原标题：ADI ADM2795E 5kVrms绝缘RS-485收发器解决方案

　　ADI公司的ADM2795E是5kVrms信号绝缘RS-485收发器.采用ADI公司的iCoupler®技术,集成了3路绝缘器,RS-485收发器和IEC电磁兼容(EMC)瞬态保护,IEC 61000-4-5 Level 4浪涌保护,RS-485总线引脚保护电压±4 kV,RS-485接口引脚保护高达±15 kV,工作温度−40°C到+125°C,主要用在加热,通风设备和空调(HVAC)网络,工业现场总线,建筑物自动化和公用事业网络.本文介绍了ADM2795E主要特性,框图,几种应用测试图以及评估板EVAL-ADM2795EEBZ主要特性,电路图,材料清单和PCB设计图.

　　The ADM2795E is a 5 kV rms signal isolated RS-485 transceiver that features up to ±42 V of ac/dc peak bus overvoltage fault protec-tion on the RS-485 bus pins. The device integrates Analog Devices, Inc., iCoupler® technology to combine a 3-channel isolator, RS-485 transceiver, and IEC electromagnetic compatibility (EMC) transient protection in a single package. The ADM2795E is a RS-485/RS-422 transceiver that integrates IEC 61000-4-5 Level 4 surge protection, allowing up to ±4 kV protection on the RS-485 bus pins (A and B). The device has IEC 61000-4-4 Level 4 EFT protection up to ±2 kV and IEC 61000-4-2 Level 4 ESD protection on the bus pins, allowing this device to withstand up to ±15 kV on the transceiver interface pins without latching up. This device has an extended common-mode input range of ±25 V to improve data communication reliability in noisy environments. The ADM2795E is capable of operating over wide power supply ranges, with a 1.7 V to 5.5 V VDD1 power supply range, allowing interfacing to low voltage logic supplies. The ADM2795E is also fully TIA/EIA RS-485/RS-422 compliant when operated over a 3 V to 5.5 V VDD2 power supply. The device is fully characterized over an extended operating temperature range of −40°C to +125°C, and is available in a 16-lead, wide-body SOIC package.

　　ADM2795E主要特性:

　　5 kV rms isolated RS-485/RS-422 transceiver

　　±42 V ac/dc peak fault protection on RS-485 bus pins

　　Certified Level 4 EMC protection on RS-485 A, B bus pins

　　IEC 61000-4-5 surge protection (±4 kV)

　　IEC 61000-4-4 electrical fast transient (EFT) protection (±2 kV)

　　IEC 61000-4-2 electrostatic discharge (ESD) protection

　　±8 kV contact discharge

　　±15 kV air discharge

　　IEC 61000-4-6 conducted radio frequency (RF) immunity (10 V/m rms)

　　Certified IEC 61000-4-x immunity across isolation barrier

　　IEC 61000-4-2 ESD, IEC 61000-4-4 EFT, IEC 61000-4-5 surge, IEC 61000-4-6 conducted RF immunity, IEC 61000-4-3 radiated immunity, IEC 61000-4-8 magnetic immunity

　　RS-485 A, B pins human body model (HBM) ESD protection: >±30 kV

　　Safety and regulatory approvals (pending)

　　CSA Component Acceptance Notice 5A, DIN V VDE V 0884-10, UL 1577, CQC11-471543-2012

　　TIA/EIA RS-485/RS-422 compliant over full supply range

　　3 V to 5.5 V operating voltage range on VDD2

　　1.7 V to 5.5 V operating voltage range on VDD1 logic supply

　　Common-mode input range of −25 V to +25 V

　　High common-mode transient immunity: >75 kV/μs

　　Robust noise immunity (tested to the IEC 62132-4 standard)

　　Passes EN55022 Class B radiated emissions by 6 dBμV/m margin

　　Receiver short-circuit, open-circuit, and floating input fail-safe

　　Supports 256 bus nodes (96 kΩ receiver input impedance)

　　−40°C to +125°C temperature option

　　Glitch free power-up/power-down (hot swap)

　　ADM2795E应用:

　　Heating, ventilation, and air conditioning (HVAC) networks

　　Industrial field buses

　　Building automation

　　Utility networks

　　图1. ADM2795E功能框图

　　图2. ADM2795E IEC6100-4-6传导RF免疫测评图

　　图3. ADM2795E IEC6100-4-3辐射RF免疫测评图

　　图4. ADM2795E IEC6100-4-8磁免疫测评图

　　图5. ADM2795E半双工绝缘RS-485通信网络图

　　Certified Evaluation Board for the ADM2795E Robust 5 kV rms Isolated RS-485/RS-422 Transceiver with Level 4 EMC and Full ±42 V Protection

　　评估板EVAL-ADM2795EEBZ

　　Use the EVAL-ADM2795EEBZ to easily evaluate the ADM2795E 5 kV rms signal isolated RS-485RS-422 transceiver with Level 4 IEC EMC and 24 V supply fault protection. The EVAL- ADM2795EEBZ evaluation board is easily configured through jumper connections and screw terminal blocks for signal and power connections. The EVAL-ADM2795EEBZ can be powered with either a 9 V battery or a standard configurable bench top power supply. An on-board trimmer potentiometer and an on- board regulator circuit on both VDD1 and VDD2 allow easy power configuration when connected to a 9 V battery.

　　CERTIFIED IEC EMC RS-485 EVALUATION BOARD

　　The EVAL-ADM2795EEBZ evaluation board has been lab tested and certified to provide RS-485 A, B bus pin protection against IEC 61000-4-5 surges to ±4 kV, IEC 61000-4-4 EFT to ±2 kV, and IEC 61000-4-2 ESD to ±8 kV for contact and ±15 kV for air. The ADM2795E isolation barrier was also tested and certified to provide robust IEC EMC immunity. The EVAL-ADM2795EEBZ can withstand high voltage faults to ±42 V ac/dc peak on RS-485 A, B bus pins. The EVAL-ADM2795EEBZ meets stringent EMI emissions targets with a 6 dB μV margin from EN 55022 Class B limits, by using a 120 pF, 0603 body size capacitor on the printed circuit board (PCB) trace connected to the RxD pin.

　　评估板EVAL-ADM2795EEBZ主要特性:

　　5 kV rms signal isolated RS-485/RS-422 transceiver

　　Convenient connections for power supplies and signals through screw terminal blocks and jumper connections

　　1.7 V to 5.5 V operating voltage range on VDD1 logic supply

　　3 V to 5.5 V operating voltage range on VDD2

　　Certified RS-485 A, B bus pin protection, passing

　　IEC 61000-4-5 surge to ±4 kV

　　IEC 61000-4-4 electrical fast transient (EFT) to ±2 kV

　　IEC 61000-4-2 electrostatic discharge (ESD) to ±8 kV (contact) ±15 kV (air)

　　IEC 61000-4-6 conducted radio frequency (RF) immunity to Level 3 (10 V/m rms) Human body model (HBM) ESD to > ±30 kV

　　Certified IEC electromagnetic compatibility (EMC) immunity provided by isolation barrier, withstands IEC 61000-4-5 surge to ±4 kV

　　IEC 61000-4-4 EFT to ±2 kV

　　IEC 61000-4-2 ESD to ±9 kV (contact) ±8 kV (air)

　　IEC 61000-4-6 conducted RF immunity Level 3 (10 V/m rms)

　　Certified evaluation board, passing

　　IEC 61000-4-3 radiated RF immunity Level 4 (30 V/m)

　　IEC 61000-4-8 magnetic field immunity Level 5 (100 A/m)

　　EN 55022 Class B radiated emissions with 6 dB μV margin

　　Provides A, B bus pin fault protection to ±42 V ac/dc peak

　　图6.评估板EVAL-ADM2795EEBZ外形图

　　评估板EVAL-ADM2795EEBZ材料清单: