Efficiently managing multiple power supplies
First Claim
1. An apparatus comprising:
- a first power supply switch including a power P-channel Metal Oxide Semiconductor Field Effect Transistor (PMOSFET) having a drain coupled to a first power rail to receive a first power voltage, a source coupled to an output node to power a load, and a gate to receive a gate voltage to selectively turn on or turn off the power PMOSFET to supply the first power voltage to the output node or isolate the first power rail from the output node, respectively;
a second power supply switch coupled to a second power rail to receive a second power voltage and to pass to the output node the second power voltage when present; and
a control circuit coupled to the second power rail and the gate, and that cooperates with the first power supply switch to control the gate voltage to (i) turn on the power PMOSFET if the first power voltage is present and the second power voltage is absent, and (ii) turn off the power PMOSFET if the second power voltage is present.
1 Assignment
0 Petitions
Accused Products
Abstract
An apparatus includes a first power supply switch, a second power supply switch, and a control circuit. The first power supply switch includes a P-channel Metal Oxide Semiconductor Field Effect Transistor (PMOSFET) having a drain coupled to a first power rail to receive a first power voltage, a source coupled to an output node, and a gate to selectively turn on or off the PMOSFET to supply the first power voltage to the output node or isolate the first power rail. The second power supply switch receives a second power voltage and passes it to the output node if the second power voltage is present. The control circuit cooperates with the first power supply switch to control the gate voltage to turn on the PMOSFET if the first power voltage is present and the second power voltage is absent, and turn off the PMOSFET if the second power voltage is present.
-
Citations
17 Claims
-
1. An apparatus comprising:
-
a first power supply switch including a power P-channel Metal Oxide Semiconductor Field Effect Transistor (PMOSFET) having a drain coupled to a first power rail to receive a first power voltage, a source coupled to an output node to power a load, and a gate to receive a gate voltage to selectively turn on or turn off the power PMOSFET to supply the first power voltage to the output node or isolate the first power rail from the output node, respectively; a second power supply switch coupled to a second power rail to receive a second power voltage and to pass to the output node the second power voltage when present; and a control circuit coupled to the second power rail and the gate, and that cooperates with the first power supply switch to control the gate voltage to (i) turn on the power PMOSFET if the first power voltage is present and the second power voltage is absent, and (ii) turn off the power PMOSFET if the second power voltage is present. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. An apparatus comprising:
-
a first power supply switch including a power P-channel Metal Oxide Semiconductor Field Effect Transistor (PMOSFET) having a first drain coupled to a first power rail to receive a first power voltage, a first source coupled to an output node to power a load, and a first gate; a second power supply switch coupled to the output node and a second power rail to receive a second power voltage, the second power supply switch to provide to the output node the second power voltage when present; and a control circuit including; a signal PMOSFET having a source-drain (SD) path coupled between the second power rail and the first gate, and a second gate; and a first voltage divider having first and second series-connected resistors respectively coupled between the second power rail and the second gate and the second gate and a ground rail. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
-
Specification