LTC3605A_15 Datasheet, PDF (1/22 Pages) Linear Technology – 20V, 5A Synchronous Step-Down Regulator

Features
nn _{High Efficiency: Up to 96%}
nn _{5A Output Current}
nn _{4V to 20V VIN Range}
nn _{Integrated Power N-Channel MOSFETs}
(70mΩ Top and 35mΩ Bottom)
nn _{Adjustable Frequency 800kHz to 4MHz}
nn _PolyPhase^® _{Operation (Up to 12 Phases)}
nn _{Output Tracking}
nn _{0.6V ±1% Reference Accuracy}
nn _{Current Mode Operation for Excellent Line and Load}
Transient Response
nn _{Shutdown Mode Draws Less Than 15µA Supply Cur-}
rent
nn _{LTC3605: 15V Absolute Maximum VIN}
nn _{LTC3605A: 22V Absolute Maximum VIN}
nn _{The LTC3605A Is Pin Compatible with the LTC3605}
nn _{Available in 24-Pin (4mm × 4mm) QFN Package}
Applications
nn _{Point of Load Power Supply}
nn _{Portable Instruments}
nn _{Distributed Power Systems}
nn _{Battery-Powered Equipment}
LTC3605A
20V, 5A Synchronous
Step-Down Regulator
Description
The LTC^®3605A is a high efficiency, monolithic synchro-
nous buck regulator using a phase lockable controlled
on-time constant frequency, current mode architecture.
PolyPhase operation allows multiple LTC3605A regula-
tors to run out of phase while using minimal input and
output capacitance. The operating supply voltage range
is from 20V down to 4V, making it suitable for dual, triple
or quadruple lithium-ion battery inputs as well as point
of load power supply applications from a 12V or 5V rail.
The operating frequency is programmable from 800kHz to
4MHz with an external resistor. The high frequency capa-
bility allows the use of small surface mount inductors. For
switching noise sensitive applications, it can be externally
synchronized from 800kHz to 4MHz. The PHMODE pin
allows user control of the phase of the outgoing clock
signal. The unique constant frequency/controlled on-time
architecture is ideal for high step-down ratio applications
that are operating at high frequency while demanding
fast transient response. Two internal phase-lock loops
synchronize the internal oscillator to the external clock
and also servos the regulator on-time to lock on to either
the internal clock or the external clock if it’s present.
L, LT, LTC, LTM, PolyPhase, OPTI-LOOP, Linear Technology and the Linear logo 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,
5847554, 6580258, 6304066, 6476589, 6774611.
Typical Application
V_IN
4V TO 20V
High Efficiency 1MHz, 5A Step-Down Regulator
22µF
×2
V_IN
PV_IN
SV_IN
CLKOUT INTV_CC
CLKIN
PGOOD ^BOOST
LTC3605A
SW
V_ON
RUN
FB
ITH
RT
162k
2.2µF
0.1µF _1µH
11.5k
16k
220pF
3605A TA01a
2.55k
V_OUT
3.3V
47µF
×2
PGND
Efficiency and Power Loss
100
10
V_OUT = 3.3V
90
80
70
1
60
50
40
30
0.1
20
10
0
0.01
0.1
1
LOAD CURRENT (A)
V_IN = 8V
V_IN = 12V
V_IN = 20V _0.01
10
3605A TA01b
For more information www.linear.com/LTC3605A
3605afc
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