# US 2014/0152287 A1 · Synchronous dc-dc converter having soft-stop function > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0152287 A1 - Document ID: US20140152287A1 - Status: Published application - Kind: A1 - Application number: 13/757,844 - Filed: 2013-02-03 - Published: 2014-06-05 - Earliest claimed: 2012-12-05 - Assignees: Anpec Electronics Corporation - Applicants: Anpec Electronics Corporation - Inventors: Chia-Chieh Weng; Po-Hsueh Kuo - Web page: https://patentgrep.com/patent/US20140152287A1 ## CPC - H02M 3/1588: {comprising at least one synchronous rectifier element (H02M3/1582, H02M3/1584 take precedence)} - H02M 1/36: Means for starting or stopping converters - Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes - 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) - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract A synchronous DC-DC converter having a soft-stop function includes an output stage for supplying an output voltage, wherein the output stage includes a high-side transistor for charging the output voltage and a low-side transistor for discharging the output voltage; an output control circuit, coupled to the output stage, for controlling the high-side transistor and the low-side transistor of the output stage; at least one protection device, for controlling the high-side transistor to be turned off when a specific situation occurs, in order to stop supplying the output voltage; and a soft-stop control circuit, coupled to the output control circuit, for controlling the low-side transistor of the output stage to be turned on when the protection device controls the high-side transistor to be turned off or the synchronous DC-DC converter is disabled, in order to discharge the output voltage. ## Claims ### Claim 1 A synchronous DC-DC converter having a soft-stop function, comprising: an output stage, for supplying an output voltage, the output stage comprising: a high-side transistor, for charging the output voltage; and a low-side transistor, for discharging the output voltage; an output control circuit, coupled to the output stage, for controlling the high-side transistor and the low-side transistor of the output stage; at least one protection device, for controlling the high-side transistor to be turned off when a specific situation occurs, in order to stop supplying the output voltage; and a soft-stop control circuit, coupled to the output control circuit, for controlling the low-side transistor of the output stage to be turned on when the protection device controls the high-side transistor to be turned off or the synchronous DC-DC converter is disabled, in order to discharge the output voltage. ### Claim 2 (depends on 1) The synchronous DC-DC converter of claim 1, wherein the specific situation comprises over-current, over-temperature, over-voltage lockout and under-voltage lockout. ### Claim 3 (depends on 1) The synchronous DC-DC converter of claim 1, wherein the soft-stop control circuit controls the low-side transistor of the output stage to be turned on and off in an intermittent manner, in order to discharge the output voltage intermittently. ### Claim 4 (depends on 1) The synchronous DC-DC converter of claim 1, wherein the soft-stop control circuit comprises: an over-current detector, for detecting a current flowing through the low-side transistor; a clock generator, for generating a control clock; a logic device, coupled to the over-current detector and the clock generator, for controlling the low-side transistor to be turned off when the current flowing through the low-side transistor exceeds a predefined current, and periodically controls the low-side transistor to be turned on according to the control clock; and a terminating device, for controlling the low-side transistor to be turned off when the output voltage is lower than a predefined voltage, and for terminating operations of the soft-stop control circuit. ### Claim 5 (depends on 4) The synchronous DC-DC converter of claim 4, wherein the terminating device comprises a comparator, for comparing the output voltage and the predefined voltage. ### Claim 6 (depends on 4) The synchronous DC-DC converter of claim 4, wherein the logic device comprises: a first logic circuit, coupled to the protection device, for generating a soft-stop signal when the protection device controls the high-side transistor to be turned off or the synchronous DC-DC converter is disabled, in order to activate the soft-stop control circuit; a second logic circuit, coupled to the clock generator, for receiving a trigger from the control clock, in order to control the low-side transistor to be turned on periodically; and a third logic circuit, coupled to the over-current detector, for controlling the low-side transistor to be turned off when the current flowing through the low-side transistor exceeds a predefined current. ### Claim 7 (depends on 6) The synchronous DC-DC converter of claim 6, wherein the first logic circuit comprises an OR-gate. ### Claim 8 (depends on 6) The synchronous DC-DC converter of claim 6, wherein the second logic circuit is further coupled to the first logic circuit, for receiving a trigger from the soft-stop signal. ### Claim 9 (depends on 8) The synchronous DC-DC converter of claim 8, wherein the third logic circuit is further coupled to the second logic circuit, for receiving a trigger from an output signal of the second logic circuit. ### Claim 10 (depends on 6) The synchronous DC-DC converter of claim 6, wherein the second logic circuit comprises an SR-latch. ### Claim 11 (depends on 6) The synchronous DC-DC converter of claim 6, wherein the third logic circuit comprises an SR-latch. ### Claim 12 (depends on 6) The synchronous DC-DC converter of claim 6, wherein the logic device further comprises a fourth logic circuit coupled to the first logic circuit and the third logic circuit, for receiving the soft-stop signal and an output signal of the third logic circuit, in order to control the output control circuit. ### Claim 13 (depends on 12) The synchronous DC-DC converter of claim 12, wherein the fourth logic circuit comprises an AND-gate. ### Claim 14 (depends on 4) The synchronous DC-DC converter of claim 4, wherein the step of the logic device periodically controlling the low-side transistor to be turned on according to the control clock comprises the logic device controlling the low-side transistor to be turned on at each positive edge of the control clock. ### Claim 15 (depends on 4) The synchronous DC-DC converter of claim 4, wherein the step of the logic device periodically controlling the low-side transistor to be turned on according to the control clock comprises the logic device controlling the low-side transistor to be turned on at each negative edge of the control clock. ### Claim 16 (depends on 1) The synchronous DC-DC converter of claim 1, wherein the output stage further comprises: a capacitor, coupled between an output terminal and a ground terminal, for storing power of the output voltage and stabling the output voltage; and an inductor, coupled between the high-side transistor, the low-side transistor and the output terminal.