POWER LOSS (W)
LTC3815
6A Monolithic Synchronous DC/DC
Step-Down Converter with PMBus Interface
FEATURES DESCRIPTION
n
2.25V to 5.5V Input Voltage Range The LTC 3815 is a high efficiency, 6A monolithic synchro-
n
1% Total Output Voltage Accuracy Over
nous buck regulator using a phase lockable controlled
Temperature at V = 3.3V or 5V
on-time, current mode architecture. The output voltage
IN
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Single Resistor-Programmable Output Voltage
is programmable from 0.4V to 72% of V with a single
IN
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PMBus Compliant Serial Interface:
external resistor or an external voltage reference through
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Programmable Output Voltage Margining:
the reference input (REF) pin. The output voltage can be
Up to 25% V Range with 0.1% Resolution
OUT margined up or down up to 25% with 0.1% resolution
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Read back of Average and Peak Temperature,
via a PMBus-compliant serial interface. The serial inter-
Current, and Voltage (25Hz Refresh Rate)
face can also be used to read back fault status and both
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Fault Status
time-averaged (~4ms) and peak input/output current,
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Phase-Lockable Fixed Frequency Up to 3MHz
input/output voltage and temperature. System configu-
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Less Than 1ms Power-Up Time
ration and monitoring is supported by the LTpowerPlay
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Integrated 13-Bit ADC
development system.
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Optional External Reference Input
The architecture provides extremely fast transient
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Pin Selectable Fast-Margining of the Output Voltage
response and allows operation at the very low on-times
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Power Good Flag with Pin Programmable Thresholds
required to regulate low output voltages at high switching
and Filter Delay
frequencies. The operating frequency is programmable
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Differential Remote Output Voltage Sensing
n from 400kHz to 3MHz with an external resistor or for
Master Shutdown Mode: <1A Supply Current
n noise sensitive applications, it can be synchronized to an
Clock Out for 2-Phase Operation (12A Output Current)
n
external clock over the same range. The operating supply
Available in a Thermally-Enhanced 38-Lead
voltage range is from 2.25V to 5.5V making it suitable
4mm 6mm QFN Package
for operation from 2.5V, 3.3V or 5V rails or Lithium-Ion
APPLICATIONS
batteries.
n
All registered trademarks and trademarks are the property of their respective owners. Protected
Intelligent Energy Efficient Power Conversion
by U.S. Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258, 5408150,
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ASIC/FPGA/Processor Power
7420359. Licensed under U.S. Patent 7000125 and other related patents worldwide.
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Distributed Power Systems
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Point of Load Power Conversion
TYPICAL APPLICATION
Efficiency and Power Loss
vs Load Current
V
IN
2.25V TO 5.5V
10
100
C V = 1.8V
IN OUT
PV V
IN IN 90
LTC3815
80
EFFICIENCY
MODE/SYNC PGLIM
70
R TRACK/SS 1
T
RUN_MSTR RUN_STBY 60
L
V
OUT
50
SCL, SDA, ALERT
PMBUS SW 0.4V TO 0.72*V
IN
V 6A
CC_SENSE
40
MARGIN
POWER LOSS
C 0.1
OUT
V
WP 30
SS_SENSE
R
PGOOD C1
20
DA
OUT V = 2.8V
CLKOUT
IN
V = 3.3V
CSLEW FB 10 IN
V = 5V
IN
REF I
TH
0 0
ASEL PGFD
R
C2 10 100 1000 10000
C
C2
LOAD CURRENT (mA)
3815 TA01a
3815 TA01b
Rev B
1
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EFFICIENCY (%)LTC3815
ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION
(Notes 1, 7)
V , P ....................................................... 0.3V to 6V TOP VIEW
IN VIN
V , V , C , R , I , MODE/SYNC,
CC_SENSE SS_SENSE SLEW T TH
REF, TRACK/SS, PGFD, PGLIM, ASEL, DA , MARGIN,
OUT
38 37 36 35 34 33 32
RUN_STBY, FB .............................. 0.3V to (V + 0.3V)
IN
R 1 31 V
T SS_SENSE
RUN_MSTR, PGOOD, ALERT, SCL,
ASEL 2 30 TRACK/SS
SDA Voltage ............................................. 0.3V to 6V
MARGIN 3 29 PGOOD
WP ............................................................ 0.3V to 2.5V
WP C
4 28
SLEW
Operating Junction Temperature Range
ALERT RUN_STBY
5 27
(Notes 2, 3) ............................................ 40C to 125C
CLKOUT 6 26 RUN_MSTR
39
PGND
Storage Temperature Range .................. 65C to 125C SDA 7 24 PGFD
SCL 8 24 V
IN
MODE/SYNC 9 23 SW
SW 22 SW
10
SW 11 21 SW
NC 12 20 NC
13 14 15 16 17 18 19
UFE PACKAGE
38-LEAD (4mm 6mm) PLASTIC QFN
T = 125C, = 38C/W
JMAX JA
EXPOSED PAD (PIN 39) IS PGND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3815EUFE#PBF LTC3815EUFE#TRPBF 3815 38-Lead (4mm 6mm) Plastic QFN 40C to 125C
LTC3815IUFE#PBF LTC3815IUFE#TRPBF 3815 38-Lead (4mm 6mm) Plastic QFN 40C to 125C
Consult ADI Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.
Rev B
2
For more information www.analog.com
SW SGND
SW PGLIM
PV REF
IN
PV FB
IN
I
PV
IN TH
SW DA
OUT
SW V
CC_SENSE