# US 2013/0278166 A1 · Semiconductor circuit and semiconductor apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0278166 A1 - Document ID: US20130278166A1 - Status: Published application - Kind: A1 - Application number: 13/864,328 - Filed: 2013-04-17 - Published: 2013-10-24 - Earliest claimed: 2012-04-20 - Assignees: Lapis Semiconductor Co., Ltd. - Applicants: Lapis Semiconductor Co., Ltd. - Inventors: TERUO KATOH - Web page: https://patentgrep.com/patent/US20130278166A1 ## CPC - H03K 17/145: {in field-effect transistor switches} - H03K 17/00: Electronic switching or gating, i.e. not by contact-making and –breaking (gated amplifiers H03F3/72; switching arrangements for exchange systems using static devices H04Q3/52) - H03K 17/063: {in field-effect transistor switches} - H05B 45/40: Details of LED load circuits - H05B 45/44: with an active control inside an LED matrix - 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) - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL ## Abstract A semiconductor circuit includes an operational amplifier, a voltage drop circuit, and a switch. The operational amplifier has an output terminal connected to an active element that produces a load drive current. A reference voltage is input to the non-inverting input of the operational amplifier. The voltage drop circuit drops a voltage outputted from the operational amplifier. The switch applies a voltage corresponding to a predetermined current flowing when the active element is on to the inverting input of the operational amplifier in a first interval in which the active element is on in response to a predetermined voltage from the operational amplifier. The switch allows the voltage dropped by the voltage drop circuit to be input to the inverting input in a second interval in which the active element is off, thereby shortening a time period until the load drive current starts to flow. ## Claims ### Claim 1 A semiconductor circuit, in which to control driving of a first load, comprising: an operational amplifier that includes a first input terminal, a second input terminal, and an output terminal, and outputs a first voltage from the output terminal; a voltage drop circuit which drops the first voltage and generates a second voltage; and an input switching part which allows a third voltage input to the second input terminal in a first interval in which an active element is turned on by the first voltage, and allows the second voltage to be input to the second input terminal in a second interval in which the active element is turned off. ### Claim 2 (depends on 1) The semiconductor circuit of claim 1, wherein the active element is turned on in response to a predetermined input voltage and allows a predetermined current for driving the first load to flow. ### Claim 3 (depends on 1) The semiconductor circuit of claim 1, wherein the operational amplifier outputs a first voltage from the output terminal such that a voltage input to the second input terminal approximates to a voltage input to the first input terminal. ### Claim 4 (depends on 1) The semiconductor circuit of claim 1, wherein the third voltage corresponds to the predetermined current flowing when the active element is turned on. ### Claim 5 (depends on 1) The semiconductor circuit of claim 1, wherein the active element includes a control terminal, a first terminal connected to the first load, and a second terminal connected to a second load, and is configured such that a difference between a voltage dropped by the voltage drop circuit and a voltage between the control terminal and the second terminal is smaller than a predetermined value when the active element is turned on and allows a predetermined current to be output to the first load and the second load. ### Claim 6 (depends on 1) The semiconductor circuit of claim 1, wherein the first load includes a light emitting element. ### Claim 7 (depends on 5) The semiconductor circuit of claim 5, wherein the first load includes a light emitting element. ### Claim 8 A semiconductor device comprising: an active element electrically connected to a first load, turned on in response to a predetermined input voltage, and allowing a predetermined current for driving the first load to flow; a second load electrically connected to the active element and generating a first voltage when the predetermined current flows through the second load; an operational amplifier that includes a first input terminal for receiving a reference voltage, a second input terminal, and an output terminal, and outputs a second voltage from the output terminal such that a voltage input to the second input terminal approximates to the reference voltage input to the first input terminal; a voltage drop circuit which drops the second voltage, which is output from the output terminal of the operational amplifier, and generates a third voltage; and an input switching part which allows the first voltage to be input to the second input terminal of the operational amplifier in a first interval in which the active element is turned on by the second voltage output from the output terminal of the operational amplifier, and allows the third voltage to be input to the second input terminal in a second interval in which the active element is turned off.