lt1303-5 Linear Technology Corporation, lt1303-5 Datasheet - Page 5

• Manufacturer Part Number: lt1303-5
• Description: Micropower High Efficiency Dc/dc Converters With Low-battery Detector Adjustable And Fixed 5v
• Manufacturer: Linear Technology Corporation

PIN
GND (Pin 1): Signal Ground. Tie to PGND under the
package.
LBO (Pin 2): Open-Collector Output of Low-Battery Com-
parator. Can sink 100 A. Disabled when device is in
shutdown.
SHDN (Pin 3): Shutdown. Pull high to shut down the
device. Ground for normal operation.
FB/Sense (Pin 4): On 1303 (adjustable) this pin connects
to the main comparator C1 input. On LT1303-5 this pin
connects to the resistor string that sets output voltage
at 5V.
BLOCK
U
FUNCTIONS
U
I D AGRA
R1
R2
V
IN
+
U
C1
4
W
FB
REFERENCE
S
1
1.24V
GND
6
V
IN
5
LBI
–
+
COMPARATOR
HYSTERETIC
Figure 2. LT1303 Block Digram
C1
–
+
C3
OSCILLATOR
LBI (Pin 5): Low-Battery Comparator Input. When voltage
on this pin below 1.24V, LBO is low.
V
value electrolytic to ground. Keep bypass within 0.2" of the
device.
SW (Pin 7): Switch Pin. Connect inductor and diode here.
Keep layout short and direct to minimize radio frequency
interference.
PGND (Pin 8): Power ground. Tie to signal ground (pin1)
under the package. Bypass capacitor from V
tied directly to PGND within 0.2" of the device.
COMPARATOR
OFF
IN
2
LBO
CURRENT
(Pin 6): Supply Pin. Must be bypassed with a large
DRIVER
A3
C2
SHUTDOWN
+
–
3
18mV
L1
Q2
1
R1
3
LT1303/LT1303-5
7
8
Q1
160
SW
PGND
D1
+
LT1303 BD01
C2
IN
should be
5