Applications which do not use measured current sensing can still report calculated input current based on the output voltage, output current and input voltage of each channel. To use calculated input current reporting, connect the VIN_CSNIN and CSPIN pins together, and to the input voltage. A connection to the input voltage is still required for the control loop to set the correct on-time. Use the CALCIIN_RD setting in MISC_OPTIONS to enable calculated input current reporting. The controller estimates the converter power efficiency for each channel by comparing the actual on-time of the PWM pins, which get wider as the conversion loss increases to maintain voltage and frequency regulation, to the idealized on-time assuming no power loss. Fine-tune the gain of the calculated input current measurement through PMBus, using the MFR_CALIBRATION_CONFIG command.

where

• V_OUT(A) is the output voltage telemetry value for channel A
• IOUT_(A) is the output current telemetry value for channel A
• V_IN is the input current telemetry value (shared)
• η_est(A) is the controller's estimated conversion efficiency on channel A
• CALCIIN_EFF_A is the PMBus programmable gain factor to fine-tune the current gain for channel A
• V_OUT(B) is the output voltage telemetry value for channel B
• IOUT_(B) is the output current telemetry value for channel B
• η_est(B) is the controller's estimated conversion efficiency on channel B
• CALCIIN_EFF_B is the PMBus programmable gain factor to fine-tune the current gain for channel B