概要

The ADM3095E is a 3.0 V to 5.5 V, 2.5 Mbps, RS-485 transceiver that features up to ±42 V ac/dc peak bus overvoltage fault protection on the RS-485 bus pins. This device is designed to withstand overvoltage faults, such as short circuits directly to power supplies, and overvoltage faults, such as ±24 V ac supplies connected in error to the RS-485 A and B bus pins. The ADM3095E is an RS-485 transceiver that integrates IEC 61000-4-5 Level 4 surge protection, allowing up to ±4 kV protection on the RS-485 bus pins. The device has IEC 61000-4-4 Level 4 electrical fast transient (EFT) protection up to ±2 kV, and IEC 61000-4-2 Level 4 electrostatic discharge (ESD) protection on the bus pins, allowing the device to withstand up to ±15 kV on the transceiver interface pins without latch-up or damage. This device has an extended common-mode input voltage range of ±25 V to improve data communication reliability in noisy environments over long cable lengths where ground loop voltages are possible. The combination of extended common-mode input voltage range, overvoltage fault protection, surge protection, EFT protection, and ESD protection make the ADM3095E a completely integrated electromagnetic compatibility (EMC) protected RS-485 transceiver. The ADM3095E also features a logic supply pin, VIO, for a flexible digital interface, operational to voltages as low as 1.62 V. The ADM3095E is PROFIBUS® compliant with a high driver differential output voltage, VOD, of 2.1 V minimum at power supply voltages greater than 4.5 V. The device is fully characterized over extended operating temperature ranges, with options of −40°C to +125°C, and is available in a 16-lead, narrow body SOIC package.

特徴

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

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

IEC 61000-4-4 EFT protection (±2 kV)

IEC 61000-4-2 ESD protection

±8 kV contact discharge

±15 kV air gap discharge

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

RS-485 A and B bus pins HBM ESD >±30 kV

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

TIA/EIA RS-485 compliant over full supply range

3.0 V to 5.5 V operating voltage range on VCC

1.62 V to 5.5 V VIO logic supply

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

2.5 Mbps data rate, maximum

Half duplex

PROFIBUS compliant at 4.5 V VCC

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

Supports 256 bus nodes (96 kΩ receiver input resistance)

−40°C to +125°C temperature option

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

16-lead narrow body SOIC package

アプリケーション

Heating ventilation and air conditioning (HVAC) networks

Industrial field buses

Building automation

Utility networks

動作理論

RS-485 WITH ROBUSTNESS

The ADM3095E is a 3.0 V to 5.5 V RS-485 transceiver with robustness that reduces system failures when operating in harsh application environments. The ADM3095E is an RS-485 transceiver that integrates IEC 61000-4-5 Level 4 surge protection, allowing up to ±4 kV protection on the RS-485 bus pins without the need for external protection components, such as transient voltage suppressors (TVSs) or totally integrated surge protectors (TISP). The ADM3095E has IEC 61000-4-4 Level 4 EFT protection up to ±2 kV, IEC 61000-4-2 Level 4 ESD protection, and IEC 61000-4-5 surge protection for the bus pins. The ADM3095E also offers a defined level of overvoltage fault protection.

CERTIFIED IEC EMC SOLUTION

The driver outputs and receiver inputs of RS-485 devices often experience high voltage faults from short circuits to power supplies that exceed the −7 V to +12 V range specified in the Telecommunications Industry Association (TIA)/Electronic Industries Alliance (EIA) RS-485 standard. Typically, RS-485 applications require costly external protection devices, such as positive temperature coefficient (PTC) fuses, for operation in harsh electrical environments. System designers must also consider common EMC problems in these harsh electrical environments, choosing components to provide IEC 61000-4-2 ESD, IEC 61000-4-4 EFT, and IEC 61000-4-5 surge protection for the RS-485 bus pins. When choosing suitable EMC protection components, achieving EMC regulations compliance and matching the EMC protection dynamic breakdown characteristics to the RS-485 transceiver can be challenging. To overcome these challenges, the designer can run multiple design, test, and printed circuit board (PCB) iterations; however, this leads to a slower time to market and project budget overruns. To reduce system cost and design complexity, the ADM3095E provides integrated EMC and overvoltage fault protection. The ADM3095E integrated EMC and overvoltage fault protection circuits are optimally performance matched, saving the circuit designer significant design and testing time. This circuit uses several discrete components, including two TISPs, two transient blocking units (TBUs), and one dual TVS. Due to the integrated protection components of the ADM3095E, the PCB area is significantly reduced when compared to a solution with discrete EMC and overvoltage fault protection components.