LTC3866 Datasheet, PDF (1/36 Pages) Linear Technology – Current Mode Synchronous Controller for Sub Milliohm DCR Sensing

LTC3866
Current Mode Synchronous
Controller for Sub Milliohm
DCR Sensing
Features
n _{Sub Milliohm DCR Current Sensing}
n _{High Efficiency: Up to 95%}
n _{Selectable Current Sensing Limit}
n _{Programmable DCR Temperature Compensation}
n _{Die Overtemperature Thermal Shutdown}
n _{± 0.5% 0.6V Output Voltage Accuracy}
n _{Programmable Fixed Frequency 250kHz to 770kHz}
n _{High Speed Differential Remote Sense Amplifier}
n _{Wide Input Voltage Range: 4.5V to 38V}
n _{Output Voltage Range: 0.6V to 3.5V with Diffamp}
n _{Adjustable Soft-Start or Output Voltage Tracking}
n _{Foldback Output Current Limit}
n _{Short-Circuit Soft Recovery}
n _{Output Overvoltage Protection}
n _{24-Lead (4mm × 4mm) QFN and 24-Lead FE Packages}
Applications
n _{Computer Systems}
n _{Telecom Systems}
n _{Industrial and Medical Instruments}
n _{DC Power Distribution Systems}
Description
The LTC^®3866 is a single phase current mode synchronous
step-down switching regulator controller that drives all
N-channel power MOSFET switches. It employs a unique
architecture which enhances the signal-to-noise ratio of
the current sense signal, allowing the use of a very low
DC resistance power inductor to maximize the efficiency
in high current applications. This feature also reduces the
switching jitter commonly found in low DCR applications.
The LTC3866 also includes a high speed remote sense dif-
ferential amplifier, a programmable current sense limit that
can be selected to 10mV, 15mV, 20mV, 25mV or 30mV,
and DCR temperature compensation to limit the maximum
output current precisely over temperature.
The LTC3866 also features a precise 0.6V reference with a
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
and various types of batteries.
The LTC3866 is offered in a low profile 24-lead 4mm ×
4mm QFN and 24-lead exposed pad FE packages.
L, LT, LTC, LTM, Burst Mode, OPTI-LOOP, Linear Technology and the Linear logo are
registered trademarks and No R_SENSE is a trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Protected by U.S. Patents, including
5481178, 5705919, 5929620, 6177787, 6580258, 6498466, 6611131, patent pending.
Typical Application
High Efficiency, 1.5V/30A Step-Down Converter with Very Low DCR Sensing
220pF
30.1k
20k
10k
1.5nF
100k
0.1µF
C1
220nF
C2
220nF
FREQ MODE/PLLIN
RUN
PGOOD
TK/SS
ITEMP
ITH
EXTV_CC
V_FB LTC3866 V_IN
DIFFOUT INTVCC
DIFFP
BOOST
DIFFN
TG
SNSD⁺
SW
SNS^–
BG
SNSA⁺
PGND
ILIM
CLKOUT
SGND
4.7µF
V_IN
4.5V TO 20V
220µF
0.1µF
0.33µH
DCR = 0.32mΩ
R2
931Ω
R1
4.64k
C_OUT
470µF
×2
V_OUT
1.5V
30A
3866 TA01a
Efficiency vs Load Current
and Mode
100
90
80
70
60
50
40
30
20
10
0
0.01
V_IN = 12V
V_OUT = 1.5V
L = 0.33µH
(DCR = 0.32mΩ TYP)
CCM
PULSE SKIPPING
Burst Mode
OPERATION
0.1
1
10
LOAD CURRENT (A)
100
3866 TA01b
3866fa
1