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

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.

  • 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
  • High Speed RS485/RS422 Transceivers
  • Level Translator
  • Backplane Transceiver
  • STS-1/OC-1 Data Transceiver
  • Fast-20, Fast-40 SCSI Transceivers
LTC1685 Package Drawing
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Design Note
Reliability Data
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LTC1685 Footprints and Symbols