Texas Instruments DV2003L1, DV2003S2, DV2003S1, BQ2003STR, BQ2003S-NTR Datasheet

1

Features

➤

Fast charge and conditioning of
nickel cadmium or nickel-metal
hydride batteries

➤

Hysteretic PWM switch-mode
current regulation or gated con

-

trol of an external regulator

➤

Easily integrated into systems
or used as a stand-alone charger

➤

Pre-charge qualification of tem

-

perature and voltage

➤

Direct LED outputs display
battery and charge status

➤

Fast-charge termination by

∆

temperature/∆time, -∆V, maxi­mum voltage, maximum tem­perature, and maximum time

➤ Optional top-off charge

General Description

The bq2003 Fast Charge IC provides
comprehensive fast charge control
functions together with high-speed
switching power control circuitry on a
monolithic CMOS device.

Integration of closed-loop current
control circuitry allows the bq2003
to be the basis of a cost-effective so

­lution for stand-alone and system­integrated chargers for batteries of
one or more cells.

Switch-activated discharge-before­charge allows bq2003-based chargers
to support battery conditioning and
capacity determination.

High-efficiency power conversion is
accomplished using the bq2003 as a
hysteretic PWM controller for
switch-mode regulation of the charg­ing current. The bq2003 may alterna­tively be used to gate an externally
regulated charging current.

Fast charge may begin on applica

-

tion of the charging supply, replace

-

ment of the battery, or switch de

­pression. For safety, fast charge is
inhibited unless/until the battery
temperature and voltage are within
configured limits.

Temperature, voltage, and time are
monitored throughout fast charge.
Fast charge is terminated by any of
the following:

n

Rate of temperature rise
(∆T/∆t)

n

Negative delta voltage (-∆V)

n

Maximum voltage

n

Maximum temperature

n

Maximum time

After fast charge, an optional top-off
phase is available. Constant-cur­rent maintenence charge is provided
by an external trickle resistor.

Fast-Charge IC

bq2003

CCMD Charge command/select

DCMD Discharge command

DVEN -∆V enable/disable

TM

1

Timer mode select 1

TM

2

Timer mode select 2

TS Temperature sense

BAT Battery voltage

V

SS

System ground

1

PN200301.eps

16-Pin DIP or SOIC

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

V

CC

DIS

MOD

CHG

TEMP

MCV

TCO

SNS

CCMD

DCMD

DVEN

TM

1

TM

2

TS

BAT

V

SS

SNS Sense resistor input

TCO Temperature cutoff

MCV Maximum voltage

TEMP Temperature status

output

CHG Charging status output

MOD Charge current control

DIS Discharge control

V

CC

5.0V±10% power

Pin Connections

Pin Names

SLUS095A - OCTOBER 1999 I

Pin Descriptions

CCMD,
DCMD

Charge initiation and discharge-before­charge control inputs

These two inputs control the conditions that
begin a new charge cycle and enable
discharge-before-charge. See Table 1.

DVEN

-∆V enable input

This input enales/disables -∆V charge termina

­tion. If DVEN is high, the -∆V test is enabled.
If DVEN is low, -∆V test is disabled. The state
of DVEN may be changed at any time.

TM

1

–

TM

2

Timer mode inputs

TM

1

and TM2are three-state inputs that con

­figure the fast charge safety timer, -∆V hold­off time, and that enhance/disable top-off.
See Table 2.

TS

Temperature sense input

Input, referenced to SNS, for an external
thermistor monitoring battery temperature.

BAT

Single-cell voltage input

The battery voltage sense input, referenced
to SNS. This is created by a high-impedance
resistor divider network connected between
the positive and the negative terminals of
the battery.

Vss

Ground

SNS

Charging current sense input

SNS controls the switching of MOD based on
the voltage across an external sense resistor
in the current path of the battery. SNS is the
reference potential for the TS and BAT pins.
If SNS is connected to V

SS

, MOD switches
high at the beginning of charge and low at
the end of charge.

TCO

Temperature cutoff threshold input

Input to set maximum allowable battery
temperature. If the potential between TS
and SNS is less than the voltage at the TCO
input, then fast charge or top-off charge is
terminated.

MCV

Maximum-Cell-Voltage threshold input

Input to set maximum single-cell equivalent
voltage. If the voltage between BAT and SNS
is greater than or equal to the voltage at the
MCV input, then fast charge or top-off charge
is inhibited.

Note: For valid device operation, the
voltage level on MCV must not exceed

0.6 ∗ V

CC

.

TEMP

Temperature status output

Push-pull output indicating temperature
status. TEMP is low if the voltage at the TS
pin is not within the allowed range to start
fast charge.

CHG

Charging status output

Push-pull output indicating charging status.
See Figure 1.

MOD

Current-switching control output

MOD is a push/pull output that is used to
control the charging current to the battery.
MOD switches high to enable charging cur

­rent flow and low to inhibit charging current
flow.

DIS

Discharge FET control output

Push-pull output used to control an external
transistor to discharge the battery before
charging.

V

CC

VCCsupply input

5.0 V, ±10% power input.

2

bq2003

Functional Description

Figure 3 shows a state diagram and Figure 4 shows a
block diagram of the bq2003.

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 bat

-

tery terminal. See Figure 1.

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

A ground-referenced negative temperature coefficient
thermistor placed in proximity to the battery may be used
as a low-cost temperature-to-voltage transducer. The tem

-

perature sense voltage input at TS is developed using a re

-

sistor-thermistor network between V

CC

and battery’s nega

-

tive terminal See Figure 1. Both the BAT and TS inputs
are referenced to SNS, so the signals used inside the IC are:

V

BAT-VSNS=VCELL

and

V

TS-VSNS=VTEMP

3

Table 1. New Charge Cycle and Discharge Stimulus

CCMD DCMD New Charge Cycle

Started by:

Discharge-Before-Charge

Started by:

Pulled Up/Down to:

V

SS

V

SS

VCCrising to valid level

A rising edge on DCMD

Battery replacement

(V

CELL

falling through V

MCV

)

A rising edge on CCMD

V

CC

V

CC

VCCrising to valid level

A rising edge on DCMD

Battery replacement

(V

CELL

falling through V

MCV

)

A falling edge on CCMD or DCMD

V

CC

V

SS

A rising edge on CCMD A rising edge on DCMD

V

SS

V

CC

A falling edge on CCMD A rising edge on DCMD

bq2003

Fg2003a2.eps

N
T
C

bq2003

V

CC

PACK +

PACK -

T

S

SNS

RT1

RT2

RB2

RB1

bq2003

V

DC

External Trickle Resistor Negative Temperature

Coefficient Thermister

Pass Element

PACK+

PACK-

MOD

BAT

SNS

Figure 1. Voltage and Temperature Monitoring and Trickle Resistor

Discharge-Before-Charge

The DCMD input is used to command discharge-before­charge via the DIS output. Once activated, DIS becomes
active (high) until V

CELL

falls below V

EDV,

at which time
DIS goes low and a new fast charge cycle begins. See
Table 1 for the conditions that initiate discharge-before­charge. Discharge-before-charge is qualified by the
same voltage and temperature conditions that qualify a
new charge cycle start (see below). If a discharge is ini

­tiated but the pack voltage or temperature is out of
range, the chip enters the charge pending mode and
trickle charges the battery until the voltage and tem

­perature qualification conditions are met, and then
starts to discharge.

Starting A Charge Cycle

The stimulus required to start a new charge cycle is de

­termined by the configuration of the CCMD and DCMD
inputs. If CCMD and DCMD are both pulled up or
pulled down, then a new charge cycle is started by (see
Figure 2):

1. V

CC

rising above 4.5V

2. V

CELL

falling through the maximum cell voltage,

V

MCV

.V

MCV

is the voltage presented at the MCV
input pin, and is configured by the user with a re­sistor divider between V

CC

and ground. The al-

lowed range is 0.2 to 0.4 ∗ V

CC

.

3. A rising edge on CCMD if it is pulled down, or a fal

-

ling edge on CCMD if it is pulled up.

Starting a new charge cycle may be limited to a push­button or logical pulse input only by pulling one member
of the DCMD and CCMD pair up while pulling the other
input down. In this configuration a new charge cycle
will be started only by a falling edge on CCMD if it is
pulled up, and by a falling edge on CCMD if it is pulled
down. See Table 1.

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

-

tery voltage range is V

EDV<VBAT<VMCV

where:

V

EDV

= 0.2 ∗ VCC± 30mV

The valid temperature range is V

HTF<VTEMP<VLTF

,

where:

V

LTF

= 0.4 ∗ VCC± 30mV

V

HTF

= [(1/8 ∗ V

LTF

) + (7/8 ∗ V

TCO

)] ± 30mV

V

TCO

is the voltage presented at the TCO input pin, and is

configured by the user with a resistor divider between V

CC

and ground. The allowed range is 0.2 to 0.4 ∗ VCC.

If the temperature of the battery is out of range, or the
voltage is too low, the chip enters the charge pending
state and waits for both conditions to fall within their
allowed limits. There is no time limit on the charge
pending state; the charger remains in this state as long
as the voltage or temperature conditons are outside of

4

bq2003

Fast Charging Top-Off

(Optional)

34 sec.

TD200301a.eps

Discharge

(Optional)

Charge

Pending

DIS

MOD Switch-Mode Configuration

MOD External Regulation
(SNS Grounded)

CHG Status Output

TEMP Status Output

Charge cycle start.
Battery outside temperature limits.

or

Battery within temperature limits.

Battery discharged to 0.2 VCC.

4

sec

.

Figure 2. Charge Cycle Phases

the allowed limits. If the voltage is too high, the chip
goes to the battery absent state and waits until a new
charge cycle is started.

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

n

Delta temperature/delta time (∆T/∆t)

n Negative delta voltage (-

∆

V)

n

Maximum voltage

n

Maximum temperature

n

Maximum time

-∆V Termination

If the DVEN input is high, the bq2003 samples the volt

-

age at the BAT pin once every 34s. If V

CELL

is lower
than any previously measured value by 12mV ±4mV,
fast charge is terminated. The -∆V test is valid in the
range V

MCV

- (0.2 ∗ VCC)<V

CELL<VMCV

.

Voltage Sampling

Each sample is an average of 16 voltage measurements
taken 57µs apart. The resulting sample period (18.18ms)
filters out harmonics around 55Hz. This technique mini

­mizes 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 ±16%.

Voltage Termination Hold-off

A hold-off period occurs at the start of fast charging.
During the hold-off period, -∆V termination is disabled.
This avoids premature termination on the voltage spikes
sometimes produced by older batteries when fast-charge
current is first applied. ∆T/∆t, maximum voltage and

maximum temperature terminations are not affected by
the hold-off period.

∆T/∆t Termination

The bq2003 samples at the voltage at the TS pin every
34s, and compares it to the value measured two samples
earlier. If V

TEMP

has fallen 16mV ±4mV or more, fast
charge is terminated. The ∆T/∆t termination test is
valid only when V

TCO<VTEMP<VLTF

.

Temperature Sampling

Each sample is an average of 16 voltage measurements
taken 57µs apart. The resulting sample period
(18.18ms) filters out harmonics around 55Hz. This tech

­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 ±16%.

Maximum Voltage, Temperature, and Time

Anytime V

CELL

rises above V

MCV,

CHG goes high (the LED
goes off) immediately. If the bq2003 is not in the voltage
hold-off period, fast charging ceases if V

CELL

remains above

MCV for a minimum of t

MCV

.IfV

CELL

then falls back be

-

low V

MCV

before 1.5t

MCV

±50ms, the chip transitions to the
Charge Complete state (maximum voltage termination). If
V

CELL

remains above V

MCV

beyond 1.5t

MCV

, the bq2003
transitions to the Battery Absent state (battery removal).
See Figure 3.

If the bq2003 is in the voltage hold-off period when
V

CELL

rises above V

MCV,

the LED goes out but fast
charging continues until the expiration of the hold-off
period. Temperature sampling continues during the
hold-off period as well. If a new battery is inserted be

­fore the hold-off period expires, it continues in the fast
charge cycle started by its predecessor. No precharge
qualification is performed, and a temperature sample

5

bq2003

Corresponding

Fast-Charge Rate TM1 TM2

Typical Fast Charge

and Top-Off
Time Limits

Typical -∆V/MCV

Hold-Off

Time (seconds)

Top-Off

Rate

C/4 Low Low 360 137 Disabled
C/2 Float Low 180 820 Disabled

1C High Low 90 410 Disabled
2C Low Float 45 200 Disabled
4C Float Float 23 100 Disabled

C/2 High Float 180 820 C/16

1C Low High 90 410 C/8
2C Float High 45 200 C/4
4C High High 23 100 C/2

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

Table 2. Fast-Charge Safety Time/Hold-Off/Top-Off Table