Other NXP Products中的主题 Optimising PCF8523T in Direct Switching Mode

Optimising PCF8523T in Direct Switching Mode

philsolomon — Tue, 11 Oct 2016 06:56:47 GMT

I am powering the VDD for the PCF8523 at 5Vdc and VBAT at 4.6Vdc. I am looking to use the "direct switching mode" to transition to VBAT when VDD is lost. The datasheet for the PCF8523 quotes:

* IDD = 150nA (typ) and 500nA (max) when configured as PM[2:0] = 111 and clock output disabled.

* IDD = 1200nA (typ) and 3600nA (max) when configured as PM[2:0] = 0000 and clock output enabled.

My application requires IDD = 500nA (max) but neither of the configurations above match my requirements which are "direct switching mode" enabled and "clock output disabled".

Can NXP please provide the equivalent data for the most efficient mode (in terms of maximum IDD) for the options for "direct switching mode" enabled and "clock output disabled".

Thank you,

Phil.

#PCF8523T

Re: Optimising PCF8523T in Direct Switching Mode

TomasVaverka — Thu, 13 Oct 2016 07:12:32 GMT

Hello Phil,

Thank you for your interest in the PCF8523T.

I am afraid we do not have the data specifically for the PCF8523T.

The current consumption will drop if CLKOUT is disabled. Also, the current consumption reduces with lower supply voltage.

With regards to the power management setting, the highest current consumption will be when PM[2:0]=000 and the lowest current consumption will be when PM[2:0]=111. The other PM settings will yield to lower current consumption than the PM[2:0]=000 setting, but not lower than the PM[2:0]=111 setting.

I hope it helps.

Best regards,

Tomas

PS: If this answer helps to solve your question, please mark it as "Correct". Thank you.

Re: Optimising PCF8523T in Direct Switching Mode

philsolomon — Fri, 14 Oct 2016 05:12:29 GMT

Thank you for the feedback Tomas. It has provided me with which direction to head now.