.44 1.49 -300 2.20 Typical 1.47 1.52 2.25 Maximum 1.50 1.55 +2000 -200 2.30 Unit (see note) (see note) Notes
affected board layout. Proper layout guidelines should followed optimal performance. "LayoutConsiderations."
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bq2050
Electrical Characteristics TOPR)
Symbol VREF RREF RSBmax IDISP ILCOM IRBI VOLSL VOLSH VOHLCL VOHLCH IOLS VIHDQ VILDQ RPROG RFLOAT Note:
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Parameter Supply voltage Reference 25°C Reference -40°C +85°C Reference input impedance Normal operation Battery input input impedance DISP input leakage LCOM input leakage data retention current Internal pulldown Sense resistor input input impedance Logic input high Logic input Logic input SEGX output low, SEGX output low, high LCOM output high, LCOM output high, high PROG1-6 input high current PROG1-6 input current SEG1-5 sink current Open-drain sink current Open-drain output input high input Soft pull-up pull-down resistor value (for programming) Float state external impedance voltages relative VSS.
Minimum Typical -0.2 -0.3 float 4.25
Maximum float 11.0
Unit
Notes excursion from 2.0V 3.0V initializes unit. IREF IREF VREF 3.0V, 4.25V, 6.5V, VDISP DISP VRBI discharge; charge -200mV PROG1-PROG6 PROG1-PROG6 PROG1-PROG6 IOLS 1.75mA SEG1-SEG5 6.5V, IOLS 11.0mA SEG1-SEG5 IOHLCOM -5.25mA 6.5V, IOHLCOM -33.0mA VPROG VCC/2 VPROG VCC/2 VOHLCH 0.6V VOLSH 0.4V 0.3V 5mA, PROG1-PROG6 PROG1-PROG6
IOHLCOM LCOM source current
bq2050
Serial Communication Timing Specification TOPR)
Symbol tCYCH tCYCB tSTRH tSTRB tDSU tSSU Note: Parameter Cycle time, host bq2050 Cycle time, bq2050 host Start hold, host bq2050 Start hold, bq2050 host Data setup Data hold Data valid Stop setup Stop hold Stop valid Break Break recovery Minimum 1.50 2.95 Typical Maximum 2.25 Unit Notes note
open-drain should pulled least host system proper operation. left floating serial interface used.
Serial Communication Timing Illustration
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bq2050
Data Sheet Revision History
Change Note: Page Description Changed reset procedure Deleted reset register Changed values VEDVF: VEDV1: Changed values Reinserted reset register Maximum offset VCC: VOS: Min. 1.45; Max. 1.49 Min. 1.44; Max. 1.50 Min. 1.50; Min. 1.49 Min. 2.5; Min. Max. Max. Was: Nature Change Reset issuing command over serial port Reset removing grounding
Change June 1995 changes from Dec. 1994. Change Sept. 1996 changes from June 1995.
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bq2050
Ordering Information
bq2050
Temperature Range:
blank Commercial +70°C) Industrial (-40 +85°C)*
Package Option:
16-pin narrow SOIC
Device:
bq2050 Power Gauge Contact factory availability.
Sept. 1996
bq2050
16-Pin SOIC Narrow (SN)
16-Pin (0.150" SOIC)
Inches
Millimeters Min. 1.52 0.10 0.33 0.18 9.78 3.81 1.14 5.72 0.38 Max. 1.78 0.25 0.51 0.25 10.16 4.06 1.40 6.22 0.89
Dimension
Min. 0.060 0.004 0.013 0.007 0.385 0.150 0.045 0.225 0.015
Max. 0.070 0.010 0.020 0.010 0.400 0.160 0.055 0.245 0.035
.004
Sept. 1996
bq2050
BENCHMARQ Microelectronics, Inc. 17919 Waterview Parkway Dallas, Texas 75252 Fax: (972) 437-9198 Tel: (972) 437-9195 http://www.benchmarq.com
Copyright 1996, BENCHMARQ Microelectronics, Inc. rights reserved. part this data sheet reproduced form means, without express permission from Benchmarq. Benchmarq reserves right make changes products without notice. Benchmarq assumes responsibility products circuitry described within. license intellectual property (patents, copyrights, other rights) owned Benchmarq other parties granted implied. Benchmarq does authorize components life-support systems where failure malfunction cause injury user. Benchmarq components used life-support systems, user assumes responsibilities indemnifies Benchmarq from liability damages. Benchmarq Power Gauge registered trademarks BENCHMARQ Microelectronics, Inc. Printed U.S.A.
Sept. 1996

Lithium Power GaugeIC Conservative repeatable measurement availab

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