PJ3800 View Datasheet(PDF) - Unspecified

Part Name

Description

Manufacturer

PJ3800

Low Voltage Switching Regulator Controller

Unspecified 

PJ3800

Low Voltage Switching Regulator Controller

3. Other Functions

(1) Soft start and short circuit detection

Soft start operation is set by connecting capacitor CPE to the SCP pin (pin 2). Soft start prevents a current spike on start-up.

On completion of soft start operation, the SCP pin (pin 2) stays low and enters the short circuit detection wait state. When an

output short circuit occurs, the error amplifier output is fixed at VOM+ and capacitor CPE starts charging. After charging to

approximately 0.8 V, the output pin (pin 5) is set low and the SCP pin (pin 2) stays low.

Once the protection circuit operates, the circuit can be restored by resetting the power supply. (See “n HOW TO SET THE TIME

CONSTANT FOR SOFT START AND SHORT CIRCUIT DETECTION”.)

(2) Circuit to prevent malfunction at low input voltage

Transients when powering on or instantaneous glitches in the supply voltage can lead to malfunction of the control IC and cause

system damage or failure. The circuit to prevent malfunction at low input voltage detects a low input voltage by comparing the

supply voltage to the internal reference voltage. On detection, the circuit fixes the output pin to low.

The system recovers when the supply voltage rises back above the threshold voltage of the malfunction prevention circuit.

APPLICATION EXAMPLE

PJ3800

USAGE PRECAUTIONS

1. Do not apply an input voltage greater than the maximum rating.

Do not input voltages greater than the maximum rating as this can cause damage to the LSI

2. Use in accordance with the recommended operating conditions.

The electrical characteristics of the LSI are not guaranteed if the input voltage is greater than the maximum. Also, LSI operation is

unstable if the input voltage is less than the minimum. Therefore, always use in accordance with the recommended operating

conditions.

3. Use a wide ground line on the printed circuit board.

As the LSI uses a high frequency and therefore can generate high frequency noise, make the ground line as wide as possible.

4. Take anti-static precautions.

• Use a holder for inserting the semiconductor which is anti-static or conductive.

• After mounting the device on a printed circuit board, store or transport the board in a conductive bag or container.

• Earth work benches, tools, and measuring equipment.

• Ensure that maintenance personnel have a resistance of 250 kW to 1 MW in series between their body and earth.

7-8

2003/04.rev.A

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