PRODUCT DATASHEET
AAT2689
TM
SystemPower PMIC Solution for 12V Adapter Systems with 2-Output High Performance Step-Down Converters
Channel 1 Current Limit
Voltage sense VS = 100mV
Total trace parasitic resistor and inductor DCR is 10mΩ
VS
DCR
100mV
10mΩ
ILIM
=
=
= 10A > 5A
VOUT1 · R2
VOCP - ILIMIT · DCR
3.3V · 2kΩ
0.1V - 5A · 10mΩ
R8 =
R7 =
=
= 133kΩ
R2 · R8
R8 - R2
2kΩ · 133kΩ
133kΩ - 2kΩ
=
= 2kΩ
AAT2689 Losses
All values assume a 25°C ambient temperature and thermal resistance of 50°C/W in the TDFN34-16 package.
PTOTAL = IOUT12 · RDS(ON)H · D + (tSW · FS · IOUT1 + IQ1) · VIN1 + (VIN2 - VOUT2) · IOUT2
2.5A2 · 70mΩ · 3.3V
PTOTAL
=
+ (5ns · 490kHz · 2.5A + 70μA) · 12V · (3.3V - 1.8V) · 600mA
12V
PTOTAL = 1.1W
J(MAX) = TAMB + ΘJA · PLOSS = 25°C + (50°C/W) · 1.1W = 80°C
T
w w w . a n a l o g i c t e c h . c o m
18
2689.2008.06.1.0
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
