Triac Control Circuit from Hendon Semiconductors

The time-out timer on the IES5521A and IES5523A will stop the triac operation after a preset time, hence switching the power applied to the heater element off. Time-out can be controlled from the AC supply frequency for a nominal period of 1 hour or adding an external resistor and capacitor components, the time out periods can be from 1 minute to more than 5 hours. The time-out function is seen as a key requirement particularly in home heating appliances where an appliance can be left unattended by the user.

The IES5523A also features a time-out indicator pin can be used to drive an LED circuit to indicate that the appliance has now gone into ‘time-out’ mode. The output from this pin can be used to drive an LED circuit. The LED can be set to either indicate on when running and off when timed-out; or vice-versa. This feature incorporated in the IES5523A provides flexibility to inform the user of the current operating mode of the appliance.

Other features of the IES5523A include 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, the IES5523A is suitable for the temperature control of heating element in cooking/ heating appliances, hair styling tools or other appliances where safety time-out is required. The IES5523A is offered in 8-pin SO package, RoHS compliant with samples available through our website and is currently in full production.