Issue with ADF4113 PLL : help welcome...

[Robert Lacoste]

Hello all,

I have an issue with a prototype build using an Analog Device ADF4113 3GHz
PLL chip. Basically the chip is working as expected, except that the charge
pump output is pumping high but never pumping low. I tested it for exemple
with the PLL in open loop and the CP pin connected to Vcc and GND through
two resistors : When the required frequency is higher than the actualone I
got pulses from 2.5V to 3-4V, but when the required frequency is lower I
just got 2.5V plus some small pulses (seems to be the antibackslash pulses).
Everything is like if the lower end of the charge pump bridge is
disconnected. I first suspected a bad chip but replacing it didn't changed
the problem. Any idea ? Any software bit error that could do that ?

Many thanks,
Yours,
Robert

 

[Robert Lacoste]

Problem solved ! Just in case someone find the same problem in the future :
I inadvertantly connected the RSET resistor to Vcc and not to GND, and this
silly error gives this more than strange behaviour...
Long life to PLLs...

Cheers,
Robert

"Robert Lacoste" <rlacoste@alciom.com> a écrit dans le message de news:
3f1d2a69$0$9625$7a628cd7@news.club-internet.fr...

Hello all,

I have an issue with a prototype build using an Analog Device ADF4113 3GHz
PLL chip. Basically the chip is working as expected, except that the
charge
pump output is pumping high but never pumping low. I tested it for exemple
with the PLL in open loop and the CP pin connected to Vcc and GND through
two resistors : When the required frequency is higher than the actualone I
got pulses from 2.5V to 3-4V, but when the required frequency is lower I
just got 2.5V plus some small pulses (seems to be the antibackslash
pulses).
Everything is like if the lower end of the charge pump bridge is
disconnected. I first suspected a bad chip but replacing it didn't changed
the problem. Any idea ? Any software bit error that could do that ?

Many thanks,
Yours,
Robert