Datasheet

LTC2974
46
2974fc
For more information www.linear.com/LTC2974
IOUT_CAL_GAIN
The IOUT_CAL_GAIN command is used to set 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 same value as the resistance of the resistor (units are expressed
in mΩ). IOUT_CAL_GAIN is internally limited to values between 0.01mΩ to 1,000mΩ. The register readback value
always returns what was last written and does not reflect internal limiting.
Calculations using IOUT_CAL_GAIN are:
V
IOUT_OC_FAULT_LIMIT
= IOUT_OC_FAULT_LIMIT • IOUT_CAL_GAIN • T
CORRECTION
V
IOUT_UC_FAULT_LIMIT
= IOUT_UC_FAULT_LIMIT • IOUT_CAL_GAIN • T
CORRECTION
Where:
T
CORRECTION
= (1 + MFR_IOUT_CAL_GAIN_TC • 1E-6 • (READ_TEMPERATURE_1 + MFR_T_SELF_HEAT – 25.0))
READ_IOUT =
V
IOUT _ SNSPn
– V
IOUT _ SNSMn
(IOUT_CAL _GAIN)• T
CORRECTION
Note:
T
CORRECTION
is limited by hardware to a value between 0.25 and 4.0.
READ_TEMPERATURE_2 is substituted for READ_TEMPERATURE_1 if the associated T
SENSE
network fails to detect
a valid temperature. See READ_TEMPERATURE_1 for more information.
pMbus coMManD DescripTion
OUTPUT CURRENT COMMANDS AND LIMITS
COMMAND NAME
CMD
CODE DESCRIPTION TYPE PAGED FORMAT UNITS EEPROM
DEFAULT
VALUE
REF
PAGE
IOUT_CAL_GAIN 0x38 The nominal resistance of the current sense
element in mΩ.
R/W Word Y L11 mΩ Y 1.0
0xBA00
46
IOUT_OC_FAULT_LIMIT 0x46 Output overcurrent fault limit. R/W Word Y L11 A Y 10.0
0xD280
47
IOUT_OC_WARN_LIMIT 0x4A Output overcurrent warning limit. R/W Word Y L11 A Y 5.0
0xCA80
47
IOUT_UC_FAULT_LIMIT 0x4B Output undercurrent fault limit. Used to
detect a reverse current and must be a
negative value.
R/W Word Y L11 A Y -1.0
0xBE00
47
MFR_IOUT_CAL_GAIN_TC 0xF6 Temperature coefficient applied to IOUT_
CAL_GAIN.
R/W Word Y CF ppm Y 0x0
47