Controlled transition to regulation

Abstract

A method includes receiving, by a regulating circuit, a battery feedback parameter and producing, by an operational transconductance amplifier, a first output current at an output terminal based on the battery feedback parameter and a battery current regulation voltage. The method also includes producing, by a current source, a second current at the output terminal based on the battery feedback parameter and a reference voltage.

What is claimed is: 
     
         1 . A method comprising:
 receiving, by a regulating circuit, a battery feedback parameter;   producing, by an operational transconductance amplifier, a first output current at an output terminal based on the battery feedback parameter and a battery current regulation voltage; and   producing, by a current source, a second current at the output terminal based on the battery feedback parameter and a reference voltage.   
     
     
         2 . The method of  claim 1 , wherein the battery feedback parameter is a sensed battery current. 
     
     
         3 . The method of  claim 2 , wherein producing the second current at the output terminal is further performed based on comparing the sensed battery current to a voltage reference. 
     
     
         4 . The method of  claim 1 , wherein the battery feedback parameter is a sensed battery voltage. 
     
     
         5 . The method of  claim 4 , wherein producing the second current at the output terminal is further performed based on comparing the sensed battery voltage to a voltage of a voltage source. 
     
     
         6 . The method of  claim 1 , wherein producing the second current comprises closing a switch coupling the current source to the output terminal. 
     
     
         7 . The method of  claim 1 , wherein producing the second current at the output terminal is further performed based on a voltage at the output terminal. 
     
     
         8 . A circuit comprising:
 an operational transconductance amplifier having a first operational transconductance amplifier input, a second operational transconductance amplifier input, and an operational transconductance amplifier output;   a switch having a first switch terminal, a second switch terminal, and a switch control terminal, the second switch terminal coupled to the operational transconductance amplifier output; and   a comparator having a first comparator input, a second comparator input, and a comparator output, the comparator output coupled to the switch control terminal.   
     
     
         9 . The circuit of  claim 8 , wherein the first comparator input is coupled to the first operational transconductance amplifier input and the second comparator input is coupled to a voltage source. 
     
     
         10 . The circuit of  claim 9 , wherein the comparator is a first comparator, and the comparator output is a first comparator output, the circuit further comprising:
 a logic gate having a first logic input, a second logic input, and a logic output, the logic output coupled to the switch control terminal and the first logic input coupled to the first comparator output; and   a second comparator having a third comparator input, a fourth comparator input, and a second comparator output, the second comparator output coupled to the second logic input.   
     
     
         11 . The circuit of  claim 10 , wherein the switch is a first switch and the switch control terminal is a first switch control terminal, the circuit further comprising:
 a transistor stack coupled to the fourth comparator input; and   a second switch having a third switch terminal, a fourth switch terminal, and a second switch control terminal, the second switch control terminal coupled to the first comparator output, the third switch terminal coupled a current source, and the fourth switch terminal coupled to the fourth comparator input and to the transistor stack.   
     
     
         12 . The circuit of  claim 8 , wherein the first comparator input is coupled to the operational transconductance amplifier output and the second comparator input is coupled to a transistor stack. 
     
     
         13 . The circuit of  claim 8 , further comprising:
 a resistor coupled between the operational transconductance amplifier output and the second switch terminal; and   a capacitor coupled between the second switch terminal and a ground terminal.   
     
     
         14 . The circuit of  claim 8 , wherein the operational transconductance amplifier is a first operational transconductance amplifier and the operational transconductance amplifier output is a first operational transconductance amplifier output, the first operational transconductance amplifier input coupled to a current source, the circuit further comprising a second operational transconductance amplifier having a third operational transconductance amplifier input, a fourth operational transconductance amplifier input, and a second operational transconductance amplifier output, the third operational transconductance amplifier input coupled to a sensed battery voltage, the fourth operational transconductance amplifier input coupled to a voltage source, and the second operational transconductance amplifier output coupled to the first operational transconductance amplifier output. 
     
     
         15 . A circuit comprising:
 a battery sense circuit having a battery sense input and a battery sense output, the battery sense input adapted to be coupled to a battery;   an operational transconductance amplifier having a first operational transconductance amplifier input, a second operational transconductance amplifier input, and an operational transconductance amplifier output, the first operational transconductance amplifier input coupled to the battery sense output;   a switch having a first switch terminal, a second switch terminal, and a switch control terminal, the second switch terminal coupled to the operational transconductance amplifier output;   a comparator having a first comparator input, a second comparator input, and a comparator output, the comparator output coupled to the switch control terminal;   a control circuit having a control input and a control output, the control input coupled to the operational transconductance amplifier output and to the second switch terminal; and   a power transistor coupled to the control output, the power transistor adapted to be coupled to the battery.   
     
     
         16 . The circuit of  claim 15 , wherein the battery sense circuit is configured to sense a current of the battery. 
     
     
         17 . The circuit of  claim 15 , wherein the battery sense circuit is configured to sense a voltage of the battery. 
     
     
         18 . The circuit of  claim 15 , wherein the first comparator input is coupled to the battery sense output and the second comparator input is coupled to a voltage source. 
     
     
         19 . The circuit of  claim 18 , wherein the comparator is a first comparator, the comparator output is a first comparator output, the switch is a first switch, and the switch control terminal is a first switch control terminal, the circuit further comprising:
 a logic gate having a first logic input, a second logic input, and a logic output, the logic output coupled to the first switch control terminal and the first logic input coupled to the first comparator output;   a second comparator having a third comparator input, a fourth comparator input, and a second comparator output, the third comparator input coupled to the operational transconductance amplifier output and the second comparator output coupled to the second logic input; and   a second switch having a third switch terminal, a fourth switch terminal, and a second switch control terminal, the second switch control terminal coupled to the first comparator output and the fourth switch terminal coupled to the fourth comparator input.   
     
     
         20 . The circuit of  claim 15 , wherein the first comparator input is coupled to the operational transconductance amplifier output and the second comparator input is coupled to a transistor stack.