LTC3866
Current Mode Synchronous
Controller for Sub Milliohm
DCR Sensing
Fea T Descrip T
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Sub Milliohm DCR Current Sensing The LTC 3866 is a single phase current mode synchronous
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High Efficiency: Up to 95% step-down switching regulator controller that drives all
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Selectable Current Sensing Limit N-channel power MOSFET switches. It employs a unique
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Programmable DCR Temperature Compensation architecture which enhances the signal-to-noise ratio of
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Die Overtemperature Thermal Shutdown the current sense signal, allowing the use of a very low
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0.5% 0.6V Output Voltage Accuracy DC resistance power inductor to maximize the efficiency
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Programmable Fixed Frequency 250kHz to 770kHz in high current applications. This feature also reduces the
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High Speed Differential Remote Sense Amplifier switching jitter commonly found in low DCR applications.
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Wide Input Voltage Range: 4.5V to 38V The LTC3866 also includes a high speed remote sense dif-
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Output Voltage Range: 0.6V to 3.5V with Diffamp ferential amplifier, a programmable current sense limit that
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Adjustable Soft-Start or Output Voltage Tracking can be selected to 10mV, 15mV, 20mV, 25mV or 30mV,
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Foldback Output Current Limit and DCR temperature compensation to limit the maximum
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Short-Circuit Soft Recovery output current precisely over temperature.
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Output Overvoltage Protection
The LTC3866 also features a precise 0.6V reference with a
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24-Lead (4mm 4mm) QFN and 24-Lead FE Packages
guaranteed limit of 0.5% that provides an accurate output
voltage from 0.6V to 3.5V. A 4.5V to 38V input voltage
range allows it to support a wide variety of bus voltages
a T
and various types of batteries.
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Computer Systems
The LTC3866 is offered in a low profile 24-lead 4mm
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Telecom Systems
4mm QFN and 24-lead exposed pad FE packages.
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Industrial and Medical Instruments
n L, LT, LTC, LTM, Burst Mode, OPTI-LOOP, Linear Technology and the Linear logo are
DC Power Distribution Systems
registered trademarks and No R is a trademark of Analog Devices, Inc. All other
SENSE
trademarks are the property of their respective owners. Protected by U.S. Patents, including
5481178, 5705919, 5929620, 6177787, 6580258, 6498466, 6611131, patent pending.
Typical a T
High Efficiency, 1.5V/30A Step-Down Converter with Very Low DCR Sensing
Efficiency vs Load Current
and Mode
100k
V
IN
FREQ MODE/PLLIN
4.5V TO 20V
100
0.1F 220F
RUN PGOOD
4.7F 90
TK/SS ITEMP
ITH EXTV 80
CC
LTC3866
V V
FB IN 70
DIFFOUT INTV
CC
60
0.1F
DIFFP BOOST
50
0.33H V = 12V
IN
30.1k DIFFN TG
DCR = 0.32m V = 1.5V
V
OUT OUT
40
+
1.5V L = 0.33H
SW
SNSD
C1 30A 30 (DCR = 0.32m TYP)
C
BG OUT
220pF 20k SNS
220nF
CCM
470F
R1
+ R2 20
10k PGND
SNSA PULSE SKIPPING
2
4.64k
C2 931
Burst Mode
ILIM CLKOUT 10
1.5nF
220nF
OPERATION
SGND
0
0.01 0.1 1 10 100
LOAD CURRENT (A)
3866 TA01b
3866 TA01a
3866fc
1
For more information www.linear.com/LTC3866
EFFICIENCY (%)
ion pplica
ions pplica
ion uresLTC3866
a T e Maxi Mu M r a T (Note 1)
Input Supply Voltage .................................. 0.3V to 40V DIFFP, DIFFN .........................................0.3V to INTV
CC
Topside Driver Voltage (BOOST) ................ 0.3V to 46V ITEMP, ITH, V Voltages ....................0.3V to INTV
FB CC
Switch Voltage(SW) ..................................... 5V to 40V INTV Peak Output Current ..............................100mA
CC
INTV , EXTV , RUN, PGOOD, Operating Junction Temperature Range
CC CC
BOOST-SW Voltages .................................... 0.3V to 6V (Notes 2, 4) ............................................ 40C to 125C
+ +
SNSD , SNSA , SNS Voltages .............0.3V to INTV Storage Temperature Range .................. 65C to 125C
CC
MODE/PLLIN, ILIM, TK/SS, FREQ, Lead Temperature (Soldering, 10 sec)
DIFFOUT Voltages .................................0.3V to INTV FE Package .......................................................300C
CC
p c F T
TOP VIEW
TOP VIEW
1 24 MODE/PLLIN
FREQ
2 23 PGOOD
RUN
3 22 ITEMP
TK/SS
24 23 22 21 20 19
4 21 EXTV
ITH
CC
ITH 1 18 EXTV
CC
5 20 V
V
FB IN
V 2 17 V
FB IN
6 19 INTV
DIFFOUT
25 CC
DIFFOUT 3 16 INTV
CC
SGND 25
7 18 BOOST
DIFFN
SGND
DIFFN 4 15 BOOST
8 17 TG
DIFFP
DIFFP 5 14 TG
+
9 16 SW
SNSD +
SNSD 6 13 SW
10 15 BG
SNS
7 8 9 10 11 12
+
11 14 PGND
SNSA
12 13 CLKOUT
ILIM
FE PACKAGE
UF PACKAGE
24-LEAD PLASTIC TSSOP
24-LEAD (4mm 4mm) PLASTIC QFN
= 33C/W, = 10C/W
JA JC = 47C/W, = 4.5C/W
JA JC
EXPOSED PAD (PIN 25) IS SGND, MUST BE SOLDERED TO PCB
EXPOSED PAD (PIN 25) IS SGND, MUST BE SOLDERED TO PCB
o r D i n F Ma T