Datasheet

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