PWM Expander PCAL9722HN/Q900MP

[labib_leggett]

Hello,

We are using FS32K116LFT0MFMT for a automotive seat massage ECU. We need to drive 24x solenoid or more. Therefore, we need 24x or more PWM channels that can generate 20kHz frequency with a duty cycle of 30% to 100%. 

In order to keep same pin-count, we are looking for SPI interfaced PWM expander. It seems PCAL9722HN/Q900MP could be good fits.

Could you please check whether we can generate  20kHz frequency with a duty cycle of 30% to 100% to drive low-side logic level MOSFET? Let me know if you have other options of expanding PWM channel from SPI.

Thanks

[guoweisun]

Hi Labib

From the theory consideration it can support up to 5 MHz of SCLK speed but need software to achieve duty cycle change and 20KHz setting.

[labib_leggett]

Thank you very much. It has 5MHz SCLK speed. Does it mean I can generate 20kHz PWM channel in all output? How can I calculate maximum allowed PWM frequency on each channel? Is there any app note? I found this in "AMF-IND-T3525.pdf". What is the maximum PWM frequency for PCAL9722HN/Q900MP?

[guoweisun]

According this algorithm,:

Continuous on three Ports
bytes = 25/5MHz=5us=200KHz/2=100KHz

[guoweisun]

Can you let me know the AMF-IND-T3525.pdf download link?

[labib_leggett]

I have attached the file herewith. I downloaded the file from NXP website.