Providing current cross-conduction protection in a power rail control system

Patent metadata

Field	Value
Publication number	US-2016308372-A1
Application number	US-201615130549-A
Country	US
Kind code	A1
Filing date	Apr 15, 2016
Priority date	Apr 15, 2015
Publication date	Oct 20, 2016
Grant date	—

Abstract

Power rail control systems that include power multiplexing circuits that include cross-current conduction protection are disclosed. Power multiplexing circuit includes supply selection circuits each coupled between a respective supply power rail and an output power rail coupled to a powered circuit. To maintain power to the powered circuit during switching coupling of the output power rail, but while also avoiding current cross-conduction path between supply power rails, diode drop control circuits are provided in supply selection circuits. In diode drop operation mode, the diode drop control circuit associated with a higher voltage supply power rail is configured to regulate voltage supplied by such supply power rail to the output power rail to power the powered circuit. A current cross-conduction path is not created, because diode drop control circuits associated with lower voltage supply power rails are reverse biased to prevent current from flowing through their associated supply selection circuits.

First claim

What is claimed is:

1 . A power multiplexing circuit, comprising:
a first supply selection circuit, comprising:
a first power switching circuit configured to receive a first supply power rail selection signal, the first power switching circuit configured to:
selectively couple a first supply power rail having a first voltage to an output power rail coupled to at least one powered circuit, in response to the first supply power rail selection signal indicating a first supply power rail selection enable state; and

a first diode drop control circuit configured to receive a supply power rail switch signal, and establish a first diode drop connection between the first supply power rail and the output power rail, in response to the supply power rail switch signal indicating a supply power rail switch enable state; and
a second supply selection circuit, comprising:
a second power switching circuit comprising a second supply power rail selection input configured to receive a second supply power rail selection signal, the second power switching circuit configured to:
selectively couple a second supply power rail having a second voltage to the output power rail, in response to the second supply power rail selection signal indicating a second supply power rail selection enable state; and

a second diode drop control circuit configured to receive the supply power rail switch signal and establish a second diode drop connection between the second supply power rail and the output power rail, in response to the supply power rail switch signal indicating a supply power rail switch enable state.

2 . The power multiplexing circuit of claim 1 , wherein:
the first power switching circuit is further configured to selectively decouple the first supply power rail from the output power rail in response to the first supply power rail selection signal indicating a first supply power rail selection disable state; and the second power switching circuit is further configured to selectively decouple the second supply power rail from the output power rail in response to the second supply power rail selection signal indicating a second supply power rail selection disable state.

3 . The power multiplexing circuit of claim 1 , wherein:
the first diode drop control circuit is further configured to disconnect the first diode drop connection between the first supply power rail and the output power rail, in response to the supply power rail switch signal indicating a supply power rail switch disable state; and the second diode drop control circuit is further configured to disconnect the second diode drop connection between the second supply power rail and the output power rail, in response to the supply power rail switch signal indicating a supply power rail switch disable state.

4 . The power multiplexing circuit of claim 1 , wherein:
in response to the first voltage being higher than the second voltage, the first diode drop control circuit further is configured to maintain a voltage of a threshold voltage below the first voltage on the output power rail, in response to the supply power rail switch signal indicating the supply power rail switch enable state.

5 . The power multiplexing circuit of claim 1 , wherein:
in response to the first voltage being lower than the second voltage, the first diode drop control circuit is further configured to prevent or reduce current flow from the output power rail to the first supply power rail, in response to the supply power rail switch signal indicating the supply power rail switch enable state.

6 . The power multiplexing circuit of claim 1 , wherein:
the first power switching circuit comprises:
a first power input coupled to the first supply power rail;
a first power output coupled to the output power rail;
a first power rail selection input configured to receive the first supply power rail selection signal;
the first power switching circuit configured to:
selectively couple the first power input to the first power output to provide the first voltage to the at least one powered circuit in response to the first supply power rail selection signal indicating the first supply power rail selection enable state; and

the second power switching circuit comprises:
a second power input coupled to the second supply power rail;
a second power output coupled to the output power rail;
a second power rail selection input configured to receive the second supply power rail selection signal;
the second power switching circuit configured to:
selectively couple the second power input to the second power output to provide the second voltage to the at least one powered circuit in response to the second supply power rail selection signal indicating the second supply power rail selection enable state.

7 . The power multiplexing circuit of claim 6 , wherein:
the first power switching circuit is further configured to selectively decouple the first power input from the first power output in response to the first supply power rail selection signal indicating a first supply power rail selection disable state; and the second power switching circuit is further configured to selectively decouple the second power input from the second power output in response to the second supply power rail selection signal indicating a second supply power rail selection disable state.

8 . The power multiplexing circuit of claim 6 , wherein:
the first power switching circuit comprises a first transistor comprising a first gate coupled to the first power rail selection input, a first source coupled to the first power input, and a first drain coupled to the first power output; and the second power switching circuit comprises a second transistor comprising a second gate coupled to the second power rail selection input, a second source coupled to the second power input, and a second drain coupled to the second power output.

9 . The power multiplexing circuit of claim 6 , wherein:
the first diode drop control circuit comprises:
a first diode drop input coupled to the first power rail selection input of the first power switching circuit;
a first diode drop control input configured to receive the supply power rail switch signal; and
a first diode drop output coupled to the first power output;
the first diode drop control circuit configured to establish the first diode drop connection between the first power rail selection input and the first power output, in response to the supply power rail switch signal indicating the supply power rail switch enable state; and
the second diode drop control circuit comprises:
a second diode drop input coupled to the second power rail selection input of the second power switching circuit;
a second diode drop control input configured to receive the supply power rail switch signal; and
a second diode drop output coupled to the second power output;
the second diode drop control circuit configured to establish the second diode drop connection between the second power rail selection input and the second power output, in response to the supply power rail switch signal indicating the supply power rail switch enable state.

10 . The power multiplexing circuit of claim 9 , wherein:
the first diode drop control circuit is further configured to disconnect the first diode drop connection between the first power rail selection input and the first power output, in response to the supply power rail switch signal indicating a supply power rail switch disable state; and the second diode drop control circuit is further configured to disconnect the second diode drop connection between the second power rail selection input and the second power output, in response to the s

Assignees

• Qualcomm Inc

Inventors

• Kolla Yeshwant Nagaraj
• Natekar Neel Shashank
• Garg Manish

Classifications

• G11C5/14

  Power supply arrangements {, e.g. power down, chip selection or deselection, layout of wirings or power grids, or multiple supply levels} · CPC title

• H02J4/00 Primary

  Circuit arrangements for mains or distribution networks not specified as AC or DC; Circuit arrangements for mains or distribution networks combining AC and DC sections or sub-networks (arrangements using intermediate DC-AC-DC conversion H02J1/002; arrangements using high-voltage DC [HVDC] links H02J3/36) · CPC title

• G06F1/263 Primary

  Arrangements for using multiple switchable power supplies, e.g. battery and AC (G06F1/30 takes precedence) · CPC title

• G06F1/3296

  by lowering the supply or operating voltage · CPC title

• Y02D10/00

  Energy efficient computing, e.g. low power processors, power management or thermal management · CPC title