TLV61220: TLV61220 about the Minimum Duty

Hi Gary:

Thanks for asking. For your questions:

1. May I know what is the minimum duty for this device?

The TLV61220 works in hysteretic current operation. The current ripple is 200mA typically. If you choose a proper inductance, it won't reach the minimum turn on time. 

2. Does the TLV61220 has pass-through mode during Vin>Vout?

There is a diode connect the Vin to Vout. 

3. What is the maximum voltage to keep output voltage in regulation?

Sorry I have no data in hand. As I'm not in office these days, may you apply an EVM and do the test to have a reference? 

And, may I ask some details about your issue? Does the Vout keep no change with different load condition?

It's appropriated to catch the waveform of Vin, Vout, FB, and Icoil. And please also attached the schematic, inductance's part number, and the layout.

Hi Minqiu,

Thanks for your support. The schematic show in below, We have remove R95 as a no-load condition. The test data show in below.

In the no-load condition, why the output voltage still have big different from 4.27V to 4.36V? I think it should be regular at around 4.25V.

BR,

Gary

Hi Gary:

According the test result, the Vout is much closer to your target.With no load, the converter will enter DCM, which is similar with PFM. Normally the Vout will be higher than loading for this mode. And please notice the FB voltage has a range and about 6% peak to peak tolerance. Details could be checked in datasheet.