Features

• Ultra Fast (5.5ns typ)
• Complementary ECL Output
• 50 ohms Line Driving Capability
• Low Offset Voltage
• Output Latch Capability
• External Hysteresis Control
• Pin Compatible with Am685

Typical Application

Description

The LT™685 is an ultrafast comparator with differential inputs and complementary outputs fully compatible with ECL logic levels. The output current capability is adequate for driving transmission lines terminated in 50 Ohm. The low input offset and high resolution make this comparator ideally suited for analog-to-digital signal processing applications.

A latch function is provided to allow the comparator to be used in a sample-hold mode. When the latch enable input is ECL high, the comparator functions normally. When the latch enable is driven low, the comparator outputs are locked in their existing logical states. If the latch function is not used, the latch enable must be connected to ground or ECL high.

The device is pin-compatible with the Am685. Hysteresis has been added to improve switching time with slow input signals as well as to minimize oscillation. A single resistor between the hysteresis pin and V� adds input hysteresis voltage as more current is drawn. If hysteresis is not required, the pin can be left unconnected.