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TL7660: Minimum clock frequency

Part Number: TL7660

Hello,

In reading the datasheet for TL7660, there is a section on changing the clock frequency.  For overclocking the frequency it shows a figure connected with an appropriate resistor to the clock pin, then for underclocking the frequency it shows a capacitor being placed between the clock pin and the Vcc.  My questions are as follows:

1) What is the minimum clock frequency allowed before there are issues with the functioning of the device?

2) Is it possible to use a PWM signal or analog timing circuit to lower the frequency as low as 10-100 Hz?

3) If not is it possible to use the capacitor -- Vcc scheme to do so?

Thanks!

  • These are good questions. The part is transferred to our group earlier this year and we need to study this in detail to answer all your questions. However, charge pump operating at sub kHz is rarely seen even if the device can support it: the switching or pump capacitor and output or reservoir capacitor would be too big and costly if you run at sub KHz. Recommended frequency should be around 10kHz for a fairly cost-effective solution.