LTC3883 Datasheet, PDF (74/112 Pages) Linear Technology – Single Phase Step-Down DC/DC Controller with Digital Power System Management

LTC3883/LTC3883-1
PMBus Command Details
At initial power up the state of the PGOOD pin will be high regardless of VOUT. If the proper state of low at power-up is
required, place a Schottky diode between RUN and PGOOD. The Anode must be tied to PGOOD and the Cathode to RUN.
The POWER_GOOD# status bit is masked from initiating an ALERT. The POWER_GOOD# status bit in the STATUS_WORD
command is always reflective of VOUT with respect to the POWER_GOOD threshold regardless of the RUN state. The
PGOOD pin state is controlled by the POWER_GOOD# status bit and is qualified by the RUN state.
This command has two data bytes and is formatted in Linear_16u format.
MFR_VOUT_MAX
The MFR_VOUT_MAX command is the maximum output voltage in volts the part can produce. If the output voltage is
set to high range (Bit 6 of MFR_PWM_CONFIG_LTC3883 set to a 0) MFR_VOUT_MAX is 5.5V. If the output voltage
is set to low range (Bit 6 of MFR_PWM_CONFIG_LTC3883 set to a 1) the MFR_VOUT_MAX is 2.75V. Entering a
VOUT_COMMAND value greater than this will result in a CML fault and the output voltage setting will be clamped to
the maximum level. This will also result in Bit 3 VOUT_MAX_Warning in the STATUS_VOUT command being set.
This read only command has 2 data bytes and is formatted in Linear_16u format.
Current
Output Current Calibration
COMMAND NAME
CMD
CODE DESCRIPTION
IOUT_CAL_GAIN
0x38 The ratio of the voltage at the current sense pins
to the sensed current. For devices using a fixed
current sense resistor, it is the resistance value
in mΩ.
MFR_IOUT_CAL_GAIN_TC 0xF6 Temperature coefficient of the current sensing
element.
MFR_T_SELF_HEAT
0xB8 Reports the calculated self heat value attributed
to the inductor.
MFR_IOUT_CAL_GAIN_
TAU_INV
0xB9 Coefficient used to emulate thermal time
constant.
MFR_IOUT_CAL_GAIN_
THETA
0xBA Used to calculate the instance inductor self
heating effect.
TYPE
R/W Word
R/W Word
R Word
R/W Word
R/W Word
DATA
FORMAT
L11
CF
L11
L11
L11
UNITS
mΩ
C
s^–1
C/W
DEFAULT
NVM
VALUE
Y
1.8
0xBB9A
Y
3900
0x0F3C
NA
Y
0.0
0x8000
Y
0.0
0x8000
IOUT_CAL_GAIN
The IOUT_CAL_GAIN command is used to set the resistance value of the current sense resistor in milliohms. (see
also MFR_IOUT_CAL_GAIN_TC).
This command has two data bytes and is formatted in Linear_5s_11s format.
MFR_IOUT_CAL_GAIN_TC
The MFR_IOUT_CAL_GAIN_TC command allows the user to program the temperature coefficient of the IOUT_CAL_GAIN
sense resistor or inductor DCR in ppm/°C.
This command has two data bytes and is formatted in 16-bit 2’s complement integer ppm. N = –32768 to 32767 •
10^–6. Nominal temperature is 27°C. The IOUT_CAL_GAIN is multiplied by:
[1.0 + MFR_IOUT_CAL_GAIN_TC • (READ_TEMPERATURE_1‑27)]. DCR sensing will have a typical value of 3900.
3883f
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