# US 9,519,337 B2 · Circuitry for controlling an output from an electronic control unit including two processors mutually monitoring each other

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- Number: US 9,519,337 B2
- Document ID: US9519337B2
- Status: Granted
- Kind: B2
- Application number: 14/496,084
- Filed: 2014-09-25
- Published: 2015-04-09
- Granted: 2016-12-13
- Earliest claimed: 2013-10-09
- Assignees: Denso Corporation
- Applicants: Denso Corporation
- Inventors: Akito Itou
- Web page: https://patentgrep.com/patent/US9519337B2

## CPC

- G06F 1/3293: by switching to a less power-consuming processor, e.g. sub-CPU
- G06F 1/3203: Power management, i.e. event-based initiation of a power-saving mode
- G06F 1/3243: {Power saving in microcontroller unit}
- G06F 1/3287: by switching off individual functional units in the computer system
- G06F 1/3296: by lowering the supply or operating voltage
- Y02D 10/00: Energy efficient computing, e.g. low power processors, power management or thermal management
- Y02D 30/50: in wire-line communication networks, e.g. low power modes or reduced link rate
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

An electronic control unit of one embodiment includes first and second microcomputers for mutually monitoring operations, an output circuit for outputting a signal that is outputted from at least one of the first and second microcomputers, a power supply circuit for supplying electric power to the output circuit, and a stop unit for stopping supply of the electric power from the power supply circuit to the output circuit. The first microcomputer has operation modes including a normal mode and a low power mode. In the low power mode, the first microcomputer stops monitoring the operation of the second microcomputer and outputs a power supply stop signal that operates the stop unit to stop the supply of the electric power from the power supply circuit to the output circuit.

## Claims

### Claim 1

An electronic control unit comprising:
a first microcomputer and a second microcomputer for mutually monitoring operations each other;
an output circuit for outputting, to an external apparatus, a signal that is outputted from at least one of the first and second microcomputers;
a power supply circuit for supplying electric power to the output circuit as operating power; and
a stop unit for stopping supply of the electric power from the power supply circuit to the output circuit;
a subject microcomputer that is at least one of the first microcomputer and the second microcomputer, and that has operation modes including a normal mode and a low power mode smaller in electric power consumption than the normal mode;
a counterparty microcomputer that is at least one of the first microcomputer and the second microcomputer other than the subject microcomputer and that is supplied with operating power from the power supply circuit; and
a communication interface that is separated from the output circuit, that is supplied with electric power from a power source other than the power supply circuit, and that is operable even when the subject microcomputer is in the low power mode, wherein
in the low power mode, the subject microcomputer stops monitoring the operation of the counterparty microcomputer, which is one of the first microcomputer and the second microcomputer other than the subject microcomputer, and outputs a power supply stop signal that operates the stop unit to stop the supply of the electric power from the power supply circuit to the output circuit, and
when the power supply stop signal is outputted from the subject microcomputer in the low power mode, the stop unit stops the supply of the electric power from the power supply circuit to the counterparty microcomputer and the output circuit, and
when a signal that is to be transmitted to an external is outputted to the communication interface from the subject microcomputer in the low power mode, the communication interface outputs a request signal to the stop unit, the request signal requesting release of the stop of the supply of the electric power from the power supply circuit to the counterparty microcomputer and the output circuit to resume the supply of the electric power from the power supply circuit to the counterparty microcomputer.

### Claim 2 (depends on 1)

The electronic control unit according to claim 1, wherein:
when the counterparty microcomputer is supplied with the operating power from the power supply circuit, the counterparty microcomputer always monitors the operation of the subject microcomputer.

### Claim 3 (depends on 1)

The electronic control unit according to claim 1, wherein:
when a startup signal instructing the subject microcomputer in the low power mode to start up in the normal mode is inputted to the communication interface from an external, the communication interface outputs the request signal to the stop unit to release the stop of the supply of the electric power from the power supply circuit to the output circuit.

### Claim 4 (depends on 1)

The electronic control unit according to claim 1, further comprising:
a driver circuit that operates by being supplied with electric power from a battery via a relay switch, wherein:
after an ignition switch is turned off, the counterparty microcomputer outputs a maintain signal for maintaining an ON state of the relay switch; and
when the maintain signal is being outputted and the driver circuit is being supplied with the electric power from the battery, the stop unit is maintained at a non-operating state and does not stop the supply of the electric power from the power supply circuit to the output circuit.