LOAD CIRCUIT FOR TESTING USB PORTS

• US 20130222000A1
• Filed: 07/18/2012
• Published: 08/29/2013
• Est. Priority Date: 02/27/2012
• Status: Active Grant

• Current Assignee: Hong Fu Jin Precision Industry (Shenzhen) Co., Ltd. (Hon Hai Precision Industry Co., Ltd.), Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hong Fu Jin Precision Industry (Shenzhen) Co., Ltd. (Hon Hai Precision Industry Co., Ltd.), Hon Hai Precision Industry Co., Ltd.
• Inventors: LI, ZHEN-SEN, SHEN, JIAN-SHE
• Granted Patent: US 8,823,403 B2
• Time in Patent Office: Days
• US Class Current: 324/750.01
• CPC Class Codes: G01R 1/28 Provision in measuring instruments for reference values, e.g. standard voltage, standard waveform
• CPC Class Codes: G06F 11/221 to test buses, lines or interfaces, e.g. stuck-at or open line faults

Abstract

An exemplary load circuit includes a switch unit and a current dividing circuit. The switch unit includes a number of switches. The current dividing circuit includes a number of sub-circuits. A terminal of a resistance module of each of the sub-circuits is connected to both a power terminal and a terminal of a corresponding one of the switches. The other terminal of the resistance module of each of the sub-circuits is connected to a drain of a transistor of each of the sub-circuits. A source of the transistor is connected to ground. A gate of the transistor is connected to ground, and is also connected to another terminal of the corresponding switch.

Claims

1. A load circuit for simulating different standard load currents for different kinds of Universal Serial Bus (USB) ports, each of the USB ports comprising a power terminal;

the load circuit comprising;

a switch unit comprising a plurality of switches; and

a current dividing circuit comprising a plurality of sub-circuits, each of the sub-circuits comprising a resistance module and a transistor, wherein a terminal of the resistance module of each of the sub-circuits is connected to both the power terminal and a terminal of a corresponding one of the switches, another terminal of the resistance module of each of the sub-circuits is connected to a drain of the transistor, a source of the transistor is connected to ground, and a gate of the transistor is connected to ground through a resistor and is also connected to another terminal of the corresponding switch through another resistor.

2. The load circuit of claim 1, further comprising a malfunction indication circuit, wherein the malfunction indication circuit comprises a light-emitting diode (LED), an anode of the LED is connected to the power terminal through a resistor, and a cathode of the LED is connected to ground.

3. The load circuit of claim 1, wherein the switch unit is a toggle switch, and comprises first to sixteenth terminals, the first terminal is electronically connectable to and disconnectable from the sixteenth terminal to form a first switch, the second terminal is electronically connectable to and disconnectable from the fifteenth terminal to form a second switch, the third terminal is electronically connectable to and disconnectable from the fourteenth terminal to form a third switch, the fourth terminal is electronically connectable to and disconnectable from the thirteenth terminal to form a fourth switch, the fifth terminal is electronically connectable to and disconnectable from the twelfth terminal to form a fifth switch, the sixth terminal is electronically connectable to and disconnectable from the eleventh terminal to form a sixth switch, the seventh terminal is electronically connectable to and disconnectable from the tenth terminal to form a seventh switch, and the eighth terminal is electronically connectable to and disconnectable from the ninth terminal to form an eighth switch.

4. The load circuit of claim 3, further comprising a function-testing circuit, wherein the function-testing circuit comprises a control switch, a terminal of the control switch is connected to the power terminal via the seventh switch, and another terminal of the control switch is connected to ground.

5. The load circuit of claim 3, wherein the eighth switch is idle.

6. The load circuit of claim 3, wherein the plurality of the sub-circuits comprises a first sub-circuit corresponding to the first switch, a second sub-circuit corresponding to the second switch, a third sub-circuit corresponding to the third switch, a fourth sub-circuit corresponding to the fourth switch, a fifth sub-circuit corresponding to the fifth switch, and a sixth sub-circuit corresponding to the sixth switch.

7. The load circuit of claim 6, wherein the resistance of the resistance module of the first sub-circuit is about 50 ohms.

8. The load circuit of claim 6, wherein the resistance of the resistance module of the second sub-circuit is about 50 ohms.

9. The load circuit of claim 6, wherein the resistance of the resistance module of the third sub-circuit is about 35 ohms.

10. The load circuit of claim 6, wherein the resistance of the resistance module of the fourth sub-circuit is about 35 ohms.

11. The load circuit of claim 6, wherein the resistance of the resistance module of the fifth sub-circuit is about 10 ohms.

12. The load circuit of claim 6, wherein the resistance of the resistance module of the sixth sub-circuit is about 7 and 1/7 ohms.

13. A load circuit, comprising:

a switch unit comprising a plurality of switches; and

a current dividing circuit comprising a plurality of sub-circuits;

wherein each of the sub-circuits is connectable to at least one Universal Serial Bus (USB) port and connected to a corresponding one of the switches;

each of the sub-circuits is configured to draw a respective load current from the at least one USB port when the sub-circuit is connected to the at least one USB port and the corresponding switch is turned on; and

when a selected one or a selected plurality of the switches is or are turned on, the corresponding one sub-circuit or corresponding plurality of sub-circuits is or are connected to the at least one USB port, and the corresponding one sub-circuit or corresponding plurality of sub-circuits draw a desired load current from the at least one USB port.