LT3681
U W
TYPICAL PERFOR A CE CHARACTERISTICS T = 25°C unless otherwise noted.
A
Efficiency (V
= 3.3V)
Efficiency vs Switching Frequency
Efficiency (V
= 5.0V)
OUT
OUT
100
90
80
70
60
50
40
30
20
90
100
90
80
70
60
50
40
30
20
V
= 12V
85
80
IN
V
= 12V
IN
V
= 7V
IN
V
= 24V
IN
V
= 24V
IN
V
= 12V
75
70
65
60
55
IN
V
= 24V
IN
V
= 3.3V
OUT
L: NEC PLC-0745-4R7
f: 800kHz
L = 10µH
L: NEC PLC-0745-4R7
f: 800kHz
10
0
10
0
LOAD = 1A
50
0.5
1
2
2.5
3
0
1.5
0.0001 0.001
0.01
0.1
1
10
0.0001 0.001
0.01
0.1
1
10
LOAD CURRENT (A)
LOAD CURRENT (A)
SWITCHING FREQUENCY (MHz)
3681 G02
3681 G01
3681 G03
No Load Supply Current vs
Temperature
No Load Supply Current
Maximum Load Current
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
4.0
3.5
3.0
V
V
= 12V
IN
OUT
= 3.3V
INCREASED SUPPLY
CURRENT DUE TO CATCH
DIODE LEAKAGE AT
2.5
2.0
HIGH TEMPERATURE
V
= 3.3V
OUT
1.5
1.0
L = 4.7µH
f = 800 kHz
FRONT PAGE APPLICATION
10
20
INPUT VOLTAGE (V)
25
30
–40 –20
0
20
40
60
80
5
15
5
10
20
25
30
35
0
15
TEMPERATURE (°C)
INPUT VOLTAGE (V)
3681 G05
3681 G06
3681 G04
Maximum Load Current
Switch Current Limit
Switch Current Limit
4.0
3.5
3.0
4.5
4.0
3.0
2.5
2.0
1.5
1.0
0.5
0
4.0
3.5
3.0
DUTY CYCLE = 10 %
DUTY CYCLE = 90 %
2.5
2.0
2.5
2.0
V
= 5.0V
OUT
1.5
1.0
1.5
1.0
L = 4.7µH
f = 800 kHz
20
60
40
DUTY CYCLE (%)
80
100
0
–50 –25
0
25
50
75 100 125
10
20
INPUT VOLTAGE (V)
25
30
5
15
TEMPERATURE (°C)
3681 G08
3681 G09
3681 G07
3681f
4
Linear [ Linear ]
