The WHY56ND is a general purpose, low cost, analog PI (Proportional, Integral) control loop for use in thermoelectric or resistive heater temperature control applications. The WHY maintains precision temperature regulation using an active resistor bridge circuit that operates directly with thermistors or RTD temperature sensors. Supply up to 2.2 Amps of heat and cool current to your thermoelectric from a single power supply. Accessories include a heatsink WHS302, thermal washer WTW002, and fans WXC303 (5 V), WXC304 (12 V), and an evaluation board WHY5690. Connect two or more WHY units together and drive higher output currents. A single resistor or trimpot sets the temperature setpoint. Independent heat and cool current limits are set by single resistors. A single resistor sets proportional gain. A resistor/capacitor in series sets the integrator time constant. WHY56ND vs. WTC32ND: – The WTC32ND incorporates remote voltage control and temperature monitor. The WHY56ND does not. – The WTC32ND supports AD590 and LM335. – The WHY56ND requires external circuits to operate anything other than resistive sensors. – Two or more WHY56NDs can be used together for more output current. – If you do not need all the features of the WTC32ND, the WHY56ND is a lower cost solution. NOTE: The WHY56ND and WTC32ND do NOT have the same pin configuration. Free, effective, and responsive technical support is available to simplify integration of Wavelength products into your OEM design. Standard product can be easily modified to meet your application requirements.