All of the necessary control circuitry and two sets of complementary outputs drivers are integrated into the LTC1923 to drive a full-bridge, providing an efficient means of bi-directional current flow to a TEC. An accurate temperature control loop to stabilize the laser diode system is easily achieved with the addition of just a few external components, allowing a set point stability of 0.1°C to be easily attained. Modified versions achieve .01°C stability. Other applications can include LAN based fiber-optic communications, medical instruments and CPU temperature regulators.
The LTC1923 includes independent adjustable heating and cooling pulse-by-pulse current limit, current soft-start for controlled start-up, output slew rate control to reduce system noise, differential current sense and voltage amplifiers and a host of auxiliary circuits to protect the laser and provide redundant system monitoring. Its adjustable/synchronizable 250kHz oscillator frequency operation allows for low profile inductors and tiny ceramic capacitors. This means that a circuit footprint of less than 1 square inch can be attained on a double-sided PCB.
The LTC1923 is housed in a small, low profile 28-pin narrow SSOP package and is characterized over the industrial temperature range of -40°C to +85°C.
