Rainbow-electronics BA3938 Bedienungsanleitung PDF herunterladen (Seite 7)

190

Regulator ICs BA3938

(5) Thermal protection circuit

A built-in thermal protection circuit prevents thermal

damage to the IC. All outputs except V

CC + B are switched

OFF when the circuit operates, and revert to the original

state when temperature drops to a certain level.

(6) Grounding

To minimize the variation of output voltage due to varia-

tions in load current, the GND (pin 12, for large current)

and the PRE GND (pin 11, for small current) pins are sep-

arately provided. Make sure to connect circuits to correct

pins.

(7) STANDBY voltage

Note that ON-state voltage and HIGH-state input current

of each output change when the external resistors of the

STANDBY pin are changed. These values are roughly

estimated as :

STB voltage when ON = 0.7 (R1 ) R2) / R2

STB current when HIGH = (5*0.7) / R1

FThermal derating cueve

Estimate of allowable power dissipation (P

MAX.)

S Power consumed by V

CC + B P1 = (VCC * VCC + B) maximum output current of VCC + B

S Power consumed by OUT 5V P

2 = (VCC * 5V) maximum output current of OUT 5V

S Power consumed by CD 8.5V P

3 = (VCC * 8.5V) maximum output current of OUT 8.5V

S Power consumed by OUT 9V P

4 = (VCC * 9V) maximum output current of OUT 9V

S Power consumed internally by each circuit P

5 = VCC supply current

MAX. = P1 ) P2 ) P3 ) P4 ) P5

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Rainbow-electronics BA3938 Bedienungsanleitung Seite 7