Texas Instruments DV2002L2, BQ2002PN, BQ2002FSNTR, BQ2002FSN, BQ2002FPN Datasheet

1

Features

➤

Fast charge of nickel cadmium
or nickel-metal hydride batter

-

ies

➤

Direct LED output displays
charge status

➤

Fast-charge termination by -∆V,
maximum voltage, maximum
temperature, and maximum
time

➤

Internal band-gap voltage ref

-

erence

➤

Optional top-off charge

➤

Selectable pulse trickle charge
rates

➤ Low-power mode

➤ 8-pin 300-mil DIP or 150-mil

SOIC

General Description

The bq2002 and bq2002/F Fast-Charge
ICs are low-cost CMOS battery-charge
controllers providing reliable charge
termination for both NiCd and NiMH
battery applications. Controlling a
current-limited or constant-current
supply allows the bq2002/F to be the
basis for a cost-effective stand-alone or
system-integrated charger. The
bq2002/F integrates fast charge with
optional top-off and pulsed-trickle con

­trol in a single IC for charging one or
more NiCd or NiMH battery cells.

Fast charge is initiated on application
of the charging supply or battery re

­placement. For safety, fast charge is
inhibited if the battery temperature
and voltage are outside configured
limits.

Fast charge is terminated by any of
the following:

n

Peak voltage detection (PVD)

n

Negative delta voltage (-∆V)

n

Maximum voltage

n

Maximum temperature

n

Maximum time

After fast charge, the bq2002/F op

­tionally tops-off and pulse-trickles the
battery per the pre-configured limits.
Fast charge may be inhibited using
the INH pin. The bq2002/F may also
be placed in low-standby-power mode
to reduce system power consumption.

The bq2002F differs from the
bq2002 only in that a slightly differ­ent set of fast-charge and top-off
time limits is available. All differ­ences between the two ICs are illus­trated in Table 1.

NiCd/NiMH Fast-Charge Management ICs

bq2002/F

TM Timer mode select input

LED

Charging status output

BAT Battery voltage input

V

SS

System ground

1

PN-200201.eps

8-Pin DIP or

Narrow SOIC

2

3

4

8

7

6

5

TM

LED

BAT

V

SS

CC

INH

V

CC

TS

TS Temperature sense input

V

CC

Supply voltage input

INH Charge inhibit input

CC Charge control output

Pin Connections

Pin Names

bq2002/F Selection Guide

Part No. TCO HTF LTF

-∆V

PVD Fast Charge t

MTO

Top-Off Maintenance

bq2002

0.5 ∗ V

CC

None None

✔ C/2 160 C/32 C/64
✔ 1C 80 C/16 C/64

✔ 2C 40 None C/32

bq2002F

0.5 ∗ V

CC

None None

✔ C/2 160 C/32 C/64
✔ 1C 100 C/16 C/64

✔ 2C 55 None C/32

SLUS131–JANUARY 1999 D

Pin Descriptions

TM

Timer mode input

A three-level input that controls the settings
for the fast charge safety timer, voltage ter

­mination mode, top-off, pulse-trickle, and
voltage hold-off time.

LED

Charging output status

Open-drain output that indicates the charging
status.

BAT

Battery input voltage

The battery voltage sense input. The input to
this pin is created by a high-impedance re

­sistor divider network connected between
the positive and negative terminals of the
battery.

V

SS

System ground

TS

Temperature sense input

Input for an external battery temperature
monitoring thermistor.

V

CC

Supply voltage input

5.0V±20% power input.

INH

Charge inhibit input

When high, INH suspends the fast charge in
progress. When returned low, the IC re

­sumes operation at the point where initially
suspended.

CC

Charge control output

An open-drain output used to control the
charging current to the battery. CC switch

­ing to high impedance (Z) enables charging
current to flow, and low to inhibit charging
current. CC is modulated to provide top-off,
if enabled, and pulse trickle.

Functional Description

Figure 2 shows a state diagram and Figure 3 shows a
block diagram of the bq2002/F.

Battery Voltage and Temperature
Measurements

Battery voltage and temperature are monitored for
maximum allowable values. The voltage presented on
the battery sense input, BAT, should represent a
single-cell potential for the battery under charge. A
resistor-divider ratio of

RB1
RB2

= N - 1

is recommended to maintain the battery voltage within
the valid range, where N is the number of cells, RB1 is
the resistor connected to the positive battery terminal,
and RB2 is the resistor connected to the negative bat­tery terminal. See Figure 1.

Note: This resistor-divider network input impedance to
end-to-end should be at least 200kΩ and less than 1 MΩ.

A ground-referenced negative temperature coefficient
thermistor placed near the battery may be used as a low­cost temperature-to-voltage transducer. The temperature
sense voltage input at TS is developed using a resistor­thermistor network between V

CC

and VSS. See Figure 1.

2

bq2002/F

Fg2002/F01.eps

bq2002/F

BAT

V

SS

N
T
C

bq2002/F

V

CC

V

CC

PACK +

T

S

V

SS

BAT pin connection Thermistor connection

TM

NTC = negative temperature coefficient thermistor.

RT

R3

R4

RB1

RB2

Mid-level

setting for TM

Figure 1. Voltage and Temperature Monitoring and TM Pin Configuration

3

bq2002/F

Battery

Temperature?

Battery
Voltage?

Chip on

V

CC

4.0V

V

CC

2V

Top-off

LED = Z

Trickle

LED = Z

Fast

LED = Low

Maximum Time-Out

or

or

V

BAT

< 2V

V

BAT

> 2V

SD2002/F01

VTS > VCC/2 VTS < VCC/2

V

BAT

> 2V

V

BAT

> 2V

VTS < VCC/2

VTS < VCC/2

((PVD or - V or
Maximum Time-Out)
and TM = high)

(PVD or - V or
Maximum Time-Out)
and TM = high

Figure 2. State Diagram

OSC

TM

CC

LED

V

CC

V

SS

BAT

INH

Clock

Phase

Generator

Timing

Control

Sample

History

A to D

Converter

MCV

Check

TS

Bd2002f.eps

Voltage

Reference

PVD, -∆V

ALU

Power-On

Reset

TCO

Check

Power

Down

Charge-Control

State Machine

Figure 3. Block Diagram

Starting A Charge Cycle

Either of two events starts a charge cycle (see Figure 4):

1. Application of power to V

CC

or

2. Voltage at the BAT pin falling through the maximum
cell voltage V

MCV

where

V

MCV

= 2V ±5%.

If the battery is within the configured temperature and
voltage limits, the IC begins fast charge. The valid bat­tery voltage range is V

BAT<VMCV

. The valid tempera-

ture range is V

TS>VTCO

where

V

TCO

= 0.5 ∗ VCC±5%.

If the battery voltage or temperature is outside of these
limits, the IC pulse-trickle charges until the next new
charge cycle begins.

Fast charge continues until termination by one or more of
the five possible termination conditions:

n

Peak voltage detection (PVD)

n

Negative delta voltage (-∆V)

n

Maximum voltage

n

Maximum temperature

n

Maximum time

4

bq2002/F

Corresponding

Fast-Charge

Rate TM Termination

Typical Fast-Charge

and Top-Off
Time Limits

(minutes) Typical PVD

and -∆V Hold-Off

Time (seconds)

Top-Off

Rate

Pulse-

Trickle

Rate

Pulse­Trickle
Period

(ms)

bq2002 bq2002F

C/2 Mid PVD 160 160 600 C/32 C/64 9.15

1C Low PVD 80 100 300 C/16 C/64 18.3

2C High -∆V 40 40 150 Disabled C/32 18.3

Notes: Typical conditions = 25°C, VCC= 5.0V.

Mid = 0.5*V

CC

±

5V

Tolerance on all timing is±20%.

Table 1. Fast-Charge Safety Time/Hold-Off Table

TD2002F1.eps

Fast ChargingVCC = 0 Fast Charging

CC Output

LED

s

s

Charge initiated by application of power

Charge initiated by battery replacement

Pulse-TrickleTop-Off

(optional)

286

See

Table 1

s

286

4576

Figure 4. Charge Cycle Phases