PCA9685 with PFET - output enable

[w1987]

Hi All!

I'm designing a circuit with PCA9685 controlling PFETs.

I'm using INVRT=1 and OUTDRV=1 as suggested in datasheets chapter 7.7.
This works as expected.

However, after a powercycle, INVRT and OUTDRV are set to 0 and also OUTNE is set to 00 and all LEDn_ON_L and LEDn_ON_H are set to 0.

This causes the LED outputs to alwas start up at 0, no matter what level is present on output enable pin. With LED outputs at 0, my PFETs will switch on, causing the LEDs to flash before i can finally configure the MODE1 and MODE2 registers how it is needed for proper PFET controls.

I don't want the PFETs to turn on automatically, i'd much rather have the LED outputs start in high-impedance mode.

Is there any way to accomplish this?

Or is there any reference design for PFETs?

Thanks in advance!

[guoweisun]

HI

For all of the registers will be set as default value after power on reset. You can't change this specification.

[w1987]

Thank you @guoweisun for your quick answer.

Does that mean it is intentional to have external P-type drivers always on after reset?

[guoweisun]

Hi

From the result it seems like that!