Power conversion circuit with indicator coupled to input terminal to signal condition of the controller

Patent metadata

Field	Value
Publication number	US-10141735-B2
Application number	US-201615193460-A
Country	US
Kind code	B2
Filing date	Jun 27, 2016
Priority date	Jun 27, 2016
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

A power conversion circuit has a controller with an input terminal and a circuit configured to drive an electric current out of the input terminal in response to a condition of the controller. An indicator is coupled to the input terminal of the controller. The controller includes a clock signal controlling the electric current out of the input terminal. The input terminal is a voltage sensing terminal or feedback input terminal in some embodiments.

First claim

What is claimed is:

1. A power conversion circuit for converting an input voltage received from a power source to a regulated output voltage, comprising: a controller comprising; a brownout terminal; a first circuit having an input coupled to the brownout terminal, and the first circuit configured to sense a voltage on the brownout terminal while refraining from driving an alarm current to the brownout terminal; assert an internal signal if the voltage sensed on the brownout terminal during the refraining falls outside a predetermined range; and drive the alarm current to the brownout terminal responsive to the assertion of the internal signal; an external indicator coupled to the brownout terminal of the controller, the external indicator being at least one selected form a group comprising; a light emitting diode; and a buzzer configured to produce sound audible to a human.

2. The power conversion circuit of claim 1 , wherein the first circuit further comprises: a logic circuit defining a first input, a second input, an output, the first input coupled to a clock signal; a current source defining a current output; an electrically controlled switch defining a control input, the electrically controlled switch coupled between the current output of the current source and the brownout terminal, and the control input coupled to the output of the logic circuit; and a comparator defining a first input, a second input and a comparator output, the first input of the comparator coupled to a reference voltage, the second input of the comparator coupled to the brownout terminal, and the comparator output coupled to the second input of the logic circuit; wherein the controller senses the voltage the electrically controlled switch is nonconductive, and when the controller drives the alarm current the electrically controlled switch is conductive.

3. The power conversion circuit of claim 1 , wherein the first circuit further comprises: a first comparator defining a first input, a second input, and an output, the first input coupled to a first reference voltage, and the second input coupled to the brownout terminal; a second comparator defining a first input, a second input, and an output, the first input of the second comparator coupled to a second reference voltage, and the second input of the second comparator coupled to the brownout terminal; a logic circuit defining a first input, a second input, and an output, the first input of the logic circuit coupled to the output of the first comparator, and the second input of the logic circuit coupled to the output of the second comparator; and a current source coupled to the brownout terminal and configured to be enabled by the output of the logic circuit.

4. The power conversion circuit of claim 2 , wherein the logic circuit includes an AND gate.

5. A controller for a power conversion circuit, comprising: brownout terminal, the controller configured to receive an input signal on the brownout terminal, the input signal proportional to an input voltage to the power conversion circuit; a gate terminal, the controller configured to drive a gate signal for a primary side field effect transistor (FET) on the gate terminal; a feedback terminal, the controller configured to receive a feedback signal indicative of an output voltage on the feedback terminal; a first circuit having an input coupled to the brownout terminal, and the first circuit configured to: sense the input signal on the brownout terminal while refraining from driving an alarm current to the brownout terminal; assert an internal signal if the input signal sensed on the brownout terminal during the refraining falls outside a predetermined range; and drive an indicator signal out of the brownout terminal responsive to the assertion of the internal signal of the controller.

6. The controller of claim 5 , wherein the first circuit further comprises:
a first comparator including a first input coupled to a first reference voltage, and a second input coupled to the brownout terminal;
a second comparator including a first input coupled to a second reference voltage, and a second input coupled to the brownout terminal;
a logic circuit including a first input coupled to an output of the first comparator, and a second input coupled to an output of the second comparator; and
a current source coupled to the brownout terminal and enabled by an output of the logic circuit.

7. The controller of claim 5 , wherein the first circuit further comprises:
an oscillator;
a logic circuit including a first input coupled to an output of the oscillator;
a current source coupled to the brownout terminal and enabled by an output of the logic circuit; and
a comparator including a first input to a reference voltage, a second input coupled to the brownout terminal, and an output coupled to a second input of the logic circuit.

8. The controller of claim 7 , wherein the logic circuit includes an AND gate.

9. A method of operating a switch-mode power supply, comprising: driving, by a controller a gate signal to a field effect transistor (FET) on a primary side of the switch-mode power supply; sensing, by the controller, a value indicative of the input voltage on an input terminal of the controller, and simultaneously refraining from driving an alarm current to the input terminal of the controller; asserting an internal signal of the controller if the value indicative of the input voltage sensed on the input terminal falls outside a predetermined range; and driving, by the controller, the alarm current to an external indicator connected to the input terminal of the controller in response to the assertion of the internal signal of the controller.

10. The method of claim 9 , wherein driving the alarm current further comprises driving the alarm current off and on at a rate set by an oscillator of the controller.

11. The method of claim 9 , wherein asserting the internal signal further comprises monitoring the value indicative of input voltage at the input terminal using a comparator with a reference voltage.

12. The method of claim 9 , wherein the external indicator is a human perceivable indicator.

Assignees

• Semiconductor Components Ind Llc

Inventors

• Basso Christophe
• Cannenterre Stephanie

Classifications

• H02H7/1222

  responsive to abnormalities in the input circuit, e.g. transients in the DC input · CPC title

• H02M2001/0022

  Electricity · mapped topic

• H02M1/32 Primary

  Means for protecting converters other than automatic disconnection · CPC title

• H02H7/10

  for converters; for rectifiers {(forming part of the control circuit of the converter, see the relevant group in H02M)} · CPC title

• H02H3/04

  with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned {(watching of pilot wires H02H1/0084; protection of protective arrangements H02H7/008; indication of the state of electronic switches H03K17/18)} · CPC title