Datasheet

LT1976/LT1976B
7
1976bfg
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Dropout Operation
INPUT VOLTAGE (V)
2
OUTPUT VOLTAGE (V)
1.5
2.0
2.5
3.5
4.5
1976 G23
1.0
0.5
0
2.5 3 4
3.0
3.5
4.0
V
OUT
= 3.3V
BOOST DIODE = DIODES INC. B1100
LOAD CURRENT = 1.25A
LOAD CURRENT = 250mA
INPUT VOLTAGE (V)
2
0
OUTPUT VOLTAGE (V)
1
2
3
4
34
5
6
1976 G24
5
6
2.5 3.5
4.5
5.5
V
OUT
= 5V
BOOST DIODE = DIODES INC. B1100
LOAD CURRENT = 1.25A
LOAD CURRENT = 250mA
LT1976 No Load 1A
Step Response
V
OUT
100mV/DIV
I
OUT
500mA/DIV
V
IN
= 12V TIME (1ms/DIV) 1976 G17
V
OUT
= 3.3V
C
OUT
= 47μF
0A
1A
LT1976 Burst Mode Operation
LT1976 Burst Mode Operation
V
OUT
50mV/
DIV
I
SW
100mA/
DIV
V
IN
= 12V TIME (10μs/DIV) 1976 G15
V
OUT
= 3.3V
I
Q
= 100μA
0A
0A
Dropout Operation
Minimum On Time Boost Current vs Load Current
TEMPERATURE (°C)
–50
0
ON TIME (ns)
50
150
200
250
500
350
–10
30
50
1976 G21
100
400
450
300
–30 10
70
90
110
LOAD CURRENT = 0.5A
LOAD CURRENT = 1A
LOAD CURRENT (mA)
0
0
BOOST CURRENT (mA)
5
15
20
25
50
35
400
800
1000
1976 G22
10
40
45
30
200 600
1200
1400
TEMPERATURE (˚C)
–50
V
C
VOLTAGE (V)
400
500
600
70 90 110
1976 G26
300
200
–10 3010–30 50
100
0
700
LT1976B V
C
Switching Threshold
vs Temperature
V
OUT
50mV/DIV
AC
COUPLED
I
SW
100mA/DIV
V
IN
= 12V TIME (10μs/DIV) 1976 G27
V
OUT
= 3.3V
I
Q
= 1.6mA
LT1976B No Load Operation
(Pulse-Skipping Mode)
V
OUT
50mV/DIV
I
SW
100mA/DIV
V
IN
= 12V TIME (5ms/DIV) 1976 G14
V
OUT
= 3.3V
I
Q
= 100μA
0A