INTERFACE CIRCUIT AND PORTABLE ELECTRONIC DEVICE EMPLOYING THE SAME

• US 20100246075A1
• Filed: 09/03/2009
• Published: 09/30/2010
• Est. Priority Date: 03/25/2009
• Status: Active Grant

• Current Assignee: Chi Mei Communication Systems Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Chi Mei Communication Systems Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: CHAO, CHIEN-YAO
• Granted Patent: US 8,009,400 B2
• Time in Patent Office: Days
• US Class Current: 361/56
• CPC Class Codes: H02H 3/06 with automatic reconnection
• CPC Class Codes: H02H 3/202 for dc systems
• CPC Class Codes: H02H 9/004 in connection with live-insertion of plug-in units involving communication with a central processing unit G06F13/40

Abstract

An interface circuit for connecting with a universal serial bus (USB) data cable includes a USB connector for connecting with the USB data cable, an over voltage protection (OVP) circuit connected to the USB connector, and a time delay circuit connected to the USB connector and the OVP circuit to control the OVP circuit. The OVP circuit is switched off in a predetermined delay time of the time delay circuit when the USB data cable is connected to the USB connector, and is then switched on after the delay time of the time delay circuit.

Claims

1. An interface circuit for connecting with a universal serial bus (USB) data cable, comprising:

a USB connector for connecting with the USB data cable;

an over voltage protection (OVP) circuit connected to the USB connector; and

a time delay circuit connected to the USB connector and the OVP circuit to control the OVP circuit, wherein the OVP circuit is switched off in a predetermined delay time of the time delay circuit when the USB data cable is connected to the USB connector, and is then switched on after the delay time of the time delay circuit.

2. The interface circuit as claimed in claim 1, wherein the OVP circuit includes an input connector, an output connector and a control connector, the input connector connected to the USB connector, and the control connector connected to the time delay circuit.

3. The interface circuit as claimed in claim 2, wherein the time delay circuit generates control electric levels inputted to the control connector to control the OVP circuit to be switched on or switched off.

4. The interface circuit as claimed in claim 3, wherein the OVP circuit is switched on when a relatively low electric level generated by the time delay circuit is inputted into the control connector and is switched off when a relatively high electric level generated by the time delay circuit is inputted into the control connector.

5. The interface circuit as claimed in claim 2, wherein the time delay circuit is an RC time delay circuit including a capacitor, a first resistor and a second resistor connected in series between the USB connector and the ground, and the control connector is connected between the first resistor and the second resistor.

6. The interface circuit as claimed in claim 5, wherein a delay time of the time delay circuit is longer than about 100 μ

s.

7. The interface circuit as claimed in claim 5, further comprising an electrostatic discharge (ESD) circuit connected to the time delay circuit.

8. A portable electronic device, comprising:

a main circuit board; and

an interface circuit for connecting with a USB data cable;

wherein the interface circuit is connected to the main circuit board and includes an OVP circuit connected to the main circuit board and a time delay circuit connected to the OVP circuit to control the OVP circuit, the OVP circuit being switched off in a predetermined delay time of the time delay circuit when the USB data cable is connected to the interface circuit to prevent the USB data cable from being connected to the main circuit board, and the OVP circuit being switched on after the delay time of the time delay circuit to connect the USB data cable to the main circuit board.

9. The portable electronic device as claimed in claim 8, wherein the interface circuit includes a USB connector for connecting with the USB data cable, the OVP circuit includes an input connector connected to the USB connector, an output connector connected to the main circuit board and a control connector connected to the time delay circuit.

10. The portable electronic device as claimed in claim 9, wherein the time delay circuit generates control electric levels inputted to the control connector to control the OVP circuit to be switched on or switched off.

11. The portable electronic device as claimed in claim 10, wherein the OVP circuit is switched on when a relatively low electric level generated by the time delay circuit is inputted into the control connector and is switched off when a relatively high electric level generated by the time delay circuit is inputted into the control connector.

12. The portable electronic device as claimed in claim 9, wherein the time delay circuit is an RC time delay circuit including a capacitor, a first resistor and a second resistor connected in series between the USB connector and the ground, and the control connector is connected between the first resistor and the second resistor.

13. The portable electronic device as claimed in claim 12, wherein a delay time of the time delay circuit is longer than about 100 μ

s.

14. The portable electronic device as claimed in claim 12, further comprising an electrostatic discharge (ESD) circuit connected to the time delay circuit.