How to use LTM4609 and DAC such as AD5696 to establish a Programmable Buck-Boost DC/DC?

Question

The pictrue is schematic of LTM4609 evalutaion kits, Can I use a DAC such as AD5696 between R5 and R9 to program the output of LTM4609?

SYoung · Accepted Answer

Yes this is possible. Note that typical FB injection scheme (ie below) de-grades load regulation if the adjustable output range is wide. If the output adjustable range is not wide then the below setup should be sufficient (Vg is DAC output).

If the adjustable output voltage is wide, to maintain good load regulation it would be recommended to insert an external error amp / compensator circuit to over-ride the internal error amp. Below is an example design verified for 0.5Vout - 15Vout adjustable output voltage. Thanks.)

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How to use LTM4609 and DAC such as AD5696 to establish a Programmable Buck-Boost DC/DC?