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LINEAR TECHNOLOGY LTC485 Low Power RS485 Interface Transceiver User's Manual

Summary

A robust, low-power differential bus transceiver engineered for reliable RS485/RS422 data transmission in industrial applications. This comprehensive manual provides engineers with detailed technical specifications for designing multi-point communication systems. Key features covered include extended common mode ranges (-7V to 12V), built-in thermal and ESD protection, and three-state outputs suitable for glitch-free operation. Essential for professionals requiring durable serialized data links in harsh environments.

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LTC485

Low Power RS485 Interface Transceiver

FEATURES DESCRIPTIO Low Power: ICC = 300µA Typ The LTC®485 is a low power differential bus/line trans- Designed for RS485 Interface Applications ceiver designed for multipoint data transmission standard

Single 5V supply RS485 applications with extended common mode range –7V to 12V Bus Common Mode Range Permits (12V to –7V). It also meets the requirements of RS422.

±7V Ground Difference Between Devices on the Bus

The CMOS design offers significant power savings over its

Thermal Shutdown Protection

bipolar counterpart without sacrificing ruggedness against

Power-Up/Down Glitch-Free Driver Outputs

overload of ESD damage.

Permit Live Insertion or Removal of Transceiver

Driver Maintains High Impedance in Three-State The driver and receiver feature three-state outputs, with or with the Power Off the driver outputs maintaining high impedance over the Combined Impedance of a Driver Output and entire common mode range. Excessive power dissipation Receiver Allows Up to 32 Transceivers on the Bus caused by bus contention or faults is prevented by a 70m V Typical Input Hysteresis thermal shutdown circuit which forces the driver outputs 30ns Typical Driver Propagation Delays into a high impedance state.

with 5ns Skew

The receiver has a fail-safe feature which guarantees a

Pin Compatible with ±60V Protected LT1785 and

high output state when the inputs are left open.

52Mbps LTC1685

The LTC485 is fully specified over the commercial and extended industrial temperature range. APPLICATIO S , LTC and LT are registered trademarks of Linear Technology Corporation.

Low Power RS485/RS422 Transceiver Level Translator

TYPICAL APPLICATIO

Driver Outputs

RO1 VCC1

DI1 GND1

RO2 VCC2

DI2 GND2

LTC485 • TA01

LTC485 • TA02

LTC485ff

Page Summary Contents For LINEAR TECHNOLOGY LTC485 Low Power RS485 Interface Transceiver User's Manual

Page 1 LTC485 Low Power RS485 Interface Transceiver FEATURES DESCRIPTIO Low Power: ICC = 300µA Typ The LTC®485 is a low power differential bus/line trans- Designed for RS485 Interface Applications ceiver des...
Page 2 LTC485 XI ARBSOLUTE TI PACKAGE/ORDER FOR ATIO (Note 1) ORDER PART Supply Voltage 12V TOP VIEW NUMBER Control Input Voltages –0.5V to VCC + 0.5V RO VCC Driver Input Voltage –0.5V to VCC + 0.5V LTC485CN...
Page 3 OU TP UT UR RE NT (m A) LTC485 SWITCHI G CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.VCC = 5V ±5%,...
Page 4 TI (n s) OU TP UT UR RE NT (m A) OU TP UT OL TA GE (V LTC485 PERFOR ATYPICAL CE CHARA TERISTICS Receiver Output Low Voltage Driver Differential Output Voltage Driver Differential Output Voltage vs Tem...
Page 5 LTC485 PI FU CTIO S RO (Pin 1): Receiver Output. If the receiver output is DI (Pin 4): Driver Input. If the driver outputs are enabled enabled(RE low), then if A > B by 200m V, RO will be high. (DE...
Page 6 LTC485 SWITCHI G TI E WAVEFOR S 3V DI 1.5V f = 1MHz, tr ≤ 10ns, t f ≤ 10ns 1.5V t ZL t LZ OUTPUT NORMALLY LOW 0.5V A, B 2.3V OUTPUT NORMALLY HIGH t ZH t HZ LTC485 • F06 Figure 6. Driver Enable and Dis...
Page 7 LTC485 APPLICATIO S I FOR ATIO Basic Theory of Operation (D1) or the N + /P-substrate diode (D2) respectively will turn on and clamp the output to the supply. Thus, the Previous RS485 transceivers hav...
Page 8 LTC485 APPLICATIO S I FOR ATIO The LTC485 output stage will maintain a high impedance Propagation Delay state until the breakdown of the N-channel or P-channel is Many digital encoding schemes are dep...
Page 9 LTC485 APPLICATIO S I FOR ATIO LTC485 Line Length vs Data Rate Figures 17 and 18 show that the LTC485 is able to comfortably drive 4000 feet of wire at 110k Hz. The maximum line length allowable for t...
Page 10 LTC485 TYPICAL APPLICATIO S Typical RS485 Network Rt Rt LTC485 • TA03 PACKAGE DESCRIPTIO J8 Package 8-Lead CERDIP (Narrow .300 Inch, Hermetic) (Reference LTC DWG # 05-08-1110) CORNER LEADS OPTION 0.40...
Page 11 LTC485 PACKAGE DESCRIPTIO N8 Package 8-Lead PDIP (Narrow .300 Inch) (Reference LTC DWG # 05-08-1510) 0.400* (10.160) MAX 0.065 (1.651) 0.009 – 0.015 TYP +0.035 MIN (0.508) 0.325 –0.015 MIN0.018 ± 0.00...
Page 12 LTC485 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC486/LTC487 Low Power Quad RS485 Drivers 110µA Supply Current LTC488/LTC489 Low Power Quad RS485 Receivers 7m A Supply Current LTC490/LTC491 Low...

Manual Details

Brand Linear
Pages 12
File Size 270.45 KB
Published June 01, 2026
56 views

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Frequently Asked Questions

What is the extended common mode range supported by this device?

The LTC485 supports an extended common mode range from –7V to 12V, and also meets RS422 requirements.

How many transceivers can be connected safely on a single bus?

The transceiver is designed to allow up to 32 transceivers on the bus itself.

What protection does the device offer regarding signal output status?

It features three-state outputs, maintaining high impedance even when the power is off.

Is the chip protected against sudden power failures or surges?

It provides protection against power-up/down glitches, overload, and ESD damage to ensure ruggedness.