Using PWM dimming at LP8557

masa0301

Intellectual 960 points

Other Parts Discussed in Thread: LP8557

If my coustomer want to use the only PWM dimming.

In this case they need to be set using the I2C BRTMODE=00 ？

Because of default is BRTMODE=11b.

Or may I enter the PWM directly to the FSET pin ?(Dont need the set using the I2C)

Best regards,

masa

over 10 years ago

0 Davor Glisic over 10 years ago

TI__Expert 7935 points

Hi-

LP8557AYFQT (or simply LP8557) is already set up for "PWM Only" operation (No I2C needed). The BRTMODE=00 is already pre-configured.

LP8557IAYFQT (or simply LP8557I) is set up for "PWM and I2C" operation (I2C required). The BRTMODE=11 is pre-configured. If brigthness control with only an external PWM signal is desired, BRTMODE needs to be set to 00 via I2C.

Regards,

Davor

0 masa0301 over 10 years ago in reply to Davor Glisic

Intellectual 960 points

Davor

Thank you for your reply.

I need the PWM only function ,so I must select the non I version.

In this case,Where can I get by connecting Fset pin ?

Best regards,

masa

0 Davor Glisic over 10 years ago in reply to masa0301

TI__Expert 7935 points

Masa,

On LP8557 (non-I version), FSET pin is used to set the boost switching frequency and PWM dimming frequency. Please refer to the device datasheet for more info.

Regards,

Davor

Power management

Power management forum

Using PWM dimming at LP8557