Use the IOUT_CAL_GAIN to adjust the gain of the output current measurements. One
gain setting is provided which applies to all phases in the channel. Use the IOUT_CAL_OFFSET to adjust the current measurement offset for each phase.
The offset for the total channel is calculated as a sum of the configured offsets
for all phases. During power supply characterization use the PHASE_CONFIG command to configure the controller for 1-phase mode, to
enable measurement of a single phase measurement offset. Refer to the example
below.
The READ_IOUT command value is calculated according to Equation 4 and Equation 5.
Equation 47.
where
- READ_IOUTTOTAL is the
total output current telemetry value, accessible with PHASE=FFh
- IOUT_CAL_GAIN is the output
current gain setting (one per channel)
- CSPi is the voltage of
the current sense signal from each power stage
- VREF is the digitized value of
the internal 1.5-V LDO
- IOUT_CAL_OFFSETi is
the output current offset setting for each phase
Equation 5.
where
- READ_IOUTPHASE i is
the per-phase current telemetry value, accessible with PHASE=00h for phase 1,
01h for phase 2, etc ...
- IOUT_CAL_GAIN is the output
current gain setting (one per channel)
- CSPi is the voltage of
the current sense signal for that phase
- VREF is the digitized value of
the internal 1.5-V LDO
- IOUT_CAL_OFFSETi is
the output current offset setting for that phase
Example procedure: Per-Phase
calibration of READ_IOUT
First select the correct IOUT_CAL_GAIN for the whole channel:
- With all phases active, apply the
first load current, IOUT1, to the converter and wait for the READ_IOUT value to stabilize. Read-back and record the value of
READ_IOUT as IMON1.
- With all phases active, apply the
second load current, IOUT2, to the converter and wait for the READ_IOUT value to stabilize. Read-back and record the value of
READ_IOUT as IMON2.
- Calculate the new gain setting
according to Equation 6.
- Write the PAGE to the current channel, and the PHASE to FFh.
- Write the newly calculated value
to IOUT_CAL_GAIN.
- Perform an NVM Store operation
and power cycle.
Equation 6.
Next, select the IOUT_CAL_OFFSET for each phase according to the procedure below:
- Record the current values of
PHASE_CONFIG and IOUT_CAL_OFFSET for each phase.
- Adjust the TON_RISE temporarily to accomodate enabling power conversion with
one phase only active, if needed.
- With power conversion disabled
for both channels, update the PHASE_CONFIG command so that only the first phase is active, and its
assigned ORDER is 0.
- Enable power conversion through
the VR_EN pins or OPERATION as configured through ON_OFF_CONFIG.
- Apply a known load current,
IOUT1. Wait for the READ_IOUT to stabilize and record the value as
IMON1.
- Calculate the new IOUT_CAL_OFFSET per Equation 7, where i is the currently configured phase.
- Store the newly calculated offset
for the first phase value in memory temporarily.
- Repeat steps 3-7 for each phase
in the converter.
- Disable power conversion.
- Set the PHASE_CONFIG back to the original value.
- Write the PAGE to the current channel, and the PHASE to 00h for the first phase.
- Write the newly calculated IOUT_CAL_OFFSET value.
- Repeat steps 11-12 for each
phase. PHASE value 01h refers to the 2nd phase, 02h refers to the 3rd phase and
so on.
- Re-set the TON_RISE to the desired value during normal operation, if
needed.
- Perform an NVM Store operation
and power cycle.
Equation 7.