LMH1983: Genlock to RS-170 video

Brandon

Prodigy 10 points

Part Number: LMH1983

Tool/software:

Can we configure a user mode to genlock to RS-170 (15.75 kHz/60 Hz) and output a 24.57 MHz reference clock on clkout1?

7 months ago

0 Noel Fung 7 months ago

TI__Guru** 107300 points

Hi Brandon,

If your required frequencies are exact (not rounded off), then LMH1983 cannot support.

The device can genlock to 15.7343kHz.

This is code 0 format.

CLKout1 output frequency must be 27MHz or 13.5MHz.

24.576MHz clock is produced from PLL4, output is CLKout4.

0 Brandon 7 months ago in reply to Noel Fung

Prodigy 10 points

What if I did it as a user defined format?

0 Noel Fung 6 months ago in reply to Brandon

TI__Guru** 107300 points

Hi Brandon,

You can try set below registers to change the N divider.

For example, N = 27MHz / 15.75kHz = 1714

Then PLL1 output will be 15.75kHz * 1714 = 26.9955MHz. This requires the pulling range of the 27MHz VCXO to be greater than 166.67ppm. it does not sound possible.

Clock & timing

Clock & timing forum

LMH1983: Genlock to RS-170 video