ZHCS823H March 2012 – March 2019 SN65HVD72 , SN65HVD75 , SN65HVD78
UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.
- 1 特性
- 2 應用
- 3 說明
- 4 修訂歷史記錄
- 5 Device Comparison Table
- 6 Pin Configuration and Functions
-
7 Specifications
- 7.1 Absolute Maximum Ratings
- 7.2 ESD Ratings
- 7.3 Recommended Operating Conditions
- 7.4 Thermal Information
- 7.5 Electrical Characteristics
- 7.6 Power Dissipation
- 7.7 Switching Characteristics: 250 kbps Device (SN65HVD72) Bit Time ≥ 4 µs
- 7.8 Switching Characteristics: 20 Mbps Device (SN65HVD75) Bit Time ≥50 ns
- 7.9 Switching Characteristics: 50 Mbps Device (SN65HVD78) Bit Time ≥20 ns
- 7.10 Typical Characteristics
- 8 Parameter Measurement Information
- 9 Detailed Description
- 10Application and Implementation
- 11Power Supply Recommendations
- 12Layout
- 13器件和文檔支持
- 14機械、封裝和可訂購信息
封裝選項
機械數據 (封裝 | 引腳)
散熱焊盤機械數據 (封裝 | 引腳)
- DRB|8
訂購信息
10.2 Typical Application
An RS-485 bus consists of multiple transceivers connected in parallel to a bus cable. To eliminate line reflections, each cable end is terminated with a termination resistor, RT, whose value matches the characteristic impedance, Z0, of the cable. This method, known as parallel termination, allows for relatively high data rates over long cable lengths.
Figure 20. Typical RS-485 Network With SN65HVD7x Transceivers Common cables used are unshielded twisted pair (UTP), such as low-cost CAT-5 cable with Z0 = 100 Ω, and
RS-485 cable with Z0 = 120 Ω. Typical cable sizes are AWG 22 and AWG 24.
The maximum bus length is typically given as 4000 ft or 1200 m, and represents the length of an AWG 24 cable whose cable resistance approaches the value of the termination resistance, thus reducing the bus signal by half or 6 dB. Actual maximum usable cable length depends on the signaling rate, cable characteristics, and environmental conditions.