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