Low-Voltage, Precision Step-Down
Controller for Portable CPU Power
_____________________________Typical Operating Characteristics (continued)
(Circuit of Figure 1, V = 7V, T = +25°C, unless otherwise noted.)
IN
A
QUIESCENT SUPPLY CURRENT
vs. INPUT VOLTAGE
EFFICIENCY vs. LOAD CURRENT
(1.8V/4A CIRCUIT)
EFFICIENCY vs. LOAD CURRENT
(1.8V/7A CIRCUIT)
1000
100
100
100
10
V
= 7V
90
80
70
60
90
80
70
60
IN
V
= 7V
IN
V
= 15V
IN
V
= 22V
IN
V
= 15V
IN
1
0.10
V
= 22V
IN
V
= 3.3V
OUT
0.01
50
50
0
5
10
15
20
25
30
1m
10m
100m
LOAD CURRENT (A)
1
10
1m
10m
100m
1
10
INPUT VOLTAGE (V)
LOAD CURRENT (A)
VL LOAD-REGULATION ERROR
vs. VL LOAD CURRENT
LOAD REGULATION
vs. LOAD CURRENT
REF LOAD-REGULATION ERROR
vs. REF LOAD CURRENT
40
35
30
25
20
15
10
5
5
4
0.6
0.5
0.4
0.3
0.2
0.1
0
PWM MODE
= 5V
V
OUT
3
2
1
0
-1
-2
-3
-4
-5
0
0
5
10 15 20 25 30 35 40 45 50
VL LOAD CURRENT (mA)
1m
10m
100m
1
10
0
10 20 30 40 50 60 70 80 90 100
LOAD CURRENT (A)
REF LOAD CURRENT (μA)
DROPOUT VOLTAGE
vs. LOAD CURRENT
RESET TIME DELAY
vs. OSC FREQUENCY
LOAD-TRANSIENT RESPONSE
(3.3V/3A, PWM MODE)
250
225
200
175
150
125
100
75
400
350
300
250
200
150
100
50
V
OUT
50mV/div
4A
2A
0A
LOAD
CURRENT
V
FORCED TO 4.95V
OUT
50
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5
LOAD CURRENT (A)
150 200 250 300 350 400 450 500
(kHz)
100μs/div)
F
OSC
6
_______________________________________________________________________________________
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
