LTC3612_15 Datasheet, PDF (1/30 Pages) Linear Technology – 3A, 4MHz Monolithic Synchronous Step-Down DC/DC Converter

LTC3612
Features
n _{3A Output Current}
n _{2.25V to 5.5V Input Voltage Range}
n _{Low Output Ripple Burst Mode}^® _{Operation: IQ = 70µA}
n _{±1% Output Voltage Accuracy}
n _{Output Voltage Down to 0.6V}
n _{High Efficiency: Up to 95%}
n _{Low Dropout Operation: 100% Duty Cycle}
n _{Shutdown Current: ≤1µA}
n _{Adjustable Switching Frequency: Up to 4MHz}
n _{Optional Active Voltage Positioning (AVP) with}
Internal Compensation
n _{Selectable Pulse-Skipping/Forced Continuous/}
Burst Mode Operation with Adjustable Burst Clamp
n _{Programmable Soft-Start}
n _{Inputs for Start-Up Tracking or External Reference}
n _{DDR Memory Mode, IOUT = ±1.5A}
n _{Available in Thermally Enhanced 20-Pin}
(3mm × 4mm) QFN and TSSOP Packages
Applications
n _{Point-of-Load Supplies}
n _{Distributed Power Supplies}
n _{Portable Computer Systems}
n _{DDR Memory Termination}
n _{Handheld Devices}
3A, 4MHz Monolithic
Synchronous Step-Down
DC/DC Converter
Description
The LTC^®3612 is a low quiescent current monolithic syn-
chronous buck regulator using a current mode, constant
frequency architecture. The no-load DC supply current
in sleep mode is only 70µA while maintaining the output
voltage (Burst Mode operation) at no load, dropping to
zero current in shutdown. The 2.25V to 5.5V input supply
voltage range makes the LTC3612 ideally suited for single
Li-Ion as well as fixed low voltage input applications. 100%
duty cycle capability provides low dropout operation,
extending the operating time in battery-powered systems.
The operating frequency is externally programmable up to
4MHz, allowing the use of small surface mount inductors.
For switching noise-sensitive applications, the LTC3612
can be synchronized to an external clock at up to 4MHz.
Forced continuous mode operation in the LTC3612 reduces
noise and RF interference. Adjustable compensation allows
the transient response to be optimized over a wide range
of loads and output capacitors.
The internal synchronous switch increases efficiency and
eliminates the need for an external catch diode, saving
external components and board space. The LTC3612 is
offered in a leadless 20-pin 3mm × 4mm QFN or a thermally
enhanced 20-pin TSSOP package.
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners. Protected by U.S. Patents, including 6580258, 5481178, 5994885, 6304066, 6498466,
6611131.
Typical Application
V_IN
2.5V TO 5.5V
SV_IN
RUN
TRACK/SS
PV_IN
PV_{IN_DRV}
DDR
RT/SYNC
LTC3612 SW
PGOOD
SGND
ITH
PGND
MODE
V_FB
210k
22µF
×2
560nH
47µF
V_OUT
2.5V
3A
665k
3612 TA01a
Efficiency and Power Loss vs Load Current
100
10
90
80
1
70
60
0.1
50
40
0.01
30
20
V_IN = 5V ^0.001
10
V_IN = 3.3V
0
V_IN = 2.8V
1
10
100
1000 10000
OUTPUT CURRENT (mA) 3612 TA01b
For more information www.linear.com/LTC3612
3612fc
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