I have several MCP1700-3300E LDO regulators that I plan to use. The datasheet claims that this LDO has:
Low Dropout (LDO) Voltage- 178 mV Typical @ 250 mA for VOUT=2.8V
And the dropout plot for 2.8V:
Actually, I am using 3.3V variant, not the 2.8V one, but unfortunately the datasheet doesn't provide dropout plot for 3.3V variant. Nevertheless, dropout should be similar, right?
So, I rigged up a simple schematic. My PSU feeding 3.7V to the MCP, and a 22 ohm resistor between the output of the MCP and the ground to give it a load. Running, my PSU says the current is 128 mA, around half of the maximum this LDO can handle. But measuring the voltage between the output and the ground of the MCP gives 2.97V, which is a 0.73V drop - far more than the datasheet suggests. This is a schematic of the exact setup I have for testing:
So, what am I missing here? According to the datasheet, I should be getting ~ 0.1V dropout, so the output should still be 3.3V. But the actual dropout is way more than that. I tried several different MCP's, thinking this one might be defected, but all of them show the same behavior. Can anyone help?