DC-DC Controller. LM5145 Datasheet

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LM5145 Datasheet
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Part LM5145
Description Synchronous Buck DC-DC Controller
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Texas Instruments LM5145
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Folder
Order
Now
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LM5145
SNVSAI4 – JUNE 2017
LM5145 6-V to 75-V Synchronous Buck DC-DC Controller With Wide Duty Cycle Range
1 Features
1 Versatile Synchronous Buck DC-DC Controller
– Wide Input Voltage Range of 6 V to 75 V
– Adjustable Output Voltage From 0.8 V to 60 V
• Meets EN55022 / CISPR 22 EMI Standards
• Lossless RDS(on) or Shunt Current Sensing
• Switching Frequency From 100 kHz to 1 MHz
– SYNC In and SYNC Out Capability
• 40-ns Minimum On-Time for High VIN / VOUT Ratio
• 140-ns Minimum Off-Time for Low Dropout
• 0.8-V Reference With ±1% Feedback Accuracy
• 7.5-V Gate Drivers for Standard VTH MOSFETs
– 14-ns Adaptive Dead-Time Control
– 2.3-A Source and 3.5-A Sink Capability
– Low-Side Soft-Start for Prebiased Start-Up
• Adjustable Soft-Start or Optional Voltage Tracking
• Fast Line and Load Transient Response
– Voltage-Mode Control With Line Feedforward
– High Gain-Bandwidth Error Amplifier
• Precision Enable Input and Open-Drain Power
Good Indicator for Sequencing and Control
• Inherent Protection Features for Robust Design
– Hiccup Mode Overcurrent Protection
– Input UVLO With Hysteresis
– VCC and Gate Drive UVLO Protection
– Thermal Shutdown Protection With Hysteresis
• VQFN-20 Package With Wettable Flanks
• Create a Custom Design Using the LM5145 With
WEBENCH® Power Designer
2 Applications
• Remote Radio Unit (RRU) and BTS
• Networking and Computing Power
• Non-Isolated PoE and IP Cameras
• Industrial Motor Drives
3 Description
The LM5145 75-V synchronous buck controller is
designed to regulate from a high input voltage source
or from an input rail subject to high voltage transients,
minimizing the need for external surge suppression
components. A high-side switch minimum on-time of
40 ns facilitates large step-down ratios, enabling the
direct step-down conversion from a 48 V nominal
input to low-voltage rails for reduced system
complexity and solution cost. The LM5145 continues
to operate during input voltage dips as low as 6 V, at
nearly 100% duty cycle if needed, making it well
suited for high-performance industrial control, robotic,
datacom, and RF power amplifier applications.
Forced-PWM (FPWM) operation eliminates frequency
variation to minimize EMI, while a user-selectable
diode emulation feature lowers current consumption
at light-load conditions. Cycle-by-cycle overcurrent
protection is accomplished by measuring the voltage
drop across the low-side MOSFET or by using an
optional current sense resistor. The adjustable
switching frequency as high as 1 MHz can be
synchronized to an external clock source to eliminate
beat frequencies in noise-sensitive applications.
Device Information(1)
PART NUMBER
PACKAGE
BODY SIZE (NOM)
LM5145
VQFN (20)
3.50 mm × 4.50 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
VOUT
RC2
CC3
SYNC In
SYNC Out
RFB1 CC1
RC1
CC2
RFB2
RRT
CSS
Typical Application Circuit and Efficiency Performance, VOUT = 5 V
VIN EN
VIN
VIN
SYNCIN
EN/UVLO
HO
Q1
SYNCOUT
COMP
FB LM5145
RT
SS/TRK
BST
SW
LO
VCC
AGND
PGND
PGOOD ILIM
CBST
Q2
CVCC
LF VOUT
CIN COUT
GND
PG RILIM
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.



Texas Instruments LM5145
LM5145
SNVSAI4 – JUNE 2017
www.ti.com
Table of Contents
1 Features .................................................................. 1
2 Applications ........................................................... 1
3 Description ............................................................. 1
4 Revision History..................................................... 2
5 Description (continued)......................................... 3
6 Pin Configuration and Functions ......................... 4
6.1 Wettable Flanks ........................................................ 5
7 Specifications......................................................... 6
7.1 Absolute Maximum Ratings ...................................... 6
7.2 ESD Ratings.............................................................. 6
7.3 Recommended Operating Conditions....................... 7
7.4 Thermal Information .................................................. 7
7.5 Electrical Characteristics........................................... 7
7.6 Switching Characteristics ........................................ 10
7.7 Typical Characteristics ............................................ 11
8 Detailed Description ............................................ 16
8.1 Overview ................................................................. 16
8.2 Functional Block Diagram ....................................... 16
8.3 Feature Description................................................. 17
8.4 Device Functional Modes........................................ 25
9 Application and Implementation ........................ 27
9.1 Application Information............................................ 27
9.2 Typical Applications ................................................ 36
10 Power Supply Recommendations ..................... 52
11 Layout................................................................... 53
11.1 Layout Guidelines ................................................. 53
11.2 Layout Example .................................................... 56
12 Device and Documentation Support ................. 58
12.1 Device Support .................................................... 58
12.2 Documentation Support ........................................ 58
12.3 Related Links ........................................................ 59
12.4 Receiving Notification of Documentation Updates 59
12.5 Community Resources.......................................... 59
12.6 Trademarks ........................................................... 59
12.7 Electrostatic Discharge Caution ............................ 59
12.8 Glossary ................................................................ 59
13 Mechanical, Packaging, and Orderable
Information ........................................................... 59
4 Revision History
SPACER
DATE
June 2017
REVISION
*
NOTES
Initial release
2 Submit Documentation Feedback
Product Folder Links: LM5145
Copyright © 2017, Texas Instruments Incorporated



Texas Instruments LM5145
www.ti.com
LM5145
SNVSAI4 – JUNE 2017
5 Description (continued)
The LM5145 voltage-mode controller drives external high-side and low-side N-channel power switches with
robust 7.5-V gate drivers suitable for standard-threshold MOSFETs. Adaptively-timed gate drivers with 2.3-A
source and 3.5-A sink capability minimize body diode conduction during switching transitions, reducing switching
losses and improving thermal performance when driving MOSFETs at high input voltage and high frequency. The
LM5145 can be powered from the output of the switching regulator or another available source, further improving
efficiency.
A 180° out-of-phase clock output relative to the internal oscillator at SYNCOUT is ideal for cascaded or multi-
channel power supplies to reduce input capacitor ripple current and EMI filter size. Additional features of the
LM5145 include a configurable soft-start, an open-drain Power Good monitor for fault reporting and output
monitoring, monotonic start-up into prebiased loads, integrated VCC bias supply regulator and bootstrap diode,
external power supply tracking, precision enable input with hysteresis for adjustable line undervoltage lockout
(UVLO), hiccup-mode overload protection, and thermal shutdown protection with automatic recovery.
The LM5145 controller is offered in a 3.5-mm × 4.5-mm thermally-enhanced, 20-pin VQFN package with
additional spacing for high-voltage pins and wettable flanks for optical inspection of solder joint fillets.
Copyright © 2017, Texas Instruments Incorporated
Product Folder Links: LM5145
Submit Documentation Feedback
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