Technical Note

11/25

BD6592MUV

www.rohm.com

2011.06 - Rev.C

© 2011 ROHM Co., Ltd. All rights reserved.

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Start to use PWMPOW terminal for the PWM control, PWM operating

After RSTB and PWMDRV is changing L  H, input PWM to PWMPOW terminal.

There is no constraint in turn of RSTB and PWMDRV.

And, because it corresponds to PWM drive of shorter ON time than soft start time (1ms), when PWMPOW is input H more

than three times, the soft start is invalidated and it enable to correspond the high-speed drive. Until RSTB is set L,

invalidation of the soft start isn't canceled.

In case of lighting  light off  lighting, when it turns off the lights with PWM=L and It starts without soft start when it sets

PWM modulated light again.

But the peak current of the coil changes owing to discharge of output capacitor, It may flow to the over current limit value, as

follows Fig.34. Because soft start can be used when it turns off the lights with RSTB=L, The peak current of the coil can be

suppressed, as follows Fig.35 and this process of light off is recommended.

RSTB

PWMDRV

PWMPOW

Output Voltage

Current coil

Fig.34 Light off control of PWMPOW pin at PWM control on PWM=L

RSTB

PWMDRV

PWMPOW

Output Voltage

Current coil

Fig.35 Light off control of PWMPOW pin at PWM control on RSTB=L