Fujitsu MB3788 User Manual download pdf (Page 13)

MB3788

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HOW TO SET OUTPUT CURRENT

The output circuit is configured in a push-pull type as shown in Figure 1. The ON current value of the output

current waveform shown in Figure 2 is a constant current and the OFF value set by RE is set by a time constant.

Each output current can be calculated from the following expression:

• ON current = 1.5/R

E (A) (Output current setting pin voltage: VE ≈ 1.5 V)

• The OFF current time constant is proportional to the value of CB.

OFF current

setting part

Drive Tr

OFF

current

ON current

Output

current

ON current

OFF current

22 µH

(5 V)

150 Ω

1000 pF

4 5

VCC

Iout

1000 pF

10 µF

-IN1 (E)

8.2 kΩ

-IN1 (C)

MB3788

Fig.1 Output Circuit Diagram

Fig.2 Output Current Waveform

Fig.3 Output Pin Voltage and Current Waveforms (Channel 1)

Fig.4 Measurement Circuit Diagram

2.7 kΩ

Vout

1 2 ... 8 9 10 11 12 13 14 15 16 17 18 19 20 21

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Fujitsu MB3788 User Manual Page 13