LT3975
TYPICAL PERFORMANCE CHARACTERISTICS
Thermal Derating
3.0
2.5
LOAD CURRENT (A)
2.0
H-GRADE
1.5
1.0
0.5
0
–50 –25
LIMITED BY MAXIMUM
JUNCTION TEMPERATURE
θ
JA
= 40°C/W
V
IN
= 12V
V
OUT
= 5V
I-GRADE
CURRENT LIMIT (A)
7
6
CURRENT LIMIT (A)
5
4
3
2
1
0
25 50 75 100 125 150
TEMPERATURE (°C)
3975 G10
T
A
= 25°C, unless otherwise noted.
Switch Current Limit
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
30% DUTY CYCLE
Switch Current Limit
0
0
0.2
0.4
0.6
0.8
1
3975 G11
3.0
–55 –25
5
DUTY CYCLE
95
65
35
TEMPERATURE (°C)
125
155
3975 G12
Current Limit Foldback
6
5
CURRENT LIMIT (A)
4
3
2
1
0
30% DUTY CYCLE
V
SS
= 3V
6
5
CURRENT LIMIT (A)
4
3
2
1
0
Soft-Start
30% DUTY CYCLE
250
V
FB
= 1V
V
FB
= 0V
V
CESAT
(mV)
200
Switch V
CESAT
150
100
50
0
0
0.2
0.4
0.6
0.8
FB PIN VOLTAGE (V)
1.0
1.2
3975 G13
0
0.5
1
1.5
SS PIN VOLTAGE (V)
2
2.5
3975 G14
0
0.5
1
1.5
2.0
SWITCH CURRENT (A)
2.5
3.0
3975 G15
BOOST Pin Current
50
45
BOOST PIN CURRENT (mA)
40
MINIMUM ON-TIME (ns)
35
30
25
20
15
10
5
0
0
0.5
1.5
2
1
SWITCH CURRENT (A)
2.5
3
3975 G16
Minimum On-Time
180
170
160
150
140
130
120
110
100
90
80
70
60
–55
–25
65
35
5
95
TEMPERATURE (°C)
125
155
LOAD = 2.5A
LOAD = 1A
V
SYNC
= 0V
f
SW
= 2MHz
MINIMUM OFF-TIME (ns)
200
190
180
170
160
150
140
130
120
110
Minimum Off-Time
V
SYNC
= 0V
f
SW
= 2MHz
LOAD = 2.5A
LOAD = 1A
100
–55
–25
65
35
5
95
TEMPERATURE (°C)
125
155
3975 G17
3975 G18
3975f
5
LINER [ LINEAR TECHNOLOGY ]
