LT1952IGN Linear Technology, LT1952IGN Datasheet - Page 9

• Manufacturer Part Number: LT1952IGN
• Description: IC,SMPS CONTROLLER,CURRENT-MODE,SOP,16PIN,PLASTIC
• Manufacturer: Linear Technology

BLOCK DIAGRA
TI I G DIAGRA
W U
ISTART = 460µA
V
ISTART = 400µA
V
V
V
IN
IN
IN
IN
LT1952-1
ON = 14.25V
OFF = 8.75V
LT1952
ON = 7.75V
OFF = 6.5V
SD_V
SYNC
R
OSC
SEC
7
3
4
V
V
IN
IN
–
–
OFF
ON
W
1.32V
V
W
15
+
IN
+
SOUT
OUT
SS_MAXDC
1.23V
FB
2
START-UP
INPUT CURRENT (ISTART)
FAULTS TRIGGERING SOFT-START
V
OR
SD_V
OR
OC > 107mV (OVER-CURRENT)
IN
< 8.75V
I
11µA SD_V
0µA SD_V
HYST
SEC
+
–
< 1.32V (UVLO)
(VOLTAGE)
ERROR AMPLIFIER
SEC
SEC
> 1.32V
t
= 1.32V
DELAY
: PROGRAMMABLE SYNCHRONOUS DELAY
–
+
(TYPICAL 200kHz)
OSC
Figure 1. Timing Diagram
(100 TO 500)kHz
COMP
1.23V
Figure 2. Block Diagram
1
V
REF
6
2.5V
SOURCE
2.5mA
SOFT-START
LATCH SET
SS_MAXDC
RAMP
5
GND
8
–
+
35µA 80% DC
SLOPE COMP
8µA 0% DC
(LINEAR)
SOFT-START LATCH RESET:
V
AND
SD_V
AND
OC < 107mV
AND
SS_MAXDC < 0.45V
DUTY CYCLE
IN
MAXIMUM
ADAPTIVE
0.45V
0mV TO 220mV
CLAMP
> 14.25V (> 8.75V IF LATCH SET BY OC)
SEC
> 1.32V
+
–
–
CURRENT
0.8V (ACTIVE THRESHOLD)
0.45V (RESET THRESHOLD)
0.2V
SENSE
S
R
Q
+
Q
R
S
SOFT-START CONTROL
DELAY
DELAY
ON
12
LT1952/LT1952-1
1952 F01
BLANK
BLANK
9
DRIVER
±1A
13V
107mV
–
CURRENT
OVER
>90%
V
±50mA
REF
+
12V
1952 BD
11 OC
10
16 SOUT
14
13
OUT
PGND
I
SENSE
19521fb
9