LT1247 Linear Technology, LT1247 Datasheet - Page 10

• Manufacturer Part Number: LT1247
• Description: 1MHz Off-Line Current Mode PWM and DC/DC Converter
• Manufacturer: Linear Technology

LT1246/LT1247
10
TYPICAL
C
R2
R1
100k
A
FEEDBACK
COMP
R
V
PPLICATI
T
REF
8
4
1
2
/C
T
C
V
CLAMP
R
2.5V
–
+
FEEDBACK
(
I
COMP
R2
R1
V
SENSE
1.67
REF
8
1
2
3
+ 1
O
(
EXTERNAL
U
INPUT
SYNC
S
–
+
I
PK (MAX)
2.5V
Adjustable Clamp Level with Soft Start
1mA
0.01 F
External Clock Synchronization
47
V
5.6V
R
CLAMP
OSCILLATOR
T
R
S
2R
R
R
V
T
REF
C
8
4
/C
T
1mA
T
Soft Start
MAIN BIAS
D1
WHERE: O V
5V REF
OSCILLATOR
1V
5.6V
–
+
5V REF
D1 IS REQUIRED IF THE SYNC AMPLITUDE IS
LARGE ENOUGH TO PULL THE BOTTOM OF C
MORE THAN 300mV BELOW GROUND.
2R
R
5V REF
CLAMP
REFERENCE PULLDOWN
REFERENCE ENABLE
1.0V
1V
–
+
BLANKING
R
S
t
SOFT START
1.5V
1.5V
= –ln 1 –
PULLDOWN
+
–
–
+
OUTPUT
LOCKOUT
T
UV
3 • V
LT1246 • TA05
18V
LT1246 • TA06
V
CLAMP
C
C
OUTPUT
I
R1 + R2
R1 R2
GND
SENSE
V
CC
7
6
5
3
LT1246 • TA07
R
S
V
IN