OM1895 simmerstat control IC
The OM1895 is a precision low power simmerstat control integrated circuit with zero crossing switching for triac applications where variable ‘On’ and ‘Off’ cycle times and zero crossing switching is required. The OM1895 uses a unique load current zero-crossing technique to control triac firing, to minimize RFI due to triac switching. It is capable of being configured for heating or cooling applications. For example, the zero crossing switching of a resistive load, or for the control of inductive loads such as motors, compressors or fans. With the OM1895, even at low temperature, control is precise. The triac is turned "On" at zero crossing, for the required (pre-set) period, and "Off" for the remainder of the fixed cycle time. Other cycle times are also available in four pre-programmed fixed times (refer to OM1895 datasheet) to cater for a range of switch times to meet EMC flicker regulations.
features
Accurate temperature control Unique triac drive minimise EMI/ RFI Negative triac gate drive Variable ON/OFF duty cycle time External ON/OFF triac control		Gate pulse width can be externally set Power Up reset Low supply current Low external component count
benefits
Simple and cost effective solution Less power dissipation allow the use of low wattage resistors Accurate energy regulation control Suitable for low power load applications
applications
OM1895 (available in SO8 and DIP8 packages) is designed for a wide range of heating (simmerstat) applications, where high accuracy and advantages of zero crossing switching is required. Electric Blanket controller Heating Pads Electric cook top Water Heater Fan motors Compressors
OM1895 block diagram
application support
Demo board HM177: OM1895 Electronic Simmerstat Control Module HM177 provides a general-purpose control module based on the OM1895 for zero crossing triac control of applications. Suited for both resistive or inductive loads. * Demo boards can be requested from Hendon Semiconductors. Application Notes Application note AN001: Power supply circuit design for OM1682A Application note AN002: Using the simple triac control IC Although these application notes were written for other control IC’s, the discussion of the mathematical concepts used applies equally well to OM1895.