BD6516FJ Просмотр технического описания (PDF) - ROHM Semiconductor

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BD6516FJ

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

ROHM Semiconductor 

BD6512F,BD6513F,BD6516F,BD6517F,BD2042AFJ,BD2052AFJ

Technical Note

●Functional description

1. Switch operation

VDD(IN) pin and OUT pin are connected to the drain and the source of switch MOSFET respectively. And the VDD(IN) pin

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

When the switch is turned on from CTRL(EN) control input, VDD(IN) and OUT is connected. In a normal condition, current

flows from VDD to OUT. If voltage of OUT is higher than VDD, current flows from OUT to VDD, since the switch is

bidirectional.

◎BD6512F/ BD6513F

There is a parasitic diode between the drain and the source of switch MOSFET. Therefore, even when the switch is off, if

the voltage of OUT is higher than that of VDD, current flows from OUT to VDD.

◎BD6516F/BD6517F/BD2042AFJ/BD2052AFJ

There is not parasitic diode, it is possible to prevent current from flowing reversely from OUT to VDD.

2. Thermal shutdown (TSD)

Thermal shut down circuit turns off the switch and outputs an error flag when the junction temperature in chip exceeds a

threshold temperature. The thermal shut down circuit works when either of two control signals is active.

In BD6512F/BD6513F/BD6516F/BD6517F, the switches of both OUTA and OUTB become off and error flags are output to the both.

BD2042AFJ/ BD2052AFJ have dual thermal shutdown threshold. Since thermal shutdown works at a lower junction

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

◎BD6512F/BD6513F

The switch off status of the thermal shut down is latched. Therefore, even when the junction temperature goes down,

switch off and error flag output status are maintained. To release the latch, it is necessary to input a signal to switch off to

CTRL pin or make UVLO status. When the switch on signal is input or UVLO is released, the switch on and error flag

output are recovered.

◎BD6516F/BD6517F/BD2042AFJ/BD2052AFJ

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.

3. Over current detection, limit circuit

The over current detection circuit limits current and outputs error flag when current flowing in each switch MOSFET

exceeds a specified value. There are three types of response against over current. The over current detection, limit circuit

works when the switch is on (CTRL・EN signal is active).

3-1 When the switch is turned on while the output is in shortcircuit status

When the switch is turned on while the output is in shortcircuit status, the switch become current limit mode soon.

3-2 When the output shortcircuits while the switch is on

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

over current limit circuit responds. 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)

When the supply voltage is below UVLO threshold level, UVLO circuit turns off switch to prevent malfunction. The UVLO

circuit works when either of two control signals is active.

◎BD6512F/BD6513F

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.

◎BD2042AFJ/BD2052AFJ

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).

5. Error flag output

Error flag output is N-MOS open drain output.

◎BD6512F/BD6513F

At detection of over current detection, thermal shutdown, UVLO, Low level is output.

◎BD6516F/BD6517F/BD2042AFJ/BD2052AFJ

At detection of over current detection, thermal shutdown, Low level is output. Error flag output at over current detection

has delay filter. This delay filter prevents instantaneous current detection such as inrush current at switch on, hot plug

from being informed to outside.

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2011.05 - Rev.B

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