LT1082
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Suggested Core Size and
Inductance for Telecom
Telecom 5V Supply Short-Circuit
Frequency Shift-Down
Telecom 5V Supply Efficiency
5V Supply
79
76
73
70
67
64
61
58
55
80
70
60
50
40
30
20
10
0
TYPE 52
POWDERED OR MOLY-
IRON PERMALLOY
KOOL Mµ
T
= 25°C
A
LOAD
V
= –20V
= –40V
= –60V
IN
CURRENT
100mA
200mA
400mA
600mA
800mA
T38 250µH T38 200µH
T50 250µH T38 150µH
T60 250µH T50 150µH
T60 250µH T50 200µH
T80 350µH T80 350µH
V
IN
IN
V
1082 GA
V
IN
= –70V
1
L = 250µH
R = 0.08Ω
2
0
3
4
6
5
4
3
2
1
0
OUTPUT VOLTAGE (V)
POWER OUTPUT (W)
NOTE: THIS GRAPH IS BASED ON LOW CORE LOSS
PERMALLOY INDUCTOR. IF POWDERED IRON CORE
INDUCTOR IS USED, THE CORE LOSS IS TYPICALLY
1082 G02
100mW HIGHER.
1082 G01
Short-Circuit Frequency
Shift-Down vs Feedback Current
Maximum Duty Cycle
Switch Current Limit
97
4
3
2
1
0
70
60
50
40
30
20
10
0
T
= –55°C
A
T
T
= 0°C
A
A
96
95
94
93
92
91
90
= 150°C
T = 25°C
J
T = –55°C
J
T = 150°C
J
100 200
800
0
10 20 30 40 50 60 70 80 90 100
–75
–50 –25
0
25
TEMPERATURE (°C)
50 75 100 125 150 175
0
300 400 500 600 700
FEEDBACK CURRENT (µA)
DUTY CYCLE (%)
1082 G05
1082 G03
1082 G04
Flyback Blanking Time
Switch Saturation Voltage
Minimum Input Voltage
2.9
2.8
2.7
2.6
2.5
2.4
2.3
2.2
2.0
1.8
1.6
1.4
1.2
1.0
2.00
1.75
1.50
1.25
1.00
0.75
0.50
0.25
0
I
= 1A
= 0A
T = 150°C
J
SW
T = 100°C
J
T = 25°C
J
I
SW
T = –50°C
J
–75
0
50 75 100 125 150
–75
–50 –25
0
25
50 75 100 125 150
–50 –25
25
0.50
1.00 1.25
1.75
1.50
2.00
0
0.25
0.75
JUNCTION TEMPERATURE (°C)
TEMPERATURE (°C)
SWITCH CURRENT (A)
1082 G06
1082 G07
1082 G08
sn1082 1082fas
4
Linear Systems [ Linear Systems ]
