Electronics Weekly Electronics Design & Components Tech News
The automotive-compliant AP74700Q operates down to 3.2V (or 3.9V at start-up) to allow for cold cranking of a vehicle engine.
Inside, a charge-pump creates enough voltage to drive the required external n-channel mosfet, whose drain-source voltage continuously monitored by the IC, which will regulate the gate to achieve the ~20mV forward conduction voltage.
When a reverse current is detected (by measuring a voltage more negative than ~10mV across the mosfet), the gate is shorted to the source to turn the mosfet off within 750ns.
The data sheet has commendable detail on selecting an appropriate mosfet to work well with the device in its various modes.
To achieve automotive ISO 7637 protection, a transient voltage suppressor needs to be connected across the input.
An enable pin can be used to shut the IC down so that it consumes only ~1μA, but the mosfet’s body diode will continue to supply the load from any input power source greater than its forward drop.
Operation is over ambients of -40 to +125°C, and packaging is SOT26.
