Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - battery management Charge indicator Li-Ion, NiCd, NiMH SOIC 16 N Surface-mount

Features

➤

Provides accurate measurement

of available charge in NiCd,

NiMH, and Li-Ion batteries

➤

Supports SBS v1.0 data set and

two-wire interface

➤

Monitors charge FET in Li-Ion

pack protection circuit

➤

Designed for battery pack inte

gration

Low operating current

Complete circuit can fit on less

than ¾ square inch of PCB

space

➤ Supports SBS charge control

commands for NiCd, NiMH, and

Li-Ion

➤ Drives a four-segment LED dis-

play for remaining capacity

indication

➤ 16-pin narrow SOIC

General Description

The bq2040 Gas Gauge IC With

SMBus Interface is intended for

battery-pack or in-system installa

tion to maintain an accurate record

of available battery charge. The

bq2040 directly supports capacity

monitoring for NiCd, NiMH, and Li-

Ion battery chemistries.

The bq2040 uses the System Man

agement Bus v1.0 (SMBus) protocol

and supports the Smart Battery

Data (SBData) commands. The

bq2040 also supports the SBData

charge control functions. Battery

state-of-charge, remaining capacity,

remaining time, and chemistry are

available over the serial link.

Battery-charge state can be directly

indicated using a four-segment LED

display to graphically depict battery

full-to-empty in 25% increments.

The bq2040 estimates battery self-

discharge based on an internal

timer and temperature sensor and

user-programmable rate informa

tion stored in external EEPROM.

The bq2040 also automatically re

calibrates or “learns” battery capac

ity in the full course of a discharge

cycle from full to empty.

The bq2040 may operate directly

from three nickel chemistry cells.

With the REF output and an exter

nal transistor, a simple, inexpensive

regulator can be built to provide

for other battery cell configu

rations.

An external EEPROM is used to

program initial values into the

bq2040 and is necessary for proper

operation.

bq2040

Gas Gauge IC With SMBus Interface

3.0–6.5V

ESCL EEPROM clock

ESDA EEPROM data

LED

1-4

LED segment 1-4

System ground

SR Sense resistor input

DISP Display control input

PN204001.eps

16-Pin Narrow SOIC

ESCL

ESDA

LED

OUT

REF

SMBC

SMBD

PSTAT

DISP

SB Battery sense input

PSTAT Protector status input

SMBD SMBus data input/output

SMBC SMBus clock

REF Voltage reference output

OUT

EEPROM supply output

SLUS005–JUNE 1999 E

Pin Connections Pin Names

Summary of content (35 pages)

PAGE 1
bq2040 Gas Gauge IC With SMBus Interface Features General Description ➤ Provides accurate measurement of available charge in NiCd, NiMH, and Li-Ion batteries The bq2040 Gas Gauge IC With SMBus Interface is intended for battery-pack or in-system installation to maintain an accurate record of available battery charge. The bq2040 directly supports capacity monitoring for NiCd, NiMH, and LiIon battery chemistries. ➤ Supports SBS v1.
PAGE 2
bq2040 DISP Pin Descriptions VCC Supply voltage input ESCL Serial memory clock DISP high disables the LED display. DISP floating allows the LED display to be active during charge if the rate is greater than 100mA. DISP low activates the display for 4 seconds. Output used to clock the data transfer between the bq2040 and the external nonvolatile configuration memory. ESDA SB LED display segment outputs PSTAT Each output may drive an external LED.
PAGE 3
bq2040 Figure 1 shows a typical battery pack application of the bq2040 using the LED capacity display, the serial port, and an external EEPROM for battery pack programming information. The bq2040 must be configured and calibrated for the battery-specific information to ensure proper operation. Table 1 outlines the configuration information that must be programmed in the EEPROM.
PAGE 4
bq2040 Table 1.
PAGE 5
bq2040 Table 1.
PAGE 6
bq2040 Voltage Thresholds Layout Considerations In conjunction with monitoring VSR for charge/discharge currents, the bq2040 monitors the battery potential through the SB pin. The voltage potential is determined through a resistor-divider network per the following equation: The bq2040 measures the voltage differential between the SR and VSS pins. VOS (the offset voltage at the SR pin) is greatly affected by PC board layout.
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bq2040 Inputs Charge Current Discharge Current Self-Discharge Timer State-of-charge and Temperature Compensation Temperature Compensation Main Counters and Capacity Reference (FCC) + - + Remaining Capacity (RM) < Full Charge Capacity (FCC) + Discharge Count Qualified Register Transfer (DCR) Temperature, Other Data Outputs Chip-Controlled Two-Wire Available Charge Serial Interface LED Display FG294501.eps Figure 2.
PAGE 8
bq2040 Charge Counting Current Taper Charge activity is detected based on a positive voltage on the SR input. If charge activity is detected, the bq2040 increments RM at a rate proportional to VSRO and, if enabled, activates an LED display. Charge actions increment the RM after compensation for charge state and temperature. For Li-Ion charge control, the ChargingVoltage must be set to the desired pack voltage during the constant voltage charge phase.
PAGE 9
bq2040 Charge Suspension Count Compensations The bq2040 may temporarily suspend charge if it detects a charging fault. The charging faults include the following conditions: Charge activity is compensated for temperature and state-of-charge before updating the RM and/or DCR. Self-discharge estimation is compensated for temperature before updating RM or DCR.
PAGE 10
bq2040 Table 3. bq2040 Current-Sensing Errors Symbol Parameter VOS Offset referred to VSR INL Integrated non-linearity error INR Integrated nonrepeatability error Typical Maximum Units ± 75 ± 150 µV Notes DISP = VCC. ±1 ±4 % Add 0.1% per °C above or below 25°C and 1% per volt above or below 4.25V. ± 0.5 ±1 % Measurement repeatability given similar operating conditions. and Remaining_Capacity_Alarm is set. VSB below EDVF (EDVF = 1) disables the display output.
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bq2040 1 S 7 Battery Address 0001011 1 1 8 1 8 1 8 1 1 0 A Command Code A Data byte low A Data byte high A P Write Word 1 S 7 Battery Address 0001011 1 1 8 1 1 7 1 1 0 A Command Code A S Battery Address 1 A 8 1 8 1 Data byte low A Data byte high A P System Host Read Word 1 S 7 Battery Address 0001011 1 1 8 1 1 7 1 1 0 A Command Code A S Battery Address 1 A bq2040 8 1 8 1 8 1 8 1 1 Byte Count =N A Data byte 1 A Data byte 2 A Dat
PAGE 12
bq2040 Table 4. bq2040 Register Functions Function Units Defaults1 Code Access ManufacturerAccess 0x00 read/write - - RemaningCapacityAlarm 0x01 read/write mAh E2 RemainingTimeAlarm 0x02 read/write minutes E2 BatteryMode 0x03 read/write bit flag - AtRate 0x04 read/write mA - AtRateTimeToFull 0x05 read minutes - AtRateTimeToEmpty 0x06 read minutes - AtRateOK 0x07 read Boolean - Temperature 0x08 read 0.
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bq2040 Table 4. bq2040 Register Functions (Continued) Code Access Units Defaults1 DeviceChemistry 0x22 read string E2 ManufacturerData 0x23 read string E2 FLAG1 and FLAG2 0x2f read bit flags E2 End of Discharge Voltage 1 (EDV1) 0x3e read - E2 End of Discharge Voltage Final (EDVF) 0x3f read - E2 Function Note: 1. Defaults after reset or power-up.
PAGE 14
bq2040 n n When the AtRate value is positive, the AtRateTimeToFull function returns the predicted time to full-charge at the AtRate value of charge. Temperature() (0x08) This read-only word returns the cell-pack's internal temperature. When the AtRate value is negative, the AtRateTimeToEmpty function returns the predicted operating time at the AtRate value of discharge. Output: unsigned integer. Returns the cell temperature in tenths of degrees Kelvin increments. Units: 0.
PAGE 15
bq2040 Accuracy: ± 1% of the DesignCapacity after calibration RemainingCapacity() (0x0f) This read-only word returns the predicted remaining battery capacity. The RemainingCapacity value is expressed in mAh. MaxError() (0x0c) Returns the expected margin of error (%) in the state of charge calculation. Output: unsigned integer. Returns the estimated remaining capacity in mAh. Output: unsigned integer. Returns the percent uncertainty for selected information.
PAGE 16
bq2040 Output: unsigned integer. Returns the minutes of operation left. BatteryStatus() (0x16) This read-only word returns the battery status word. Units: minutes Output: unsigned integer. Returns the status register with alarm conditions bitmapped as shown in Table 5. Range: 0 to 65,534min Granularity: 2min or better Some of the BatteryStatus flags (Remaining_Capacity_Alarm and Remaining_Time_Alarm) are calculated based on current. See Table 8 and 9 for definitions.
PAGE 17
bq2040 Table 6. Bit Descriptions for FLAGS1 and FLAGS2 (MSB) 7 FLAGS2 DMODE FLAGS1 Note: 6 5 4 3 2 1 0 (LSB) PSTAT CHM CC - OV LTF OC IMIN VQ - VDQ OVLD EDV1 EDVF ∆T/∆t - = Reserved Range: 0 to 65,535 cycles; 65,535 indicates battery has experienced 65,535 or more cycles. SerialNumber() (0x1c) This read-only word returns a serial number. This number, when combined with the ManufacturerName, the DeviceName, and the ManufactureDate, uniquely identifies the battery.
PAGE 18
bq2040 The CHM value is: End of Discharge Voltage1 (0x3e) This read-only word returns the first end-of-discharge voltage programmed for the pack. 7 - Output: two’s complemented unsigned integer. Returns battery end-of-discharge voltage programmed in EEPROM in mV. 6 - 5 CHM FLAGS2 Bits 4 3 - 2 - 1 - Where CHM is: End of Discharge VoltageF (0x3f) This read-only word returns the final end-of-discharge voltage programmed for the pack.
PAGE 19
bq2040 The IMIN value is: Where LTF is: 0 Temperature > 15°C 1 Temperature < 12°C Where IMIN is: Bit 0, the Overcurrent flag (OC), is set when Current is 25% greater than the programmed charging current. If the charging current is programmed less than 1024mA, overcurrent is set if Current is 256mA greater than the programmed charging current. This flag is cleared when Current falls below 256mA. 0 A valid current taper termination condition is not present.
PAGE 20
bq2040 The OVLD value is: SBD Seal Where OVLD is: 0 Current < programmed rate 1 Current > programmed rate The bq2040 address space can be “locked” to enforce the SBS specified access to each command code. To lock the address space, the bq2040 must be initialized with EE 0x3d set to b0h. Once this is done, only commands 0x00-0x04 may be written. Attempting to write to any other address will cause a “no acknowledge” of the data.
PAGE 21
bq2040 Table 8. Error Codes (BatteryStatus() (0x16)) Error Code Access Description OK 0x0000 read/write bq2040 processed the function code without detecting any errors. Busy 0x0001 read/write bq2040 is unable to process the function code at this time. ReservedCommand 0x0002 read/write UnsupportedCommand 0x0003 read/write bq2040 does not support the requested function code.
PAGE 22
bq2040 Table 9. BatteryStatus Bits Alarm Bits Bit Name Set When: Reset When: OVER_CHARGED_ALARM The bq2040 detects a ∆T/∆t or current taper termination. (Note: ∆T/∆t and current taper are valid charge terminations.) A discharge occurs or when the ∆T/∆t or current taper termination condition ceases during charge. TERMINATE_CHARGE_ALARM The bq2040 detects an over-current, over-voltage, over-temperature, ∆T/∆t, or current taper condition during charge.
PAGE 23
bq2040 Table 10. Example Register Contents EEPROM Address Description Low Byte High Byte EEPROM Hex Contents Low Byte High Byte Example Values Notes EEPROM length 0x00 64 100 Must be equal to 0x64. EEPROM check 1 0x01 5b 91 Must be equal to 0x5b. Remaining time alarm 0x02 0x03 0a 00 Remaining capacity alarm 0x04 0x05 f0 00 240mAh Sets the low capacity alarm level. Reserved 0x06 0x07 00 00 0 Not currently used by the bq2040.
PAGE 24
bq2040 Table 10. Example Register Contents (Continued) EEPROM Address Description Low Byte High Byte EEPROM Hex Contents Low High Byte Byte 00 Example Values Reserved 0x2f Li-Ion taper current 0x38 0x39 10 ff 240mA Sets the upper taper limit for Li-Ion charge termination. Stored in 2’s complement. Maxi m um overcha r g e lim it 0x3a 0x3b 9c ff 100mAh Sets the maximum amount of overcharge before a maximum overcharge charge suspend occurs. Stored in 2’s complement.
PAGE 25
bq2040 Table 10. Example Register Contents (Continued) EEPROM Address Description Digital filter EEPROM Hex Contents Low High Low High Byte Byte Byte Byte 0x4d 96 Example Values Notes 0.30mV Used to set the digital magnitude filter as described in Table 2. 3.2/0.05 Represents the following: 3.2/sense resistor in ohms. It is used by the bq2040 to scale the measured voltage values on the SR pin in mA and mAh. This register also compensates for variations in the reported sense resistor value. 0.
PAGE 26
bq2040 Table 11.
PAGE 27
bq2040 Absolute Maximum Ratings Minimum Maximum Unit VCC Symbol Relative to VSS -0.3 +7.0 V All other pins Relative to VSS -0.3 +7.0 V REF Relative to VSS -0.3 +8.5 V Current limited by R11 (see Figure 1) VSR Relative to VSS -0.3 +7.0 V Minimum 100Ω series resistor should be used to protect SR in case of a shorted battery. TOPR Operating temperature 0 +70 °C Commercial Note: Parameter Notes Permanent device damage may occur if Absolute Maximum Ratings are exceeded.
PAGE 28
bq2040 Recommended DC Operating Conditions (TA = TOPR) Symbol VCC VREF RREF ICC Parameter Minimum Typical Maximum Unit Notes Supply voltage 3.0 4.25 6.5 V VCC excursion from < 2.0V to ≥ 3.0V initializes the unit. Reference at 25°C 5.7 6.0 6.3 V IREF = 5µA Reference at -40°C to +85°C 4.5 - 7.5 V IREF = 5µA Reference input impedance 2.0 5.0 - MΩ VREF = 3V - 90 135 µA VCC = 3.0V - 120 180 µA VCC = 4.25V - 170 250 µA VCC = 5.
PAGE 29
bq2040 AC Specifications Min Max Units FSMB Symbol SMBus operating frequency Parameter 10 100 KHz TBUF Bus free time between stop and start condition 4.7 µs THD:STA Hold time after (repeated) start condition 4.0 µs TSU:STA Repeated start condition setup time 4.7 µs TSU:STO Stop condition setup time 4.0 µs THD:DAT Data hold time 300 ns TSU:DAT Data setup time 250 ns TLOW Clock low period 4.7 µs THIGH Clock high period 4.
PAGE 30
bq2040 16-Pin SOIC Narrow (SN) 16-Pin SN (SOIC Narrow) D e Dimension Minimum A 0.060 A1 0.004 B 0.013 C 0.007 D 0.385 E 0.150 e 0.045 H 0.225 L 0.015 All dimensions are in inches. B E H A C A1 .004 L 30 Maximum 0.070 0.010 0.020 0.010 0.400 0.160 0.055 0.245 0.
PAGE 31
bq2040 Data Sheet Revision History ChangeNo. Page No. 3 3 Updated recommended application schematic. 3 9 Changed overcurrent fault conditon for ChargingCurrent < 1024mA. 3 10 4Hz operation of LED clarification. 3 11 Added descriptions for bits 7 and 13 of BatteryMode. 3 14 AtRateTimeToEmpty and AtRateTimeToFull invalid data indication correction. 3 15, 16 RunTimeToEmpty, AverageTimeToEmpty and AverageTimeToFull invalid data indication corrections.
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PACKAGE OPTION ADDENDUM www.ti.
PAGE 33
PACKAGE MATERIALS INFORMATION www.ti.com 22-Sep-2009 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant BQ2040SN-C408TR SOIC D 16 2500 330.0 16.4 6.5 10.3 2.1 8.0 16.0 Q1 BQ2040SN-D111TR SOIC D 16 2500 330.0 16.4 6.5 10.3 2.1 8.0 16.
PAGE 34
PACKAGE MATERIALS INFORMATION www.ti.com 22-Sep-2009 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) BQ2040SN-C408TR SOIC D 16 2500 346.0 346.0 33.0 BQ2040SN-D111TR SOIC D 16 2500 346.0 346.0 33.
PAGE 35
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