2
LT1425
ABSOLUTE MAXIMUM RATINGS
W
WW
U
PACKAGE/ORDER INFORMATION
W
U
U
T
JMAX
= 145°C, θ
JA
= 75°C/ W
TOP VIEW
S PACKAGE
16-LEAD PLASTIC SO
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
GND
NC
R
FB
V
C
R
REF
SYNC
SGND
GND
GND
SHDN
R
OCOMP
R
CCOMP
V
IN
V
SW
PGND
GND
ORDER PART
NUMBER
LT1425CS
LT1425IS
ELECTRICAL CHARACTERISTICS
V
IN
= 5V, T
J
= 25°C, V
SW
open, V
C
= 1.4V, unless otherwise specified.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Feedback Amplifier
I
REF
Reference Current Measured at R
FB
Pin with R
REF
= 3.000k 402 408 414 µA
● 396 420 µA
I
IN
R
REF
Pin Input Current 500 nA
g
m
Feedback Amplifier Transconductance ∆I
C
= ±10µA (Note 2) ● 400 1000 1600 µmho
I
SOURCE
, I
SINK
Feedback Amplifier Source or Sink Current ● 30 50 80 µA
V
CL
Feedback Amplifier Clamp Voltage 1.9 V
Reference Voltage/Current Line Regulation 5V ≤ V
IN
≤ 18V ● 0.01 0.04 %/V
Voltage Gain (Note 3) 500 V/V
V
IN
Sense Error ● 10 25 mV
Output Switch
BV Output Switch Breakdown Voltage I
C
= 5mA ● 35 50 V
V(V
SW
) Output Switch ON Voltage I
SW
= 1A ● 0.55 0.85 V
I
LIM
Switch Current Limit Duty Cycle = 50%, 0°C ≤ T
J
≤ 100°C ● 1.35 1.60 1.9 A
Duty Cycle = 50%, –40°C ≤ T
J
≤ 100°C ● 1.25 1.60 1.9 A
Duty Cycle = 80% 1.30 A
Current Amplifier
Control Pin Threshold Duty Cycle = Minimum 0.95 1.2 1.3 V
● 0.85 1.4 V
Control Voltage to Switch Transconductance 2 A/V
Timing
f Switching Frequency 260 285 300 kHz
● 240 320 kHz
t
ON
Minimum Switch ON Time 170 210 260 ns
t
ED
Flyback Enable Delay Time 150 ns
t
EN
Minimum Flyback Enable Time 180 ns
Maximum Switch Duty Cycle ● 85 90 95 %
Consult factory for Military grade parts.
(Note 1)
Supply Voltage ........................................................ 20V
Switch Voltage......................................................... 35V
SHDN, SYNC Pin Voltage........................................... 7V
R
FB
Pin Current....................................................... 2mA
Operating Junction Temperature Range
Commercial .......................................... 0°C to 100°C
Industrial ......................................... –40°C to 100°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)..................300°C
