Voltage overshoot reduction circuits
AssigneeLinear Technology Corporation
InventorChiawei Liao
Life of this patent
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Abstract
Feedback circuits capable of preventing output voltage overshoot in closed-loop DC regulated power supplies are presented. The circuits employ hysteresis at the input of an operational amplifier to improve the response time of the feedback circuits to a rising output voltage reaching a threshold. The feedback circuits substantially reduce, if not prevent, output voltage overshoot during start-up and hard and soft output shorts.
Claims24
An integrated circuit operative to respond to a voltage threshold being met at an integrated circuit node, said circuit comprising:
- a first circuit element having an input coupled to said integrated circuit node, said first circuit element having an output that changes logic state in response to said voltage threshold being met;
- and
- a second circuit element having an output that changes logic state in response to a change of logic state at said first circuit element output, said second circuit element having an input coupled to a voltage that begins to change from a first logic state substantially immediately after said first circuit element output begins to change to said first logic state.
An integrated circuit operative to respond to a voltage threshold being met at an integrated circuit node, said circuit comprising:
- a first operational amplifier having an input coupled to said integrated circuit node, said first operational amplifier having an output that changes logic state in response to said voltage threshold being met;
- and
- a second operational amplifier having an output that changes logic state in response to said first operational amplifier output changing logic state, said second operational amplifier having an input coupled to a voltage, said voltage responsive to voltage at said first operational amplifier output;
- wherein:
- said voltage at said second operational amplifier input begins to change from a first logic state substantially immediately after said first operational amplifier output begins changing to said first logic state, said second operational amplifier output changing logic state in response to its input voltage moving and said first operational amplifier output changing logic state.
A method of responding to a voltage threshold being met at a node in an integrated circuit, said method comprising:
- coupling a first voltage to a first input of a circuit device, said first voltage having a voltage value representing a first logic state;
- coupling a second voltage to a second input of said circuit device, said second voltage having a voltage value representing said first logic state, said second voltage responsive to said threshold being met at said node;
- changing said value of said second voltage to a voltage representing a second logic state in response to said voltage at said node meeting said threshold;
- and
- beginning to change said value of said first voltage from a voltage representing said second logic state substantially immediately after said second voltage value begins changing in response to said voltage at said node meeting said threshold;
- wherein:
- said circuit device produces an output voltage having a voltage value representing one of said first and second logic states when the difference between said first and second input voltage values is less than a first amount and having another voltage value representing the other of aid first and second logic states when the difference between said first and second input voltage values is greater than a second amount.
Dependencies are inferred from the claim text.