Datasheet
10
LT1249
TYPICAL APPLICATION
U
300W, 382V Preregulator
–
+
–
+
VA
OUT
7.5V
EA
1V
–
+
M1
–
+
–
+
–
+
I
M
=
I
A
2
I
B
200µA
2
25k
I
A
I
B
I
M
16V/10V
g
m
= 1/3k
0.7V
–
+
OSC
SYNC
R
S
Q
6
5
3
4
2
1
8
MULTIPLIER
I
AC
V
SENSE
M
OUT
7
CA
OUT
V
CC
CA
RUN
RUN
GTDR
16V
35pF
20µA
MAX
250µA
1N5819
+
4.7nF
1M
0.047µF
0.47µF
330k
10k
44µA
22µA
15µA
100pF
1nF
20k
4k
V
OUT
180µF
90V
TO
270V
EMI
FILTER
+
–
R
MOUT
4k
R
S
0.2Ω
750µH*
1M
MURH860
V
CC
GND
†
1249 TA01
IRF840
6A
10Ω
7.5V
V
REF
**
1.COILTRONICS CTX02-12236 (TYPE 52 CORE)
AIR MOVEMENT NEEDED AT POWER LEVEL GREATER THAN 250W.
2.COILTRONICS CTX02-12295 (MAGNETICS Kool M µ
®
77930 CORE)
THIS SCHOTTKY DIODE IS TO CLAMP GTDR WHEN MOS SWITCH TURNS OFF.
PARASITIC INDUCTANCE AND GATE CAPACITANCE MAY TURN ON CHIP SUBSTRATE
DIODE AND CAUSE ERRATIC OPERATIONS IF GTDR IS NOT CLAMPED.
*
**
† SEE APPLICATIONS INFORMATION SECTION FOR CIRCUITRY TO SUPPLY POWER TO V
CC
.
Kool Mµ is a registered trademark of Magnetics, Inc.