Rohm Co., Ltd.

Kei Nagao

Toru Takahashi

Masaaki Nakayama

Toru Takuma

Shigeharu Nakao

A semiconductor device includes a reception data input terminal configured such that reception data, which is serial data, is input; a transmission data output terminal configured such that transmission data, which is serial data, is output; and a communication part configured to receive the reception data and transmit the transmission data, wherein the communication part includes: a counter; and a synchronization part configured to monitor the transmission data if the semiconductor device is other than a target device set in the reception data, and reset a count by the counter upon detecting a stop bit and a start bit at frame switching in the transmission data.

Semiconductor device and communication system

In a normal mode in which light emission control of the light emitting element is performed by a dimming controller (), if no communication signal from an external microprocessor () is recognized beyond a first predetermined period, the control logic circuit () shifts from the normal mode to a first limp home mode (limp homemode). In the first limp home mode, the dimming controller sets a light emitting element current set value based on a terminal current set value commensurate with a resistance value of a setting resistor (Rextiset) and a DC dimming set value for each of the channel set in the register (A), controls the current driver () so as to generate a current of the set light emitting element set value, and turns on and off the current driver based on a PWM on-duty for each of the channels set in the register.

Light emitting element driving device

A light emitting element driving device includes a receiver that receives a predetermined communication signal transmitted across a communication line, a generator that generates a reference signal based on the start time point of a start bit in the predetermined communication signal, and a determiner that determines, based on the reference signal, the timing of switching a light emitting element from extinction to lighting. The predetermined communication signal is a signal in which the start bit with a first logic level is transmitted at a prescribed period from a transmitter and in which the data bits succeeding each start bit do not have a second logic level a predetermined number of times or more consecutively.

A semiconductor device includes an oscillator configured to generate a first clock signal, a first terminal via which an input clock signal is fed in from the outside, a first counter configured to count a clock signal based on the first clock signal between edges in the input clock signal, and a controller configured to send to the oscillator an instruction to adjust the frequency of the first clock signal based on the result of comparison of the count value by the first counter with an expected value.

Semiconductor device and semiconductor device system

An object of the present invention is to optimize a light-emitting driving voltage for each light-emitting portion. A light-emitting diode (LED) driver (A) includes: driver blocks () of a plurality of channels, each driver block () having a light-emitting portion connecting terminal (CH) to be connected to a light-emitting portion (LL) including one or more than one LED, the light-emitting portion being caused to emit light by a current flowing through the light-emitting portion connecting terminal to the light-emitting portion; a lowest voltage detection circuit (), detecting and outputting a lowest voltage among voltages of the light-emitting portion connecting terminals of each channel; a sample hold circuit (), comparing an output voltage (V) of the lowest voltage detection circuit with a hold voltage (V) thereof, and updating the hold voltage to the output voltage if the output voltage is lower than the hold voltage; and a feedback control circuit (), outputting a feedback signal according to the hold voltage and a predetermined reference voltage to a power supply device () providing a light emission driving voltage (Vo) to the light-emitting portions of the plurality of channels, so as to control the light emission driving voltage.

Light emitting device driving apparatus, light emitting device driving system and light emitting system

A semiconductor device includes a first overvoltage detection unit including a first comparator arranged to output a first detection signal based on a first divided voltage after dividing an output voltage of a power supply circuit by first resistors disposed externally and a second overvoltage detection unit including second resistors and a second comparator arranged to output a second detection signal based on a second divided voltage after dividing the output voltage by the second resistors.

Semiconductor device

A semiconductor device includes: a diagnosis portion which diagnoses, when the device is started up, whether an abnormality occurs in a component for setting that is externally connected; and a control portion which stops the startup of the device when the diagnosis portion diagnoses that an abnormality occurs, the diagnosis portion diagnoses whether an abnormality occurs in which the connection of the component for setting that is a resistor is disconnected, the semiconductor device further includes an external terminal which is connected to one end of the resistor and the diagnosis portion includes a constant current circuit which passes a constant current through the resistor via the external terminal, a comparator to which a voltage produced at the external terminal is input and a transistor which switches between the connection and interruption of a path along which the constant current is passed.

An apparatus for driving a light emitting device includes a constant current control circuit configured to control a current flowing through the light emitting device to be constant, and an extension circuit configured to generate a post-extending PWM signal obtained by extending a period of an input PWM signal having a first level. The constant current control circuit is turned on during the period of the post-extending PWM signal having the first level, and the constant current control circuit is turned off during a period of the post-extending PWM signal having a second level.

Apparatus for driving light emitting device

A counter circuit increments a count value bit by bit in synchronization with a clock pulse received from an oscillating portion. A lower order decoder receives the count value output from the counter circuit, compares a bit or bits on a lower side with a set value, and outputs an H-level only in a time period when the bit or bits match a bit pattern of set value. Similarly, an upper order decoder compares a bit or bits on an upper side with a set value, and outputs an H-level only in a time period when the bit or bits match the bit pattern of set value. An AND circuit renders a transistor conductive in a time period when both lower and upper order decoders are outputting signals of the H-level.

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Kyoto, Japan

Kei Nagao