IES5521A

ing and F b ab ing IC’s fo ver ro Integrated Electronic Solutions 35 ars Ye Simple Zero-Crossing Triac Control Circuit with Adjustable Time-out 3 GENERAL DESCRIPTION The IES5521A is a derivative of the OM1654A, but offering the extra safety feature of a nominal 1 hour time-out. This is a key safety requirement for a range of personal and home appliance applications. The time-out function will stop the triac operation and thus prevent power from being applied to the heating elements. Time-out can be accurately controlled from the AC supply frequency for a period of 1 hour (60Hz, or 71minutes at 50Hz), or can be adjusted by adding external resistor and capacitor components to set the frequency of an on-chip RC oscillator. In this manner, time-out periods from 1 minute to more than 5 hours, are possible. The IES5521A is a monolithic bipolar control circuit for zero-crossing triggering of a triac in applications where it is controlled by a resistive sensor such as an NTC thermistor. In a typical application it can be used for the temperature control of a heating element in a cooker or another home heating appliance. It is designed to control a suitable triac with a resistive load ranging from 400 watts on a nominal 220/250 volt mains supply. It can also be easily applied to 120Vac mains applications. IES5521A 1 FEATURES Time-out function stops triac operation after a set time. Reset time-out by turning mains supply off and on. Low external component count Consta...