AAT1189 Datasheet, PDF (17/19 Pages) Advanced Analogic Technologies – High Voltage Step-Down Regulator

DATA SHEET
AAT1189
High Voltage Step-Down Regulator
Current Limit
Over-Current Offset Voltage: V_OCP = 100mV
Total trace parasitic resistor and inductor DCR is 10m
I_LIMIT = 5A
I_PRESET =
V_OCP
DCR
=
100mV
10mΩ
= 10A > I_LIMIT
R₇ =
V_OUT · R₁
=
V_OCP - I_LIMIT · DCR
5V · 6.34kΩ _{= 634kΩ}
0.1V - 5A · 10mΩ
R₆ =
R₁ · R₇
R₇ - R₁
=
6.34kΩ · 634kΩ
634kΩ - 6.34kΩ
= 6.40kΩ
AAT1189 Losses
All values assume an 85°C ambient temperature and thermal resistance of 50°C/W in the TDFN34-16 package.
P_TOTAL = I_OUT2 · R_DS(ON)H · D + (t_SW · F_S · I_OUT + I_Q) · V_IN
P_TOTAL = ^{2.5A2 · 70mΩ · 5V} + (5ns · 490kHz · 2.5A + 70µA) · 12V
12V
P_TOTAL = 257mW
T_J(MAX) = T_AMB + Θ_JA · P_LOSS = 85°C + (50°C/W) · 257mW = 98°C
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