Datasheet
LTC3617
1
3617fa
Features
applications
Description
±6A Monolithic Synchronous
Step-Down Regulator
for DDR Termination
The LTC
®
3617 is a high efficiency monolithic synchronous
buck regulator utilizing a current mode, constant frequency
architecture. It operates from an input voltage range of
2.25V to 5.5V and provides a regulated output voltage
equal to 0.5 • VDDQIN while sourcing and sinking up to
6A of load current. An internal amplifier provides a VTTR
output voltage equal to 0.5 • VDDQIN with an output cur-
rent capability of ±10mA.
The operating frequency is externally programmable up to
4MHz, allowing the use of small surface mount inductors.
For switching-noise-sensitive applications, the LTC3617
can be synchronized to an external clock up to 4MHz.
Forced continuous mode operation in the LTC3617 reduces
noise and RF interference. Adjustable external compensa-
tion 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, minimizing
external component count and board space. The LTC3617
is offered in a leadless 24-pin 3mm × 5mm thermally
enhanced QFN package.
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode 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, 6498466, 6611131.
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±6A Output Current
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2.25V to 5.5V Input Voltage Range
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±10mV Output Voltage Accuracy
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Optimized for Low Output Voltages Down to 0.5V
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High Efficiency
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Integrated Buffer for VTTR = VDDQIN • 0.5
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Shutdown Current: <1µA
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Adjustable Switching Frequency: Up to 4MHz
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Optional Internal Compensation
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Internal Soft-Start
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Power Good Status Output
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Input Overvoltage Protected
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Thermally Enhanced 24-Pin 3mm × 5mm
QFN Package
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DDR Termination
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Supports DDR, DDR2 and DDR3 Standards
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Tracking Supplies
typical application
Efficiency and Power Loss
vs Load Current
LOAD CURRENT (A)
30
EFFICIENCY (%)
POWER LOSS (W)
90
100
20
10
80
50
70
60
40
0.1 1 10
3617 TA01b
0
1
10
0.1
0.01
0.1µF
V
REF
1.25V
±10mA
RUN
VDDQIN
RT
PGOOD
ITH
SGND
PGND
V
IN
2.5V
VTTR
SV
IN
LTC3617
SW
PV
IN
0.15µH
3617 TA01a
22µF
×4
SYNC V
FB
47µF
×2
VTT
1.25V
±6A