SLVAFK1 January 2025 INA228 , INA232 , INA234 , INA236 , INA237 , INA238 , MSPM0C1103 , MSPM0C1103-Q1 , MSPM0C1104 , MSPM0C1104-Q1 , MSPM0G1105 , MSPM0G1106 , MSPM0G1107 , MSPM0G1505 , MSPM0G1506 , MSPM0G1507 , MSPM0G1519 , MSPM0G3105 , MSPM0G3105-Q1 , MSPM0G3106 , MSPM0G3106-Q1 , MSPM0G3107 , MSPM0G3107-Q1 , MSPM0G3505 , MSPM0G3505-Q1 , MSPM0G3506 , MSPM0G3506-Q1 , MSPM0G3507 , MSPM0G3507-Q1 , MSPM0G3519 , MSPM0L1105 , MSPM0L1106 , MSPM0L1117 , MSPM0L1227 , MSPM0L1228 , MSPM0L1228-Q1 , MSPM0L1303 , MSPM0L1304 , MSPM0L1304-Q1 , MSPM0L1305 , MSPM0L1305-Q1 , MSPM0L1306 , MSPM0L1306-Q1 , MSPM0L1343 , MSPM0L1344 , MSPM0L1345 , MSPM0L1346 , MSPM0L2227 , MSPM0L2228 , MSPM0L2228-Q1 , TPS62866 , TPS62868 , TPS62869 , TPS6286A06 , TPS6286B10
Many applications require accurate temperature control of a heating element. Closed loop control based on temperature requires measurement of the heater temperature using a thermistor or thermocouple. This can sometimes be mechanically challenging and costly. Additionally, in battery powered applications, traditional PWM drive and associated high current pulses, can reduce battery life and lifetime.
Heater temperature is not linear with voltage or current due to changes in resistance with temperature. However, temperature is close to linear with applied power. By implementing a closed loop constant power drive the temperature can be controlled needing only to measure power and not temperature directly.
This reference design uses a closed loop constant power topology to drive a low impedance heater element. This application note includes the choices and challenges within the hardware and software implementation. The document also shows initial results and discusses advantages of this method of temperature control.