Datasheet

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

Features

➤

Conservative and repeatable

measurement of available charge

in rechargeable batteries

➤

Charge control output operates an

external charge controller such as

the bq2004 Fast Charge IC

➤

Designed for battery pack inte

gration

120µA typical standby current

➤

Display capacity via single-wire

serial communication port or di

rect drive of LEDs

➤

Measurements compensated for

current and temperature

➤ Self-discharge compensation using

internal temperature sensor

➤ User-selectable end-of-discharge

threshold

➤ Battery voltage, nominal avail-

able charge, temperature, etc.

available over serial port

➤

16-pin narrow SOIC

General Description

The bq2014 Gas Gauge IC is in

tended for battery-pack or in-system

installation to maintain an accurate

record of available battery charge.

The IC monitors the voltage drop

across a sense resistor connected in

series between the negative battery

terminal and ground to determine

charge and discharge activity of the

battery.

Self-discharge of NiMH and NiCd

batteries is estimated based on an

internal timer and temperature sen

sor. Compensations for battery tem

perature and rate of charge or dis

charge are applied to the charge, dis

charge, and self-discharge calcula-

tions to provide available charge in-

formation across a wide range of op-

erating conditions. Battery capacity

is automatically recalibrated, or

“learned,” in the course of a dis-

charge cycle from full to empty.

The bq2014 includes a charge con-

trol output that controls an external

Fast Charge IC such as the bq2004.

Nominal Available Charge (NAC)

may be directly indicated using a

five-segment LED display.

The bq2014 supports a simple single-

line bidirectional serial link to an ex

ternal processor (with a common

ground). The bq2014 outputs battery

information in response to external

commands over the serial link.

Internal registers include available

charge, temperature, capacity, bat

tery voltage, battery ID, battery

status, and programming pin set

tings. To support subassembly test

ing, the outputs may also be con

trolled. The external processor may

also overwrite some of the bq2014

gas gauge data registers.

The bq2014 may operate directly

from three or four cells. With the

REF output and an external transis-

tor, a simple, inexpensive regulator

can be built to provide V

across a

greater number of cells.

LCOM LED common output

SEG

/PROG

LED segment 1/

program 1 input

SEG

/PROG

LED segment 2/

program 2 input

SEG

/PROG

LED segment 3/

program 3 input

SEG

/PROG

LED segment 4/

program 4 input

SEG

/PROG

LED segment 5/

program 5 input

DONE Fast charge complete

PN201401.eps

16-Pin Narrow SOIC

LCOM

SEG

/PROG

SEG

/PROG

SEG

/PROG

SEG

/PROG

SEG

/PROG

DONE

REF

CHG

EMPTY

DISP

REF Voltage reference output

CHG Charge control output

DQ Serial communications

input/output

EMPTY Empty battery indicator

output

SB Battery sense input

DISP

Display control input

SR Sense resistor input

3.0–6.5V

System ground

12/95 C

Pin Connections Pin Names

bq2014

Gas Gauge IC with External Charge Control

Summary of content (26 pages)

PAGE 1
bq2014 Gas Gauge IC with External Charge Control Features General Description ➤ Conservative and repeatable measurement of available charge in rechargeable batteries The bq2014 Gas Gauge IC is intended for battery-pack or in-system installation to maintain an accurate record of available battery charge. The IC monitors the voltage drop across a sense resistor connected in series between the negative battery terminal and ground to determine charge and discharge activity of the battery.
PAGE 2
bq2014 SR Pin Descriptions LCOM The voltage drop (VSR) across the sense resistor RS is monitored and integrated over time to interpret charge and discharge activity. The SR input is tied to the high side of the sense resistor. VSR < VSS indicates discharge, and VSR > VSS indicates charge. The effective voltage drop VSRO, as seen by the bq2014, is VSR + VOS (see Table 5). LED common output Open-drain output switches VCC to source current for the LEDs.
PAGE 3
bq2014 Figure 1 shows a typical battery pack application of the bq2014 using the LED display capability as a chargestate indicator. The bq2014 is configured to display capacity in a relative display mode. The relative display mode uses the last measured discharge capacity of the battery as the battery “full” reference. The LED segments output a percentage of the available charge based on NAC and LMD. A push-button display feature is available for momentarily enabling the LED display.
PAGE 4
bq2014 compensations, self-discharge counting, and available charge display translation. The temperature range is available over the serial port in 10°C increments as shown below: Voltage Thresholds In conjunction with monitoring VSR for charge/discharge currents, the bq2014 monitors the single-cell battery potential through the SB pin.
PAGE 5
bq2014 charge lasts long enough to cause an increment in NACH. Small increments of charging are not considered “valid” if they result in counts in NACL but do not generate a roll-over (carry) that increments NACH. NACL is reset anytime the counter direction changes from down to up, so the number of counts required to cause a roll-over and a valid charge is always 256. The counter may be incrementing by 2, 4, 8, or more counts per increment, however, depending on the scaling factors selected.
PAGE 6
bq2014 Relative display mode Serial port only Self-discharge = C 64 Voltage drop over sense resistor = 5mV to 400mV determined by multiplying the rated battery capacity in mAh by the sense resistor value: Battery capacity (mAh) * sense resistor (Ω) = Therefore: PFC (mVh) 2200mAh ∗ 0.1Ω = 220mVh Selecting a PFC slightly less than the rated capacity for absolute mode provides capacity above the full reference for much of the battery's life.
PAGE 7
bq2014 The initial full battery capacity is 211mVh (2110mAh) until the bq2014 “learns” a new capacity with a qualified discharge from full to EDV1. 3. Charge Control Charge control is provided by the CHG output. This output is asserted continuously when NAC > 0.94 ∗ LMD. CHG is also asserted when a valid charge is detected (CHGS in the FLGS1 register is also set). CHG is low when NAC < 0.94 ∗ LMD and there is no valid charge activity.
PAGE 8
bq2014 Temperature adapts the charge rate compensation factors over three ranges between nominal, warm, and hot temperatures. The compensation factors are shown below. Charge Temperature Trickle Charge Compensation Table 3. Self-Discharge Compensation Temperature Step Fast Charge Compensation Typical Rate PROG5 = Z < 10°C NAC < 40°C 0.80 0.95 10–20°C NAC > 40°C 0.75 0.
PAGE 9
bq2014 Table 5. Current-Sensing Error as a Function of VSR Symbol Parameter Typical INL Integrated non-linearity error ±2 INR Integrated nonrepeatability error ±1 Maximum Units Notes ±4 % Add 0.1% per °C above or below 25°C and 1% per volt above or below 4.25V. ±2 % Measurement repeatability given similar operating conditions. either polled or interrupt processing. Data input from the bq2014 may be sampled using the pulse-width capture timers available on some microcontrollers.
PAGE 10
bq2014 Where CHGS is: bq2014 Registers The bq2014 command and status registers are listed in Table 6 and described below. Command Register (CMDR) W/R bit n Command address Either discharge activity detected or VSRO < VSRQ 1 VSRO > VSRQ The battery replaced flag (BRP) is asserted whenever the potential on the SB pin (relative to VSS), VSB, falls from above the maximum cell voltage, MCV (2.25V), or rises above 0.1V. The BRP flag is also set when the bq2014 is reset (see the RST register description).
PAGE 11
bq2014 Table 6.
PAGE 12
bq2014 Where EDV1 is: The CI values are: FLGS1 Bits 7 6 5 4 3 2 1 0 - - - CI - - - - When LMD is updated with a valid full discharge 1 After the 64th valid charge action with no LMD updates or when the device is reset The valid discharge flag (VDQ) is asserted when the bq2014 is discharged from NAC = LMD or DONE is valid.
PAGE 13
bq2014 Temperature and Gas Gauge Register (TMPGG) Table 7. Temperature Register Translation The read-only TMPGG register (address=02h) contains two data fields. The first field contains the battery temperature. The second field contains the available charge from the battery. TMPGG Temperature Bits 7 6 5 TMP3 TMP2 4 TMP1 TMP0 3 2 1 - - - 0 The bq2014 contains an internal temperature sensor.
PAGE 14
bq2014 The CR values are: pull-down resistors, the contents of PPD are xx101001. (Note: DONE must be pulled down for proper operation.) FLGS2 Bits 7 6 5 4 3 2 1 0 Program Pin Pull-Up Register (PPU) CR - - - - - - - The read-only PPU register (address=08h) contains the rest of the programming pin information for the bq2014. The segment drivers, SEG1–5 and DONE, have corresponding PPU register locations, PPU1–6.
PAGE 15
bq2014 When DISP is tied to VCC, the SEG1–5 outputs are inactive. Note: DISP must be tied to VCC if the LEDs are not used. When DISP is left floating, the display becomes active whenever the NAC registers are counting at a rate equivalent to VSRO < -4mV or charge current is detected, VSRO > VSRQ. When pulled low, the segment outputs become active immediately. A capacitor tied to DISP allows the display to remain active for a short period of time after activation by a push-button switch.
PAGE 16
bq2014 Absolute Maximum Ratings Minimum Maximum Unit VCC Symbol Relative to VSS Parameter -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 R1 (see Figure 1) VSR Relative to VSS TOPR Operating temperature Note: Notes -0.3 7.0 V Minimum 100Ω series resistor should be used to protect SR in case of a shorted battery (see the bq2014 application note for details).
PAGE 17
bq2014 DC Electrical Characteristics (TA = TOPR) Symbol Parameter Minimum Typical Maximum Unit VCC Supply voltage 3.0 4.25 6.5 V VOS Offset referred to VSR ±50 6.0 5.0 90 120 170 - ±150 6.3 7.5 135 180 250 2.4 5 0.2 - µV V V MΩ µA µA µA V MΩ µA µA KΩ Notes VCC excursion from < 2.0V to ≥ 3.0V initializes the unit.
PAGE 18
bq2014 Serial Communication Timing Specification Symbol Parameter Minimum Typical Maximum Unit tCYCH Cycle time, host to bq2014 3 - - ms tCYCB Cycle time, bq2014 to host 3 - 6 ms tSTRH Start hold, host to bq2014 5 - - ns tSTRB Start hold, bq2014 to host 500 - - µs tDSU Data setup - - 750 µs tDH Data hold 750 - - µs tDV Data valid 1.50 - - ms tSSU Stop setup - - 2.25 ms tSH Stop hold 700 - - µs tSV Stop valid 2.
PAGE 19
bq2014 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 Maximum 0.070 0.010 0.020 0.010 0.400 0.160 0.055 0.245 0.035 .004 L Data Sheet Revision History ChangeNo. Page No.
PAGE 20
bq2014 Ordering Information bq2014 Temperature Range: blank = Commercial (0 to +70°C) Package Option: SN = 16-pin narrow SOIC Device: bq2014 Gas Gauge IC 17919 Waterview Parkway Dallas, Texas 75252 Fax: (972) 437-9198 Tel: (972) 437-9195 www.benchmarq.com or www.unitrode.com Copyright © 1995, Unitrode Corporation. All rights reserved. No part of this data sheet may be reproduced in any form or means, without express permission from Unitrode.
PAGE 21
PACKAGE OPTION ADDENDUM www.ti.
PAGE 22
PACKAGE MATERIALS INFORMATION www.ti.com 14-Jul-2012 TAPE AND REEL INFORMATION *All dimensions are nominal Device BQ2014SN-D120TR Package Package Pins Type Drawing SOIC D 16 SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 2500 330.0 16.4 Pack Materials-Page 1 6.5 B0 (mm) K0 (mm) P1 (mm) 10.3 2.1 8.0 W Pin1 (mm) Quadrant 16.
PAGE 23
PACKAGE MATERIALS INFORMATION www.ti.com 14-Jul-2012 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) BQ2014SN-D120TR SOIC D 16 2500 367.0 367.0 38.
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