LT1952 Linear Technology, LT1952 Datasheet - Page 9

• Manufacturer Part Number: LT1952
• Description: Single Switch Synchronous Forward Controller
• Manufacturer: Linear Technology

BLOCK DIAGRA
TI I G DIAGRA
W U
SD_V
SYNC
R
SEC
OSC
7
3
4
14.25V ON
8.75V OFF
–
–
1.32V
V
15
+
IN
+
W
1.23V
FB
W
460µA START-UP
INPUT CURRENT
2
SOUT
OUT
SS_MAXDC
I
11µA SD_V
0µA SD_V
FAULTS TRIGGERING SOFT-START
V
OR
SD_V
OR
OC > 100mV (OVER-CURRENT)
HYST
IN
+
–
< 8.75V
SEC
(VOLTAGE)
ERROR AMPLIFIER
< 1.32V (UVLO)
SEC
SEC
> 1.32V
= 1.32V
t
DELAY
–
+
: PROGRAMMABLE SYNCHRONOUS DELAY
(TYPICAL 200kHz)
OSC
(100 TO 500)kHz
COMP
1.23V
1
Figure 1. Timing Diagram
Figure 2. Block Diagram
V
REF
6
2.5V
SOURCE
2.5mA
SS_MAXDC
SOFT-START
RAMP
LATCH SET
5
GND
8
–
+
35µA 80% DC
SLOPE COMP
8µA 0% DC
(LINEAR)
DUTY CYCLE
MAXIMUM
ADAPTIVE
0.45V
0mV TO 220mV
CLAMP
SOFT-START LATCH RESET:
V
AND
SD_V
AND
OC < 100mV
AND
SS_MAXDC < 0.45V
IN
> 14.25V (> 8.75V IF LATCH SET BY OC)
SEC
+
–
> 1.32V
–
CURRENT
SENSE
S
R
0.8V (ACTIVE THRESHOLD)
0.45V (RESET THRESHOLD)
0.2V
Q
+
Q
R
S
SOFT-START CONTROL
DELAY
DELAY
ON
12
BLANK
BLANK
9
1952 F01
DRIVER
±1A
13V
100mV
www.DataSheet4U.com
–
CURRENT
OVER
>90%
V
±50mA
REF
+
12V
1952 BD
11 OC
10
16 SOUT
14
13
LT1952
OUT
PGND
I
SENSE
9
1952f