AN8018SA Ver la hoja de datos (PDF) - Panasonic Corporation

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Fabricante

AN8018SA

1.8-volt 2-channel step-up, step-down, or inverting DC-DC converter control IC

Panasonic Corporation 

AN8018SA

Voltage Regulators

s Application Notes (continued)

[7] Parallel synchronous operation of multiple ICs (continued)

2. About the operation of short-circuit protection at parallel synchronous operation

In the case of the operation in parallel, if the single output (or multiple outputs) of them is short-circuited and

the timer latch short circuit protection of the IC is operated, the output of other ICs will be also shut down, then

enter into latch mode.

In figure 8, if the IC-2 entered timer latch mode, Q1 turns on and the OSC terminal (pin 1) is fixed to

approximately 1.1 V and the oscillator stops.

Then channel 1 of IC-1 becomes low level than the DT1 terminal (pin 6) voltage or high-level voltage (0.9 V)

of the FB1 terminal set by terminal voltage, and then output 2 stops by PWM1 circuit of inside. The channel 2 stops

output 2 by oscillator high-level detection comparator.

And then, the IC-1 becomes short-circuit state and enters latch mode after a certain time.

It becomes the same operation in case of the IC-1 enters latch mode previously.

IC-1

0.9 V

Channel 2 goes off

at high

Oscillator high-level

detection comparator

The IC entering to the lach mode,

IC-2

Q1 turns on and,

Q1

VOSC = VREF − VCE(sat)

= becomes approximately 1.1 V

IC-2 side

IC-2 latch

output short-circuited

1.19 V

IC-1 latch

S.C.P.

OSC

DT1

FB1

Out1

OSC

FB2

DT2

Out2

Since the OSC terminal voltage

becomes higher than

the DT1 terminal voltage,

the Out1 becomes fully off state.

Forced to be in off state

inside the IC

1.19 V

S.C.P.

Figure 8. Operation of short-circuit protection at parallel synchronous operation

18

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