LT3975
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted.
SS Pin Current
Boost Capacitor Charger
Boost Diode Forward Voltage
2.6
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
160
140
120
100
80
V
= 0.5V
V
= V
IN
SS
BST
2.4
2.2
2.0
1.8
1.6
1.4
1.2
60
40
20
1.0
0
1
–25
5
65
95 125 155
0
0.5
1.5
2
–55
35
8
10
0
2
4
6
12 14 16
BOOST DIODE CURRENT (A)
TEMPERATURE (°C)
OUT PIN VOLTAGE (V)
3975 G30
3975 G28
3975 G29
Dropout Comparator Thresholds
Start-Up/Dropout Performance
Start-Up/Dropout Performance
600
580
560
540
520
500
480
460
440
420
400
V
V
IN
V
IN
V
IN
IN
1V/DIV
1V/DIV
V
V
OUT
OUT
V
RISING
OUT
V
V
OUT
1V/DIV
OUT
1V/DIV
V
FALLING
OUT
3975 G32
3975 G33
2.5Ω LOAD
100ms/DIV
1kΩ LOAD
100ms/DIV
(2A IN REGULATION)
(5mA IN REGULATION)
–55
5
35
65
95 125 155
–25
TEMPERATURE (°C)
3975 G31
Full Frequency Switching
Waveforms
Burst Mode Switching Waveforms
Dropout Switching Waveforms
V
V
SW
2V/DIV
SW
V
SW
5V/DIV
5V/DIV
I
I
I
L
L
L
1A/DIV
1A/DIV
0.5A/DIV
V
V
V
OUT
50mV/DIV
OUT
OUT
10mV/DIV
20mV/DIV
3975 G34
3975 G35
3975 G36
V
V
= 12V
5µs/DIV
V
V
= 12V
1µs/DIV
V
= 5V
IN
5µs/DIV
IN
IN
= 3.3V
= 20mA
= 47µF
= 3.3V
= 1A
V
SET FOR 5V
= 0.5A
OUT
OUT
OUT
I
LOAD
C = 47µF
OUT
I
I
LOAD
LOAD
C
C
= 47µF
OUT
OUT
3975f
7
Linear [ Linear ]
