Temperature controlling circuit for a semiconductor light-emitting device

摘要

The present invention provides a temperature control circuit for a semiconductor light-emitting device, in which scale of the circuit is not enlarged and noise due to the current switching is not generated. In the temperature control circuit of the present invention, although the DC voltage V_ATC supplied to the Peltier device is generated by the DC-to-DC converting from the external power V_CC, the DC voltage V_ATC is feedback controlled so as to coincide with a target value of the DC voltage that is set based on an error signal generated by detecting a voltage drop of the Peltier device and comparing this drop voltage with a reference voltage. A control signal for setting the temperature of the laser diode to the target temperature through heating up or cooling down the Peltier device by flowing a current corresponding to an error between the target temperature and a practical temperature detected by the thermistor in the Peltier device from the thermoelectric controller current driver.