TDA4AL-Q1: VPAC And DMPAC Max frequencies

Hi Daviel,

The issue is that both DMPAC and VPAC are driven from the same PLL, and rely on HSDIV dividers to divide down a valid PLL frequency to valid DMPAC and VPAC frequencies, while DMPAC and VPAC are limited to a maximum speed according to each speed grade.

For the T superset speed, VPAC and DMPAC can independently operate at 720 and 520.

DMPAC == 720 can be achieved with PLL rate of 1440 MHz with DMPAC = PLL/2 = 720 MHz and VPAC = PLL/3 = 480 MHz.  

Similarly ...

VPAC = 520 can be achieved with PLL rate of 2600 with VPAC = PLL/4 and DMPAC = PLL/5 = 520 MHZ.

All of that gets simpler for the H speed grade since VPAC <= 600 MHz and DMPAC <= 300 Mhz are evenly divisible.

So you can set PLL = say 2400 MHz and VPAC = PLL/4 and DMPAC = PLL/8.

Regards,

Kyle