Datasheet

LTC2974
50
2974fc
For more information www.linear.com/LTC2974
Initially self heat is set to zero. After each temperature measurement self heat is updated to be the previous value of
self heat incremented or decremented by ∆MFR_T_SELF_HEAT.
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
INV
= 5 seconds then:
MFR_IOUT_CAL_GAIN_TAU_INV = (4 • t
CONV_SENSE
)/5 = 4 • 66ms/5s = 0.0528
Refer to the application section for more information on calibrating θ
IS
and τ
INV
.
READ_TEMPERATURE_2 is substituted for READ_TEMPERATURE_1 if the associated T
SENSE
network fails to detect
a valid temperature. Under these conditions T
S
= READ_TEMPERATURE_2 and the self-heating correction is applied
using the internal die temperature. See READ_TEMPERATURE_1 for more information.
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
).
pMbus coMManD DescripTion