PRODUCT DATASHEET
AAT2689
SystemPower
TM
PMIC Solution for 12V Adapter Systems with 2-Output High Performance Step-Down Converters
Typical Characteristics
Step-Down Converter Efficiency vs. Load
(V
OUT1
= 3.3V; L = 4.7µH)
100
90
80
2.0
1.5
Step-Down Converter DC Regulation
(V
OUT1
= 3.3V; L = 4.7µH)
Output Error (%)
Efficiency (%)
70
60
50
40
30
20
10
0
0.1
1
10
100
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
0.1
1
10
100
V
IN1
= 6V
V
IN1
= 8V
V
IN1
= 12V
V
IN1
= 18V
V
IN1
= 24V
1000
10000
V
IN1
= 6V
V
IN1
= 8V
V
IN1
= 12V
V
IN1
= 18V
V
IN1
= 24V
1000
10000
Output Current (mA)
Output Current (mA)
Step-Down Converter Line Regulation
(V
OUT1
= 3.3V; L = 4.7µH)
Output Voltage (AC coupled)
(bottom) (V)
1.00
0.75
Step-Down Converter Output Ripple
(V
IN1
= 12V; V
OUT1
= 3.3V; I
OUT1
= 1mA)
LX Voltage (top) (V)
Inductor Current (middle) (A)
12V
0V
0.4
0.2
0.0
3.31
3.30
3.29
Accuracy (%)
0.50
0.25
0.00
-0.25
-0.50
-0.75
-1.00
6
8
10
12
14
16
18
I
OUT1
= 0.1mA
I
OUT1
= 1mA
I
OUT1
= 1250mA
I
OUT1
= 2500mA
20
22
24
Input Voltage (V)
Time (2µs/div)
Step-Down Converter Output Ripple
(V
IN1
= 12V; V
OUT1
= 3.3V; I
OUT1
= 2.5A)
LX Voltage (top) (V)
Inductor Current (middle) (A)
Output Voltage (AC coupled)
(bottom) (V)
12V
0V
4.0
3.0
2.0
3.32
3.30
3.28
Step-Down Converter Load Transient Response
(I
OUT1
= 1.875A to 2.5A; V
IN1
= 12V;
V
OUT1
= 3.3V; C
OUT1
= 2x22µF)
Output Voltage
(AC Coupled) (bottom) (V)
2.5A
3.0
2.5
Output Current
(top) (A)
2.0
1.875A
1.5
3.4
3.3
3.2
Time (1µs/div)
Time (100µs/div)
2689.2008.06.1.0
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