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ST A7987汽车61V 3A降压开关电源解决方案

ST公司的A7987是单片降压开关稳压器,可提供高达3A的DC电源.输出电压可在0.8V到VIN间调整.其宽输入电压范围和几乎100%占空比满足工业系统的故障安全规范.输入工作电压4.5V-61V, RDS(on) = 250 mΩ,可调开关频率fsw(250 kHz-1.5 MHz),低IQ-SHD (11 μA typ. from VIN)和低IQ(1mA typ.-VIN 24V-VOUT 3.3V),具有同步和可调软起动时间,可调电流极限,低压降工作,轻负载时VBIAS提高了效率,短路数字频率折返,热关断自动恢复,满足AEC-Q100规范要求.主要用于汽车24V电池系统,工业和商用电动汽车.本文介绍了A7987主要特性,框图和多种应用电路,演示板电路图及其元件列表,演示板布局图,以及基于A7987 3A降压DC/DC开关稳压器(VIN = 4.5 V-60 V)的评估板STEVAL-ISA207V1主要特性,电路图和材料清单.

The A7987 is a step down monolithic switching regulator able to deliver up to 3 A DC.The output voltage adjustability ranges from 0.8 V to VIN. The wide input voltagerange and the almost 100% duty cycle capability meet the fail-safe specifications forindustrial systems. The embedded switch-over feature on the VBIAS pin maximizesthe efficiency at light load. The adjustable current limitation, designed to select theinductor RMS current in accordance with the nominal output current, and the highswitching frequency capability make the size of the application compact. Pulse bypulse current sensing with digital frequency fold-back implements an effectiveconstant current protection over the different application conditions. The peak currentfold-back decreases the stress of the power components in heavy short-circuitcondition. The PGOOD open collector output can also implement output voltagesequencing during the power-up phase. Multiple devices can be synchronizedsharing the SYNCH pin to prevent beating noise for low noise requirements such asin infotainment applications.

A7987主要特性:

• 3 A DC output current
• 4.5 V to 61 V operating input voltage
• RDS(on) = 250 mΩ typ.
• Adjustable fsw (250 kHz to 1.5 MHz)
• Low IQ-SHD (11 μA typ. from VIN)
• Low IQ (1 mA typ. - VIN 24V - VOUT 3.3V)
• Output voltage adjustable from 0.8 V to VIN
• Synchronization
• Adjustable soft-start time
• Adjustable current limitation
• Low-dropout operation
• VBIAS improves efficiency at light load
• PGOOD open collector output
• Output voltage sequencing
• Digital frequency fold-back in short-circuit
• Auto recovery thermal shutdown
• Qualified following AEC-Q100 requirements

A7987应用:

• Designed for 24 V automotive battery systems
• Industrial and commercial vehicles

图1.A7987框图

图2. A7987应用电路图

图3. A7987演示板电路图
A7987演示板电路元件列表:


图4. A7987演示板布局图:左:顶层;右:底层

图5. A7987正的降压-升压电路图

图6. A7987正的降压-升压PCB布局图:左:顶层;右:底层

图7. A7987负的降压-升压电路图

图8. A7987负的降压-升压PCB布局图:左:顶层;右:底层

评估板STEVAL-ISA207V1:基于A7987 3A降压DC/DC开关稳压器(VIN = 4.5 V - 60 V)
The STEVAL-ISA207V1 evaluation board is a step-down switching power supplybased on the A7987 regulator in an HTSSOP16 package. It is designed forautomotive system battery-powered applications. The output voltage can be setstarting from 0.8 V. Almost low drop-out operation, due to the advanced integratedswitch management, can be achieved.

The A7987 is a 61 V, 3 A step-down asynchronous switching regulator withembedded high-side power MOSFET is capable of delivering up to 3 A of current,depending on the application conditions.

The embedded switchover feature on the VBIAS pin and the light load management(pulse skipping) are included to maximize power conversion efficiency across theentire load range, and the soft-start current limit threshold and switching frequencycan be adjusted according to specific application requirements.

The device includes an internal 250 kHz oscillator that can be set up to 1.5 MHz bychanging an on-board resistor. Two A7987 regulators can be synchronized in a 180°out-of-phase configuration for reduced total input RMS current.

评估板STEVAL-ISA207V1主要特性:

• 4.5 V to 60 V input voltage
• Step-down (buck) conversion
• 3.3 V output voltage
• Up to 3 A DC output current
• 500 kHz switching frequency
• 3.5 ms programmed soft-start
• Compliant with ceramic output capacitors
• 180° out-of-phase synchronization available
• Auto recovery overcurrent and thermal protection
• RoHS and China RoHS compliant
• WEEE compliant (2012/19/UE RAEE II)
https://www.st.com/content/ccc/fragment/product_related/rpn_information/board_photo/group1/98/1c/c0/00/2c/50/47/14/STEVAL-ISA207V1_IMAGE/files/steval-mki207v1_image.JPG/_jcr_content/translations/en.steval-mki207v1_image.JPG
图9.评估板STEVAL-ISA207V1外形图

图10.评估板STEVAL-ISA207V1电路图
STEVAL-ISA207V1材料清单:


详情请见:
https://www.st.com/content/ccc/resource/technical/layouts_and_diagrams/schematic_pack/group1
/6c/74/41/c2/25/01/4e/86/STEVAL-ISA207V1_SCHEMATIC/files/steval-isa207v1_schematic.pdf/jcr:content/translations/en.steval-isa207v1_schematic.pdf

https://www.st.com/content/ccc/resource/technical/document/bill_of_materials/group1/31/44/60
/47/69/83/48/f2/STEVAL-ISA207V1_BOM/files/steval-isa207v1_bom.pdf/jcr:content/translations/en.steval-isa207v1_bom.pdf

en.steval-isa207v1_bom.pdf
en.steval-isa207v1_schematic.pdf
a7987.pdf
steval-isa207v1.pdf

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