7660 operating frequency

[1843]

Hi all,
I want to increase the ICL7660S operating frequency up to 20 MHz by using an external clocking.
Is it possible? If so, How?

Regards

[Unregistered]

Hi,
I think it's possible to use the hi-freq (internal 120Khz) version from Microchip, TC7660H:

see the datasheet at the following link

ww1.microchip.com/downloads/en/devicedoc/21466a.pdf

that says:

"
Changing the TC7660H Oscillator Frequency
It may be desirable in some applications (due to noise or
other considerations) to increase or decease the oscillator
frequency. This can be achieved by overdriving the oscillator
from an external clock, as shown in Figure 6. In order to
prevent possible device latch-up, a 1kΩ resistor must be
used in series with the clock output. In a situation where the
designer has generated the external clock frequency using
TTL logic, the addition of a 10kΩ pull-up resistor to V+ supply
is required. Note that the pump frequency with external
clocking, as with internal clocking, will be 1/2 of the clock
frequency. Output transitions occur on the positive-going
edge of the clock.
"

So e.g. ttl clocks (max 20mhz) or other faster clocks may be used but efficiency and consumptions considerations should be considered before any attempt.

Best regards,
Max

[1843]

Thank you Max,
But I don't reach to that version of 7660...

[Carl-NC]

I doubt you can run it up to 20MHz. The data sheet only specs performance up to 10kHz, and efficiency is beginning to roll off.

- Carl