Indicator using existing power supply controller terminals

Patent metadata

Field	Value
Publication number	US-10243354-B2
Application number	US-201816167816-A
Country	US
Kind code	B2
Filing date	Oct 23, 2018
Priority date	Jun 27, 2016
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

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 comprising: a primary side defining an input voltage, a primary winding of a transformer coupled to the input voltage, and a primary switch coupled to the primary winding; a secondary side defining an output voltage, and a secondary winding coupled to the output voltage; a controller comprising: a brownout terminal coupled to the input voltage; a feedback terminal coupled to the output voltage; a first circuit having a first input coupled to the feedback terminal and a second input coupled to the brownout terminal, the first circuit configured to: sense a voltage on the brownout terminal; sense a voltage on the feedback terminal indicative of output voltage of the power conversion circuit while refraining from driving the alarm current to the feedback terminal; assert an internal signal if the voltage sensed on the brownout terminal during the refraining falls outside a predetermined range; and drive an alarm current to the feedback terminal responsive to the assertion of the internal signal; an external indicator coupled to the feedback terminal, the external indicator configured to activate responsive to the alarm current.

2. The power conversion circuit of claim 1 wherein the external indicator is at least one selected from a group comprising: a light emitting diode; and a buzzer configured to produce sound audible to a human.

3. The power conversion circuit of claim 1 wherein the external indicator is a means for providing human perceptible visual or auditory alarm indication.

4. The power conversion circuit of claim 1 wherein when the controller drives the alarm current, the controller is configured to drive the alarm current at a voltage above a predetermined threshold.

5. The power conversion circuit of claim 1 wherein when the controller senses the voltage on the feedback terminal and refrains from driving the alarm current, the controller is configured to perform at least one selected from a group comprising:
sense a current driven into the feedback terminal at a voltage below a predetermined threshold; and
drive a current out of the feedback terminal and sense a voltage below the predetermined threshold.

6. The power conversion circuit of claim 5 wherein when the controller drives the alarm current, the controller is configured to drive the alarm current at a voltage above the predetermined threshold.

7. The power conversion circuit of claim 1 , wherein the first circuit further comprises:
a comparator defining a first input, a second input, and a comparison output, the first input coupled to the brownout terminal, the second input coupled to a reference voltage, and the comparison output is the internal signal;
a first current mirror coupled to the feedback terminal, the first current mirror defining a sense side and a mirror side;
a means for producing a voltage drop coupled between the sense side of the first current mirror and the feedback terminal;
an electrically controlled switch coupled in parallel with the means for producing between the sense side of the first current mirror and the feedback terminal, the electrically controlled switch having a control input coupled to the comparison output;
the electrically controlled switch configured to be conductive when the comparison output is asserted, and the alarm current is driven to the feedback terminal through the electrically controlled switch; and
the electrically controlled switch is configured to be non-conductive when the comparison output is non-asserted.

8. The power conversion circuit of claim 7 wherein the means for producing further comprises at least one selected from the group comprising: a diode; and a plurality of diodes; exactly two diodes.

9. The power conversion circuit of claim 1 , wherein the first circuit further comprises:
a comparator defining a first input, a second input, and a comparison output, the first input coupled to the brownout terminal, the second input coupled to a reference voltage, and the comparison output is the internal signal;
a first current mirror circuit coupled to the feedback terminal, the first current mirror defining a sense side and a mirror side;
a plurality of diodes coupled in series between the sense side of the first current mirror and the feedback terminal;
an electrically controlled switch coupled in parallel with the plurality of diodes, the electrically controlled switch having a control input coupled to the comparison output;
a second current mirror defining a sense side and a mirror side;
a Zener diode having an anode and a cathode, the cathode coupled to the sense side of the second current mirror, and the anode coupled to the feedback terminal;
the mirror side of the first current mirror, and the mirror side of the second current mirror, each configured to drive an current indicative of output voltage of the power conversion circuit;
the electrically controlled switch configured to be conductive when the comparison output is asserted, and the alarm current is driven to the feedback terminal through the electrically controlled switch; and
the electrically controlled switch is configured to be non-conductive when the comparison output is non-asserted.

10. A controller for a power conversion circuit, comprising:
a 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 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 a first input coupled to the feedback terminal and a second input coupled to the brownout terminal, the first circuit configured to:
sense the input signal on the brownout terminal;
sense the feedback signal on the feedback terminal;
assert an internal signal if the input signal sensed on the brownout terminal falls outside a predetermined range; and
drive an alarm current to the feedback terminal responsive to the assertion of the internal signal.

11. The controller of claim 10 wherein when the controller drives the alarm current, the controller is configured to drive the alarm current at a voltage above a predetermined threshold.

12. The controller of claim 10 wherein when the controller senses the feedback signal on the feedback terminal, the controller is configured to perform at least one selected from a group comprising:
sense a current driven into the feedback terminal at a voltage below a predetermined threshold; and
drive a current out of the feedback terminal and sense a voltage below the predetermined threshold.

13. The controller of claim 12 wherein when the controller drives the alarm current, the controller is configured to drive the alarm current at a voltage above the predetermined threshold.

14. The controller of claim 10 , wherein the first circuit further comprises:
a comparator defining a first input, a second input, and a comparison output, the first input coupled to the brownout terminal, the second input coupled to a reference voltage, and the comparison output is the internal signal;
a first current mirror coupled to the feedback terminal, the first current mirror defining a sense side and a mirror side;
a means for producing a voltage drop coupled between the sense side of the first current mirror and the feedback terminal;
an electrically controlled switch coupled in parallel with the means for producing betwee

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

• H02H7/12

  for static converters or rectifiers {(for discharge lamp power supplies using static converters H05B41/2851, H05B41/2921, H05B41/2981)} · CPC title

• H02H7/00

  Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions · 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

• H02M2001/0022

  Electricity · mapped topic