Data Sheet
11
LT1248
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
300W, 382V Preregulator
Kool Mµ is a registered trademark of Magnetics, Inc.
–
+
–
+
I
M
=
I
A
2
I
B
200µA
2
VA
OUT
7.5V
7.9V
12µA
5V
EA
V
REF
–
+
–
+
–
+
2.2V
25k
I
A
I
B
7µA
I
M
7.5V
V
REF
–
+
V
CC
16V TO 10V
2.6V/2.2V
–
+
0.7V
–
+
OSC
R
R
S
Q
C
SET
R
SET
6
11
10
7
9
5
4
2
1
15
16
12
14
SS
OVP
I
AC
V
SENSE
EN/SYNC
M
OUT
I
SENSE
3
CA
OUT
V
CC
RUN
CA
RUN
16V
GND
–
+
GTDR
1000pF
SYNC
1N5819
+
+
†
4.7nF
1M
20k
0.47µF
0.047µF
330k
0.1µF
1nF
8
0.01µF
13
100pF
PK
LIM
20k
1%
R
REF
4k
V
OUT
180µF
T
90V
TO
270V
EMI
FILTER
+
–
4k
20k
R
S
0.2Ω
50k
750µH*
1M
1%
MURH860
V
CC
= 18V**
56µF
35V
10Ω
15k
–
+
1248 TA01
IRF840
ONE SHOT
200ns
6A
M1
1.COILTRONICS CTX02-12236-1 (TYPE 52 CORE)
AIR MOVEMENT NEEDED AT POWER LEVEL GREATER THAN 250W.
2.COILTRONICS CTX02-12295 (MAGNETICS Kool M µ
®
77930 CORE)
SEE STARTUP AND SUPPLY VOLTAGE SECTION FOR V
CC
GENERATOR.
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.
*
**
†
U
A
O
PP
L
IC
AT
ITY
P
I
CA
L