Datasheet
LT1170/LT1171/LT1172
6
117012fg
TYPICAL PERFORMANCE CHARACTERISTICS
Line Regulation
Reference Voltage vs Temperature
Feedback Bias Current
vs Temperature
Supply Current vs Supply Voltage
(Shutdown Mode) Driver Current* vs Switch Current Supply Current vs Input Voltage*
Switch Current Limit vs Duty Cycle* Minimum Input Voltage Switch Saturation Voltage
DUTY CYCLE (%)
0
SWITCH CURRENT (A)
16
12
8
4
0
40
1170/1/2 G01
20
30
50 60
70
80 90 100
25°C
125°C
–55°C
10
* DIVIDE VERTICAL SCALE BY TWO FOR
LT1171, BY FOUR FOR LT1172.
TEMPERATURE (°C)
–75
MINIMUM INPUT VOLTAGE (V)
–25
25
50 150
1170/1/2 G02
–50 0
75
100
125
2.9
2.8
2.7
2.6
2.5
2.4
2.3
SWITCH CURRENT = 0A
SWITCH CURRENT = I
MAX
SWITCH CURRENT (A)*
0
SWITCH SATURATION VOLTAGE (V)
8
1170/1/2 G03
1
2
3
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
4567
25°C
150°C
–55°C
100°C
* DIVIDE CURRENT BY TWO FOR
LT1171, BY FOUR FOR LT1172.
INPUT VOLTAGE (V)
0
REFERENCE VOLTAGE CHANGE (mV)
10
20
30 40
1170/1/2 G04
50
5
4
3
2
1
0
–1
–2
–3
–4
–5
60
T
J
= 150°C
T
J
= –55°C
T
J
= 25°C
TEMPERATURE (°C)
REFERENCE VOLTAGE (V)
1170/1/2 G05
1.250
1.248
1.246
1.244
1.242
1.240
1.238
1.236
1.234
–75 –25
25
50 150
–50 0
75
100
125
TEMPERATURE (°C)
FEEDBACK BIAS CURRENT (nA)
1170/1/2 G06
800
700
600
500
400
300
200
100
0
–75 –25
25
50 150
–50 0
75
100
125
SUPPLY VOLTAGE (V)
0
SUPPLY CURRENT (µA)
10 20
30
40
160
140
120
100
80
60
40
20
0
50
60
1170/1/2 G07
V
C
= 50mV
V
C
= 0V
T
J
= 25°C
SWITCH CURRENT (A)
0
DRIVER CURRENT (mA)
123
160
140
120
100
80
60
40
20
0
4
5
1170/1/2 G08
T
J
= –55°C
T
J
= ≥ 25°C
* AVERAGE LT1170 POWER SUPPLY CURRENT IS
FOUND BY MULTIPLYING DRIVER CURRENT BY
DUTY CYCLE, THEN ADDING QUIESCENT CURRENT.
INPUT VOLTAGE (V)
0
SUPPLY CURRENT (mA)
10
20
30 40
1170/1/2 G09
50
15
14
13
12
11
10
9
8
7
6
5
60
T
J
= 25°C
NOTE THAT THIS CURRENT DOES NOT
INCLUDE DRIVER CURRENT, WHICH IS
A FUNCTION OF LOAD CURRENT AND
DUTY CYCLE.
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.