The LTC1923 is a pulse width modulator intended for thermoelectric cooler (TEC) or heater applications requiring either unidirectional or bidirectional drive circuits. All of the necessary control circuitry and two sets of complementary output drivers are integrated into the LTC1923 to drive a full bridge, providing an efficient means of bidirectional current flow to the TEC. An accurate temperature control loop to stabilize the temperature of a laser diode system is easily achieved with the addition of just a few external components. Typical temperature setpoint accuracy of 0.1C is achievable with the LTC1923. Adding an instrumentation amplifier front end allows setpoint stability of 0.01C.