Technical Note

4/8

BD63821EFV, BD63823EFV

www.rohm.com

2012.02 - Rev.A

© 2012 ROHM Co., Ltd. All rights reserved.

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Points to notice for terminal description

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PS/ Power save terminal

PS can make circuit standby state and make motor output open

Please be careful of delay 40μs(max.) before it is returned from off state to normal state.

PS

State

L

POWER SAVE (STANDBY)

H

ACTIVE

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IN1A,I N1B, IN2A, IN2B/ H bridge control terminal

Input

Output

State

PS

IN1A

IN2A

IN1B

IN2B

OUT1A

OUT2A

OUT1B

OUT2B

L

X

X

OPEN

OPEN

POWER SAVE (STANDBY)

H

L

L

OPEN

OPEN

STOP

H

H

L

H

L

FORWARD

H

L

H

L

H

REVERSE

H

H

H

L

L

BRAKE

X: H or L

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Protection Circuits

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Thermal Shutdown (TSD)

This IC has a built-in thermal shutdown circuit for thermal protection. When the IC’s chip temperature rises above 175°C

(Typ.), the motor output becomes open. Also, when the temperature returns to under 150°C (Typ.), it automatically

returns to normal operation. However, even when TSD is in operation, if heat is continued to be added externally, heat

overdrive can lead to destruction.

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Over Current Protection (OCP)

This IC has a built in over current protection circuit as a provision against destruction when the motor outputs are shorted

each other or VCC-motor output or motor output-GND is shorted. This circuit latches the motor output to open condition

when the regulated threshold current flows for 4μs (typ.). It returns with power reactivation or a reset of the PS terminal.

The over current protection circuit’s only aim is to prevent the destruction of the IC from irregular situations such as motor

output shorts, and is not meant to be used as protection or security for the set. Therefore, sets should not be designed to

take into account this circuit’s functions. After OCP operating, if irregular situations continues and the return by power

reactivation or a reset of the PS terminal is carried out repeatedly, then OCP operates repeatedly and the IC may

generate heat or otherwise deteriorate. When the L value of the wiring is great due to the wiring being long, after the over

current has flowed and the output terminal voltage jumps up and the absolute maximum values may be exceeded and as

a result, there is a possibility of destruction. Also, when current which is over the output current rating and under the OCP

detection current flows, the IC can heat up to over Tjmax=150°C and can deteriorate, so current which exceeds the

output rating should not be applied.

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Under Voltage Lock Out (UVLO)

This IC has a built-in under voltage lock out function to prevent false operation such as IC output during power supply

under voltage. When the applied voltage to the VCC terminal goes under 15V (Typ.), the motor output is set to open. This

switching voltage has a 1V (Typ.) hysteresis to prevent false operation by noise etc. Please be aware that this circuit

does not operate during power save mode.

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Over Voltage Lock Out (OVLO)

This IC has a built-in over voltage lock out function to protect the IC output and the motor during power supply over

voltage. When the applied voltage to the VCC terminal goes over 32V (Typ.), the motor output is set to OPEN. This

switching voltage has a 1V (Typ.) hysteresis and a 4μs (Typ.) mask time to prevent false operation by noise etc. Although

this over voltage locked out circuit is built-in, there is a possibility of destruction if the absolute maximum value for power

supply voltage is exceeded, therefore the absolute maximum value should not be exceeded. Please be aware that this

circuit does not operate during power save mode.

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Ghost Supply Prevention (protects against malfunction when power supply is disconnected)

If a signal (IN1A, IN1B, IN2A, IN2B, PS, VREF1, VREF2) is input when there is no power supplied to this IC, there is a

function which prevents the false operation by voltage supplied via the electrostatic destruction prevention diode from

these input terminals to the VCC to this IC or to another IC’s power supply. Therefore, there is no malfunction of the

circuit even when voltage is supplied to these input terminals while there is no power supply.