JAJSQK1 july 2023 AFE539F1-Q1
PRODUCTION DATA
This design uses the AFE539F1-Q1 to maintain constant power dissipation on a restive load, independent of the applied voltage. Modulating the power resistor via a switch can change the effective resistance and maintain constant power as the supply voltage (VBUS) changes. The AFE539F1-Q1 has an integrated state machine that converts the ADC input to a PWM output based on the transfer function in Equation 2. Parameters such as the PWM frequency, maximum and minimum duty cycle outputs, and the K term in Equation 2 are user programmable and can be saved in the NVM. The control loop runs standalone without the need for a processor after initial programming. Use this circuit in constant power heating, or automotive DC-link capacitor discharge applications. Figure 8-1 shows an example schematic for this application.