LT1264 and charge pump IC as supply

[GoKid]

I was using a transformer based -5 supply to the LT1264 Bandpass filter without a problem until I tried using Microchip TC962 negative charge pump for the same negative supply instead of the transformer. The TC962 has 80ma output LT1264=23ma, max. Any conceptual blunders in trying this approach?

 

[nbucska]

Assuming you info is correct, I can't see anything wrong.
Any problem ?


Plesae read FAQ240-1032
My WEB: <

http://geocities.com/nbucska/>

 

[Comcokid]

I do not know how sensitive a switch-capacitor filter like the LT1264 will be to noise on a power line. The TC962 does not show any noise or typical output ripple graphs - a little suspicious.

If you are having problems, you may want to use a device to generate your -5V that has low noise and ripple on the output. Some voltage inverters are designed for low noise for use in VCO or RF circuits, and some are followed by a low noise LDO.

 

[itsmoked]

Are the frequencies, (chopper from the charge pump), in the same pass-band as you are interested in with the filter? If they are far apart you may not have much of a problem.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[VEBill]

OP wrote: '...without a problem until...', but he didn't mention what the problem was (if any).