# US 2014/0191736 A1 · Active Transient Response for DC-DC Converters > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0191736 A1 - Document ID: US20140191736A1 - Status: Published application - Kind: A1 - Application number: 13/737,331 - Filed: 2013-01-09 - Published: 2014-07-10 - Earliest claimed: 2013-01-09 - Assignees: Infineon Technologies North America Corp. - Inventors: Amir Babazadeh; Benjamim Tang - Web page: https://patentgrep.com/patent/US20140191736A1 ## CPC - H02M 3/1582: {Buck-boost converters (H02M3/1584 takes precedence)} - H02M 3/1588: {comprising at least one synchronous rectifier element (H02M3/1582, H02M3/1584 take precedence)} - H02M 3/156: with automatic control of output voltage or current, e.g. switching regulators - H02M 3/1566: {with means for compensating against rapid load changes, e.g. with auxiliary current source, with dual mode control or with inductance variation} - H02M 3/158: including plural semiconductor devices as final control devices for a single load - 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 first power transistor of a DC-DC converter is connected between a voltage supply node and a common node, a second power transistor is connected between a reference node and the common node, and an inductor is connected between the common node and the output node of the DC-DC converter. A controller switches the first transistor off and the second transistor off during a step-down event at the load if current in the inductor exceeds a positive threshold value. ## Claims ### Claim 1 A DC-DC converter having an output node for connecting to a load, comprising: a first power transistor connected between a voltage supply node and a common node; a second power transistor connected between a reference node and the common node; an inductor connected between the common node and the output node; and a controller operable to switch the first transistor off and the second transistor off during a step-down event at the load if current in the inductor exceeds a positive threshold value. ### Claim 2 (depends on 1) The DC-DC converter according to claim 1, wherein the positive threshold value is programmable. ### Claim 3 (depends on 1) The DC-DC converter according to claim 1, wherein the controller is further operable to switch the first transistor off and the second transistor on during the step-down event if the inductor current drops below a second threshold value. ### Claim 4 (depends on 3) The DC-DC converter according to claim 3, wherein the positive threshold value and the second threshold value are set to the same value. ### Claim 5 (depends on 3) The DC-DC converter according to claim 3, wherein both threshold values are programmable. ### Claim 6 (depends on 1) The DC-DC converter according to claim 1, wherein the controller is further operable to switch the first transistor off and the second transistor on during the step-down event if the inductor current is below the positive threshold value. ### Claim 7 (depends on 1) DC-DC converter according to claim 1, wherein the controller is further operable to switch the first transistor off and the second transistor off during the step-down event if the inductor current exceeds the positive threshold value for a maximum time limit, switch the first transistor off and the second transistor on during the step-down event if the inductor current is above the positive threshold value and the maximum time limit is exceeded, and switch the first transistor off and the second transistor on during the step-down event if the inductor current is below the positive threshold value and the maximum time limit is not exceeded. ### Claim 8 (depends on 7) The DC-DC converter according to claim 7, wherein the maximum time limit value is programmable. ### Claim 9 (depends on 8) The DC-DC converter according to claim 8, wherein the maximum time limit is selected so that the second transistor is switched on during the step-down event before a driver of the second transistor enters a low power sleep mode. ### Claim 10 (depends on 7) The DC-DC converter according to claim 7, wherein the controller is further operable to switch the second transistor off again during the step-down load event after the second transistor is on for a predetermined amount of time and the inductor current continues to remain above the positive threshold value after the predetermined amount of time lapses. ### Claim 11 (depends on 6) The DC-DC converter according to claim 6, wherein the first and second transistors are collectively further operable to supply high current, medium current and low current to the load depending on operating conditions at the load, wherein the step-down load event occurs when the load current changes from high-to-low, high-medium or medium-to-low, wherein the controller is further operable to switch the first transistor off and the second transistor on during a high-to-medium or medium-to-low step-down load current event, and wherein the controller is further operable to switch the first transistor off and the second transistor off during a high-to-low step-down load current event. ### Claim 12 (depends on 1) The DC-DC converter according to claim 1, wherein the controller is further operable to control the first and second transistors via a variable duty cycle control signal input to the first and second transistors, and wherein the controller is further operable to override the variable duty cycle control signal to the second transistor during the step-down load event. ### Claim 13 A multi-phase DC-DC converter, comprising: a power stage including a plurality of phases, each phase having a high-side transistor and a low-side transistor for coupling to a load through a respective inductor; a pulse width modulator operable to switch the phases of the power stage via a variable duty cycle control signal for delivering current to the load through one or more of the inductors; and a transient response unit operable to switch the high-side transistors off and the low-side transistors off during a step-down event at the load if a measured inductor current in any of the inductors or collectively in all of the inductors exceeds a positive threshold value. ### Claim 14 (depends on 13) The multi-phase DC-DC converter according to claim 13, wherein the transient response unit is further operable to switch the high-side transistors off and the low-side transistors on during the step-down event if the measured inductor current drops below a second threshold value. ### Claim 15 (depends on 13) The multi-phase DC-DC converter according to claim 13, wherein the transient response unit is further operable to switch the high-side transistors off and the low-side transistors on during the step-down event if the measured inductor current is below the positive threshold value. ### Claim 16 (depends on 13) The multi-phase DC-DC converter according to claim 13, wherein the transient response unit is further operable to switch the high-side transistors off and the low-side transistors off during the step-down event if the measured inductor current exceeds the positive threshold value for a maximum time limit, switch the high-side transistors off and the low-side transistors on during the step-down event if the measured inductor current is above the positive threshold value and the maximum time limit is exceeded, and switch the high-side transistors off and the low-side transistors on during the step-down event if the measured inductor current is below the positive threshold value and the maximum time limit is not exceeded. ### Claim 17 (depends on 16) The multi-phase DC-DC converter according to claim 16, wherein the transient response unit is further operable to switch the low-side transistors off again during the step-down load event if the low-side transistors are on for a predetermined amount of time and the measured inductor current continues to remain above the positive threshold value after the predetermined amount of time lapses. ### Claim 18 (depends on 16) The multi-phase DC-DC converter according to claim 16, wherein the high-side and low-side transistors are collectively further operable to supply high current, medium current and low current to the load depending on operating conditions at the load, wherein the step-down load event occurs when the measured load current changes from high-to-low, high-medium or medium-to-low, wherein the transient response unit is further operable to switch the high-side transistors off and the low-side transistors on during a high-to-medium or medium-to-low step-down load current event, and wherein the transient response unit is further operable to switch the high-side transistors off and the low-side transistors off during a high-to-low step-down load current event. ### Claim 19 A method of operating a DC-DC converter including a first power transistor connected between a voltage supply node and a common node, a second power transistor connected between a reference node and the common node, and an inductor connected between the common node and the output node, the method comprising: switching the first and second transistors via a variable duty cycle control signal to deliver current to the load through the inductor; switching the first transistor off during a step-down event at the load; and switching the second transistor off during the step-down event irrespective of the state of the variable duty cycle control signal if current in the inductor exceeds a positive threshold value. ### Claim 20 (depends on 19) The method according to claim 19, further comprising switching the first transistor off and the second transistor on during the step-down event if the inductor current drops below a second threshold value. ### Claim 21 (depends on 19) The method according to claim 19, further comprising switching the first transistor off and the second transistor on during the step-down event if the inductor current is below the positive threshold value. ### Claim 22 (depends on 19) The method according to claim 19, further comprising: switching the first transistor off and the second transistor off during the step-down event if the inductor current exceeds the positive threshold value for a maximum time limit; switching the first transistor off and the second transistor on during the step-down event if the inductor current is above the positive threshold value and the maximum time limit is exceeded; and switching the first transistor off and the second transistor on during the step-down event if the inductor current is below the positive threshold value and the maximum time limit is not exceeded. ### Claim 23 (depends on 22) The method according to claim 22, further comprising switching the second transistor off again during the step-down load event if the second transistor is on for a predetermined amount of time and the inductor current continues to remain above the positive threshold value after the predetermined amount of time lapses. ### Claim 24 (depends on 22) The method according to claim 22, wherein the first and second transistors are collectively further operable to supply high current, medium current and low current to the load depending on operating conditions at the load, wherein the step-down load event occurs when the load current changes from high-to-low, high-medium or medium-to-low, the method further comprising: switching the first transistor off and the second transistor on during a high-to-medium or medium-to-low step-down load current event; and switching the first transistor off and the second transistor off during a high-to-low step-down load current event.