# US 12,601,769 B2 · Input isolated voltage monitor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,601,769 B2 - Document ID: US12601769B2 - Status: Granted - Kind: B2 - Application number: 18/348,440 - Filed: 2023-07-07 - Published: 2024-08-08 - Granted: 2026-04-14 - Earliest claimed: 2023-02-06 - Assignees: Hamilton Sundstrand Corporation - Applicants: Hamilton Sundstrand Corporation - Inventors: Nageswara Rao Kalluri; Tanay Ghose; Manish Kumar; Bapu Kallappa Banahatti; Premanshi Jain - Web page: https://patentgrep.com/patent/US12601769B2 ## CPC - G01R 19/16576: {comparing DC or AC voltage with one threshold (G01R19/16514, G01R19/16519, G01R19/16528, G01R19/16533 and G01R19/1659 take precedence)} - H02M 3/33523: {with galvanic isolation between input and output of both the power stage and the feedback loop} - G01R 15/04: Voltage dividers - H02M 1/32: Means for protecting converters other than automatic disconnection - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) ## Abstract A voltage monitor for a fly-back circuit. The circuit includes a voltage source, a transformer comprising a primary winding electrically coupled to the voltage source and a secondary winding electrically coupled to a load, a diode connected between the secondary winding and the load, a switch electrically coupled to the primary winding and a controller operable to open and close the switch to control energy transfer from the primary winding to the secondary winding. The voltage monitor is connected to a node between the secondary winding and the diode that generates an output signal that is a toggling output when the voltage source is operating above an input voltage threshold and a constant output when the voltage source is operating below the input voltage threshold. ## Claims ### Claim 1 A fly-back circuit comprising: a voltage source; a transformer comprising a primary winding electrically coupled to the voltage source and a secondary winding electrically coupled to a load; a diode connected between the secondary winding and the load; a switch electrically coupled to the primary winding; a controller operable to open and close the switch to control energy transfer from the primary winding to the secondary winding; and wherein a voltage monitor includes a comparator that generates an output signal, the comparator having a first input connected to a node between the secondary winding and the diode and a second input connected to a monitor threshold voltage, and wherein the output signal being a toggling output when the voltage source is operating above an input voltage threshold and a constant output when the voltage source is operating below the input voltage threshold. ### Claim 2 (depends on 1) The fly-back circuit of claim 1, further comprising: a control device connected to an output of the voltage monitor that determines that the voltage based on whether the output signal is toggling or not toggling. ### Claim 3 (depends on 1) The fly-back circuit of claim 1, further comprising a voltage divider between the node and the first input. ### Claim 4 (depends on 3) The fly-back converter of claim 3, wherein the first input is an inverting input and the second input is a non-inverting input. ### Claim 5 (depends on 1) The fly-back circuit of claim 1, wherein the first input is an inverting input and the second input is a non-inverting input. ### Claim 6 (depends on 1) The fly-back converter of claim 1, wherein the controller is a pulse width modulation controller operable to output a sequence of pulses to open and close the switch based on determining that the voltage source exceeds a minimum control voltage. ### Claim 7 A method comprising: providing with a voltage source an input voltage to a primary side of a fly-back circuit that includes primary winding and a secondary winding; controlling a switch electrically coupled to the primary winding to transition between an open state and a closed state to control energy transfer from the primary winding to the secondary winding; monitoring voltage with a voltage monitor at a node between the secondary winding and a diode with a comparator whose first input is connected to the node and whose second input is connected to a monitor threshold voltage; and generating with the comparator an output signal with the voltage monitor that is a toggling output when the voltage source is operating above an input voltage threshold and a constant output when the voltage source is operating below the input voltage threshold. ### Claim 8 (depends on 7) The method of claim 7, further comprising: analyzing with a control device connected to an output of the voltage monitor to determine that determines that the voltage based on whether the output signal is toggling or not toggling. ### Claim 9 (depends on 8) The method of claim 8, wherein analyzing includes: taking first and second measurements of a signal at the output of the voltage monitor, wherein the first and second measurement are delayed in time from one another; determining that the first and second measurements are different from one another; and returning to the step of taking. ### Claim 10 (depends on 8) The method of claim 8, wherein analyzing includes: taking first and second measurements of a signal at the output of the voltage monitor, wherein the first and second measurement are delayed in time from one another; determining that the first and second measurements are the same; and generating a flag indicating that the input voltage has fallen below a desired threshold. ### Claim 11 (depends on 7) The method of claim 7, wherein the first input is an inverting input and the second input is a non-inverting input.