SEMICONDUCTOR APPARATUS

• US 20120023344A1
• Filed: 10/04/2010
• Published: 01/26/2012
• Est. Priority Date: 10/02/2009
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Miyanaga, Koichi
• Granted Patent: US 8,639,959 B2
• Time in Patent Office: Days
• US Class Current: 713/310
• CPC Class Codes: G06F 13/4072 Drivers or receivers G06F13/4086 takes precedence; for multistate logic circuits H03K19/0002
• CPC Class Codes: G06F 13/426 using an embedded synchronisation, e.g. Firewire bus, Fibre Channel bus, SSA bus
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H03K 5/082 with an adaptive threshold
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A first switch is arranged between a judgment unit and a signal line. The first switch is turned on during a period in which the judgment unit judges a device, after which the first switch is turned off. A second switch is turned off during a period in which the judgment unit judges the device, after which the second switch is turned on. The signal line connects a communication interface port, which allows various different kinds of devices to be connected, and a communication terminal of a processor configured to perform data communication with the device. The judgment unit monitors the electrical state of the signal line, and judges the device connected to the port.

Claims

1. A semiconductor apparatus comprising:

a signal line that connects a communication interface port via which various different kinds of devices can be connected and a communication terminal of a processor configured to perform data communication with the device;

a judgment unit configured to monitor the electrical state of the signal line, and to judge the device connected to the port; and

a first switch arranged between the judgment unit and the signal line,

wherein the first switch is turned on during a period in which the judgment unit judges the device, following which the first switch is turned off.

2. A semiconductor apparatus according to claim 1, further comprising a second switch arranged on a path of the signal line,

wherein the second switch is turned off during a period in which the judgment unit judges the device, following which the second switch is turned on.

5. A semiconductor apparatus according to claim 2, further comprising a connection detection unit configured to judge whether or not a device of some kind is connected to the port,

and wherein the period during which the judgment unit judges the device is set to be a predetermined time that elapses after the connection detection unit detects that the device has been connected.

7. A semiconductor apparatus according to claim 5, wherein the port is configured as a terminal via which a differential signal line of a USB (Universal Serial Bus) interface is connected,

and wherein the connection detection unit monitors the electrical state of a second port via which a power supply line of the USB interface is connected, and judges whether or not electrical power is being supplied via the USB interface, thereby judging whether or not a device has been connected.

9. A semiconductor apparatus according to claim 7, wherein the connection detection unit includes a voltage comparison circuit configured to compare an input voltage applied to the second port with a predetermined threshold voltage,

and wherein the voltage comparison circuit comprises:

a first voltage comparison unit configured to compare the input voltage with a predetermined first threshold voltage, and to generate a judgment signal which is asserted when the input voltage is higher than the first threshold voltage; and

a second voltage comparison unit configured such that, when the judgment signal is asserted, the second voltage comparison unit is switched to the active state, and compares the input voltage with a predetermined second threshold voltage.

11. An electronic device comprising:

a communication interface port via which any device from among a multiplicity of different devices is connected;

a processor configured to perform data communication with the device; and

a semiconductor apparatus according to claim 1, connected to the port and the processor.

3. A semiconductor apparatus comprising:

a signal line that connects a communication interface port via which various different kinds of devices can be connected and a communication terminal of a processor configured to perform data communication with the device; and

a judgment unit configured to monitor the electrical state of the signal line, and to judge the device connected to the port,

wherein the judgment unit is in the active state during a period in which the judgment unit judges the device, following which the judgment unit is switched to the inactive state.

4. A semiconductor apparatus according to claim 3, further comprising a second switch arranged on a path of the signal line,

wherein the second switch is turned off during a period in which the judgment unit judges the device, following which the second switch is turned on.

6. A semiconductor apparatus according to claim 4, further comprising a connection detection unit configured to judge whether or not a device of some kind is connected to the port,

and wherein the period during which the judgment unit judges the device is set to be a predetermined time that elapses after the connection detection unit detects that the device has been connected.

8. A semiconductor apparatus according to claim 6, wherein the port is configured as a terminal via which a differential signal line of a USB (Universal Serial Bus) interface is connected,

and wherein the connection detection unit monitors the electrical state of a second port via which a power supply line of the USB interface is connected, and judges whether or not electrical power is being supplied via the USB interface, thereby judging whether or not a device has been connected.

10. A semiconductor apparatus according to claim 8, wherein the connection detection unit includes a voltage comparison circuit configured to compare an input voltage applied to the second port with a predetermined threshold voltage,

and wherein the voltage comparison circuit comprises:

a first voltage comparison unit configured to compare the input voltage with a predetermined first threshold voltage, and to generate a judgment signal which is asserted when the input voltage is higher than the first threshold voltage; and

a second voltage comparison unit configured such that, when the judgment signal is asserted, the second voltage comparison unit is switched to the active state, and compares the input voltage with a predetermined second threshold voltage.

12. An electronic device comprising:

a communication interface port via which any device from among a multiplicity of different devices is connected;

a processor configured to perform data communication with the device; and

a semiconductor apparatus according to claim 3, connected to the port and the processor.

13. A voltage comparison circuit configured to compare an input voltage applied to an input terminal with a predetermined threshold voltage, the voltage comparison circuit comprising:

a first voltage comparison unit configured to compare the input voltage with a predetermined first voltage, and to generate a judgment signal which is asserted when the input voltage is higher than the first threshold voltage; and

a second voltage comparison unit configured such that, when the judgment signal is asserted, the second voltage comparison unit is set to the active state, and compares the input voltage with a predetermined second threshold voltage.

14. A voltage comparison circuit according to claim 13, wherein a first voltage or a second voltage that is higher than the first voltage is applied to the input terminal,

and wherein the first threshold voltage is set to a value that is higher than the first voltage.

15. A voltage comparison circuit according to claim 13, wherein the first voltage comparison unit comprises a P-channel first MOSFET (Metal Oxide Semiconductor Field Effect Transistor) arranged such that a predetermined voltage is input to a gate thereof, and a source thereof is connected to the input terminal,

and wherein the first voltage comparison unit generates a judgment signal according to the ON/OFF operation of the first MOSFET.

16. A voltage comparison circuit according to claim 13, wherein the first voltage comparison unit comprises:

a P-channel first MOSFET (Metal Oxide Semiconductor Field Effect Transistor) arranged such that a predetermined voltage is input to a gate thereof, and a source thereof is connected to the input terminal; and

an N-channel second MOSFET arranged such that the output voltage of the dividing circuit is applied to a gate thereof, and the electric potential at a source thereof is fixed,

and wherein the first comparison unit generates a judgment signal having a level which corresponds to the ON/OFF operation of the second MOSFET.

17. A voltage comparison circuit according to claim 13, wherein the first voltage comparison unit comprises:

a dividing circuit configured to divide the input voltage;

an N-channel third MOSFET arranged such that the divided input voltage is input to a gate thereof, and the electric potential at a source thereof is fixed,

and wherein the first voltage comparison unit generates the judgment signal having a level according to the ON/OFF operation of the third MOSFET.

18. A voltage comparison circuit according to claim 13, wherein the second voltage comparison unit comprises:

a comparator arranged such that a voltage that corresponds to the input voltage is received via a first terminal thereof and a predetermined reference voltage is received via a second terminal thereof, and such that a comparison is made between the voltage at the first terminal and the voltage at the second terminal; and

a switch arranged between a power supply terminal of the comparator and the input terminal,

and wherein the switch is turned on when the judgment signal is asserted.

19. A voltage comparison circuit according to claim 18, wherein the second voltage comparison unit further comprises a reference voltage generating unit configured to generate the reference voltage,

and wherein a power supply terminal of the reference voltage generating unit is connected to the input terminal via the switch.

20. A voltage comparison circuit according to claim 18, wherein the second voltage comparison unit further comprises a second switch arranged between the input terminal and the first terminal of the comparator.

21. A power supply management circuit comprising:

a first terminal, via which an external power supply is connected;

a second terminal, via which a battery is connected;

a voltage comparison circuit according to claim 13, configured to receive, as the input voltage, via the input terminal, a voltage applied to the first terminal from the external power supply;

a selection circuit configured to select, based upon the comparison result obtained by the voltage comparison circuit, one from among the voltage output from the external power supply and a battery voltage output from the battery; and

an output terminal via which the voltage selected by the selection circuit is output to an external load circuit.

22. An electronic device comprising:

a battery;

an adapter terminal via which an external power supply can be detachably mounted;

a power supply management circuit according to claim 21; and

a load circuit connected to the output terminal of the power supply management circuit.