Vclamp8

Upd_pcb

VCLAMP8

• The P-FET is static sensitive.

testing

• use the smaller MPJA supplies for the test
• limit the power supply current to ~100mA
• apply 27V - you should see no load current
• (for 1sec) apply 28V - you should see supply voltage drop to ~27.5 - and see 100mA of load current
• the clamp P-FET is not well heat sunk and applying a load current will overheat it.

common failures

• the power resistor fails - typically it fails "open". With an ohm meter it should measure ~1 ohm.
• the power transistor fails - typically the drain to source is shorted (it should be an open circuit when tested with an ohm meter). Also the gate fails. It should also be an open circuit to the other pins. When failed it has measured between 100 and 200 ohms.