LT1300 Linear Technology, LT1300 Datasheet - Page 4

• Manufacturer Part Number: LT1300
• Description: Micropower High Efficiency 3.3/5V Step-Up DC/DC Converter
• Manufacturer: Linear Technology

BLOCK
LT1300
PIN
GND (Pin 1): Signal Ground.
Sel (Pin 2): Output Select. When tied to V
converter regulates at 5V. When grounded converter
regulates at 3.3V.
SHDN (Pin 3): Shutdown. Pull high to effect shutdown. Tie
to ground for normal operation.
Sense (Pin 4): “Output” Pin.
I
for approximately 400mA. A resistor between I
ground sets peak current to some intermediate value (see
Figure 5).
4
LIM
U
(Pin 5): Float for 1A switch current limit. Tie to ground
FUNCTIONS
V
U
IN
+
DIAGRAM
C1
REFERENCE
U
1.25V
W
1
4
GND
SENSE
144k
161k
500k
2
SELECT
+
–
A1
COMPARATOR
IN
or V
LIM
ENABLE
and
OUT
Figure 1.
SHUTDOWN
OSCILLATOR
2
155kHZ
V
value electrolytic to ground. A 0.1 F ceramic capacitor
close to the pin may be needed in some cases.
SW (Pin 7): Switch Pin. Connect inductor and diode here.
Keep layout short and direct to minimize electronic radia-
tion.
PGND (Pin 8): Power Ground. Tie to signal ground (pin 1)
under the package. Bypass capacitor from V
tied directly to the pin.
3
V
IN
IN
OFF
(Pin 6): Supply Pin. Must be bypassed with a large
COMPARATOR
A2 CURRENT
A3 DRIVER
BIAS
L1
+
–
5
Q3
8.5k
730
18mV
I
R2
LIM
Q2
1x
3
R1
7
8
PGND
Q1
160x
SW
D1
LT1300 F1
IN
should be
V
+
OUT
C2