US 5,177,371 A · Auxiliary battery operation detection circuit

Abstract

A power supply which senses whether a primary battery is discharging to below a predetermined dead battery level or the primary battery has been removed and the system is operating from an auxiliary battery, which has a lower voltage. When the battery voltage goes below the dead voltage level, the system is in a low power mode and the power supply output voltages are satisfactory, a timer may be started. If the battery voltage does not drop to the auxiliary battery voltage level within a predetermined time, a shutdown signal is generated and the power supply ceases providing output voltage levels. In this manner the primary battery can be removed and the system can continue running on the auxiliary battery until a charged primary battery is installed and yet the primary battery discharge rate will be greatly slowed when the primary battery voltage is below a given level and the primary battery is still installed in the system.

Claims14

Dependent claims

An auxiliary battery operation circuit for use in a system having an operating voltage provided by a higher voltage primary battery and a lower voltage auxiliary battery, the circuit comprising:

means for determining if the operating voltage is below a given level indicating a discharged state of the primary battery, wherein said given level is greater than the voltage level of the auxiliary battery;
means for determining if the operating voltage is above the auxiliary battery voltage;
means coupled to said primary battery discharged state determining means for timing entry into said discharged state;
and
means coupled to said discharged state timing means and said auxiliary battery operating voltage determining means for determining if said operating voltage level becomes the auxiliary battery voltage before said discharged state timing means indicates a predetermined time, and if so, indicating auxiliary battery operation, wherein said auxiliary battery operation indication means indicates auxiliary battery operation past said predetermined time.

2 more elements

A power supply for a system having an operating voltage provided by a higher voltage primary battery and a lower voltage auxiliary battery, the power supply comprising:

means coupled to the primary and auxiliary batteries to receive the operating voltage for producing a DC output voltage from the operating voltage, said DC output voltage means including an input for receiving a signal requesting cessation of providing said DC output voltage from said DC output voltage means and being responsive to said input signal to cease providing said DC output voltage;
means for determining if the operating voltage is below a given level indicating a discharged state of the primary battery, wherein said given level is greater than the voltage of the auxiliary battery;
means for determining if the operating voltage is above the auxiliary battery voltage;
means coupled to said primary battery discharged state determining means for timing entry into said discharged state;
and
means coupled to said discharged state timing means and said operating voltage determining means for determining if said operating voltage level becomes the auxiliary battery voltage before said discharged state timing means indicates a first predetermined time, and if so, providing a signal indicating continuation of providing said DC output voltage wherein said signal is provided past said first predetermined time, said signal coupled to said DC output voltage means cessation input.

3 more elements

Dependencies are inferred from the claim text.

Auxiliary battery operation detection circuit

Life of this patent

Auxiliary battery operation detection circuit

Life of this patent

Abstract

Claims14