LTC3883 Datasheet, PDF (69/112 Pages) Linear Technology – Single Phase Step-Down DC/DC Controller with Digital Power System Management

LTC3883/LTC3883-1
PMBus Command Details
Bit[3] Setting this bit to a 1 starts the patent pending inductor DCR auto calibration to determine the DCR of the
inductor. This will update the value of IOUT_CAL_GAIN using the READ_IIN, READ_IOUT, and DUTY_CYCLE values.
IOUT_CAL_GAIN is adjusted so that READ_IOUT • DUTY_CYCLE = READ_IIN. The auto calibration procedure will only
complete successfully if the following conditions are met.
1) The PWM is enabled
2) DUTY_CYCLE is at least 3%
3) READ_IIN is at least 10mA
4) The calibrated IOUT_CAL_GAIN is within ±30% of the uncalibrated IOUT_CAL_GAIN
If any of the above conditions are not met, bit 0 of the STATUS_CML command will be set, and the value of IOUT_
CAL_GAIN will not be changed. Bit[3] must then be reset to a 0 by the user. A STORE_USER_ALL command must be
issued to store the updated IOUT_CAL_GAIN value into NVM.
Bit[1:0] determine the PWM mode of operation.
This command has one data byte.
MFR_PWM_CONFIG_LTC3883
The MFR_PWM_CONFIG_LTC3883 command sets the switching frequency and phase offset with respect to the falling
edge of the SYNC signal. The part must be in the OFF state to process this command. The RUN pin must be low or
the part must be commanded off. If the part is in the RUN state and this command is written, the command will be
ignored and a BUSY fault will be asserted. Bit 6 of this command affects the loop gain of the PWM output which may
require modifications to the external compensation network.
BIT
7
6
5
4
3
BIT [2:0]
000b
001b
010b
011b
100b
101b
110b
111b
MEANING
Reserved, set to 0.
If V_OUT RANGE = 1, the maximum output voltage is
2.75V. If RANGE = 0, the maximum output voltage
is 5.5V.
Reserved
Share Clock Enable : If this bit is 1, the
SHARE_CLK pin will not be released until
V_IN > VIN_ON. The SHARE_CLK pin will be
pulled low when V_IN < VIN_OFF. If this bit is 0, the
SHARE_CLK pin will not be pulled low when VIN <
VIN_OFF except for the initial application of VIN.
Reserved, set to 0
Phase Offset
0
90
180
270
60
120
240
300
This command has one data byte.
3883f
69