# US 12,604,377 B2 · Light driver with improved dimming profile > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,604,377 B2 - Document ID: US12604377B2 - Status: Granted - Kind: B2 - Application number: 18/419,786 - Filed: 2024-01-23 - Published: 2024-05-16 - Granted: 2026-04-14 - Earliest claimed: 2021-11-03 - Assignees: Erp Power, LLC - Applicants: Erp Power, LLC - Inventors: Michael Archer; Louis Chen; James H. Mohan - Web page: https://patentgrep.com/patent/US12604377B2 ## CPC - H05B 45/10: Controlling the intensity of the light - H05B 45/325: Pulse-width modulation [PWM] - H05B 45/355: Power factor correction [PFC]; Reactive power compensation - H05B 45/31: Phase-control circuits - H05B 45/38: using boost topology - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL ## Abstract A light driver includes a pulse generator circuit configured to generate a pulsed signal based on a rectified input line voltage, a dimming detection circuit configured to determine whether phase-cut dimming is present at an input of the light driver based on the pulsed signal and to generate a phase-cut detection signal, and an input selection circuit configured to apply a first voltage or a second voltage to a reference input of a power factor correction (PFC) circuit of the light driver based on the phase-cut detection signal. ## Claims ### Claim 1 A light driver comprising: a power factor correction (PFC) circuit having a reference input and configured to receive a PFC input voltage; a second voltage divider configured to generate a first voltage based on a rectified input line voltage; a third voltage divider configured to generate a second voltage based on the PFC input voltage; a dimming detection circuit configured to determine whether phase-cut dimming is present at an input of the light driver based on an input line voltage of the light driver and to generate a phase-cut detection signal; and an input selection circuit comprising a switching circuit configured to receive the first voltage and the second voltage, and to selectively apply one of the first voltage and the second voltage to the reference input of the PFC circuit based on the phase-cut detection signal. ### Claim 2 (depends on 1) The light driver of claim 1, wherein the light driver further comprises: a rectifier configured to rectify the input line voltage of the light driver and to generate the rectified input line voltage; and a pulse generator circuit configured to generate a pulsed signal based on the rectified input line voltage, wherein the dimming detection circuit is configured to determine whether the phase-cut dimming is present based on the pulsed signal. ### Claim 3 (depends on 2) The light driver of claim 2, further comprising: a first voltage divider configured to generate an attenuated rectified voltage based on the rectified input line voltage, wherein the pulse generator circuit comprises: a reference generator configured to generate a reference signal; and a first comparator configured to receive the reference signal and the attenuated rectified voltage, and to generate the pulsed signal based on a comparison of the reference signal and the attenuated rectified voltage. ### Claim 4 (depends on 3) The light driver of claim 3, wherein the reference generator comprises: a zener diode coupled to a negative input of the first comparator, and wherein the reference signal is 2 V to 12 V. ### Claim 5 (depends on 3) The light driver of claim 3, wherein the first comparator comprises: a first operational amplifier having a positive input terminal and a negative input terminal, and configured to receive the attenuated rectified voltage at the positive input terminal and the reference signal at the negative input terminal. ### Claim 6 (depends on 3) The light driver of claim 3, wherein the dimming detection circuit comprises: a filter configured to low pass filter the pulsed signal and to produce a filtered signal; and a second comparator configured to receive the reference signal and the filtered signal and to produce the phase-cut detection signal, wherein a level of the phase-cut detection signal is indicative of a presence or absence of phase-cut dimming. ### Claim 7 (depends on 6) The light driver of claim 6, wherein the filter comprises a passive low pass RC filter, and wherein the filtered signal is a quasi-sawtooth signal. ### Claim 8 (depends on 6) The light driver of claim 6, wherein the second comparator comprises: a second operational amplifier having a positive input terminal and a negative input terminal, and configured to receive the reference signal at the positive input terminal and the filtered signal at the negative input terminal. ### Claim 9 (depends on 2) The light driver of claim 2, wherein the pulsed signal is a pulse-width-modulated (PWM) signal having a duty cycle corresponding to a phase-cut of the rectified input line voltage. ### Claim 10 (depends on 2) The light driver of claim 2, wherein the pulse generator circuit is configured to transmit the pulsed signal to a channel controller of the light driver. ### Claim 11 (depends on 2) The light driver of claim 2, further comprising: the PFC circuit configured to reduce a total harmonic distortion (THD) of the light driver and to increase a power factor (PF) of the light driver. ### Claim 12 (depends on 2) The light driver of claim 2, wherein the input of the light driver is coupled to a phase-cut dimmer configured to perform phase-cutting of the input line voltage based on a dimmer setting. ### Claim 13 (depends on 2) The light driver of claim 2, further comprising: a converter configured to convert the rectified input line voltage into a drive signal for powering a light source coupled to the light driver. ### Claim 14 (depends on 2) The light driver of claim 2, wherein the input line voltage from which the rectified input line voltage is generated is from 100 Vac to 277 Vac. ### Claim 15 (depends on 2) The light driver of claim 2, wherein the switching circuit comprises: a first switch configured to activate in response to the phase-cut detection signal being at a first level to apply the first voltage to the reference input of the PFC circuit, and to deactivate in response to the phase-cut detection signal being at a second level to decouple the reference input of the PFC circuit from the second voltage divider; and a second switch configured to deactivate in response to the phase-cut detection signal being at the first level to decouple the reference input of the PFC circuit from the third voltage divider, and to activate in response to the phase-cut detection signal being at the second level to apply the second voltage to the reference input of the PFC circuit. ### Claim 16 (depends on 15) The light driver of claim 15, wherein the PFC circuit is configured to deactivate a current limit and a dimming control function of the PFC circuit in response to receiving the second voltage at the reference input. ### Claim 17 (depends on 15) The light driver of claim 15, wherein the first switch comprises a p-channel junction field effect transistor (JFET) and the second switch comprise an n-channel metal-oxide semiconductor field-effect transistor (MOSFET), each of the p-channel JFET and the n-channel MOSFET having a gate electrode coupled to an output of the input selection circuit. ### Claim 18 (depends on 15) The light driver of claim 15, wherein the first level is at a voltage lower than that of the second level, and wherein the phase-cut detection signal being at the first level indicates absence of phase-cut dimming at the input of the light driver, and the phase-cut detection signal being at the second level indicates a presence of phase-cut dimming at the input of the light driver.