BD2066FJ-E2_11 查看數據表（PDF） - ROHM Semiconductor

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BD2066FJ-E2_11

2ch High Side Switch ICs for USB Devices and Memory Cards

ROHM Semiconductor 

BD2062FJ,BD2066FJ

Technical Note

●Functional Description

1. Switch operation

IN terminal and OUT terminal are connected to the drain and the source of switch MOSFET respectively. And the IN

terminal is used also as power source input to internal control circuit.

When the switch is turned on from EN/EN control input, IN terminal and OUT terminal are connected by a 100mΩ switch.

In on status, the switch is bidirectional. Therefore, when the potential of OUT terminal is higher than that of IN terminal,

current flows from OUT terminal to IN terminal.

Since a parasitic diode between the drain and the source of switch MOSFET is canceled, in the off status, it is possible to

prevent current from flowing reversely from OUT to IN.

2. Thermal shutdown circuit (TSD)

Thermal shut down circuit have dual thermal shutdown threshold. Since thermal shutdown works at a lower junction

temperature when an over-current occurs, only the switch of an over-current state become off and error flag is output.

Thermal shut down action has hysteresis. Therefore, when the junction temperature goes down, switch on and error flag

output automatically recover. However, until cause of junction temperature increase such as output shortcircuit is

removed or the switch is turned off, thermal shut down detection and recovery are repeated. The thermal shut down

circuit works when the switch of either OUT1 or OUT2 is on (EN,/EN signal is active).

3. Over-current detection (OCD)

The over-current detection circuit limits current (ISC) and outputs error flag (/OC) when current flowing in each switch

MOSFET exceeds a specified value. There are three types of response against over-current. The over-current detection

circuit works when the switch is on (EN,/EN signal is active).

3-1. When the switch is turned on while the output is in short-circuit status

When the switch is turned on while the output is in short-circuit status or so, the switch gets in current limit status

soon.

3-2. When the output short-circuits while the switch is on

When the output short-circuits or large capacity is connected while the switch is on, very large current flows until the

over-current limit circuit reacts. When the current detection, limit circuit works, current limitation is carried out.

3-3. When the output current increases gradually

When the output current increases gradually, current limitation does not work until the output current exceeds the

over-current detection value. When it exceeds the detection value, current limitation is carried out.

4. Under-voltage lockout (UVLO)

UVLO circuit prevents the switch from turning on until the VIN exceeds 2.3V(Typ.). If the VIN drops below 2.2V(Typ.)

while the switch turns on, then UVLO shuts off the switch. UVLO has hysteresis of a 100mV(Typ).

Under-voltage lockout circuit works when the switch of either OUT1 or OUT2 is on (EN,/EN signal is active).

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11/16

2011.05 - Rev.B

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