LTC3613
24V, 15A Monolithic
Step Down Regulator with
Differential Output Sensing
DESCRIPTION
The LTC®3613 is a monolithic synchronous step-down
switching regulator capable of regulating outputs from 0.6V
to5.5Vwithupto15Aoutputcurrent.Thecontrolledon-time
constantfrequencyvalleycurrentmodearchitectureallowsfor
bothfasttransientresponseandconstantfrequencyswitch-
FEATURES
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Wide V Range: 4.5V to 24V;
IN
V
OUT
Range: 0.6V to 5.5V at up to 15A
0.67% Output Voltage Accuracy
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Controlled On-Time Valley Current Mode Architecture,
Excellent Current Sharing Capability
Frequency Programmable from 200kHz to 1MHz
and Synchronizable to External Clock
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ing in steady-state operation, independent of V , V
and
IN OUT
load. This also provides excellent current sharing capability.
R
or Inductor DCR Current Sensing With
SENSE
Differential output voltage sensing along with a precision
internal reference combine to offer 0.6ꢀ7 output regula-
tion, even if the output ground reference deviates from
local ground by 500mV. The switching frequency can be
programmedfrom200kHzto1MHzwithanexternalresis-
tor. The switching frequency is also phase synchronizable
to an external clock in applications where switching noise/
EMI reduction is crucial.
Accurate Current Limit
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Fast Transient Response
Differential Output Voltage Sensing Allowing 500mV
Common Mode Remote Ground
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t
= 65ns; t
= 105ns
ON(MIN)
OFF(MIN)
Overvoltage Protection and Current Limit Foldback
Power Good Output Voltage Monitor
Voltage Tracking Start-Up
Verylowt andt timesallowfornear07andnear1007
External V Input for Bypassing Internal LDO
Micropower Shutdown: I = 15μA
ꢀmm × 9mm 56-pin QFN Package
ON
OFF
CC
duty cycles, respectively. Voltage tracking soft start-up is
providedfortrackingandsequencingapplications.Safetyfea-
turesincludeoutputovervoltageprotection, programmable
current limit with foldback, and power good monitoring.
L, LT, LTC, LTM, OPTI-LOOP, Linear Technology and the Linear logo are registered trademarks
Q
APPLICATIONS
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Distributed Power System
and Hot Swap and No R
is a trademark of Linear Technology Corporation. All other
SENSE
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trademarks are the property of their respective owners. Protected by U.S. Patents including
54811ꢀ8, 548ꢀ554, 6580258, 6304066, 64ꢀ6589, 6ꢀꢀ4611.
Point-of-Load Converters
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Servers
TYPICAL APPLICATION
Efficiency and Power Loss
vs Load Current
High Efficiency High Power Step-Down Converter
INTV
CC
PV
SV
100
90
80
ꢀ0
60
50
40
30
20
10
0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
IN
IN
V
IN
4.5V TO 24V
PULSE-SKIPPING MODE
+
0.1μF
82μF
LTC3613
PGOOD
100k
V
OUT
–
10Ω
10Ω
0.4ꢀμH
SENSE
SENSE
RUN
1000pF
0.1μF
FORCED
CONTINUOUS
MODE
+
V
RNG
V
1.5V
15A
1.5mΩ
OUT
MODE/PLLIN
SW
0.1μF
EXTV
CC
15k
TRACK/SS
BOOST
4ꢀpF
V
= 12V
OUT
IN
10k
V
= 1.5V
INTV
CC
+
2ꢀ0pF
4.ꢀμF
330μF
×2
0.01
0.1
1
10
21k
PGND
ITH
LOAD CURRENT (A)
115k
3613 TA01a
+
OSNS
–
RT
SGND
V
V
OSNS
3613 TA01
3613fa
1