# US 10,374,411 B2 · Adjustable over-current detector circuit for universal serial bus (USB) devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,374,411 B2 - Document ID: US10374411B2 - Status: Granted - Kind: B2 - Application number: 15/873,248 - Filed: 2018-01-17 - Published: 2018-07-05 - Granted: 2019-08-06 - Earliest claimed: 2016-05-16 - Assignees: Cypress Semiconductor Corporation - Applicants: Cypress Semiconductor Corporation - Inventors: Derwin W. Mattos; Arnab Chakraborty; Ramakrishna Venigalla; Gerard Kato; Vaidyanathan Varsha - Web page: https://patentgrep.com/patent/US10374411B2 ## CPC - H02H 3/08: responsive to excess current (responsive to abnormal temperature caused by excess current H02H5/04) - G01R 17/02: Arrangements in which the value to be measured is automatically compared with a reference value - G01R 19/165: Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values - G01R 19/16538: {in AC or DC supplies (G01R19/16519 and G01R19/16528 take precedence)} - H02H 1/0007: {concerning the detecting means (in general G01R or other subclasses of G01; reed switches H01H71/2445)} - H02H 3/087: for DC applications - H03K 3/02337: {Bistables with hysteresis, e.g. Schmitt trigger (non-regenerative amplitude discriminators G01R19/165)} - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - 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) ## Abstract In an example embodiment, a device comprises a gate driver and a current detector circuit. The gate driver is configured to be coupled to a power switch on the VBUS line of a USB connector. The current detector circuit is configured to be coupled to the VBUS line and comprises a current sense amplifier, a reference voltage generator circuit, and a comparator. The current sense amplifier is configured to receive a pair of input voltages and to output an indicator signal responsive to the input voltage difference. The reference voltage generator circuit comprises a digital-to-analog converter configured to generate a reference voltage signal based on a received voltage selector signal that is a binary input signal comprising multiple bit values. The comparator is configured to receive the indicator signal and the reference voltage signal and to output an interrupt signal responsive to the indicator signal exceeding the reference voltage signal. ## Claims ### Claim 1 A device comprising: a gate driver configured to control a power switch on a voltage bus (VBUS) line of a universal serial bus (USB) connector; and a current detector circuit configured to couple to the VBUS line, the current detector circuit comprising: a current sense amplifier configured to receive a pair of input voltages and to output an indicator signal responsive to an input voltage difference that is sensed based on the pair of input voltages; a reference voltage generator circuit comprising a digital-to-analog converter and configured to receive a voltage selector signal, wherein the digital-to-analog converter is configured to generate a reference voltage signal based on the voltage selector signal, and wherein the voltage selector signal is a binary input signal comprising multiple bit values; and a comparator coupled to the current sense amplifier and to the reference voltage generator circuit, wherein the comparator is configured to receive the indicator signal and the reference voltage signal and to output an interrupt signal responsive to the indicator signal exceeding the reference voltage signal. ### Claim 2 (depends on 1) The device of claim 1, wherein the digital-to-analog converter is configured to generate the reference voltage signal to correspond to any of a plurality of reference voltages indicated by the voltage selector signal. ### Claim 3 (depends on 1) The device of claim 1, wherein the digital-to-analog converter comprises a bank of multiple voltage dividers, wherein the multiple voltage dividers are respectively activated based on the multiple bit values of the binary input signal. ### Claim 4 (depends on 1) The device of claim 1, wherein the digital-to-analog converter comprises a bank of multiple resistors of varying resistance, wherein the multiple resistors are respectively selected based on the multiple bit values of the binary input signal. ### Claim 5 (depends on 1) The device of claim 1, wherein the digital-to-analog converter comprises a decoder, a series of resistors, an analog output, and a buffer coupled between the analog output and the series of resistors; and wherein the decoder is configured to select any number of resistors from the series of resistors based on the multiple bit values of the binary input signal, and the buffer is configured to generate the reference voltage signal at the analog output as a sum of voltage drops across the selected number of resistors. ### Claim 6 (depends on 1) The device of claim 1, further comprising a controller coupled to the current detector circuit and to the gate driver, the controller configured to receive the interrupt signal from the current detector circuit and to trigger the gate driver. ### Claim 7 (depends on 1) The device of claim 1, wherein in a continuous mode of operation, the comparator is configured to continuously track the input voltage difference versus a voltage of the reference voltage signal. ### Claim 8 (depends on 1) The device of claim 1, wherein in a latched mode of operation, the comparator is configured to reset itself after the interrupt signal is output. ### Claim 9 (depends on 1) The device of claim 1, wherein the voltage selector signal is received from a configuration channel line of the USB connector. ### Claim 10 (depends on 9) The device of claim 9, wherein the current sense amplifier is configured to receive a programmable trim signal from the USB connector. ### Claim 11 A system comprising: a universal serial bus (USB) connector comprising a voltage bus (VBUS) line; a power switch coupled inline on the VBUS line and configured to turn off in response to an interrupt signal; a sense resistor coupled in series with the power switch on the VBUS line; and a current detector circuit coupled to the VBUS line, the current detector circuit comprising: a current sense amplifier configured to sense an input voltage difference across the sense resistor and to output an indicator signal responsive to the input voltage difference; a reference voltage generator circuit comprising a digital-to-analog converter and configured to receive a voltage selector signal, wherein the digital-to-analog converter is configured to generate a reference voltage signal based on the voltage selector signal, and wherein the voltage selector signal is a binary input signal comprising multiple bit values; and a comparator coupled to the current sense amplifier and to the reference voltage generator circuit, wherein the comparator is configured to receive the indicator signal and the reference voltage signal and to output the interrupt signal responsive to the indicator signal exceeding the reference voltage signal. ### Claim 12 (depends on 11) The system of claim 11, wherein the digital-to-analog converter is configured to generate the reference voltage signal to correspond to any of a plurality of reference voltages indicated by the voltage selector signal. ### Claim 13 (depends on 11) The system of claim 11, wherein the digital-to-analog converter comprises a bank of multiple voltage dividers, wherein the multiple voltage dividers are respectively activated based on the multiple bit values of the binary input signal. ### Claim 14 (depends on 11) The system of claim 11, wherein the digital-to-analog converter comprises a bank of multiple resistors of varying resistance, wherein the multiple resistors are respectively selected based on the multiple bit values of the binary input signal. ### Claim 15 (depends on 11) The system of claim 11, wherein the digital-to-analog converter comprises a decoder, a series of resistors, an analog output, and a buffer coupled between the analog output and the series of resistors; and wherein the decoder is configured to select any number of resistors from the series of resistors based on the multiple bit values of the binary input signal, and the buffer is configured to generate the reference voltage signal at the analog output as a sum of voltage drops across the selected number of resistors. ### Claim 16 (depends on 11) The system of claim 11, further comprising: a gate driver coupled to drive the power switch; and a controller coupled to the current detector circuit and to the gate driver, the controller configured to receive the interrupt signal from the current detector circuit and to trigger the gate driver. ### Claim 17 (depends on 11) The system of claim 11, wherein in a continuous mode of operation, the comparator is configured to continuously track the input voltage difference versus a voltage of the reference voltage signal. ### Claim 18 (depends on 11) The system of claim 11, wherein in a latched mode of operation, the comparator is configured to reset itself after the interrupt signal is output. ### Claim 19 (depends on 11) The system of claim 11, wherein the USB connector comprises a configuration channel line, and wherein the voltage selector signal is received from the configuration channel line. ### Claim 20 (depends on 11) The system of claim 11, further comprising an AC adapter and an electronic device, wherein the electronic device is coupled to the AC adapter over the USB connector.