LTC1685 - 52Mbps, Precision Delay, RS485 Fail-Safe Transceiver


  • Precision Propagation Delay Over Temperature: Receiver/Driver: 18.5ns ±3.5ns
  • High Data Rate: 52Mbps
  • Low tPLH/tPHL Skew: Receiver/Driver: 500ps Typ
  • –7V to 12V RS485 Input Common Mode Range
  • Guaranteed Fail-Safe Receiver Operation Over the Entire Common Mode Range
  • High Receiver Input Resistance: >/=22k, Even When Unpowered
  • Short-Circuit Protected
  • Thermal Shutdown Protected
  • Driver Maintains High Impedance in Three-State or with Power Off
  • Single 5V Supply
  • Pin Compatible with LTC485
  • 45dB CMRR at 26MHz

Typical Application

LTC1685 Typical Application
LTC1685 Typical Application


The LTC®1685 is a high speed, precision delay RS485 transceiver that can operate at data rates as high as 52Mbps. The device also meets the requirements of RS422. A unique architecture provides very stable propagation delays and low skew over a wide common mode and ambient temperature range. The driver and receiver feature three-state outputs, with disabled driver outputs maintaining high impedance over the entire common mode range. A short circuit feature detects shorted outputs and substantially reduces driver output current. A similar feature also protects the receiver output from short circuits. Thermal shutdown circuitry protects from excessive power dissipation. The receiver has a fail-safe feature that guarantees a high output state when the inputs are shorted or are left floating. The LTC1685 RS485 transceiver guarantees receiver fail-safe operation over the entire common mode range (–7V to 12V). Input resistance will remain >/=22k when the device is unpowered or disabled. The LTC1685 operates from a single 5V supply and draws only 7mA of supply current.


CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
LTC1685CS8#PBF SO-8 S8 C 05-08-1610 (S8) Yes
LTC1685CS8#TRPBF SO-8 S8 C 05-08-1610 (S8) Yes
LTC1685IS8#PBF SO-8 S8 I 05-08-1610 (S8) Yes
LTC1685IS8#TRPBF SO-8 S8 I 05-08-1610 (S8) Yes

LTC1685 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
LTC1685CS8#PBF SO-8 C $3.40 $2.95 Yes
LTC1685CS8#TRPBF SO-8 C $3.01 Yes
LTC1685IS8#PBF SO-8 I $3.80 $3.20 Yes
LTC1685IS8#TRPBF SO-8 I $3.26 Yes
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Click here to view our complete list of demo boards


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