LTC1626 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC1626' PDF : 12 Pages View PDF
LTC1626
PIN FUNCTIONS
PWR VIN (Pins 1, 13): Supply for the Power MOSFET and
Its Driver. Decouple this pin properly to ground.
VIN (Pin 2): Main Supply for All the Control Circuitry in
the LTC1626.
LBO (Pin 3): Open-Drain Output of the Low-Battery Com-
parator. This pin will sink current when Pin 4 (LBI) goes
below 1.25V. During shutdown, this pin is high imped-
ance.
LBI (Pin 4): The (–) Input of the Low-Battery Comparator.
The (+) input is connected to a reference voltage of 1.25V.
If not used, connect to VIN.
CT (Pin 5): External capacitor CT from Pin 5 to ground sets
the switch off-time. The operating frequency is dependent
on the input voltage and CT.
ITH (Pin 6): Feedback Amplifier Decoupling Point. The
current comparator threshold is proportional to Pin 6
voltage.
SENSE – (Pin 7): Connects to the (–) Input of the Current
Comparator.
SENSE + (Pin 8): The (+) Input to the Current Comparator.
A built-in offset between Pins 7 and 8 in conjunction with
RSENSE sets the current trip threshold.
VFB (Pin 9): This pin serves as the feedback pin from an
external resistive divider used to set the output voltage.
SHDN (Pin 10): Shutdown Pin. Pulling this pin to VIN
keeps the internal switch off and puts the LTC1626 in
micropower shutdown. If not used, connect to SGND.
SGND (Pin 11): Small-Signal Ground. Must be routed
separately from other grounds to the (–) terminal of COUT.
PWR GND (Pin 12): Switch Driver Ground. Connects to
the (–) terminal of CIN.
SW (Pin 14): Drain of the P-Channel MOSFET Switch.
Cathode of the Schottky diode must be connected closely
to this pin.
BLOCK DIAGRAM
PWR VIN
1 13
SENSE+ SENSE–
8
7
PWR GND
12
14 SW
V
SLEEP
S
VTH2
VTH1
R
Q
S
–
T
+
OFF-TIME
CONTROL
5 CT
C
ITH
6
VIN
LBO
2
3
SENSE–
VFB
SGND 11
25mV TO 150mV
+
VOS
13k
G
REFERENCE
A3
9 VFB
10 SHDN
4 LBI
1626 BD
4
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