Method of on-chip current measurement and semiconductor IC

1. A method of on-chip current measurement in a semiconductor integrated circuit including a circuit block having a predetermined function, and a power switch that supplies an operating power to the circuit block, the method comprising:

obtaining a voltage between terminals of the power switch in a state in which the power switch is turned on; and

calculating a current flowing to the circuit block based on the obtained voltage between terminals of the power switch in the turned on state and an on-resistance of the power switch.

2. The method of on-chip current measurement according to claim 1 , wherein a result of the calculation of the current is output to outside the semiconductor integrated circuit through an external terminal of the semiconductor integrated circuit so that the result of the calculation of the current can be monitored externally.

3. The method of on-chip current measurement according to claim 1 ,

wherein the semiconductor integrated circuit further includes a current calculating circuit, and

wherein the current flowing to the circuit block is calculated by the current calculating circuit.

4. A semiconductor integrated circuit comprising:

a circuit block having a predetermined function;

a power switch that supplies an operating power to the circuit block; and

a current measuring circuit that obtains a current flowing to the circuit block based on a voltage between terminals of the power switch in a state in which the power switch is turned on and an on-resistance of the power switch.

5. The semiconductor integrated circuit according to claim 4 , wherein the current measuring circuit includes:

an amplifier that converts the voltage between terminals of the power switch in the state in which the power switch is turned on into a corresponding current;

an AD converter that converts a signal output from the amplifier into a digital signal; and

a calculating circuit that calculates the current flowing to the circuit block based on the converted output of the AD converter.

6. The semiconductor integrated circuit according to claim 5 , wherein the circuit block and the power switch are provided in plural sets, with each said set being associated with a corresponding amplifier.

7. The semiconductor integrated circuit according to claim 6 , wherein the current measuring circuit includes a multiplexer that selectively outputs signals received from the amplifiers to the AD converter.

8. The semiconductor integrated circuit according to claim 6 , wherein the current measuring circuit includes a controller configured to selectively output signals sent from the amplifiers to the AD converter by controlling the amplifiers.

9. The semiconductor integrated circuit according to claim 4 , wherein the current measuring circuit includes:

a voltage and frequency converting circuit that converts the voltage between terminals of the power switch in the state in which the power switch is turned on into a corresponding oscillating frequency;

a frequency and voltage converting circuit that converts a signal output from the voltage and frequency converting circuit into a corresponding voltage; and

a calculating circuit that calculates the current flowing to the circuit block based on the converted output of the frequency and voltage converting circuit.

10. The semiconductor integrated circuit according to claim 9 , wherein the circuit block and the power switch are provided in plural sets, with each said set being associated with a corresponding voltage and frequency converting circuit.

11. The semiconductor integrated circuit according to claim 4 , further comprising a resource manager that controls an operating clock frequency of the circuit block, the resource manager being configured to determine the operating clock frequency based on a result of a measurement of the current measuring circuit and a preset maximum current value.