Technical Note

4/8

BD6393FP, BD6395FP

www.rohm.com

2012.02 - Rev.A

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

●Points to notice for terminal description

○PS／Power save terminal

PS can make circuit standby state and make motor output OPEN. Please be careful because there is a delay of

40

μs(max.) before it is returned from standby state to normal state and the motor output becomes ACTIVE.

PS

State

L

Standby state (RESET)

H

ACTIVE

○PHASE1,PHASE2／Logic input terminal

These terminals decide output state.

PHASEX

OUTXA

OUTXB

L

L

H

H

H

L

○I01,I02,I11,I12／Logic input terminal for DAC

These terminals decide internal DAC output voltage for current limit.

I0X

I1X

Output current

level(%)

L

L

100

H

L

67

L

H

33

H

H

0

(I0X,I1X)=(H,H) : motor output are open.

●Protection Circuits

○Thermal Shutdown (TSD)

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

175℃ (Typ.), the motor output becomes OPEN. Also, when the temperature returns to under 150℃ (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.

○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 4

μs (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 repeatly, then OCP operates repeatly 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

which exceeds the output rating should not be applied.

○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 11V (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.

○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 33V (Typ.), the motor output is set to OPEN. This

switching voltage has a 1V (Typ.) hysteresis and a 4

μs (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.

○False operation prevention function in no power supply (Ghost Supply Prevention)

If a logic control signal 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 the logic control input terminal 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 the logic control input terminal while there is no power supply.