Good afternoon
We have been using the LM2736 in some of our devices for a number of years now. A recent batch of circuit boards using this IC, has failed after a short period of operation.
We have identified that the regulator is passing almost full supply voltage to the output (approximately 90% of supply) and thus to the rest of the circuit. After checking the data sheet, we believe that the layout is correct, to the manufactures recommendations.
When testing failed IC's, it has been found that the is a resistance between Vin and SW of ~800R. All support components ave been removed and tested for correct operation. The current to be drawn by the circuit is not expected to exceed 30mA, typically 20mA
It appears to be a faulty batch of components.