POWER LOSS (mW)
LTC3869/LTC3869-2
Dual, 2-Phase
Synchronous Step-Down
DC/DC Controllers
Fea T
Descrip T
n
Dual, 180 Phased Controllers Reduce Required The LTC 3869 is a high performance dual synchronous
Input Capacitance and Power Supply Induced Noise step-down switching regulator controller that drives all
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Accurate Multiphase Current Matching N-channel synchronous power MOSFET stages. A constant
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R or DCR Current Sensing frequency current mode architecture allows a phase-
SENSE
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0.75% 0.6V Output Voltage Accuracy lockable frequency of up to 780kHz. Power loss and noise
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Phase-Lockable Fixed Frequency 250kHz to 780kHz due to the ESR of the input capacitors are minimized by
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High Efficiency: Up to 95% operating the two controller output stages out-of-phase.
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Dual N-channel MOSFET Synchronous Drive
OPTI-LOOP compensation allows the transient response
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Wide V Range: 4V to 38V (40V Max) Operation
IN
to be optimized over a wide range of output capacitance
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Wide V Range: 0.6V to 12.5V Operation
OUT
and ESR values. A wide 4V to 38V input supply range
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Adjustable Soft-Start Current Ramping or Tracking
encompasses most battery chemistries. Independent TK/
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Foldback Output Current Limiting
SS pins for each controller ramp the output voltage during
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Output Overvoltage Protection
start-up. Current foldback limits MOSFET heat dissipation
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Power Good Output Voltage Monitor
during short-circuit conditions. The MODE/PLLIN pin
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5V Low Dropout Regulator
selects among Burst Mode operation, pulse-skipping
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Small 28-Lead QFN and Narrow SSOP Packages
mode, or continuous inductor current mode and allows
the IC to be synchronized to an external clock.
a T
The LTC3869 is available in low profile 4mm 4mm and
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Server Systems
4mm 5mm QFN packages. The LTC3869-2 is available
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Telecom Systems
in an SSOP-28 package. The LTC3869 is pin-compatible
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Industrial and Medical Instruments
with the LTC3850.
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High Power Battery-Operated Devices
L, LT, LTC, LTM, Linear Technology, the Linear logo, Module, OPTI-LOOP, Burst Mode
n
DC Power Distribution Systems and PolyPhase are registered trademarks and No R is a trademark of Linear Technology
SENSE
Corporation. All other trademarks are the property of their respective owners. Protected by
U.S. Patents including 5481178, 5705919, 5929620, 6100678, 6144194, 6177787, 6580258,
6498466, 6611131.
Typical a T
High Efficiency Dual 5V/3.3V Step-Down Converter Efficiency and Power Loss
V
IN
7V TO
100 1300
24V
V = 12V, V = 3.3V
IN OUT
+
22F 90 V = 12V, V = 5V
IN OUT 1200
4.7F
V INTV
IN CC
80
1100
TG1 TG2
70
1000
EFFICIENCY
BOOST1 BOOST2
60
900
SW1 SW2
50
LTC3869
BG1 BG2
800
40
PGND
700
30
600
+ +
20
SENSE2
SENSE1
POWER LOSS
500
10
SENSE1
SENSE2
V V
OUT2
OUT1
V V 3.3V 0 400
5V
FB1 FB2
0.01 0.1 1 10
5A
5A 147k 90.9k
I
FREQ +
TH1
LOAD CURRENT (A)
I 56F
470pF TH2 3869 TA01b
470pF
TK/SS1 SGND TK/SS2
+
20k PINS NOT USED IN
47F 122k 20k
THIS CIRCUIT:
15k 0.1F 0.1F
15k
I , MODE/PLLIN,
LIM
PGOOD, RUN1, RUN2
3869 TA01
38692fb
1
For more information www.linear.com/LTC3869
EFFICIENCY (%)
ion pplica
ions pplica
ion
uresLTC3869/LTC3869-2
a T e Maxi Mu M r a T
(Note 1)
Input Supply Voltage: V ........................... 40V to 0.3V I , I , V , V Voltages .............INTV to 0.3V
IN TH1 TH2 FB1 FB2 CC
Top Side Driver Voltages: INTV Peak Output Current ................................100mA
CC
BOOST1, BOOST2 ...................................... 46V to 0.3V Operating Junction Temperature Range
Switch Voltage: SW1, SW2 ........................... 40V to 5V (Note 2) ..................................................40C to 125C
INTV , RUN1, RUN2, PGOOD, EXTV , Junction Temperature (Note 3) ............................. 125C
CC CC
BOOST1-SW1, BOOST2-SW2 ....................... 6V to 0.3V Storage Temperature Range ..................65C to 150C
+ +
SENSE1 , SENSE2 , SENSE1 , Lead Temperature (Soldering, 10 sec)
SENSE2 Voltages ......................................13V to 0.3V GN Package ......................................................300C
MODE/PLLIN, I , TK/SS1, TK/SS2,
LIM
FREQ Voltages ......................................INTV to 0.3V
CC
p c F T
TOP VIEW
TOP VIEW
TOP VIEW
1 FREQ
RUN1 28
+
2 27 MODE/PLLIN
SENSE1
SENSE1 3 26 SW1
28 27 26 25 24 23
28 27 26 25 24 23 22
SENSE1 1 22 BOOST1
V 4 25 TG1
FB1
TK/SS1 1 21 BOOST1
TK/SS1 2 21 BG1
5 24 BOOST1
TK/SS1
I 2 20 BG1
TH1
I 3 20 V
TH1 IN I 6 23 BG1
TH1
V 3 19 V
FB1 IN
V 4 19 INTV
SGND
FB1 SGND CC
SGND 7 22 V
IN
V 4 18 INTV
FB2 CC
29
29
V 5 18 BG2
FB2
8 INTV
I 21 I BG2
TH2 CC 5 17
TH2
I 6 17 PGND
TH2
9 20 BG2 TK/SS2 6 16 PGND
TK/SS2
TK/SS2 7 16 BOOST2
SENSE2 7 15 BOOST2
V 10 19 PGND
FB2
SENSE2 8 15 TG2
11 BOOST2
SENSE2 18 8 9 10 11 12 13 14
9 10 11 12 13 14
+
12 17 TG2
SENSE2
RUN2 13 16 SW2
EXTV 14 15 PGOOD
CC
UF PACKAGE
UFD PACKAGE
28-LEAD (4mm 4mm) PLASTIC QFN
28-LEAD (4mm 5mm) PLASTIC QFN
GN PACKAGE
T = 125C, = 37C/W, = 2.6C/W
JMAX JA JC
28-LEAD PLASTIC SSOP
T = 125C, = 34C/W,
JMAX JA
EXPOSED PAD (PIN 29) IS SGND, MUST BE
EXPOSED PAD (PIN 29) IS SGND, MUST BE T = 125C, = 80C/W
JMAX JA
SOLDERED TO PCB
SOLDERED TO PCB
o r D i n F Ma T
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3869EUF#PBF LTC3869EUF#TRPBF 3869 40C to 125C
28-Lead (4mm 4mm) Plastic QFN
LTC3869IUF#PBF LTC3869IUF#TRPBF 3869 40C to 125C
28-Lead (4mm 4mm) Plastic QFN
LTC3869EUFD#PBF LTC3869EUFD#TRPBF 3869 28-Lead (4mm 5mm) Plastic QFN 40C to 125C
LTC3869IUFD#PBF LTC3869IUFD#TRPBF 3869 28-Lead (4mm 5mm) Plastic QFN 40C to 125C
LTC3869IGN-2#PBF LTC3869IGN-2#TRPBF LTC3869GN-2 28-Lead Narrow Plastic SSOP 40C to 125C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on nonstandard lead based finish parts.
For more information on lead free part marking, go to: