TEMIC U2403B Datasheet

Charge Timer

Description

The U2403B is a monolithic, integrated-bipolar circuit
which can be used in applications for time-controlled,
constant-current charge. Selection of charge current
versus timing is carried out by using the external circuit
at Pins 2, 3 and 4. For high current requirement, an
external transistor is recommended in series with the
battery. To protect the IC against high power loss

U2403B

(typically > 140°C), the oscillator is shut down when the
reference voltage is switched off (0 V). The latter also
takes place when there is a saturation caused by collector
voltage at Pin 1. When the overtemperature has
disappeared and the collector voltage at Pin 1 has
exceeded the supply voltage (V
operation continues (see flow chart in figure 3).

> VS), charge time

1

Features

D

Easy-to-run autonomous dual rate charger

D

Constant charge current

D

3 h – 24 h charge time programmable

D

Low cost dc regulator

D

Overtemperature protection

D

Charge-mode indication

D

Operation starts at the moment of battery insertion

D

Fast charge time-test mode

Block Diagram

LED

Power

supply

AC/DC

Battery

inserted

2

Charge

R

5

LED

8

Charge mode

indicator

Applications

D

Cordless telephones

D

Low-cost battery-charge timer

D

Entertainment

Package: DIP8, SO8

R

1

LED

1

Ready

V

Power supply

V

= 3.5 to 12 V

S

C

1

GND

S

6

7

Test

mode

94 8629

S

5

TM

TELEFUNKEN Semiconductors

Rev . A2, 14–Nov–96

í

max

140°C

1

V

1

Shunt

Figure 1. Block diagram with external circuit

í

2

Timer and control logic

= 1.5 V/ 0.1 V/ 0 V

V

Ref

V

Ref

+

–

Sense

R

3

R

4

RC

oscillator

43

Osc

C

4

1 (12)

U2403B

Pin Description

1

V

1

2

V

2

Sense

Osc

3

4

Pin 1, Collector Voltage V

94 8685

1

8

LED

7

GND

6

V

S

S

5

TM

Pin 1 is an open collector output. When V1 ≤ 3 V, the
charge cycle is switched off until it is above the supply
voltage, as shown in figure 6.

Pin 2, Shunt Emitter

The constant current source is supplied by the internal
operational amplifier. The voltage across R

is deter-

3

mined via the internal reference source.
Ich = V3/R3(V3 = V

sense

)

Pin 3, Amplifier Sense Input (Inverted)

Pin Symbol Function

1 V
2 V
3 V

Collector terminal

1

Shunt emitter terminal

2

Amplifier sense input

3

4 Osc Oscillator input
5 S
6 V

TM

Test mode switch
Supply voltage

S

7 GND Reference point, GND
8 LED Charge mode indicator

2 3 256

1

Pin 4

Pin 5

Figure 2. Quick test timer 1/3

Oscillator

Test – Mode

Pulse

94 8839

The voltage-regulated current source has a closed loop at
Pin 2, Pin 3, and resistor R

Pin 4, Oscillator Input R4, C

.

3

4

Selection of current charge versus timing is carried out by
using the external circuit at Pins 2, 3, and 4. Typical
values are given in charge characteristics (see table next
page).

Pin 5, Test-Mode Switch for Charging Time

The charging time, t

1

+

t

ch

osc

2

f

where:
f

= oscillator frequency (see figure 2)

osc

n = frequency divider

= 26, if S
= 17, if S
= 8, if S

The first eight divider stages can be tested directly.
256 input tact signals at Pin 4 create one tact signal at
Pin 5.

is given by the following equation.

ch,

n

open

TM

= GND

TM

= V

TM

S

Example

Assume a charge time of 6 h.
Select the values of R

For example: R

and C4 from the tables next page.

4

= 470 k

4

= 680 pF

C

4

W

There is a frequency of approximately 3100 Hz at Pin 4.
It is possible to test the charge time of 6 h by running
through the charge cycle for a very short time. By
connecting Pin 5 with GND, the test time is 42 s. By
connecting Pin 5 with Pin 1 (V
to about 82.4 ms. R

is connected in parallel to the LED

5

), the test time is reduced

1

and provides a protective bypass function for the LED
(see figure 1).

Pin 6, Supply Voltage, V

S

VS [ 3.1 V power-on reset release (turn-on)

[ 2.9 V under-voltage reset

V

S

[ 13 V supply voltage limitation

V

S

Pin 7, Ground

2

2 (12)

TELEFUNKEN Semiconductors

Rev . A1, 20-Mar-96

U2403B

Pin 8, Charge Mode Indicator

An open-collector output supplies constant current to

after the active charge phase has been terminated.

LED

1

controls the function temperature for the final stage

í

max

range. This is when the temperature is above 140°C and
the charge function is therefore switched off.

Charge Characteristics

Charge Time

Test time/ Test-Mode Switch S

Open V

3 h 41.2 ms 21 s 510

4 h 54.9 ms 28 s 620

5 h 68.6 ms 35 s 510

6 h 82.4 ms 42 s 620

7 h 96.1 ms 49 s 560

8 h 109.8 ms 56 s 620

9 h 123.6 ms 1 min 3 s 750

10 h 137.3 ms 1 min 10 s 620

12 h 164.8 ms 1 min 24 s 390

16 h 219.7 ms 1 min 56 s 470

S

TM

GND R4 (K

Trickle Charge

The trickle charge starts after the charge has been termi­nated. In this case, the internal reference voltage is
reduced from 1.5 V to approximately 0.1 V. This means
the charge current is decreased by the factor:

K = 1.5 V/ 0.1 V = 15.
Trickle current = I
It is possible to reduce the trickle charge with resistor R

as shown in figures 6 and 7.

Oscillator Components Frequency

W)

430
300

430
300

390
300

470
360

430
220

470
200

510
240

270
130

150

200

/ 15 + I6 (supply current) + I

ch

C4 (pF) f

270
330
470

330
470
680

470
680

1000

470
680

1000

680
1000
2200

680
1000
2200

680
1000
2200

820
2200
4700

2200
4700

2200
4700

osc

6213

4660

3728

3105

2663

2330

2071

1864

1553

1165

8

(Hz)

6,

TELEFUNKEN Semiconductors

Rev . A2, 14–Nov–96

3 (12)

U2403B

start

no

Battery

inserted

Turn on VS > 3.5 V

V

= 1.5 V

3

LED2 “ON”

Timer start

Test

Open

mode

Divider

2262172

Tj > T

V1 < 3.0 V

GND

max

no

no

V

S
8

yes

yes

V3[

0 V

Interrupt charging

LED2 “OFF”

Interrupt

no

Tj < T

max

no

End of
timing

LED2 “OFF”
LED

1

Trickle charge mode

= 100 mV

V

3

Battery

removed

Undervoltage reset

Figure 3. Flow chart

yes

“ON”

yes

yes

no

V1 > V

S

yes

V3 = 0 V

Continuous charging

LED2 “ON”

Continuous timing

no

95 9624

4 (12)

TELEFUNKEN Semiconductors

Rev . A1, 20-Mar-96