Datasheet

LT3988
4
3988f
Typical perForMance characTerisTics
Feedback Voltage vs Temperature
Switch Current Limit
vs Temperature
Switch Current Limit
vs Duty Cycle
Switching Frequency vs R
T
Switching Frequency
vs Temperature Switching Frequency Foldback
Efficiency, V
OUT
= 2.5V Efficiency, V
OUT
= 3.3V Efficiency, V
OUT
= 5V
LOAD CURRENT (A)
0 0.2 0.4 0.6 0.80.1 0.3 0.5 0.7 0.9
EFFICIENCY (%)
1.0
3988 G01
V
IN
= 48V
V
IN
= 24V
V
IN
= 12V
45
60
40
55
50
80
65
70
75
f = 500kHz
V
BD
= 3V
TEMPERATURE (°C)
–50
FEEDBACK VOLTAGE (V)
0.760
0.755
0.750
0.745
0.740
0 50–25 25 100
3988 G04
15075 125
R
T
(kΩ)
0
FREQUENCY (MHz)
2.5
2.1
1.7
1.3
0.9
0.5
2.3
1.9
1.5
1.1
0.7
0.3
0.1
80 16040 120 180
3988 G07
20060 14020 100
0 0.2 0.4 0.6 0.80.1 0.3 0.5 0.7 0.9
EFFICIENCY (%)
1.0
3988 G02
V
IN
= 48V
V
IN
= 24V
V
IN
= 12V
LOAD CURRENT (A)
85
55
60
50
90
65
70
75
80
f = 500kHz
TEMPERATURE (°C)
–50
CURRENT LIMIT (A)
2.5
2.0
1.5
1.0
0.5
0 50–25 25 100
3988 G05
15075 125
DUTY CYCLE = 35%
TEMPERATURE (°C)
–50
FREQUENCY CHANGE (%)
10
5
0
–5
–10
0 50–25 25 100
3988 G08
15075 125
0 0.2 0.4 0.6 0.80.1 0.3 0.5 0.7 0.9
EFFICIENCY (%)
1.0
3988 G03
V
IN
= 48V
V
IN
= 24V
V
IN
= 12V
LOAD CURRENT (A)
85
55
60
50
90
65
70
75
80
f = 500kHz
DUTY CYCLE (%)
0
CURRENT LIMIT (A)
2.5
2.0
1.5
1.0
0.5
20 40 60
3988 G06
10080
TYPICAL
MINIMUM
FEEDBACK VOLTAGE (V)
0
f/f
NOM
1.2
0.6
0.4
0.8
1.0
0.2
0.40.2 0.6
3988 G09
0.70.30.1 0.5
T
A
= 25°C, unless otherwise noted.