# US 2018/0324913 A1 · Ripple suppression circuit and light emitting diode driver > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0324913 A1 - Document ID: US20180324913A1 - Status: Published application - Kind: A1 - Application number: 15/968,896 - Filed: 2018-05-02 - Published: 2018-11-08 - Earliest claimed: 2017-05-05 - Assignees: Silergy Semiconductor Technology (Hangzhou) LTD - Applicants: Silergy Semiconductor Technology (Hangzhou) LTD - Inventors: Jian Deng - Web page: https://patentgrep.com/patent/US20180324913A1 ## CPC - H05B 45/3725: Switched mode power supply [SMPS] - H02M 1/15: using active elements - H05B 45/10: Controlling the intensity of the light - H02M 1/14: Arrangements for reducing ripples from DC input or output - H02M 1/143: {using compensating arrangements (for reducing noise from the supply in transmission systems H04B15/005)} - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL - 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 ripple suppression circuit for suppressing a ripple component in a drive current for an LED load, can include: an output port connected to the LED load; a current filter circuit connected in series with the output port, and being configured to control the drive current based on an output voltage after a ripple component is filtered out, where the drive current is maintained as substantially stable; and a ripple shunt circuit connected between a drive current input terminal and a ground terminal, and being configured to shunt the drive current in response to the output voltage, where the output voltage is a voltage output from a previous stage of circuit to the ripple suppression circuit. ## Claims ### Claim 1 A ripple suppression circuit for suppressing a ripple component in a drive current for a light-emitting diode (LED) load, the ripple suppression circuit comprising: a) an output port connected to the LED load; b) a current filter circuit connected in series with the output port, and being configured to control the drive current based on an output voltage after a ripple component is filtered out, wherein the drive current is maintained as substantially stable; and c) a ripple shunt circuit connected between a drive current input terminal and a ground terminal, and being configured to shunt the drive current in response to the output voltage, wherein the output voltage is a voltage output from a previous stage of circuit to the ripple suppression circuit. ### Claim 2 (depends on 1) The ripple suppression circuit of claim 1, wherein the ripple shunt circuit is configured to shunt the drive current in response to a voltage drop of the current filter circuit. ### Claim 3 (depends on 2) The ripple suppression circuit of claim 2, wherein a shunting current of the ripple shunt circuit is in direct proportion to the voltage drop of the current filter circuit. ### Claim 4 (depends on 1) The ripple suppression circuit of claim 1, wherein the current filter circuit comprises: a) a voltage filter circuit configured to perform filtering on at least one of a voltage drop of the current filter circuit and the output voltage to generate a control voltage; and b) a voltage-controlled current source connected in series with the output port, and being configured to generate a corresponding current under control of the control voltage. ### Claim 5 (depends on 4) The ripple suppression circuit of claim 4, wherein: a) the voltage-controlled current source is connected between the drive current input terminal and the output port; and b) the voltage filter circuit comprises a first diode, a first resistor, and a first capacitor that are sequentially connected between the drive current input terminal and the ground terminal, wherein the control voltage is generated from a common node of the first resistor and the first capacitor. ### Claim 6 (depends on 5) The ripple suppression circuit of claim 5, wherein the voltage filter circuit further comprises a second diode connected in parallel with the first resistor. ### Claim 7 (depends on 4) The ripple suppression circuit of claim 4, wherein: a) the voltage-controlled current source is connected between the output port and the ground terminal; and b) the voltage filter circuit comprises a first diode, a first resistor, and a first capacitor that are sequentially connected between two terminals of the voltage-controlled current source, wherein the control voltage is generated form a common node of the first resistor and the first capacitor. ### Claim 8 (depends on 6) The ripple suppression circuit of claim 6, wherein the voltage filter circuit further comprises a second diode connected in parallel with the first resistor. ### Claim 9 (depends on 3) The ripple suppression circuit of claim 3, wherein the voltage-controlled current source comprises a transistor. ### Claim 10 (depends on 4) The ripple suppression circuit of claim 4, wherein the ripple shunt circuit comprises: a) a triode having an emitter connected to a first terminal of the voltage-controlled current source; b) a second resistor connected between a base of the triode and a second terminal of the voltage-controlled current source; and c) a third resistor connected between a collector of the triode and a first terminal of the output port, wherein a second terminal of the output port is connected to the second terminal of the voltage-controlled current source. ### Claim 11 (depends on 1) An LED driver, comprising the ripple suppression circuit of claim 1, and further comprising: a) a dimmer; b) a rectification circuit connected to the dimmer; and c) a switching converter connected to an output terminal of the rectification circuit, wherein the ripple suppression circuit is connected between the switching converter and the LED load.