# US 2018/0026629 A1 · Output driver having pull-down capability > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0026629 A1 - Document ID: US20180026629A1 - Status: Published application - Kind: A1 - Application number: 15/214,750 - Filed: 2016-07-20 - Published: 2018-01-25 - Earliest claimed: 2016-07-20 - Assignees: Semiconductor Components Industries, LLC - Applicants: Semiconductor Components Industries, LLC - Inventors: Karel PTACEK - Web page: https://patentgrep.com/patent/US20180026629A1 ## CPC - H03K 17/687: the devices being field-effect transistors - H02M 3/07: using capacitors charged and discharged alternately by semiconductor devices with control electrode {, e.g. charge pumps} - H03K 19/00361: {in field effect transistor circuits} - H03K 19/018585: {programmable} - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) - 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 An output driver includes a switching device having a first node coupled to a gate of a power switch and pulling down a voltage level of the gate of the power switch to prevent a premature turn-on of the power switch. A pull-down circuit is coupled to the switching device and keeping the switching device from being turned on to prevent the premature turn-on of the power switch. ## Claims ### Claim 1 An output driver, comprising: a switching device having a first node coupled to a gate of a power switch and pulling down a voltage level of the gate of the power switch to prevent a premature turn-on of the power switch; and a pull-down circuit coupled to the switching device and keeping the switching device from being turned on to prevent the premature turn-on of the power switch. ### Claim 2 (depends on 1) The output driver of claim 1, wherein the switching device includes a depletion type n-channel metal-oxide-semiconductor field-effect transistor having a drain coupled to the first node, and wherein the pull-down circuit turns off the switching device when the power switch is in or transitions to a power-on mode. ### Claim 3 (depends on 2) The output driver of claim 2, wherein the pull-down circuit includes: a control circuit generating an activation signal based on a supply voltage, a first reference voltage, and a feedback signal; and a negative charge pump generating a control signal according to the activation signal and outputting the control signal to the switching device. ### Claim 4 (depends on 3) The output driver of claim 3, wherein the feedback signal is the control signal, and wherein the control circuit includes: a first comparator comparing the supply voltage and the first reference voltage to output a first input signal; a second comparator comparing the feedback signal with a second reference voltage to output a second input signal; and a logic gate performing a logical operation on the first and second input signals to output the activation signal. ### Claim 5 (depends on 4) The output driver of claim 4, wherein the power switch is in a power-off mode when the supply voltage is less than the first reference voltage and the power switch is in an intermediate mode at a time interval between the power-off mode and the power-on mode, and wherein preventing the premature turn-on of the power switch by the switching device involves keeping the power switch off during the power-off mode and the intermediate mode. ### Claim 6 (depends on 5) The output driver of claim 5, wherein the logic gate is an AND logic gate, and wherein the logic gate outputs the activation signal indicative of a logic high value while the power switch is in the intermediate mode, and outputs the activation signal indicative of a logic low value while the power switch is in the power-off mode or the power-on mode. ### Claim 7 (depends on 3) The output driver of claim 3, wherein the switching device is a first switching device, and wherein the control circuit includes: a first comparator comparing the supply voltage and the first reference voltage to output a first input signal; a second switching device coupled between a second node and a ground and receiving the feedback signal, a voltage at the second node corresponding to a second input signal; a resistor coupled between the supply voltage and the second node; and a logic gate performing a logical operation on an inverted version of the first input signal and the second input signal to output the activation signal. ### Claim 8 (depends on 7) The output driver of claim 7, wherein the power switch is in a power-off mode when the supply voltage is less than the first reference voltage and the power switch is in an intermediate mode at a time interval between the power-off mode and the power-on mode, and wherein the logic gate outputs the activation signal indicative of a logic low value while the power switch is in the intermediate mode, and outputs the activation signal indicative of a logic high value while the power switch is in the power-off mode or the power-on mode. ### Claim 9 (depends on 7) The output driver of claim 7, wherein the negative charge pump causes an absolute magnitude of the control signal to be substantially two times as large as an absolute magnitude of the feedback signal at the end of the intermediate mode. ### Claim 10 (depends on 9) The output driver of claim 9, wherein the second switching device is a depletion type n-channel metal-oxide-semiconductor field-effect transistor. ### Claim 11 (depends on 9) The output driver of claim 9, wherein the negative charge pump includes: an oscillator coupled to the logic gate and generating an oscillating signal during the second time interval; a first capacitor coupled to the oscillator; a first diode coupled between the first capacitor and the ground; a second diode coupled between the first capacitor and a third node, the third node being coupled to a gate of the second switching device; a second capacitor coupled to the second diode; a third diode coupled between the second capacitor and the third node; a third capacitor coupled between the third node and the ground; a fourth capacitor coupled between a fourth node and the ground, a voltage at the fourth node corresponding to the control signal; and a fourth diode coupled between the second capacitor and the fourth node. ### Claim 12 (depends on 3) The output driver of claim 3, wherein the control signal is a control voltage, and wherein the negative charge pump decreases the control voltage until the control voltage becomes substantially equal to a threshold voltage of the switching device during the second time interval. ### Claim 13 (depends on 3) The output driver of claim 3, wherein the output driver is included in a controller, the controller being in a package. ### Claim 14 An apparatus, comprising: a controller; and an output driver including a switching device having a first node coupled to a gate of a power switch and pulling down a voltage level of the gate of the power switch to prevent a premature turn-on of the power switch, and a pull-down circuit coupled to the switching device and keeping the switching device from being turned on to prevent the premature turn-on of the power switch. ### Claim 15 A method for controlling an output driver, the method comprising: pulling down a level of a voltage at a first node to prevent a premature turn-on of a power switch coupled to the output driver, the first node being coupled to a switching device and a gate of the power switch; turning off the switching device using a pull-down circuit; and outputting a driving signal to the power switch. ### Claim 16 (depends on 15) The method of claim 15, wherein the switching device is a depletion type n-channel metal-oxide-semiconductor field-effect transistor having a drain coupled to the first node, the method further comprising: generating an activation signal based on a supply voltage, a first reference voltage, and a feedback signal; and generating a control signal according to the activation signal and outputting the control signal to the switching device. ### Claim 17 (depends on 16) The method of claim 16, further comprising: increasing a level of the supply voltage until the level of the supply voltage becomes substantially equal to a level of the first reference voltage while the power switch is in a power-off mode. ### Claim 18 (depends on 16) The method of claim 16, wherein the feedback signal is the control signal, the method further comprising: comparing the supply voltage and the first reference voltage to output a first input signal; comparing the feedback signal with a second reference voltage to output a second input signal; and performing a logical operation on the first and second input signals to output the activation signal. ### Claim 19 (depends on 16) The method of claim 16, wherein the switching device is a first switching device, the method further comprising: comparing the supply voltage and the first reference voltage to output a first input signal; generating a second input signal using a second switching device according to the feedback signal; and performing a logical operation on an inverted version of the first signal and the second input signal to output the activation signal. ### Claim 20 (depends on 19) The method of claim 19, wherein the power switch is in a power-off mode when the supply voltage is less than the first reference voltage and the power switch is in an intermediate mode at a time interval between the power-off mode and the power-on mode, the method further comprising: causing an absolute magnitude of the control signal to be substantially two times as large as an absolute magnitude of the feedback signal at the end of the intermediate mode.