PRODUCT DATASHEET
AAT2688
TM
SystemPower
4.5A 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 = 10mΩ
VS
DCR
100mV
10mΩ
IPRESET
=
=
= 10A > ILIMIT
VOUT · R2
VS - ILIMIT · DCR
3.3V · 2kΩ
0.1V - 6A · 10mΩ
R8 =
=
= 165kΩ
R2 · R8
R8 - R2
2kΩ · 165kΩ
165kΩ - 2kΩ
R7 =
=
= 2kΩ
AAT2688 Losses
All values assume 25°C ambient temperature and thermal resistor of 50°C/W in the TQFN45-24 package.
PTOTAL = IOUT12 · RDS(ON)H · D + (tSW · FS · IOUT1 + IQ) · VIN + (VIN2 - VOUT2) · IOUT2
4.5A2 · 70mΩ · 3.3V
PTOTAL
PTOTAL = 1.42W
J(MAX) = TAMB + ΘJA · PLOSS = 85°C + (33°C/W) · 1.42W = 131°C
=
+ (5ns · 490kHz · 4.5A + 70μA) · 12V + (3.3 - 1.8) · 600mA
12V
T
w w w . a n a l o g i c t e c h . c o m
18
2688.2008.06.1.0
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
