LTC1701 Datasheet, PDF (1/12 Pages) Linear Technology – 1MHz Step-Down DC/DC Converter in SOT-23

Final Electrical Specifications
LTC1701
1MHz Step-Down
DC/DC Converter in SOT-23
December 1999
FEATURES
DESCRIPTIO
s _{Tiny 5-Lead SOT-23 Package}
s _{Uses Tiny Capacitors and Inductor}
s _{High Frequency Operation: 1MHz}
s _{High Output Current: 500mA}
s _{Low RDS(ON) Internal Switch: 0.28Ω}
s _{High Efficiency: Up to 94%}
s _{Current Mode Operation for Excellent Line}
and Load Transient Response
s _{Short-Circuit Protected}
s _{Low Quiescent Current: 135µA}
s _{Low Dropout Operation: 100% Duty Cycle}
s _{Ultralow Shutdown Current: IQ < 1µA}
s _{Peak Inductor Current Independent of Inductor Value}
s _{Output Voltages from 5V Down to 1.25V}
U
APPLICATIO S
s _{PDAs/Palmtop PCs}
s _{Digital Cameras}
s _{Cellular Phones}
s _{Portable Media Players}
s _{PC Cards}
s _{Handheld Equipment}
The LTC^®1701 is the industry’s first 5-lead SOT-23 step
down, current mode, DC/DC converter. Intended for small
to medium power applications, it operates from 2.5V to
5.5V input voltage range and switches at 1MHz, allowing
the use of tiny, low cost capacitors and inductors 2mm or
less in height. The output voltage is adjustable from 1.25V
to 5V. A built-in 0.28Ω switch allows up to 0.5A of output
current at high efficiency. OPTI-LOOP^TM compensation
allows the transient response to be optimized over a wide
range of loads and output capacitors.
The LTC1701 incorporates automatic power saving Burst
Mode^TM operation to reduce gate charge losses when the
load current drops below the level required for continuous
operation. With no load, the converter draws only 135µA.
In shutdown, it draws less than 1µA, making it ideal for
current sensitive applications.
In dropout, the internal P-channel MOSFET switch is
turned on continuously, thereby maximizing battery life.
Its small size and switching frequency enables the com-
plete DC/DC converter function to consume less than 0.3
square inches of PC board area.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode and OPTI-LOOP are trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
V_IN
2.5V TO
5.5V
C1 ⁺
10µF
V_IN
SW
R4
1M
LTC1701
I_TH/RUN
V_FB
R3
GND
5.1k
C3
330pF
L1
4.7µH
D1
R2
121k
+
R1
121k
C1: TAIYO YUDEN JMK316BJ106ML
C2: SANYO POSCAP 6TPA47M
D1: MBRM120L
L1: SUMIDA CD43-4R7
Figure 1. Step-Down 2.5V/500mA Regulator
V_OUT
(2.5V/
500mA)
C2
47µF
1701 F01
Efficiency Curve
100
V_IN = 3.3V
95
90
85
80
75
70
1
10
100
LOAD CURRENT (mA)
1000
1701 F01a
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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