U2403B Datasheet, PDF (9/12 Pages) TEMIC Semiconductors – Charge Timer

U2403B
Booster and Trickle Charge Reduction
Basic Example
NiCd battery 1000 mAh
Charging time: 2 h
Charge current: 500 mA
Trickle charge:
22 mA < 1/22 C
W R₁ = 510 , 1/8 W
C₁ = 100 mF/ 16 V
R₃ = 3 W/ 1 W
R₄ = 300 kW
C₄ = 330 pF
R₅ = 3.9 W/ 1 W
C₂ = 1 mF
Supply Voltage
No of Cells
1
2
3
4
5
DC Supply Minimum
V_S = 6.5 V
8.0 V
9.5 V
11.0 V
12.5 V
Special Requirements for Different Charge
Times
R₄, C₄ values for different charge times
2 h 4 h 6 h 7 h 12 h
R₄ 300 kW 430 kW 470 kW 470 kW 390 kW
C₄ 330 pF 470 pF 680 pF 1 nF 2.2 nF
Special Requirements for Different Charge
Current
R₃, R₅ values for different charge currents
616 mA 493 mA 411 mA 296 mA
R₃
2.4 W
3W
3.6 W
5W
R₅
3W
3.9 W
4.7 W
6.8 W
R₆ = 560 W, reduced trickle charge
Basic Equations
R₁ = 0.5 V / I_S
R₅ = V(LED₂)/ (I_ch – 20 mA)
Nominal Charge Current:
I_ch = V₃/ R₃
V₃ = 1.48 V, typically
Trickle Current:
I_ch = V₃/R₃ + I_LED1 + I_S – I₆
Typical values:
V₃ = 100 mV
I_LED1 = 4.5 mA
I_S = 1.8 mA
Trickle-Charge Reduction (I₆)
I₆ = (V_Batt + V_D1)/R₆
V_D1 = 0.75 V
BYW52
DC
supply I₆
D₁
R₁
C₁
R₆ READY
LED₁ I_S
S1
I_ch
8
7
6
5
C₂
R₂
10 kW
BD 136
or
1
BC 636
Charge
R₅
LED₂
U2403B
2
3
4
R₄
R₃
C₄
S1: use for test only
Figure 7. Application for charge current > 250 mA
To fulfill requirements of higher charge current an exter-
nal booster transistor can be used (see figure 7). As the
temperature cannot be monitored in this case a heat sink
with a resonable size should be used for safe operation.
Test mode switch S₁ can be used for accelerated produc-
tion check.
TELEFUNKEN Semiconductors
Rev. A2, 14–Nov–96
9 (12)