ADP7142
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The ADP7142 is a CMOS, low dropout (LDO) linear regulator that operates from 2.7 V to 40 V and provides up to 200 mA of output current. This high input...
ADP7142 on Analog.com
Hi,
I am using two chips of the ADP7142 family on a board, but neither seems to be working.
In one case, the output seems to be disabled. In the other case, the output weakly regulates to a voltage lower than expected.
Schematic is attached below.
U3: ADP7142ACPZN5.0: should be regulating 12V to 5V. Output is inactive: Output floats up when injecting current, and clips down to -0.7V when drawing current.
U4: ADP7142ACPZN3.3: should be regulating 5V to 3.3V. Output weakly regulates to ~2V instead of 3.3V. When drawing a few mA, output drops below -5V (instrument compliance voltage). I understand -5V is below rating and the device might be damaged. However, it never worked to begin with, and after reducing the load, it goes back up to ~2V.
Input voltages are clean and driven by instruments. Outputs are isolated from the rest of the board through headers.
I am directly tying the Enable pins to inputs. I wonder if the chips expect some delay between the inputs and EN. The datasheet says it is OK to tie EN to VIN, and LTspice simulation works even if EN precedes VIN.
I appreciate any comments!
