Thanks! I'm using the MAX3140 with no troubles so far driving the clock
with 8MHz from the PIC oscillator out.

Harold


> Harold Hallikainen wrote:
>
>>I'm working on a project right now where I run the output of the PIC
>>oscillator (8 MHz) from one side of the resonator to a couple Maxim SPI
>>UARTs. I see no evidence of loading the oscillator.
>>
>>
>>
> A word of warning: Maxim only makes two SPI uarts. Be aware that the
> only problem I had
> with them is accidentally overdriving the crystal input. The problem was
> not noticeable until
> writing the code. The  clock in the pic was skipping cycles. I'd reserve
> space for a resistor
> before each Maxim UART  osc input. I was using a commercial oscillator,
> and had to use
> 220-470 ohm resistors to knock the drive level down.
>
> If you use the one with built-in RS232 level drivers, it needs a
> tantalum 10uF very close to
> VCC and GND pins.
>
> Once you fix that, those uarts work very well.
>
>
>>In another project, I used a dual varactor as the load capacitors on a
>>crystal on a PIC oscillator. The output side of the oscillator goes
>>through a 10k resistor to an op amp voltage follower to a BNC on the
>> front
>>panel. This allows the user to adjust the PIC oscillator frequency to
>>exactly 10MHz. This also seems to have worked fine.
>>
>>Harold
>>
>>
>>
>>
>
> --Bob
>
> --
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