FREQ datasheet(16/56 Pages) FUJITSU

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MB39A214A

Limitation : development tool vendor use only

FUJITSU SEMICONDUCTOR CONFIDENTIAL

DS405-00007-1v0-E

(5) DC/DC converter stop sequence (Discharge, standby)

When the EN1 pin (pin 2) or EN2 pin (pin 11) is set to the “L” level, the output capacitor is discharged

using the discharge FET (RON

25 Ω) in the IC. If the voltage of the VOUT1 pin (pin 3) and VOUT2 pin

(pin 10) is below 0.2 V (Typ) by discharging the output capacitor, the IC stops discharge operation. Further,

if both the EN1 and EN2 pins are set to the “L” level, the IC also stops the output of the VB pin and enters

the standby state after detecting UVLO. The current of the VCC pin (IVCC) is then 10 µA (Max).

EN1

UVLO VTHL

CS1

DRVH1

DRVL1

VOUT1

EN2

0.2 V

1.6 V

0.2 V

CS2

DRVH2

DRVL2

VOUT2

(6) Under Voltage Lockout Protection (UVLO)

The under voltage lockout protection (UVLO) protects ICs from malfunction and protects the system from

destruction/deterioration, according to the reasons mentioned below.

Transitional state when the bias voltage (VB) or the reference voltage (VREF) starts.

Momentary decrease

To prevent such a malfunction, this function detects a voltage drop of the VB pin (pin 18) using the

comparator (UVLO Comp.), and stops IC operations.

When the VB pin exceeds the threshold voltage of the under voltage lockout protection circuit, the system

is restored.

CH2 discharge FET ON

CH1 discharge FET ON

Standby

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