Datasheet
5
LT1082
sn1082 1082fas
CCHARA TERIST
ICS
UW
AT
Y
P
I
CA
LPER
F
O
R
C
E
Isolated Mode Flyback
Reference Voltage
TEMPERATURE (°C)
FLYBACK VOLTAGE (V)
25
24
23
22
21
20
19
18
17
16
15
1082 G09
–75
–50
50
100
25
150
175
–25
0
75 125
R
FB
= 3k
R
FB
= 6k
R
FB
= 10k
Supply Current vs Input Voltage**
SUPPLY VOLTAGE (V)
0
SUPPLY CURRENT (µA)
200
160
120
80
40
0
30 50 80
1082 G15
10 20
40
60 70
V
C
= 50mV
V
C
= 0V
Supply Current vs Supply Voltage
(Shutdown Mode)
INPUT VOLTAGE (V)
0
SUPPLY CURRENT (mA)
20 40
60
80
1082 G14
14
13
12
11
10
9
8
7
6
5
4
3
2
10 30
50 70
90% DUTY CYCLE
50% DUTY CYCLE
10% DUTY CYCLE
0% DUTY CYCLE
**UNDER VERY LOW OUTPUT CURRENT CONDITIONS,
DUTY CYCLE FOR MOST CIRCUITS WILL APPROACH
10% OR LESS.
Feedback Bias Current vs
Temperature
TEMPERATURE (°C)
FEEDBACK BIAS CURRENT (nA)
1082 G12
800
700
600
500
400
300
200
100
0
–75
–50
50
100
25
150
175
–25
0
75 125
Normal/Feedback Mode
Threshold on Feedback Pin
TEMPERATURE (°C)
V
C
PIN VOLTAGE (mV)
750
725
700
675
650
625
600
575
550
525
500
1082 G16
–75
–50
50
100
25
150
175
–25
0
75 125
–24
–22
–20
–18
–16
–14
–12
–10
–8
–6
–4
V
C
PIN CURRENT (µA)
FEEDBACK PIN VOLTAGE
(AT THRESHOLD)
FEEDBACK PIN CURRENT
(AT THRESHOLD)
V
C
PIN VOLTAGE (mV)
SUPPLY CURRENT (µA)
200
180
160
140
120
100
80
60
40
20
0
1082 G17
0
10
50
70
40
90
100
20
30
60 80
–55°C ≤ T
J
≤ 125°C
T
J
= 150°C
Shutdown Mode Supply Current
Reference Voltage and Switching
Frequency vs Temperature
TEMPERATURE (°C)
FREQUENCY (kHz)
70
65
60
55
50
45
1082 G11
1.250
1.245
1.240
1.235
1.230
1.225
REFERENCE VOLTAGE (V)
–75
–50
50
100
25
150
175
–25
0
75 125
FREQ
V
REF
INPUT VOLTAGE (V)
0
REFERENCE VOLTAGE CHANGE (mV)
5
4
3
2
1
0
–1
–2
–3
–4
–5
20
40
50
1082 G10
10 30
60
70
80
T
J
= 25°C
T
J
= –55°C
T
J
= 150°C
Line Regulation
SWITCH CURRENT (A)
DRIVER CURRENT (mA)
100
90
80
70
60
50
40
30
20
10
0
1082 G13
0
0.2
1.0
1.4
0.8
1.8
2.0
0.4
0.6
1.2 1.6
* AVERAGE SUPPLY CURRENT
= I
Q
+ DC(2.9 + 10
–2
I
SW
+ 10
–5
I
SW
2
)
I
Q
= QUIESCENT CURRENT, DC = DUTY CYCLE,
I
SW
= SWITCH CURRENT
Driver Current* vs Switch Current