Other Parts Discussed in Thread: TINA-TI
I want to power a chip that requires input voltage 3.30 V to 3.5 V. Power supply current is up to 500 mA.
This is a high speed communication chip, so low power supply ripple is critical. Low cost and small board area are also important for this application.
The power input voltage to my board can range from 3.135 to 3.465 V.
Putting these requirements into WebBench, I was expecting buck boost solutions. But, rather cleverly, I guess, the proposed solution is a boost converter using TPS61252, allowing the converter to go into pass through mode when the input voltage goes above the nominal output voltage.
I attached a "TINA Diagram" output from TINA-TI. "VM1" is the input voltage, which I simulate ramping from below the nominal output voltage to above it.
When I simulate this design in TINA-TI, the converter generates some switching activity, even when the circuit could just keep the low side switch open and synchronous rectifier switch closed to pass the input through to the output, and this causes substantial output ripple (~70 mV p-p).
Is there any preferred part for a boost converter that needs to have low output ripple when input voltage goes above the output voltage target and duty cycle goes (notionally) to zero?
Or is there a way to use the TPS61252 in this mode?
Thanks,
Matt
