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Disruption Free Power Supply Circuit

IP.com Disclosure Number: IPCOM000085053D
Original Publication Date: 1976-Feb-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Najmann, K: AUTHOR [+2]

Abstract

The circuit described permits an electronic device being supplied with power off the mains, while buffering is effected via an accumulator. It also permits an automatic and disruption-free change from mains to accumulator operation. The circuit is particularly suitable for computers to prevent the data stored in the large-scale integration (LSI) memory circuits from being destroyed in the case of a mains failure, as well as for portable small-scale computers to permit changing from mains to accumulator operation.

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Disruption Free Power Supply Circuit

The circuit described permits an electronic device being supplied with power off the mains, while buffering is effected via an accumulator. It also permits an automatic and disruption-free change from mains to accumulator operation. The circuit is particularly suitable for computers to prevent the data stored in the large-scale integration (LSI) memory circuits from being destroyed in the case of a mains failure, as well as for portable small-scale computers to permit changing from mains to accumulator operation.

In the case of mains operation point E in the circuit of Fig. 1 receives a DC voltage UA from DC source 11. In this state accumulator 12 is loaded, and the power required for load 13 (computer) is made available. At point E supply current I is subdivided into partial currents I1, I2, and I3. The relatively low current I1 flows via diode D1 and limiting resistor R1 to accumulator 12, loading the latter. Current I3 flows via diode D2 and resistor R2 as well as closed switch 14 to the minus pole of voltage source 11. During this, the transistor T1 is blocked, since its base has a more positive voltage than the emitter.

Current I2 subdivides at point F into partial currents I4 and I5. Current I4 flows via resistor R3 and zener diode 15 to the minus pole of voltage source 11. This current serves to set a constant-base voltage for transistor T2. Current I5 is the actual user current which is fed to load 13 via the collector...