Step-Down Controllers with
Synchronous Rectifier for CPU Power
____________________________Typical Operating Characteristics (continued)
(T = +25°C, unless otherwise noted.)
A
QUIESCENT SUPPLY CURRENT
vs. SUPPLY VOLTAGE,
3.3V/3A CIRCUIT IN IDLE MODE
QUIESCENT SUPPLY CURRENT
vs. SUPPLY VOLTAGE,
5V/3A CIRCUIT IN IDLE MODE
QUIESCENT SUPPLY CURRENT
vs. SUPPLY VOLTAGE, LOW-NOISE MODE
30
20
10
0
16m
1400
1200
1000
800
15m
14m
SWITCHING
STANDARD MAX797 APPLICATION
CONFIGURED FOR 5V
SKIP = LOW
f = 300kHz
f = 150kHz
800μ
SYNC = REF
600
NOT SWITCHING
(FB FORCED TO 3.5V)
600μ
400μ
400
STANDARD MAX797 3.3V/3A
CIRCUIT, FIGURE 1
SKIP = HIGH
STANDARD MAX797 3.3V/3A
CIRCUIT, FIGURE 1
SKIP = LOW
200
0
200μ
SYNC = REF
0
0
4
8
12 16 20 24 28 32
0
4
8
12 16 20 24 28 32
0
4
8
12 16 20 24 28 32
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
DROPOUT VOLTAGE
vs. LOAD CURRENT
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
REF LOAD-REGULATION ERROR
vs. LOAD CURRENT
800
700
600
500
1.6
1.4
20
15
10
5
1.2
1.0
0.8
0.6
0.4
f = 300kHz
400
300
200
100
DEVICE CURRENT ONLY
SHDN = LOW
f = 150kHz
STANDARD MAX797 APPLICATION
CONFIGURED FOR 5V
0.2
0
V
> 4.8V
OUT
0
0
0.01
0.1
1
10
1
10
100
1000
0
4
8
12 16 20 24 28 32
LOAD CURRENT (A)
REF LOAD CURRENT (μA)
SUPPLY VOLTAGE (V)
MAX796
MAXIMUM SECONDARY CURRENT
vs. SUPPLY VOLTAGE, 5V/15V CIRCUIT
SWITCHING FREQUENCY
vs. LOAD CURRENT
VL LOAD-REGULATION ERROR
vs. LOAD CURRENT
1000
500
450
400
350
300
250
200
150
100
50
I
(MAIN) = 0A
OUT
SYNC = REF (300kHz)
SKIP = LOW
400
300
100
10
1
+5V, V = 7.5V
IN
I
(MAIN) = 3A
OUT
+5V, V = 30V
IN
200
100
0
+3.3V, V = 7.5V
IN
CIRCUIT OF FIGURE 11
TRANSFORMER = TTI5870
V
SEC
> 12.75V
0.1
100μ
0
1m
10m
100m
1
0
20
40
60
80
0
4
8
12 16 20 24 28 32
LOAD CURRENT (A)
VL LOAD CURRENT (mA)
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
7
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
