PRODUCT DATASHEET
AAT1189
TM
SwitchReg
High Voltage Step-Down Regulator
Current Limit
Over-Current Offset Voltage: VOCP = 100mV
Total trace parasitic resistor and inductor DCR is 10mΩ
ILIMIT = 5A
VOCP
DCR
100mV
10mΩ
IPRESET
=
=
= 10A > ILIMIT
VOUT · R1
VOCP - ILIMIT · DCR
5V · 6.34kΩ
0.1V - 5A · 10mΩ
R7 =
=
= 634kΩ
R1 · R7
R7 - R1
6.34kΩ · 634kΩ
634kΩ - 6.34kΩ
R6 =
=
= 6.40kΩ
AAT1189 Losses
All values assume an 85°C ambient temperature and thermal resistance of 50°C/W in the TDFN34-16 package.
PTOTAL = IOUT2 · RDS(ON)H · D + (tSW · FS · IOUT + IQ) · VIN
2.5A2 · 70mΩ · 5V
PTOTAL
=
+ (5ns · 490kHz · 2.5A + 70µA) · 12V
12V
PTOTAL = 257mW
T
J(MAX) = TAMB + ΘJA · PLOSS = 85°C + (50°C/W) · 257mW = 98°C
w w w . a n a l o g i c t e c h . c o m
1189.2008.06.1.0
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ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
