Item #2561 efficiency is horrible - why?

I am getting very poor performance from the #2561. I have 1.5V going in, and I cannot get this thing to output more than about 100mA before the Vout nosedives and the Iin goes through the roof, and at 100mA output, it’s only ~50% efficient.
The best efficiency seems to be about 65% with Iout at only ~60mA (Iin is about 200mA).
Also, this thing won’t startup under load. It needs to startup without load, then have load applied.
I can buy better performance modules at 3pcs for $8 at amazon (85% eff with same Vin/Iout shown above).
I was expecting far better here.
Did I get a bad device?

What are you using to measure the input and output current and voltages? What supply and load are you using? Could you post pictures of your setup that show all connections including the measurement instruments?


Using an agilent power supply that shows the voltage and current supplied - displayed values have been checked against a calibrated DMM. Output voltage and current are monitored using a DMM that has also been verified with a calibrated DMM. Loads tried are resistors and LEDs.
No, I cannot post pictures of the setup. It’s real simple. Agilent supply to the input. Output goes to either a resistor or LED (LED running below threshold, for example can easily handle 600mA but I’m only driving it at the 70mA indicated here - it needs to be in series with a resistor to prevent the DC DC converter from dropping output voltage). Current meter in series. Voltmeter on output. simple

From the efficiency graph on the product page for the U1V11F3, around 65% efficiency for an input around 1.5V and loads of 70-100mA seems right. However, I expect the regulator to handle 200-300mA of load depending on how enclosed it is (or how much cooling is implemented). I also expect the regulator to start into those kinds of currents without issue, especially for purely resistive loads. We test all of our regulators before they ship, so the best first step is to thoroughly check your setup. Things like wire length, the type of connections, how a board is mounted, etc. can sometimes make a big difference, so pictures are really helpful even for seemingly simple setups.