Datasheet

LT1940/LT1940L
2
1940fa
V
IN
Voltage
LT1940 .................................................... (–0.3), 25V
LT1940L ................................................... (–0.3), 7V
BOOST Pin Voltage
LT1940 ................................................................ 35V
LT1940L ............................................................. 16V
BOOST Pin Above SW Pin
LT1940 ................................................................ 25V
LT1940L ............................................................. 16V
PG Pin Voltage
LT1940 ................................................................ 25V
LT1940L ............................................................... 7V
SW Voltage ................................................................V
IN
RUN/SS, FB Pins ...................................................... 6V
Maximum Junction Temperature .......................... 125°C
Operating Temperature Range (Note 2) ...–40°C to 85°C
Storage Temperature Range ..................–65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
T
JMAX
= 125°C, θ
JA
= 45°C/W, θ
JC
= 10°C/W
LT1940EFE
LT1940LEFE
ABSOLUTE AXI U RATI GS
W
WW
U
PACKAGE/ORDER I FOR ATIO
UUW
(Note 1)
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 5V, V
BOOST
= 8V unless otherwise noted. (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Operating Voltage ● 3.4 3.6 V
Quiescent Current Not Switching 3.8 4.8 mA
Shutdown Current V
RUNSS
= 0V 30 45 µA
Feedback Voltage 1.230 1.250 1.270 V
0°C to 70°C
● 1.225 1.250 1.270 V
–40°C to 85°C ● 1.215 1.250 1.270 V
FB Pin Bias Current V
FB
= 1.25V, V
C
= 0.4V ● 240 1200 nA
Reference Line Regulation LT1940: V
IN
5V to 25V 0.005 %/V
LT1940L: V
IN
4V to 7V 0.005 %/V
Error Amp GM 330 uMhos
Error Amp Voltage Gain 180
V
C
Source Current V
FB
= 1V 42 µA
V
C
Sink Current V
FB
= 1.5V 60 µA
V
C
Pin to Switch Current Gain 2.4 A/V
V
C
Switching Threshold 0.75 V
V
C
Clamp Voltage 1.8 V
Switching Frequency V
FB
= 1.1V 1 1.1 1.25 MHz
● 0.95 1.1 1.35 MHz
Switching Phase 150 180 210 Deg
Maximum Duty Cycle ● 78 88 %
Frequency Shift Threshold on FB f
SW
= 1MHz 0.5 V
Consult LTC Marketing for parts specified with wider operating temperature ranges.
FE PACKAGE
16-LEAD PLASTIC TSSOP
EXPOSED PAD (PIN 17) IS GND
MUST BE SOLDERED TO PCB
1
2
3
4
5
6
7
8
TOP VIEW
16
15
14
13
12
11
10
9
BOOST1
SW1
V
IN
V
IN
V
IN
V
IN
SW2
BOOST2
FB1
V
C1
PG1
RUN/SS1
RUN/SS2
PG2
V
C2
FB2
17
FE PART
MARKING
1940EFE
1940LEFE