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What is the maximum slew rate for PCF8523 battery switch over?

Question asked by Milo Oien-Rochat on Oct 6, 2017
Latest reply on Oct 25, 2017 by Dario Arias

Background

https://www.nxp.com/docs/en/data-sheet/PCF8523.pdf 

According to the datasheet (page 53) the maximum slew rate is 0.7 V/ms between 2.5V (typical Vthreshold switch battery) and 1.8V (power management operating limit). Also according to the datasheet the VDD is 'monitored' every 1 ms.

 

So the datasheet's maximum slew rate for a typical Vth(sw)bat:

(2.5V-1.8V)/1ms = 0.7 V/ms

 

However if the Vth(sw)bat is the minimum value (2.1V), see the static characteristics table on page 50:

(2.1V-1.8V)/1ms = 0.3 V/ms

 

Question

Am I misunderstanding something or is the maximum slew rate actually 0.3 V/ms to cover the full range of part tolerances? Also the slew rate would be measured between 2.1 and 1.8V.

 

Assumption

I don't know how your VDD 'monitor' works. I am assuming it works like a sample and hold ADC so you are sampling for a period much shorter than 1ms eg 50us every 1ms.

 

#pcf8523

Tomas Vaverka - it looks like you answered other questions related to this part

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