Datasheet

LTC3600
1
3600fc
Typical applicaTion
FeaTures DescripTion
15V, 1.5A Synchronous
Rail-to-Rail Single Resistor
Step-Down Regulator
The LTC3600 is a high efficiency, monolithic synchronous
buck regulator whose output is programmed with just one
external resistor. The accurate internally generated 50µA
current source on the ISET pin allows the use of a single
external resistor to program an output voltage that ranges
from 0V to 0.5V below V
IN
. The V
OUT
voltage feeds directly
back to the error amplifier in unity gain fashion and equals
the ISET voltage. The operating supply voltage range is 4V
to 15V, making it suitable for dual lithium-ion battery and
5V or 12V input point-of-load power supply applications.
The operating frequency is synchronizable to an external
clock or programmable from 200kHz to 4MHz with an
external resistor. High switching frequency allows the use
of small surface mount inductors. The unique constant
on-time architecture is ideal for operating at high frequency
in high step-down ratio applications that also demand fast
load transient response.
Efficiency and Power Loss vs
Output Current
applicaTions
n
Single Resistor Programmable V
OUT
n
±1% I
SET
Accuracy
n
Tight V
OUT
Regulation Independent of V
OUT
Voltage
n
Easy to Parallel for Higher Current and Heat Spreading
n
Wide V
OUT
Range 0V to V
IN
– 0.5V
n
High Efficiency: Up to 96%
n
1.5A Output Current
n
Adjustable Frequency: 200kHz to 4MHz
n
4V to 15V V
IN
Range
n
Current Mode Operation for Excellent Line and Load
Transient Response
n
Zero Supply Current in Shutdown
n
Available in Thermally Enhanced 12-Pin
(3mm × 3mm) DFN and MSOP Packages
n
Voltage Tracking Supplies
n
Point-of-Load Power Supplies
n
Portable Instruments
n
Distributed Power Systems
L, LT, LTC, LTM, Linear Technology, the Linear logo and OPTI-LOOP are registered trademarks
and Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents, including 5481178, 5705919,
5847554, 6580258.
LOAD CURRENT (A)
EFFICIENCY (%)
POWER LOSS (W)
0.001 0.1 1 100.01
3600 TA01b
V
IN
= 12V
V
OUT
= 2.5V
CCM
CCM
DCM
40
50
60
70
80
30
20
10
0
90
100
0.4
0.5
0.6
0.7
0.8
0.3
0.2
0.1
0
0.9
1.0
DCM
POWER
LOSS
High Efficiency, 1MHz, 1.5A Step-Down Converter
3600 TA01a
50µA
10µF
F
0.1µF
22µF
2.2µH
V
IN
12V
V
OUT
V
OUT
2.5V
V
IN
INTV
CC
ISET
RT PGFBGND ITH PGOOD
RUN
BOOST
SW
LTC3600
MODE/
SYNC
0.1µF
49.9k
PWM CONTROL
AND SWITCH
DRIVER
8
5
7
9
1 6 10
3 4 2 12
11
13
+
ERROR
AMP

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