Datasheet

3
LT1170/LT1171/LT1172
117012ff
T
JMAX
θ
JC
θ
JA
LT1170MK 150°C2°C/W 35°C/W
LT1170CK 100°C2°C/W 35°C/W
LT1171MK 150°C4°C/W 35°C/W
LT1171CK 100°C4°C/W 35°C/W
LT1172MK 150°C8°C/W 35°C/W
LT1172CK 150°C8°C/W 35°C/W
Based on continuous operation.
T
JMAX
= 125°C for intermittent fault conditions.
LT1170MK
LT1170CK
LT1171MK
LT1171CK
LT1172MK
LT1172CK
ORDER PART
NUMBER
2
4
1
3
V
SW
V
C
FB
CASE
IS GND
V
IN
K PACKAGE
4-LEAD TO-3 METAL CAN
BOTTOM VIEW
PACKAGE/ORDER I FOR ATIO
UU
W
ORDER PART
NUMBER
LT1172MJ8
LT1172CJ8
T
JMAX
= 150°C, θ
JA
= 100°C/W
* Do not connect Pin 4 of the LT1172 DIP or SO to external
circuitry. This pin may be active in future revisions.
1
2
3
4
8
7
6
5
TOP VIEW
GND
V
C
FB
NC*
E2
V
SW
E1
V
IN
J8 PACKAGE
8-LEAD CERDIP
OBSOLETE PACKAGES
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
REF
Reference Voltage Measured at Feedback Pin 1.224 1.244 1.264 V
V
C
= 0.8V ● 1.214 1.244 1.274 V
I
B
Feedback Input Current V
FB
= V
REF
350 750 nA
● 1100 nA
g
m
Error Amplifier ∆I
C
= ±25µA 3000 4400 6000 µmho
Transconductance ● 2400 7000 µmho
Error Amplifier Source or V
C
= 1.5V 150 200 350 µA
Sink Current ● 120 400 µA
Error Amplifier Clamp Hi Clamp, V
FB
= 1V 1.80 2.30 V
Voltage Lo Clamp, V
FB
= 1.5V 0.25 0.38 0.52 V
Reference Voltage Line 3V ≤ V
IN
≤ V
MAX
● 0.03 %/V
Regulation V
C
= 0.8V
A
V
Error Amplifier Voltage Gain 0.9V ≤ V
C
≤ 1.4V 500 800 V/V
Minimum Input Voltage (Note 5) ● 2.6 3.0 V
I
Q
Supply Current 3V ≤ V
IN
≤ V
MAX
, V
C
= 0.6V 6 9 mA
Control Pin Threshold Duty Cycle = 0 0.8 0.9 1.08 V
● 0.6 1.25 V
Normal/Flyback Threshold 0.4 0.45 0.54 V
on Feedback Pin
V
FB
Flyback Reference Voltage I
FB
= 50µA 15.0 16.3 17.6 V
(Note 5) ● 14.0 18.0 V
Change in Flyback Reference 0.05 ≤ I
FB
≤ 1mA 4.5 6.8 9 V
Voltage
Flyback Reference Voltage I
FB
= 50µA 0.01 0.03 %/V
Line Regulation (Note 5) 7V ≤ V
IN
≤ V
MAX
Flyback Amplifier ∆I
C
= ±10µA 150 300 650 µmho
Transconductance (g
m
)
The ● denotes the specifications which apply over the full operating tem-
perature range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V, V
C
= 0.5V, V
FB
= V
REF
, output pin open, unless otherwise noted.
ELECTRICAL CHARACTERISTICS