LMS3655 Datasheet, PDF (1/49 Pages) Texas Instruments – 5.5-A, 36-V Synchronous, 400-kHz DC-DC Step-Down Converter

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LMS3655
SNAS744 – JULY 2017
LMS3655 5.5-A, 36-V Synchronous, 400-kHz DC-DC Step-Down Converter
1 Features
•1 96% Peak Efficiency While Converting 12 V to 5 V
• Low EMI and Switch Noise
– Minimized Switch Node Ringing
– Pseudo-Random Spread Spectrum
• 400-kHz (±10%) Fixed Switching Frequency
• –40°C to +150°C Junction Temperature Range
• External Frequency Synchronization
• RESET Output With Internal Filter and 3-ms
Release Timer
• Automatic Light Load Mode for Improved
Efficiency
• Pin-Selectable Forced PWM Mode
• Built-In Compensation, Soft Start, Current Limit,
Thermal Shutdown, and UVLO
• 0.35-V Dropout With 3.5-A Load at 25°C (Typical)
• 32-µA I_{Q_VIN}: Quiescent Current at 3.3 V_OUT and
No Load (Typical)
• 5.5-A Continuous Load Current
• Adjustable Output Voltage (1 V to 15 V)
• ±1.5% Reference Voltage Tolerance
• 4-mm × 5-mm, 0.5-mm Pitch SON Package
2 Applications
• Noise-Sensitive Medical Applications
• Telecom
• High Performance Industrial
3 Description
The LMS3655 synchronous buck regulators are
optimized for high performance applications,
providing an adjustable output of 1 V to 15 V.
Seamless transition between PWM and PFM modes,
along with a low quiescent current, ensures high
efficiency and superior transient responses at all
loads.
Advanced high speed circuitry allows the LMS3655 to
regulate an input of 24V to an output of 3.3V at a
fixed frequency of 400kHz while also enabling a
continuous load current of 5.5 A. An innovative
frequency foldback architecture allows this device to
regulate a 3.3-V output from an input voltage of only
3.5 V. The input voltage can range up to 36 V, with
transient tolerance up to 42 V, easing input surge
protection design.
An open-drain reset output, with built-in filtering and
delay, provides a true indication of system status.
This feature negates the requirement for an additional
supervisory component, saving cost and board
space.
Device Information⁽¹⁾
DEVICE NAME
PACKAGE
BODY SIZE
LMS3655
VQFN-HR (22)
4.00 mm × 5.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
VIN
3.5 V to 36 V
10 µF
10 µF
4.7 µF
Typical Application Circuit
PVIN 1
PGND1
AVIN
VCC
AGND
NC
FPWM
EN
LMS3655
PVIN 2
PGND2
RESET
10 µF
SYNC
CBIAS
FB
CBOOT
SW
0.1 µF
RFBB
470 nF
RFBT
L1=10 µH
CFF
3 X 47 µF
VOUT
Copyright © 2017, Texas Instruments Incorporated
LMS3655 Efficiency: V_OUT = 5 V
100%
98%
96%
94%
92%
90%
88%
86%
84%
82%
80%
0.001
V_IN = 12
V_IN = 24
0.01
0.1
1
Output Current (A)
10
LMS3
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.