Texas Instruments DV2002TL2, BQ2002TSNTR, BQ2002TSN, BQ2002TPN, BQ2002DSNTR Datasheet

Features

➤

Fast charge of nickel cadmium
or nickel-metal hydride batter

-

ies

➤

Direct LED output displays
charge status

➤

Fast-charge termination by
rate of rise of temperature,
maximum voltage, maximum
temperature, and maximum
time

➤

Internal band-gap voltage ref

-

erence

➤

Optional top-off charge (bq2002T
only)

➤ Selectable pulse-trickle charge

rates (bq2002T only)

➤ Low-power mode

➤ 8-pin 300-mil DIP or 150-mil

SOIC

General Description

The bq2002D/T Fast-Charge IC are
low-cost CMOS battery-charge control

-

lers able to provide reliable charge ter

-

mination for both NiCd and NiMH bat

­tery applications. Controlling a
current-limited or constant-current
supply allows the bq2002D/T to be the
basis for a cost-effective stand-alone or
system-integrated charger. The
bq2002D/T 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

Rate of temperature rise

n

Maximum voltage

n

Maximum temperature

n

Maximum time

After fast charge, the bq2002T option

­ally tops-off and pulse-trickles the
battery per the pre-configured limits.
Fast charge may be inhibited using
the INH pin. The bq2002D/T may be
placed in low-standby-power mode to
reduce system power consumption.

1

NiCd/NiMH Fast-Charge Management ICs

bq2002D/T

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

bq2002D/T Selection Guide

Part No. TCO HTF LTF Fast Charge Time-Out Top-Off Maintenance

bq2002D

0.225 ∗ V

CC

0.25 ∗ V

CC

0.4 ∗ V

CC

C/4 320 min C/64 C/256

1C 80 min C/16 C/256
2C 40 min None C/128

bq2002T

0.225 ∗ V

CC

0.25 ∗ V

CC

None

C/4 440 min None None

1C 110 min None None
2C 55 min None None

SLUS133–JANUARY 2000 E

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

Figures 2 and 3 show state diagrams of bq2002D/T and
Figure 4 shows the block diagram of the bq2002D/T

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.

2

bq2002D/T

F2002DT1.eps

bq2002D/T

BAT

V

SS

N
T
C

bq2002D/T

V

CC

V

CC

PACK +

T

S

V

SS

BAT pin connection Thermistor connection

TM

NTC = negative temperature coefficient thermistor.

RT1

RT2

R3

R4

RB1

RB2

Mid-level

setting for TM

Figure 1. Voltage and Temperature Monitoring and TM Pin Configuration

3

bq2002D/T

Chip on

V

CC

4.0V

Battery Voltage

too High?

Battery

Temperature?

Charge
Pending

Fast Charge,

CC = Z

LED = Low

SD2002D.eps

V

BAT

< 2V

V

BAT

< 2V and

V

BAT

>

2V

Off,

CC = Low

LED = Low

Off,

CC = Low

LED = Z

V

BAT

> 2V

V

BAT

2V

V

TS

> 0.25V

V

CC

V

TS

> 0.25V

V

CC

V

TS

< 0.25V

V

CC

V

BAT

> 2V or

V

TS

< 0.25V

V

CC

or

Maximum Time Out

T/ t or

Figure 2. bq2002D State Diagram

Chip on

V

CC

4.0V

Battery Voltage

too High?

( T/

t or
Maximum Time Out)
and TM = High

Battery

Temperature?

Charge
Pending

Fast

LED =

Low

Top-off

LED = Z

SD2002T.eps

V

BAT

< 2V

V

BAT

>

2V

0.25 VCC < VTS < 0.6 V

CC

Trickle
LED =

Low

Trickle

LED = Z

V

BAT

> 2V or
VTS < 0.225 VCC or
Maximum Time Out

V

BAT

> 2V or
VTS < 0.225 VCC or
(( T/ t or
Maximum Time Out)
and TM = High)

V

BAT

< 2V and
VTS < 0.6 VCC and
VTS > 0.25 V

CC

V

BAT

> 2V

V

BAT

2V

VTS > 0.6 VCC or
VTS < 0.25 V

CC

Figure 3. bq2002T State Diagram

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 ther

­mistor placed in proximity to the battery may be used as a
low-cost temperature-to-voltage transducer. The tempera

­ture sense voltage input at TS is developed using a
resistor-thermistor network between V

CC

and VSS. See

Figure 1.

Starting A Charge Cycle

Either of two events starts a charge cycle (see Figure 5):

1. Application of power to V

CC

or

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

V

MCV

= 2V ±5%.

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

­tery voltage range is V

BAT<VMCV

. The valid tempera

­ture range is V

HTF<VTS<VLTF

for the bq2002T and

V

HTF<VTS

for the bq2002D where:

V

LTF

= 0.4 ∗ VCC±5%.

V

HTF

= 0.25 ∗ VCC±5% (bq2002T only).

If the battery voltage or temperature is outside of these
limits, the IC pulse-trickle charges until the tempera­ture falls within the allowed fast charge range or a new
charge cycle is started.

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

n

Rate of temperature rise

n

Maximum voltage

n

Maximum temperature

n

Maximum time

∆T/∆t Termination

The bq2002D/T samples at the voltage at the TS pin ev

­ery 19s and compares it to the value measured three
samples earlier. If the voltage has fallen 25.6mV or
more, fast charge is terminated. The ∆T/∆t termination
test is valid only when V

TCO<VTS<VLTF

for the

bq2002T and V

TCO<VTS

for the bq2002D.

Temperature Sampling

A sample is taken by averaging together 16 measure

­ments taken 57µs apart. The resulting sample period
(18.18ms) filters out harmonics around 55Hz. This tech

-

4

bq2002D/T

OSC

TM

CC

LED

V

CC

V

SS

BAT

INH

Clock

Phase

Generator

Timing

Control

Sample

History

A to D

Converter

MCV

Check

Power

Down

TS

Bd2002TD.eps

Voltage

Reference

Power-On

Reset

TCO

Check

HTF/

LTF

Check

Charge-Control

State Machine

T/ t

ALU

Figure 4. Block Diagram

nique minimizes the effect of any AC line ripple that
may feed through the power supply from either 50Hz or
60Hz AC sources. Tolerance on all timing is ±20%.

Maximum Voltage, Temperature, and Time

Any time the voltage on the BAT pin exceeds the maxi­mum cell voltage, V

MCV

, fast charge or optional top-off

charge is terminated.

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

TCO

where:

V

TCO

= 0.225 ∗ VCC±5%

Maximum charge time is configured using the TM pin.
Time settings are available for corresponding charge
rates of C/4, 1C, and 2C. Maximum time-out termina­tion is enforced on the fast-charge phase, then reset, and

5

bq2002D/T

Corresponding

Fast-Charge Rate TM

Typical Fast-Charge

and Top-Off
Time Limits

(minutes)

Top-Off

Rate

Pulse-

Trickle Rate

Pulse-

Trickle

Period (ms)

bq2002D

C/4 Mid 440 NA NA NA

1C Low 110 NA NA NA

2C High 55 NA NA NA

bq2002T

C/4 Mid 320 C/64 C/256 18.3

1C Low 80 C/16 C/256 73.1

2C High 40 Disabled C/128 73.1

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

Mid = 0.5*V

CC

±0.5V

Tolerance on all timing is ±20%

Table 1. Fast-Charge Safety Time/Top-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-Trickle

Top-Off

(optional,

bq2002T only)

(optional,

bq2002T only)

286

See

Table 1

s

286

4576

Figure 5. Charge Cycle Phases

enforced again on the top-off phase, if selected (bq2002T
only). There is no time limit on the trickle-charge
phase.

Top-off Charge—bq2002T Only

An optional top-off charge phase may be selected to
follow fast charge termination for 1C and C/4 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

­mum voltage, time, and temperature are the only ter

­mination methods enabled during top-off.

Pulse-Trickle Charge—bq2002T Only

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 72.9ms of inactivity for 1C and
2C selections, and 286µs for every 17.9ms of inactivity
for C/4 selection. This results in a trickle rate of C/256
for the top-off enabled mode and C/128 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 mid­level selection input is developed by a resistor di

­vider between V

CC

and ground that fixes the voltage

on TM at V

CC

/2 ± 0.5V. See Figure 5.

Charge Status Indication

In the fast charge and charge pending states, and when

-

ever the inhibit pin is active, the LED

pin goes low. The

LED

pin is driven to the high-Z state for all other condi

-

tions. Figure 3 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

until inhibit is re

­moved. Temperature monitoring is not affected by the
INH pin. During charge inhibit, the bq2002D/T contin

­ues to pulse-trickle charge the battery per the TM selec

­tion. When INH returns low, charge control and the
charge timer resume from the point where INH became
active. The V

TS

sample history is cleared by INH.

Low-Power Mode

The IC enters a low-power state when V

BAT

is driven

above the power-down threshold (V

PD

) where:

V

PD

= VCC- (1V ±0.5V)

Both the CC pin and the LED

pin are driven to the
high-Z state. The operating current is reduced to less
than 1µA in this mode. When V

BAT

returns to a value

below V

PD

, the IC pulse-trickle charges until the next

new charge cycle begins.

6

bq2002D/T

7

bq2002D/T

Absolute Maximum Ratings

Symbol Parameter Minimum Maximum Unit Notes

V

CC

VCCrelative to V

SS

-0.3 +7.0 V

V

T

DC voltage applied on any pin
excluding V

CC

relative to V

SS

-0.3 +7.0 V

T

OPR

Operating ambient temperature 0 +70 °C Commercial

T

STG

Storage temperature -40 +85 °C

T

SOLDER

Soldering temperature - +260 °C 10 sec max.

T

BIAS

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.

DC Thresholds (T

A

= 0 to 70°C; V

CC

±

20%)

Symbol Parameter Rating Tolerance Unit Notes

V

TCO

Temperature cutoff

0.225*V

CC

±5%

V

V

TS

≤ V

TCO

terminates fast charge

and top-off

V

HTF

High-temperature fault

0.25 ∗ V

CC

±5%

V

VTS≤ V

HTF

inhibits fast charge start

V

LTF

Low-temperature fault

0.4 ∗ V

CC

±5%

V

V

TS

≥ V

LTF

inhibits fast charge start

(bq2002T only)

V

MCV

Maximum cell voltage 2 ±5% V

V

BAT

≥ V

MCV

inhibits/terminates fast

charge

8

bq2002D/T

Recommended DC Operating Conditions (T

A

= 0 to 70°C)

Symbol Condition Minimum Typical Maximum Unit Notes

V

CC

Supply voltage 4.0 5.0 6.0 V

V

BAT

Battery input 0 - V

CC

V

V

TS

Thermistor input 0.5 - V

CC

VVTS< 0.5V prohibited

V

IH

Logic input high 0.5 - - V INH

Logic input high V

CC

- 0.5 - - V TM

V

IM

Logic input mid

V

CC

2

- 0.5

-

V

CC

2

05+ .

VTM

V

IL

Logic input low - - 0.1 V INH

Logic input low - - 0.5 V TM

V

OL

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

V

PD

Power down

V

CC

- 1.5

-

VCC- 0.5

V

V

BAT

≥

V

PD

max. powers
down bq2002D/T;
V

BAT

< VPDmin. =

normal operation.

I

CC

Supply current - - 500

µ

A

Outputs unloaded,
V

CC

= 5.1V

I

SB

Standby current - - 1

µ

AVCC= 5.1V, V

BAT

= V

PD

I

OL

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

I

L

Input leakage - -

±

1

µ

A INH, CC, V = VSSto V

CC

I

OZ

Output leakage in
high-Z state

-5 - -

µ

A

LED

,CC

Note: All voltages relative to VSS.

9

Impedance

Symbol Parameter Minimum Typical Maximum Unit

R

BAT

Battery input impedance 50 - - M

Ω

R

TS

TS input impedance 50 - - M

Ω

Timing (T

A

= 0 to +70°C; V

CC

±

10%)

Symbol Parameter Minimum Typical Maximum Unit Notes

d

FCV

Time-base variation -20 - 20 %

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

bq2002D/T

10

D

E1

E

C

e

L

G

B

A

A1

B1

S

8-Pin DIP(PN

)

8-Pin PN(0.300" DIP

)

Dimension

Inches Millimeters

Min. Max. Min. Max.

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

bq2002D/T

8-Pin SOIC Narrow (SN)

8-Pin SN(0.150" SOIC

)

Dimension

Inches Millimeters

Min. Max. Min. Max.

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

11

bq2002D/T

Data Sheet Revision History

Change No. Page No. Description Nature of Change

13

Was: Table 1 gave the bq2002D/T Operational Summary.
Is: Figure 2 gives the bq2002D/T Operational Summary.

Changed table to figure.

1 5 Added top-off values. Added column and values.

2 All Revised and expanded this data sheet

3 All Revised and included bq2002D Addition of device

4 Specified package information for the bq2002D

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

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

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

Change 4 = Jan. 2000 E changes from Jan. 1999 D.

bq2002

Package Option:

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

Device:

D = bq2002D Fast-Charge IC
T = bq2002T Fast-Charge IC

Ordering Information

* bq2002D is only available in the 8-pin narrow SOIC
package

12

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