LT1082_1 Datasheet, PDF (4/12 Pages) Linear Integrated Systems – 1A High Voltage, Efficiency Switching Voltage Regulator

LT1082
TYPICAL PERFOR A CE CHARACTERISTICS
Suggested Core Size and
Inductance for Telecom
5V Supply
LOAD
CURRENT
100mA
200mA
400mA
600mA
800mA
TYPE 52
KOOL Mµ
POWDERED OR MOLY-
IRON
PERMALLOY
T38 250µH
T50 250µH
T60 250µH
T60 250µH
T80 350µH
T38 200µH
T38 150µH
T50 150µH
T50 200µH
T80 350µH
1082 GA
Short-Circuit Frequency
Shift-Down vs Feedback Current
70
60 ^{TA = 0°C}
T_A = – 55°C
50 ^{TA = 150°C}
Telecom 5V Supply Efficiency
79
76 _{VIN = –20V}
73
70 ^{VIN = –40V}
67
V_IN = –60V
64
61
58 ^{VIN = –70V}
L = 250µH
R = 0.08Ω
55
0
1
2
3
4
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
100mW HIGHER.
1082 G01
Switch Current Limit
4
3
40
30
2
T_J = –55°C T_J = 25°C
20
1
T_J = 150°C
10
0
0 100 200 300 400 500 600 700 800
FEEDBACK CURRENT (µA)
1082 G03
0
0 10 20 30 40 50 60 70 80 90 100
DUTY CYCLE (%)
1082 G04
Flyback Blanking Time
2.2
Minimum Input Voltage
2.9
2.0
2.8
I_SW = 1A
1.8
2.7
I_SW = 0A
1.6
2.6
1.4
2.5
1.2
2.4
1.0
–75 –50 –25 0 25 50 75 100 125 150
JUNCTION TEMPERATURE (°C)
1082 G06
2.3
–75 –50 –25 0 25 50 75 100 125 150
TEMPERATURE (°C)
1082 G07
4
Telecom 5V Supply Short-Circuit
Frequency Shift-Down
80
T_A = 25°C
70
60
50
40
30
20
10
0
654
3
2
1
0
OUTPUT VOLTAGE (V)
1082 G02
Maximum Duty Cycle
97
96
95
94
93
92
91
90
–75 –50 –25 0 25 50 75 100 125 150 175
TEMPERATURE (°C)
1082 G05
Switch Saturation Voltage
2.00
1.75
T_J = 150°C
1.50
T_J = 100°C
1.25
T_J = 25°C
1.00
0.75
T_J = –50°C
0.50
0.25
0
0 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00
SWITCH CURRENT (A)
1082 G08
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