ST485A STMICROELECTRONICS | Alldatasheet

Document overview

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Technical content

Datasheet sections

  • 1 Pin configuration
  • 1.1 Pin description
  • 2 Truth tables
  • 3 Maximum ratings
  • 4 Electrical characteristics
  • 4.1 Logic input
  • 4.2 Transmitter
  • 4.3 Receiver
  • 4.4 Driver switching
  • 4.5 Receiver switching
  • 5 Test circuit and typical characteristics
  • 6 Package mechanical data
  • 7 Revision history

Part number Temperature range Package Comments ST485ACN 0 to 70 °C DIP-8 50parts per tube / 40tube per box ST485ABN -40 to 85 °C DIP-8 50parts per tube / 40tube per box ST485ACDR 0 to 70 °C SO-8 (Tape & reel) 2500 parts per reel ST485ABDR -40 to 85 °C SO-8 (Tape & reel) 2500 parts per ree ST485A Very high speed low power RS-485/RS-422 transceiver General features I Low supply current: 5mA max I High data rate > 30Mbps I Designed for RS 485 interface applications I -7 to 12 common mode input voltage range I Driver maintains high impedance in 3-state or with the power off I 70mV typical input hysteresis I Operate from single 5 supply I ±4kV ESD protection I Current limiting and thermal shutdown for driver overload protection I Latch-up free up to 500mA

Description

The ST485A is a low power, high speed transceiver for RS-485 and RS-422 communications. The device contains one driver and one receiver in half duplex configuration. The ST485A draws 3mA (typ.) of supply current when unloaded or fully loaded with disabled drivers. It operates from a single 5V supply. Driver is short-circuit current limited and is protected against excessive power dissipation by thermal shutdown circuitry that place the driver outputs into a high-impedance state. The receiver input has a fail-safe feature that guarantees a logic high output if both inputs are open circuit. The ST485A is designed for bi-directional data communications or multipoint bus transmission lines. DIP-8 SO-8

1 Pin configuration

Figure 1. Pin configuration

1.1 Pin description

Table 1. Pin description driver, while they are high impedance, it functions as line receivers if RE is low.

5 GND Ground

6 A Non-inverting receiver input and non-inverting driver output

7 B Inverting receiver input and inverting driver output

2 Truth tables

Table 2. Truth table (driver) Table 3. Truth table (receiver)

3 Maximum ratings

Note: Absolute maximum ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied. Table 4. Absolute maximum ratings

4 Electrical characteristics

4.1 Logic input

4.2 Transmitter

Table 5. DC Electrical characteristics Table 6. Logic input electrical characteristics Table 7. Transmitter electrical characteristics

4.3 Receiver

4.4 Driver switching

Table 8. Receiver electrical characteristics Table 9. Driver switching characteristics

4.5 Receiver switching

voltages are referenced to device ground unless specified. 2 Applies to peak current. See typical Operating Characteristics. Table 10. Driver switching characteristics

5 Test circuit and typical characteristics

Figure 2. Driver DC test load Figure 3. Receiver timing test load Figure 4. Driver/receiver timing test circuit

6 Package mechanical data

In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. These packages have a Lead-free second level interconnect. The category of second level interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com

DIM. mm. inch A 3.3 0.130 a1 0.7 0.028 B 1.39 1.65 0.055 0.065 B1 0.91 1.04 0.036 0.041 b 0.5 0.020 b1 0.38 0.5 0.015 0.020 D 9.8 0.386 E 8.8 0.346 e 2.54 0.100 e3 7.62 0.300 e4 7.62 0.300 F 7.1 0.280 I 4.8 0.189 L 3.3 0.130 Z 0.44 1.6 0.017 0.063 Plastic DIP-8 MECHANICAL DATA P001F

DIM. mm. inch A 1.35 1.75 0.053 0.069 A1 0.10 0.25 0.04 0.010 A2 1.10 1.65 0.043 0.065 B 0.33 0.51 0.013 0.020 C 0.19 0.25 0.007 0.010 D 4.80 5.00 0.189 0.197 E 3.80 4.00 0.150 0.157 e 1.27 0.050 H 5.80 6.20 0.228 0.244 h 0.25 0.50 0.010 0.020 L 0.40 1.27 0.016 0.050 k ˚ (max.) ddd 0.1 0.04 SO-8 MECHANICAL DATA 0016023/C

DIM. mm. inch A 330 12.992 C 12.8 13.2 0.504 0.519 D 20.2 0.795 N 60 2.362 T 22.4 0.882 Ao 8.1 8.5 0.319 0.335 Bo 5.5 5.9 0.216 0.232 Ko 2.1 2.3 0.082 0.090 Po 3.9 4.1 0.153 0.161 P 7.9 8.1 0.311 0.319 Tape & Reel SO-8 MECHANICAL DATA

7 Revision history

Table 11. Revision history 28-Mar-2006 2 Order codes has been updated and new template.