PJ3800 データシートの表示（PDF） - Unspecified

部品番号

コンポーネント説明

メーカー

PJ3800

Low Voltage Switching Regulator Controller

Unspecified 

DIAGRAM

PJ3800

Low Voltage Switching Regulator Controller

HOW TO SET THE TIME CONSTANT FOR SOFT START AND SHORT CIRCUIT DETECTION

1. Soft Start

At power on, the capacitor CPE connected to the SCP pin starts charging. The PWM comparator compares the soft start setting

voltage as a proportion of the voltage at the SCP pin with the saw tooth waveform. The comparison controls the ON duty of the

OUT pin, causing the soft start operation. On completion of soft start operation, the voltage at the SCP pin stays low, the soft

start setting voltage stays high, and the circuit enters the output short circuit detection wait state.

Soft start time (The time until the output ON duty reaches approximately 50%)

tS [s] ≅ 0.35 × CPE [μF]

2. Short Circuit Protection

If the switching regulator output suddenly drops due to load effect, the error amplifier output (FB pin) is fixed at VOM + and

capacitor CPE starts charging. When the voltage at the SCP pin reaches approximately 0.8V, the output pin is set low and the

SCP pin stays low.

Once the protection circuit operates, the circuit can be restored by resetting the power supply.

• Short circuit detection time

tPE [s] ≅ 0.8 × CPE [μF]

4-8

2003/04.rev.A

Share Link: