+/-15 kV ESD protected, low power RS-485/RS-422 transceiver

Document overview

  • Manufacturer or author: STMICROELECTRONICS
  • PDF pages: 18

Technical content

Datasheet sections

  • 1 Pin configuration
  • 2 Truth tables
  • 3 Maximum ratings
  • 4 Electrical characteristics
  • 5 Test circuit and typical characteristics
  • 6 Package mechanical data
  • 7 Revision history

Features

■ Low quiescent current: 300 µA ■ Designed for RS-485 interface application ■ - 7 V to 12 V common mode input voltage range ■ Driver maintains high impedance in 3-state or with the power OFF ■ 70 mV typical input hysteresis ■ 30 ns propagation delay, 5 ns skew ■ Operates from a single 5 V supply ■ Current limiting and thermal shutdown for driver overload protection ■ ESD protection: – ± 15 kV (HBM) – ± 8 kV (IEC-1000-4-2 contact discharge) ■ Allows up to 256 transceivers on the bus

Description

The ST485E is a low power transceiver for RS- 485 and RS-422 communication. Each driver output and receiver input is protected against ± 15 kV electrostatic discharge (HBM) (ESD) shocks, without latch-up. These parts contain one driver and one receiver in half duplex configuration. This transceiver draws 300 µA (typ.) of supply current when unloaded or fully loaded with disabled drivers. It operates from a single 5 V 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 ST485E is designed for bi-directional data communications on multipoint bus transmission lines (half-duplex applications). SO-8 Table 1. Device summary

1 Pin configuration

Figure 1. Pin connections (top view) Table 2. Pin description

1 RO Receiver output

3 DE Driver output enable

4 DI Driver input

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 3. Truth table (driver) Table 4. 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 is not implied. Table 5. Absolute maximum ratings

4 Electrical characteristics

Table 6. ESD performance: transmitter outputs, receiver inputs Table 7. DC electrical characteristics

  1. All currents into device pins are positive; all out of device pins are negative; all voltages are referenced to device ground
  2. Supply current specification is valid for loaded transmitters when VDE = 0 V
  3. Applies to peak current. See ty pical Operating Characteristics.

Table 7. DC electrical characteristics (continued) Table 8. Driver switching characteristics

  1. All currents into device pins are positive; all out of device pins are negative; all voltages are referenced to device ground

Table 9. Receiver switching characteristics

  1. All currents into device pins are positive; all out of device pins are negative; all voltages are referenced to device ground

5 Test circuit and typical characteristics

Figure 2. Driver DC test load Figure 3. Receiver timing test load Figure 4. Drive/receiver timing test circuit Figure 5. Driver timing test load

6 Package mechanical data

In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at: www.st.com. ECOPACK is an ST trademark.

Dim. mm. inch. A1 . 35 1.75 0.05 3 0.069 A1 0.10 0.25 0.04 0.010 A2 1.10 1.65 0.04 3 0.065 B0 . 33 0.51 0.01 3 0.020 C0 . 1 9 0.25 0.007 0.010 D4 . 80 5.00 0.1 89 0.197 E 3.80 4.00 0.150 0.157 e 1.27 0.050 H5 . 80 6.20 0.22 8 0.244 h 0.25 0.50 0.010 0.020 L 0.40 1.27 0.016 0.050 k 8° (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 0.51 9 D 20.2 0.7 95 N6 0 2 . 362 T 22.4 0. 882 Ao 8.1 8.5 0. 319 0.335 Bo 5.5 5. 9 0.216 0.2 32 Ko 2.1 2. 3 0.082 0.0 90 Po 3.9 4.1 0.15 3 0.161 P7 . 98 .1 0. 311 0. 319 Tape & reel SO-8 mechanical data

7 Revision history

Table 10. Document revision history 21-Mar-2006 9 Order codes has been updated and new template. 05-Jun-2006 10 Change value row 10 on the features and R IN in Table 7. 29-Jan-2007 11 Typo mistake on page 1. 29-Aug-2007 12 Change value R IN min. on Table 7. 07-Feb-2008 13 Modified: Table 1 on page 1. 16-Feb-2009 14 Modified: Note: on page 5.