Method and apparatus for battery power pre-check at system power-on

Abstract

A system including at least one electronic component and a battery check circuit. When a power consumption level of the at least one electronic component is increased, the battery check circuit determines whether to provide power from a battery to the at least one electronic component by comparing a power level of the battery to a first power level.

1 . A system comprising:
 at least one electronic component;   a battery check circuit for determining, when a power consumption level of the at least one electronic component is increased, whether to provide power from a battery to the at least one electronic component by comparing a battery power level to a predetermined power level.   
     
     
         2 . The system of  claim 1  wherein the battery check circuit provides power from the battery to the at least one electronic component if the battery power level is at least the predetermined power level and wherein the battery check circuit prevents the battery from providing power to the at least one electronic component if the battery power level is less than the predetermined power level. 
     
     
         3 . The system of  claim 1  wherein the predetermined power level is based on a voltage or power requirement of one or more of the at least one electronic component. 
     
     
         4 . The system of  claim 1  wherein the battery check circuit comprises:
 a latch which is set to a first state when the system is turned on, the battery check circuit providing power from a back-up supply node that is coupled to receive power from at least a back-up battery to the battery check circuit when the latch is in the first state. 
 
     
     
         5 . The system of  claim 4  wherein the latch which is reset to a second state when a signal indicating availability to the at least one electronic component of power from the battery is received by the latch, the battery check circuit disconnecting the back-up supply node from the battery check circuit when the latch is in a second state. 
     
     
         6 . The system of  claim 4  wherein power from the back-up battery is supplied to the at least one electronic component while the latch is in the first state, and wherein power from the back-up battery is disconnected from the at least one electronic component when the latch is in a second state. 
     
     
         7 . A method comprising:
 testing whether a first battery has a power level less than a first level;   preventing the first battery from powering an electronic component if the power level is less than the first level; and   enabling circuitry to provide power from the first battery to the electronic component if the power level is at least the first level.   
     
     
         8 . The method of  claim 7  further comprising:
 powering, using a second battery, a battery check circuit for testing the power level of the first battery upon system startup. 
 
     
     
         9 . The method of  claim 7  wherein the first level is based on a safe voltage supply range for the electronic component. 
     
     
         10 . The method of  claim 8  further comprising:
 disconnecting power provided by the second battery from the battery check circuit after testing the power level of the first battery. 
 
     
     
         11 . The method of  claim 8  wherein powering the battery check circuit comprises
 sensing an on button being depressed; 
 enabling power to the battery check circuit; 
 maintaining power to the battery check circuit while the power level of the first battery is tested. 
 
     
     
         12 . The method of  claim 11  wherein maintaining power to the battery check circuit comprises setting a latch which has its output coupled to enable a gate connecting the battery check circuit to the second battery. 
     
     
         13 . The method of  claim 12  wherein preventing the first battery from powering the electronic component comprises:
 maintaining the electronic component in a disconnected state from the first battery; and 
 disabling the battery check circuit. 
 
     
     
         14 . The method of  claim 13  wherein disabling the battery check circuit comprises resetting the latch to disconnect the battery check circuit from the second battery. 
     
     
         15 . A battery check circuit comprising:
 a latch circuit which latches power from a first battery upon receiving an enabling signal; and   a test circuit which receives power from the first battery via the latch circuit, the test circuit testing a charge level of a second battery and, if the charge level is less than a predetermined charge level, asserting a shutdown signal.   
     
     
         16 . The battery check circuit of  claim 15  wherein the battery check circuit asserts a power supply enabling signal if the charge level is greater than or equal to the predetermined charge level. 
     
     
         17 . The battery check circuit of  claim 16  wherein the test circuit resets the latch to disconnect the startup power supply circuit and the first battery if the second battery has insufficient remaining power. 
     
     
         18 . An apparatus comprising:
 a latch having a delay circuit coupled to a preset input to set the latch to a first value as a voltage is applied to the latch on a first supply line;   a first gate having a control input which enables the first gate when a push button switch is closed or when the latch stores the first value, the first gate being disabled when the latch stores a second value and the push button switch is open;   a first battery switchably coupled to the first supply line by the first gate when the first gate is enabled;   a second battery; and   a controller which tests a charge level of the second battery and, if the charge level of the second battery is less than a predetermined charge level, to reset the latch to the second value.   
     
     
         19 . The apparatus of  claim 18  further comprising a voltage regulator, wherein the controller enables the voltage regulator if the charge level of the second battery is at least the predetermined charge level. 
     
     
         20 . The apparatus of  claim 19  wherein the voltage regulator resets the latch to the second value when sufficient power is available from the voltage regulator. 
     
     
         21 . The apparatus of  claim 18  wherein the predetermined charge level is determined by an operating voltage range for a plurality of components which are connected to the second battery if the charge level of the second battery is greater than the predetermined charge level. 
     
     
         22 . The apparatus of  claim 21  wherein the first battery also provides power to the plurality of components when the latch stores the first value.