TI Application Note SLVAE10 shows us how to contruct an inverting power supply using the TPS560430 device with figure 3 on page 4 providing a design example. We have constructed this circuit (and it works) but we need to add the ability to enable and disable the device, this is a problem as most of the pins are 'inverted'..
The transistor side of an opto-isolator connected between pins 4 and 5 should provide a suitable ON signal when activated but where do we connect the pulldown on pin 4 to turn the device OFF when not required?
We cannot use the ground pin (2) as this is now the output and its voltage will vary from (say) -3.3V to -12V. It seems that we cannot connect the pulldown to ground either, experiments this morning using a 10K potentiometer connected between Vin and Ground with the wiper connected to pin 4 resulted in three burnt out chips, good business for TI but bad news for us.
So, TPS560430 connected as an inverting power supply with remote enable, ideas please!
Thank you
