Patent ID: 9570941
Date: 2017-02-14
CPC Classifications: G11C,H02J,H02M,H03L

Claim:
1. An apparatus comprising: an internal power rail configured and arranged to provide power to circuits in the apparatus; a switching circuit including a switching transistor having a first source/drain region connected to a primary power supply circuit and to the internal power rail, having a second source/drain region connected to a backup power supply circuit, and having a control terminal coupled to the primary power supply circuit, the switching transistor being configured and arranged with the primary power supply circuit and with the backup power supply circuit to another circuit configured and arranged to use power provided by the primary power supply circuit to operate the switching transistor in an OFF state by applying the voltage to the control terminal in the blocking state wherein the other circuit is configured and arranged to cease applying the voltage to the control terminal in response to power dropping on the primary power supply circuit, and wherein the switching transistor is configured and arranged to automatically switch to an ON state in response to the other circuit ceasing to apply the voltage.