Backup battery power controller having channel regions of transistors being biased by power supply or battery
US5341034A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 11, 1993 |
| Grant date | Aug 23, 1994 |
| Priority date | — |
| Expiry date | Feb 11, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02J9/061
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A power control circuit (10) is operable to select between a backup battery (14) on a terminal (16) and a primary power supply voltage on a terminal (12) to output a voltage to a powered device (20). The two voltages are compared by a comparator (28) that drives a well bias node (44) with transistors (36) and (38). The comparator (28) selects the highest of two voltages on either the battery supply terminal (16) or the power supply terminal (12) to power the node (44), which node (44) is then connected to the wells of switching transistors (40) and (42) which are operable to select the battery terminals (16) in the event of a fail of the power supply on terminal (12). This decision is made with a power failure device (20). In the event that both the primary power supply voltage falls below a predetermined threshold and the battery supply voltage is at a higher level, the battery (14 ) is selected for output on the line (18).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.