Datasheet

5
LT1170/LT1171/LT1172
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.
Supply Current vs Input Voltage*
V
C
PIN VOLTAGE (mV)
0
SUPPLY CURRENT (µA)
200
180
160
140
120
100
80
60
40
20
0
40
1170/1/2 G10
10
20
30
50
60
70
80
90 100
T
J
= 150°C
–55°C ≤ T
J
≤ 125°C
Shutdown Mode Supply Current
TEMPERATURE (°C)
TRANSCONDUCTANCE (µmho)
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
1170/1/2 G11
–75 –25
25
50 150
–50 0
75
100
125
g
m
=
∆I (V
C
PIN)
∆V (FB PIN)
Error Amplifier Transconductance V
C
Pin Characteristics
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
Supply Current vs Supply Voltage
(Shutdown Mode)
Driver Current* vs Switch Current
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.
V
C
PIN VOLTAGE (V)
300
200
100
0
–100
–200
–300
–400
1170/1/2 G12
V
C
PIN CURRENT (µA)
0 2.0
0.5
1.0
1.5
2.5
V
FB
= 1.5V (CURRENT INTO V
C
PIN)
V
FB
= 0.8V (CURRENT OUT OF V
C
PIN)
T
J
= 25°C
Reference Voltage vs Temperature
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
Line Regulation
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
Feedback Bias Current vs
Temperature
TYPICAL PERFOR A CE CHARACTERISTICS
UW