Texas Instruments BQ2168MODULE, BQ2168LMODULE, BQ2168LB-KT, BQ2168B-KT, BQ2168B-005 Datasheet

Features

➤

Complete and compact lithium ion gas gauge and
protection solution for three or four series cells

➤

Accurate measurement of available battery
capacity

➤

Provides overvoltage, undervoltage, and
overcurrent protection

➤

Designed for battery pack integration

–

Small size

–

Includes bq2050H and bq2058 ICs

–

On-board charge and discharge control FETs

–

Low operating current for minimal battery drain

➤ High side FET control

➤ Battery capacity available through single-wire

serial port

➤ “L” version includes 5 push-button activated LEDs

to display state-of-charge information

General Description

The bq2168 Power Gauge Module provides a complete and
compact battery management solution for Li-Ion battery
packs. Designed for battery pack integration, the bq2168
combines the bq2050H Power Gauge IC with the bq2058
Supervisor IC on a small printed circuit board. The board
includes all the necessary components to accurately monitor
battery capacity and protect the cells from overvoltage, un

­dervoltage, and overcurrent conditions. The board works
with three or four Li-Ion series cells.

The Power Gauge IC uses the on-board sense resistor to
track charge and discharge activity of the battery pack.
Critical battery information can be accessed through the
serial communications port at HDQ. The supervisor cir

­cuit consists of the bq2058 and two FETs. The bq2058
controls the FETs to protect the batteries during
charge/discharge cycles and short circuit conditions. The
bq2168 provides contacts for the positive and negative
terminals of each battery in the stack. Please refer to
the bq2050H and bq2058 data sheets for the specifics on
the operation of the power gauge and supervisor ICs.

Unitrode configures the bq2168 based on the informa

­tion requested in Table 1. The configuration defines the
number of series cells, the nominal battery pack capac

­ity, the self-discharge rate, the Li-Ion battery type (coke

or graphite anode), and the threshold limits. Figure 1
shows how the module connects to the cells.

The bq2168L includes five LEDs to display remaining capac­ity in 20% increments of the learned capacity. The LEDs are
activated with the onboard push-button switch.

A module development kit is also available for the
bq2168. The bq2168B-KT or the bq2168LB-KT includes
one configured module and the following:

1) An EV2200-50H interface board that allows con­nection to the serial port of any AT-compatible com

-

puter.

2) Menu driven software to display charge/discharge
activity and to allow user interface to the bq2050H
from any standard Windows 3.1x or 95 PC.

Pin Descriptions

POS

Pack positive

B1P

BAT

1P

/Battery 1 positive input

B1N

BAT

1N

/Battery 1 negative input

B2N

BAT

2N

/Battery 2 negative input

B3N

BAT

3N

/Battery 3 negative input

B4N

BAT

4N

/Battery 4 negative input

ITEST

Overcurrent test input

HDQ

Serial communications port

NEG

Pack negative

1

bq2168

5/99 B

Li-Ion Power Gauge™ Module

with Pack Supervisor

2

bq2168

FG2168-1.eps

Battery Pack

B4N

B3N B2N B1N

B1P

NEG POS

bq2168

Load

Charger

Cells

PACK+PACK-

Figure 1. Module Connection Diagram

Customer Name: ___________________________________________________________________________

Contact: _________________________________________ Phone: ______________________________

Address: _________________________________________________________________________________

_________________________________________________________________________________

Sales Contact: ____________________________________ Phone: ______________________________

Number of series cells (3 or 4) _____________

Coke or graphite cell anode _____________

Battery pack capacity (mAh) _____________

Discharge current into load (3.9A max.) min. ________ avg. _________ max. _________

Charge current (3.9A max) _____________

Self-discharge compensation (Y/N) _____________

Overvoltage threshold (4.25, 4.30, or 4.35V) _____________

LEDs and switch (Y/N) _____________

FAE approval: ____________________________________ Date: _______________________________

Table 1. bq2168 Module Configuration

3

bq2168

FG2158cc.eps

B1P

NC

Load

or

Charger

Three-Cell Configuration

POS

NEG

B1N

B2N

B3N

B4N

B1P

Load

or

Charger

Four-Cell Configuration

POS

NEG

B1N

B2N

B3N

B4N

Note: B1P, B4N, POS, and NEG accomodate a #20 AWG stranded wire.
B1N, B2N, and B3N accomodate a #24 AWG stranded wire.

Figure 1. Module Connection Diagram

4

Component values depend on user-provided information in Table 1.

2168La.eps

1 2 3 4

bq2168 Schematic

bq2168

5

2168Lb

bq2168 Schematic (Continued)

bq2168

6

bq2168

bq2168 Board

7

Absolute Maximum Ratings

Symbol Parameter Value Unit Conditions

V

OP

Supply voltage (B1P to B4N) 18 V DC

V

TR

Maximum transient voltage (B1P to B4N) 32 V

Maximum duration =

1.5µs

V

CHG

Charging voltage (POS to NEG) 18 V

I

CHG

Continuous charge/discharge current 3.9 A

V

OP

> 6V

T

A

= 25°C

T

OPR

Operating temperature 0 to +70 °C

T

STG

Storage temperature -55 to +125 °C

Note: Permanent device damage may occur if Absolute Maximum Ratings are exceeded. Functional operation

should be limited to the Recommended DC Operating Conditions detailed in this data sheet. Exposure to con

-

ditions beyond the operational limits for extended periods of time may affect device reliability.

DC Electrical Characteristics (T

A=TOPR

)

Symbol Parameter Minimum Typical Maximum Unit Conditions/Notes

V

OP

Operating voltage, B1P to
B4N

4.0 - 18 V

I

CCA

Operating current - - 350

µ

A

R

ON

On resistance, B1P to POS - - 50

m

Ω

T

A

= 25°C

V

OP

= 10V

bq2168

8

DC Thresholds (T

A=TOPR

)

Symbol Parameter Value Tolerance Unit Notes

V

OV

Overvoltage threshold 4.25

±

50mV V

V

CE

Charge enable voltage VOV- 100mV

±

50mV V

V

UV

Undervoltage limit 2.25

±

100mV V

I

OC

Overcurrent limit

3.4 A

T

A

= 25°C

3.8 A

T

A

= 60°C

t

UVD

Undervoltage delay 950

±50%

ms

T

A

= 30°C

V

CD

Charge detect threshold 70 -60, +80 mV

t

OVD

Overvoltage delay 950

±50%

ms

T

A

= 30°C

t

OCD

Overcurrent delay 12

±60%

ms

T

A

= 30°C

Note: The thresholds above reflect the operation of a bq2158 using the standard bq2058 IC (VOV= 4.25V).

Specify other versions of the bq2058 by indicating the appropriate V

OV

threshold in Table 1.

bq2168

LED Option:

L = LEDs plus switch
Blank = No LEDs or switch

Notes: 1. Requires configuration sheet (Table 1)

2. Example production part number: bq2168LB-001

Ordering Information

bq2168 B —

Customer Code:

Blank = Sample or Pre-production

1

KT = Evaluation system
XXX = Customer-specific; assigned by Unitrode

2

Package Option:

B = Board-level product

Device:

Li-Ion Power Gauge Module with Pack Supervisor

Change No. Page No. Description Nature of Change

1 All From Preliminary to Final

Note: Change 1 = May 1999 B changes from Apr. 1999.

Data Sheet Revision History

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Copyright  1999, Texas Instruments Incorporated