LTC1624
High Efficiency SO-8
N-Channel Switching
Regulator Controller
FEATURES
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DESCRIPTION
The LTC
®
1624 is a current mode switching regulator
controller that drives an external N-channel power MOSFET
using a fixed frequency architecture. It can be operated in
all standard switching configurations including boost,
step-down, inverting and SEPIC. Burst Mode
TM
operation
provides high efficiency at low load currents. A maximum
high duty cycle limit of 95% provides low dropout operation
which extends operating time in battery-operated systems.
The operating frequency is internally set to 200kHz, allowing
small inductor values and minimizing PC board space. The
operating current level is user-programmable via an external
current sense resistor. Wide input supply range allows
operation from 3.5V to 36V (absolute maximum).
A multifunction pin (I
TH
/ RUN) allows external
compensation for optimum load step response plus
shutdown. Soft start can also be implemented with the
I
TH
/RUN pin to properly sequence supplies.
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N-Channel MOSFET Drive
Implements Boost, Step-Down, SEPIC
and Inverting Regulators
Wide V
IN
Range: 3.5V to 36V Operation
Wide V
OUT
Range: 1.19V to 30V in Step-Down
Configuration
±
1% 1.19V Reference
Low Dropout Operation: 95% Duty Cycle
200kHz Fixed Frequency
Low Standby Current
Very High Efficiency
Remote Output Voltage Sense
Logic-Controlled Micropower Shutdown
Internal Diode for Bootstrapped Gate Drive
Current Mode Operation for Excellent Line and
Load Transient Response
Available in an 8-Lead SO Package
APPLICATIONS
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Notebook and Palmtop Computers, PDAs
Cellular Telephones and Wireless Modems
Battery-Operated Digital Devices
DC Power Distribution Systems
Battery Chargers
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
TYPICAL APPLICATION
1000pF
SENSE
–
I
TH
/RUN
V
FB
100pF
GND
SW
V
IN
BOOST
TG
V
IN
4.8V TO 28V
R
SENSE
0.05Ω
M1
Si4412DY
C
B
0.1µF
D1
MBRS340T3
L1
10µH
C
C
470pF
R
C
6.8k
LTC1624
R2
35.7k
R1
20k
Figure 1. High Efficiency Step-Down Converter
U
U
U
+
C
IN
22µF
35V
×
2
V
OUT
3.3V
2A
+
C
OUT
100µF
10V
×
2
1624 F01
1
LINER [ LINEAR TECHNOLOGY ]
