TEXAS INSTRUMENTS bq2002, bq2002F Technical data

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bq2002/F

NiCd/NiMH Fast-Charge Management ICs

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

Pin Connections

TM

LED

BAT

V

1

2

3

4

SS

8

CC

7

INH

V

6

CC

TS

5

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.

Pin Names

TM Timer mode select input

LED

BAT Battery voltage input

V

SS

Charging status output

System ground

Fast charge is terminated by any of
the following:

Peak voltage detection (PVD)

n

Negative delta voltage (-∆V)

n

Maximum voltage

n

Maximum temperature

n

Maximum time

n

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.

TS Temperature sense input

V

CC

Supply voltage input

INH Charge inhibit input

CC Charge control output

-

8-Pin DIP or

Narrow SOIC

PN-200201.eps

bq2002/F Selection Guide

Part No. TCO HTF LTF

bq2002

bq2002F

SLUS131–JANUARY 1999 D

0.5 ∗ V

0.5 ∗ V

None None

CC

None None

CC

PVD Fast Charge t

-∆V

MTO

Top-Off Maintenance

✔ C/2 160 C/32 C/64
✔ 1C 80 C/16 C/64

✔ 2C 40 None C/32

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

✔ 2C 55 None C/32

1

bq2002/F

Pin Descriptions

TM

LED

BAT

V

SS

TS

V

CC

INH

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.

Charging output status

Open-drain output that indicates the charging
status.

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.

System ground

Temperature sense input

Input for an external battery temperature
monitoring thermistor.

Supply voltage input

5.0V±20% power input.

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

= N - 1

RB2

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

and VSS. See Figure 1.

CC

-

V

CC

RB1

BAT

bq2002/F

BAT pin connection Thermistor connection

RB2

V

SS

NTC = negative temperature coefficient thermistor.

R3

R4

Mid-level

setting for TM

V

CC

TM

bq2002/F

T

V

SS

PACK +

RT

S

N
T
C

Fg2002/F01.eps

Figure 1. Voltage and Temperature Monitoring and TM Pin Configuration

2

bq2002/F

OSC

Chip on

4.0V

V

CC

VTS > VCC/2 VTS < VCC/2

V

BAT

VTS < VCC/2

((PVD or - V or
Maximum Time-Out)

Fast

LED = Low

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

and TM = high)

< 2V

V

BAT

Temperature?

> 2V

Battery
Voltage?

Battery

Top-off

LED = Z

V

V

CC

Maximum Time-Out

Figure 2. State Diagram

Clock

Phase

Generator

> 2V

BAT

2V

or

or

VTS < VCC/2

Trickle

LED = Z

V

BAT

SD2002/F01

> 2V

TM

INH

Charge-Control

State Machine

Power-On

Reset

Timing

Control

PVD, -∆V

CC

LED

Figure 3. Block Diagram

3

Sample

History

ALU

TCO

Check

TS

Voltage

Reference

A to D

Converter

Check

Power

Down

V

CC

MCV

V

BAT

SS

Bd2002f.eps

bq2002/F

Fast ChargingVCC = 0 Fast Charging

CC Output

Charge initiated by application of power

LED

(optional)

286

4576

Figure 4. Charge Cycle Phases

Starting A Charge Cycle

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

1. Application of power to V

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

MCV

where

V

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

TS>VTCO

V

TCO

or

CC

= 2V ±5%.

MCV

BAT<VMCV

. The valid tempera-

where

= 0.5 ∗ VCC±5%.

Pulse-TrickleTop-Off

See

Table 1

286

s

TD2002F1.eps

s

s

Charge initiated by battery replacement

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:

Peak voltage detection (PVD)

n

n

Negative delta voltage (-∆V)

n

Maximum voltage

n

Maximum temperature

n

Maximum time

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

Typical Fast-Charge

and Top-Off
Time Limits

Corresponding

Fast-Charge

Rate TM Termination

(minutes) Typical PVD

and -∆V Hold-Off

bq2002 bq2002F

Time (seconds)

Top-Off

Rate

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%.

4

Pulse-

Trickle

Rate

Pulse­Trickle
Period

(ms)

bq2002/F

PVD and -∆V Termination

There are two modes for voltage termination depending
on the state of TM. For -∆V (TM = high), if V
lower than any previously measured value by 12mV
±3mV, fast charge is terminated. For PVD (TM = low or
mid), a decrease of 2.5mV ±2.5mV terminates fast
charge. The PVD and -∆V tests are valid in the range
1V<V

BAT

<2V.

BAT

Voltage Sampling

Voltage is sampled at the BAT pin for PVD and -∆V ter
mination once every 17s. The sample is an average of
voltage measurements taken 57µs apart. The IC takes
32 measurements in PVD mode and 16 measurements
in -∆V mode. The resulting sample periods (9.17 and

18.18ms, respectively) filter out harmonics centered
around 55 and 109Hz. This technique minimizes the ef
fect of any AC line ripple that may feed through the
power supply from either 50 or 60Hz AC sources. Toler
ance on all timing is ±20%.

Voltage Termination Hold-off

A hold-off period occurs at the start of fast charging.
During the hold-off time, the PVD and -∆V terminations
are disabled. This avoids premature termination on the
voltage spikes sometimes produced by older batteries
when fast-charge current is first applied. Maximum
voltage and temperature terminations are not affected
by the hold-off period.

Maximum Voltage, Temperature, and Time

Any time the voltage on the BAT pin exceeds the maxi
mum cell voltage,V
charge is terminated.

Maximum temperature termination occurs anytime the
voltage on the TS pin falls below the temperature cut-off
threshold V

Maximum charge time is configured using the TM pin.
Time settings are available for corresponding charge
rates of C/2, 1C, and 2C. Maximum time-out termina
tion is enforced on the fast-charge phase, then reset, and
enforced again on the top-off phase, if selected. There is
no time limit on the trickle-charge phase.

TCO

.

, fast charge or optional top-off

MCV

Top-off Charge

An optional top-off charge phase may be selected to
follow fast charge termination for 1C and C/2 rates.
This phase may be necessary on NiMH or other bat
tery chemistries that have a tendency to terminate
charge prior to reaching full capacity. With top-off en
abled, charging continues at a reduced rate after
fast-charge termination for a period of time selected
by the TM pin. (See Table 1.) During top-off, the CC

pin is modulated at a duty cycle of 286µs active for
every 4290µs inactive. This modulation results in an
average rate 1/16th that of the fast charge rate. Maxi

is

mum voltage, time, and temperature are the only ter
mination methods enabled during top-off.

Pulse-Trickle Charge

Pulse-trickle is used to compensate for self-discharge
while the battery is idle in the charger. The battery is
pulse-trickle charged by driving the CC pin active for a
period of 286µs for every 18.0ms of inactivity for 1C and
2C selections, and 286µs for every 8.86ms of inactivity

­for C/2 selection. This results in a trickle rate of C/64
for the top-off enabled mode and C/32 otherwise.

TM Pin

The TM pin is a three-level pin used to select the

­charge timer, top-off, voltage termination mode, trickle

rate, and voltage hold-off period options. Table 1 de

­scribes the states selected by the TM pin. The mid-

level selection input is developed by a resistor di
vider between V
on TM at V

CC

and ground that fixes the voltage

CC

/2 ± 0.5V. See Figure 4.

Charge Status Indication

A fast charge in progress is uniquely indicated when the
LED

pin goes low. The LED pin is driven to the high-Z
state for all conditions other than fast charge. Figure 2
outlines the state of the LED

pin during charge.

Charge Inhibit

Fast charge and top-off may be inhibited by using the

­INH pin. When high, INH suspends all fast charge and

top-off activity and the internal charge timer. INH
freezes the current state of LED
moved. Temperature monitoring is not affected by the
INH pin. During charge inhibit, the bq2002/F continues
to pulse-trickle charge the battery per the TM selection.
When INH returns low, charge control and the charge
timer resume from the point where INH became active.

-

Low-Power Mode

The IC enters a low-power state when V
above the power-down threshold (V

= VCC- (1V ±0.5V)

V

PD

Both the CC pin and the LED
high-Z state. The operating current is reduced to less
than 1µA in this mode. When V

­below V

new charge cycle begins.

-

, the IC pulse-trickle charges until the next

PD

until inhibit is re

BAT

) where

PD

pin are driven to the

returns to a value

BAT

-

-

-

-

-

is driven

5

bq2002/F

Absolute Maximum Ratings

Symbol Parameter Minimum Maximum Unit Notes

V

CC

V

T

T

OPR

T

STG

T

SOLDER

T

BIAS

VCCrelative to V

SS

DC voltage applied on any pin
excluding V

relative to V

CC

SS

Operating ambient temperature 0 +70 °C Commercial

Storage temperature -40 +85 °C

Soldering temperature - +260 °C 10 sec max.

Temperature under bias -40 +85 °C

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

tion should be limited to the Recommended DC Operating Conditions detailed in this data sheet. Expo
sure to conditions beyond the operational limits for extended periods of time may affect device reliability.

-0.3 +7.0 V

-0.3 +7.0 V

-

-

DC Thresholds (T

= 0 to 70°C; V

A

CC

20%)

±

Symbol Parameter Rating Tolerance Unit Notes

inhibits/terminates

V

V

≤

TCO

V

TCO

V

MCV

-∆V

PVD

Temperature cutoff

0.5*V

Maximum cell voltage 2

BAT input change for

-∆V detection

BAT input change for
PVD detection

-12

-2.5

CC

±5%

±5%

±3

±2.5

mV

mV

TS

V

fast charge and top-off

≥ V

V

BAT

V

fast charge and top-off

inhibits/terminates

MCV

6

bq2002/F

Recommended DC Operating Conditions (T

= 0 to 70°C)

A

Symbol Condition Minimum Typical Maximum Unit Notes

V

CC

V

DET

V

BAT

V

TS

Supply voltage 4.0 5.0 6.0 V

-∆V, PVD detect voltage 1 - 2 V

Battery input 0 - V

Thermistor input 0.5 - V

CC

CC

V

VVTS< 0.5V prohibited

Logic input high 0.5 - - V INH

V

IH

V

IM

Logic input high V

Logic input mid

- 0.5 - - V TM

CC

V

CC

- 0.5

2

-

V

CC

05+ .

2

VTM

Logic input low - - 0.1 V INH

V

IL

Logic input low - - 0.5 V TM

V

OL

V

PD

Logic output low - - 0.8 V LED,CC,IOL= 10mA

max. powers

V

V

≥

BAT

Power down

- 1.5

V

CC

-

VCC- 0.5

down bq2002/F;

V

V

< VPDmin. =

BAT

PD

normal operation.

I

CC

I

SB

I

OL

I

L

I

OZ

Supply current - - 250

Standby current - - 1

LED, CC sink 10 - - mA @VOL= VSS+ 0.8V

Input leakage - -

Output leakage in
high-Z state

Note: All voltages relative to VSS.

-5 - -

7

Outputs unloaded,

A

µ

V

= 5.1V

CC

AVCC= 5.1V, V

µ

1

±

A INH, CC, V = VSSto V

µ

A

µ

LED

,CC

BAT

= V

PD

CC

bq2002/F

Impedance

Symbol Parameter Minimum Typical Maximum Unit

R

BAT

R

TS

Battery input impedance 50 - - M

TS input impedance 50 - - M

Ω

Ω

Timing (T

Symbol Parameter Minimum Typical Maximum Unit Notes

d

FCV

Note: Typical is at TA= 25°C, VCC= 5.0V.

= 0 to +70°C; V

A

Base time variation -20 - 20 %

CC

10%)

±

8

bq2002/F

8-Pin DIP(PN

E1

E

C

e

)

8-Pin PN(0.300" DIP

B1

B

Dimension

A 0.160 0.180 4.06 4.57

A1 0.015 0.040 0.38 1.02

B 0.015 0.022 0.38 0.56

B1 0.055 0.065 1.40 1.65

C 0.008 0.013 0.20 0.33

D 0.350 0.380 8.89 9.65

E 0.300 0.325 7.62 8.26

E1 0.230 0.280 5.84 7.11

e 0.300 0.370 7.62 9.40

G 0.090 0.110 2.29 2.79

L 0.115 0.150 2.92 3.81

S 0.020 0.040 0.51 1.02

D

A

A1

L

S

G

Min. Max. Min. Max.

)

Inches Millimeters

9

bq2002/F

8-Pin SOIC Narrow (SN)

8-Pin SN(0.150" SOIC

Inches Millimeters

Dimension

A 0.060 0.070 1.52 1.78

A1 0.004 0.010 0.10 0.25

B 0.013 0.020 0.33 0.51

C 0.007 0.010 0.18 0.25

D 0.185 0.200 4.70 5.08

E 0.150 0.160 3.81 4.06

e 0.045 0.055 1.14 1.40

H 0.225 0.245 5.72 6.22

L 0.015 0.035 0.38 0.89

Min. Max. Min. Max.

)

10

bq2002/F

Data Sheet Revision History

Change No. Page No. Description Nature of Change

13

1 5 Added Termination column to table and Top-off values. Added column and values.

2 All Revised and expanded this data sheet to include bq2002F

3 1 Addition of selection guide

Notes: Change 1 = Sept. 1996 B changes from July 1994.

Change 2 = Aug. 1997 C changes from Sept. 1996 B.

Change 3 = Jan. 1999 D changes from Aug. 1997 C.

Was: Table 1 gave the bq2002/F Operational Summary.
Is: Figure 2 gives the bq2002/F Operational Summary.

Changed table to figure.

Ordering Information

bq2002/F

Package Option:

PN = 8-pin plastic DIP
SN = 8-pin narrow SOIC

Device:

bq2002 Fast-Charge IC
bq2002F Fast-Charge IC

11

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