Datasheet

LTC3883/LTC3883-1
76
3883fa
For more information www.linear.com/LTC3883
PMBus COMMAND DETAILS
The actual value of C
τ
is not required. The important quantity is the thermal time constant τ
INV
= (θ
IS
C
τ
). For example,
if an inductor has a thermal time constant τ
THERMAL
= 5 seconds then:
MFR_IOUT_CAL_GAIN_TAU_INV = ∆t / τ
THERMAL
= 1/5 = 0.2
Refer to the application section for more information on calibrating θ
IS
and τ
INV
.
If the external temperature sense network fails to detect a READ_TEMPERATURE_1 reading of –50°C to 150°C, the
variable T
S
in the self-heating algorithm will be set to a fixed value of –50°C. See READ_TEMPERATURE_1 for more
information.
MFR_T_SELF_HEAT is a read-only command that has two data bytes and is formatted in Linear_5_11s format.
MFR_IOUT_CAL_GAIN_TAU_INV has two data bytes and is formatted in Linear_5_11 format.
MFR_IOUT_CAL_GAIN_THETA has two data bytes and is formatted in Linear_5_11 format.
MFR_T_SELF_HEAT Data Content
Bit(s) Symbol Operation
b[15:0] Mfr_t_self_heat Values are limited to the range 0°C to 50°C.
MFR_IOUT_CAL_GAIN_THETA Data Content
Bit(s) Symbol Operation
b[15:0] Mfr_iout_cal_gain_theta Values ≤ 0 set MFR_T_SELF_HEAT to zero.
MFR_IOUT_CAL_GAIN_TAU_INV Data Content
Bit(s) Symbol Operation
b[15:0] Mfr_iout_cal_gain_tau_inv Values ≤ 0 set MFR_T_SELF_HEAT to zero.
Values ≥ 1 set MFR_T_SELF_HEAT to MFR_IOUT_CAL_GAIN_THETA • READ_IOUT • (V
ISENSEP
– V
ISENSEM
).
Output Current
COMMAND NAME CMD CODE DESCRIPTION TYPE
DATA
FORMAT UNITS NVM
DEFAULT
VALUE
IOUT_OC_FAULT_LIMIT 0x46 Output overcurrent fault limit. R/W Word L11 A Y 29.75
0xDBB8
IOUT_OC_WARN_LIMIT 0x4A Output overcurrent warning limit. R/W Word L11 A Y 20.0
0xDA80