JAJST19 February 2024 DRV8262-Q1
PRODUCTION DATA
The following calculations assume a use case where the supply voltage is 24 V, full-scale current is 5 A, and input PWM frequency is 30-kHz.
The total power dissipation constitutes of three main components - conduction loss (PCOND), switching loss (PSW) and power loss due to quiescent current consumption (PQ).
The conduction loss (PCOND) depends on the motor rms current (IRMS) and high-side (RDS(ONH)) and low-side (RDS(ONL)) on-state resistances as shown in Equation 8.
The conduction loss for the typical application shown in Section 7.1.2.1 is calculated in Equation 9.
The power loss due to the PWM switching frequency depends on the output voltage rise/fall time (tRF), supply voltage, motor RMS current and the PWM switching frequency. The switching losses in each H-bridge during rise-time and fall-time are calculated as shown in Equation 10 and Equation 11.
After substituting the values of various parameters, the switching losses in each H-bridge are calculated as shown below -
The total switching loss for the stepper motor driver (PSW) is calculated as twice the sum of rise-time (PSW_RISE) switching loss and fall-time (PSW_FALL) switching loss as shown below -
The output rise/fall time (tRF) is expected to change based on the supply-voltage, temperature and device to device variation.
When the VCC pin is connected to an external voltage, the quiescent current is typically 5 mA. The power dissipation due to the quiescent current consumed by the power supply is calculated as shown below -
Substituting the values, quiescent power loss can be calculated as shown below -
The quiescent power loss is calculated using the typical operating supply current (IVM) which is dependent on supply-voltage, temperature and device to device variations.
The total power dissipation (PTOT) is calculated as the sum of conduction loss, switching loss and the quiescent power loss as shown in Equation 17.