BD6520F(2008) Просмотр технического описания (PDF) - ROHM Semiconductor

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BD6520F
(Rev.:2008)

Large Current Output Power Management Switch ICs

ROHM Semiconductor 

3. Low voltage malfunction prevention circuit (UVLO)

The UVLO circuit monitors the voltage of the VDD pin, when the CTRL input is active. UVLO circuit prevents the switch from

turning on until the VDD exceeds 2.5V(Typ.). If the VDD drops below 2.3V(Typ.) while the switch turns on, then UVLO shuts off

the switch.

4. Soft start control

In BD6520F/22F, soft start is carried out in order to reduce inrush current at switch on. Further, in order to reduce inrush

current, soft start control pin (SSCTL) is prepared.

By connecting external capacitor to between SSCTL and GND, it is possible to make smoother the switch rise time. When the

switch is enabled, SSCTL outputs voltage of about 13.5V.

SSCTL terminal requires high impedance, so pay attention in packaging it so that there should not be leak current. And when

voltage is impressed from the outside to SSCTL terminal, switch on, off cannot be made correctly.

5. Discharge circuit

When the switch between the VDD and the OUT is OFF, the 200Ω(Typ.) discharge switch between OUT and GND turns on.

By turning on this switch, electric charge at capacitive load is discharged.

In BD6522F, the input of discharge circuit is separately prepared as DISC pin. When to use the discharge circuit, connect

OUT pin and DISC pin outside.

●Timing diagram

VDD

VCTRL

VOUT

Discharge circuit ON

OFF

ON

Fig.61 Normal operation

VDD

VCTRL

VOUT

Discharge circuit ON

VUVLOL

OFF

Fig.62 UVLO operation

VUVLOH

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