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[原创] TI LM5145100W高密度同步降压电源评估方案

关键词:电源管理 DC/DC转换器 通信设备 工厂自动化 马达控制 测试测量

时间:2017-12-22 11:20:35       作者:TI       来源:中电网

TI公司的LM5145是42V同步降压控制器,其7.5V栅极驱动器能驱动外接高边和低边N沟功率开关,其自适应时间栅极驱动器能最小化开关瞬态时体二极管导通,从而降低开关损耗和提高了热效率,输入电压6V-42V,可调输出电压0.8V-40V,满足EN55022/CISPR 22 EMI标准,开关频率从100kHz到1MHz,主要用在通信设备,工厂自动化,马达控制和测试测量.本文介绍了LM5145主要特性,功能框图和几种应用电路,以及100W高密度评估板LM5145EVM-HD-20A特性和电性能,测试建立图,电路图,材料清单和PCB设计图.

The LM25145 42-V synchronous buck controller isdesigned to regulate from a high input voltage sourceor from an input rail subject to high voltage transients,minimizing the need for external surge suppressioncomponents. A high-side switch minimum on-time of40 ns facilitates large step-down ratios, enabling thedirect step-down conversion from a 24 V nominalinput to low-voltage rails for reduced systemcomplexity and solution cost. The LM25145 continuesto operate during input voltage dips as low as 6 V, atnearly 100% duty cycle if needed, making it wellsuited for high-performance industrial control, robotic,datacom, and RF power amplifier applications.

Forced-PWM (FPWM) operation eliminates frequencyvariation to minimize EMI, while a user-selectablediode emulation feature lowers current consumptionat light-load conditions. Cycle-by-cycle overcurrentprotection is accomplished by measuring the voltagedrop across the low-side MOSFET or by using anoptional current sense resistor. The adjustableswitching frequency as high as 1 MHz can besynchronized to an external clock source to eliminatebeat frequencies in noise-sensitive applications.

The LM25145 voltage-mode controller drives external high-side and low-side N-channel power switches withrobust 7.5-V gate drivers suitable for standard-threshold MOSFETs. Adaptively-timed gate drivers with 2.3-Asource and 3.5-A sink capability minimize body diode conduction during switching transitions, reducing switchinglosses and improving thermal performance when driving MOSFETs at high input voltage and high frequency. TheLM25145 can be powered from the output of the switching regulator or another available source, furtherimproving efficiency.

A 180° out-of-phase clock output relative to the internal oscillator at SYNCOUT is ideal for cascaded or multichannelpower supplies to reduce input capacitor ripple current and EMI filter size. Additional features of theLM25145 include a configurable soft-start, an open-drain Power Good monitor for fault reporting and outputmonitoring, 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 LM25145 controller is offered in a 3.5-mm × 4.5-mm thermally-enhanced, 20-pin VQFN package withadditional spacing for high-voltage pins and wettable flanks for optical inspection of solder joint fillets.

LM5145主要特性:

1• Versatile Synchronous Buck DC-DC Controller
– Wide Input Voltage Range of 6 V to 42 V
– Adjustable Output Voltage From 0.8 V to 40 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 PowerGood 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 WithWettable Flanks
• Create a Custom Design Using the LM25145 WithWEBENCH® Power Designer

LM5145应用:

• Telecom Infrastructure
• Factory Automation
• Test and Measurement
• Industrial Motor Drives

图1. LM5145功能框图

图2. LM5145应用电路图(1):VIN工作范围6V-42V

图3. LM5145应用电路图(2):500kHz降压稳压器,24V/5V,20A

图4. LM5145应用电路图(3):425kHz同步降压稳压器,24V/12V

图5. LM5145应用电路图(4):DSP核电源电压

100W高密度评估板LM5145EVM-HD-20A

The LM5145EVM-HD-20A 100-W high density evaluation module (EVM) is a synchronous buck DC-DCregulator that employs synchronous rectification to achieve high conversion efficiency in a small footprint.

It operates over a wide input voltage range of 24 V to 72 V providing a regulated 5-V output. The outputvoltage has better than 1% setpoint accuracy and is adjustable using an external resistor or voltagesource, permitting the user to customize the output voltage from 3.3 V to 8 V as needed.

The module design uses the LM5145 75-V synchronous buck controller with wide input voltage (wide VIN)range, wide duty cycle range, voltage-mode PWM control loop, integrated high-side and low-sideMOSFET gate drivers, cycle-by-cycle overcurrent protection, precision enable, and power supply trackingfeatures. The EVM ’ s free-running switching frequency is 220 kHz and is synchronizable to a higher orlower frequency if required. Moreover, a synchronization output signal (SYNCOUT) 180°phase-shifted relative to the internal clock is available for master-slave configurations. VCC voltage rail UVLO protectsthe converter at low input voltage conditions, and the EN/UVLO pin supports adjustable input UVLO forapplication specific power-up and power-down requirements.

The LM5145 is available in a 20-pin VQFN package with 3.5-mm × 4.5-mm footprint to enable DC-DCsolutions with high density and low component count. Please consult the LM5145 6-V to 75-VSynchronous Buck DC-DC Controller With Wide Duty Cycle Range data sheet for more information. Usethe LM5145 with WEBENCH® Power Designer to create a custom regulator design. Furthermore, the usercan download the LM5145 Quickstart Calculator to optimize component selection and examine predictedefficiency performance across line and load ranges.

100W高密度评估板LM5145EVM-HD-20A特性和电性能:

• Tightly-regulated output voltage of 5 V with better than ±1% setpoint accuracy
• Wide input voltage operating range of 24 V to 72 V
• Full load current of 20 A available with recommended airflow of 200 LFM
• Switching frequency of 220 kHz externally synchronizable up or down
• Ultra-high power conversion efficiency across wide load current range
– Full load efficiency of 94% and 92.5% at VIN = 24 V and 48 V, respectively
– 93% efficiency at half-rated load, VIN = 48 V
• 24-mA no-load supply current at VIN = 48 V
• Input π-stage EMI filter with resistive damping
– Meets EN55022 / CISPR 22 EMI standards
• Voltage-mode control architecture provides fast line and load transient response
– PWM line feedforward
– Forced PWM (FPWM) or diode emulation mode operation
– 94dB, 6.5-MHz voltage-loop error amplifier
• Integrated high-side and low-side power MOSFET gate drivers
– 2.3-A and 3.5-A sink/source drive current capability
– 14-ns adaptive dead-time control reduces power dissipation and MOSFET temperature rise
• Overcurrent protection (OCP) with valley current sensing using low-side MOSFET RDS(on)
• Monotonic prebias output voltage start-up
• User-adjustable soft-start time set to 4 ms by 47-nF capacitor connected between SS/TRK and AGND
– Option for output voltage tracking using master track signal connected to SS/TRK
• SYNCOUT signal 180° out-of-phase with internal clock
• PGOOD indicator with 20-kΩ pullup resistor to VCC
• Selectable forced-PWM (FPWM) or diode emulation (DEM) modes using SYNCIN pin
• Resistor-programmable input voltage UVLO with customizable hysteresis for applications with wideturnon and turnoff voltage difference
– Input UVLO set to turn on and off at VIN of 22 V and 19 V, respectively
• Fully assembled, tested, and proven PCB layout with 50-mm × 30-mm total footprint
100W高密度评估板LM5145EVM-HD-20A典型应用:
• Distributed point-of-load (POL) regulator modules
• Industrial and commercial vehicles
• Battery-powered drones
• Network and computing voltage regulators
• RF power amplification, PoE, and IP camera systems
100W高密度评估板LM5145EVM-HD-20A电性能指标:


图6.评估板LM5145EVM-HD-20A外形图

图7.评估板LM5145EVM-HD-20A测试建立图

图8.评估板LM5145EVM-HD-20A电路图
评估板LM5145EVM-HD-20A材料清单:


图9.评估板LM5145EVM-HD-20A PCB设计图(1):顶层铜

图10.评估板LM5145EVM-HD-20A PCB设计图(2):层2铜

图11.评估板LM5145EVM-HD-20A PCB设计图(3):层3铜

图12.评估板LM5145EVM-HD-20A PCB设计图(4):底层铜

图13.评估板LM5145EVM-HD-20A PCB设计图(5):顶层装配

图14.评估板LM5145EVM-HD-20A PCB设计图(6):底层装配
详情请见:
http://www.ti.com/lit/ds/snvsat9/snvsat9.pdf
http://www.ti.com/lit/ug/snvu545a/snvu545a.pdf
snvsat9.pdf
snvu545a.pdf

 

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