The HI-8427 is a galvanically isolated Ground/Open discrete-to-digital sensor with six inputs, similar to Holt's other well-known D-to-D products. It has two GND/Open threshold detection modes, the first designed to sense lower threshold levels in the 0V to 5V range, the other designed to sense analog input levels compliant to Airbus ABD0100H specification (Standard Mode).  

 

When any of the analog sensor inputs are "Open", the corresponding digital output will read logic "1". When any of the sense input lines are at “Ground” potential, the corresponding digital output will read logic "0". In Low Threshold Mode, a DISCONNECT output signal will be asserted when all the analog sensor inputs are "Open" (all digital outputs read logic “1”). In addition, a minimum of 5mA "wetting" current is provided to the sense input wire when any of the sense input lines are at “Ground” potential. In Standard Mode, the wetting current is 1mA. 

 

The HI-8427 is designed with robust Silicon-on-Insulator (SOI) CMOS technology, providing galvanic isolation up to 400V between the sensor inputs and the logic interface. All sense inputs can withstand MIL-STD-704 power transients. In Standard Mode, sense inputs are lightning protected to RTCA/DO-160G, Section 22 Pin Injection Test Waveform Set AZ (3 & 4), Set BZ (3 & 5A) and Set ZZ (3 & 5B) without any external components. Additional level 3 protection may be accomplished by use of an external 470 Ohm resistor.

 

  

Features

• 6-Channel galvanically isolated GND/Open discrete-to-digital sensor
• 400V isolation between sensor inputs and the logic interface
• In Low Threshold Mode, DISCONNECT signal indicates all sense input lines are “Open” (all digital outputs read logic “1”)
• Wetting current of 5mA provided in Low Threshold Mode
• Standard Mode detects Airbus ABD0100H and MIL-STD-704 standard compliant sensor thresholds with 1mA wetting current
• Robust Silicon-On-Insulator (SOI) CMOS technology
• In Standard Mode, sense inputs are lightning protected to RTCA/DO-160G, Section 22, Level 3 with external 470 Ohm resistor
• Supports 28V analog supply
• Withstands inadvertent application of 115 Vrms (60 - 400 Hz) power to sense inputs
• 3.3V, 2.5V or 1.8V compatible logic levels
• Compact thermally enhanced TSSOP package
• Single die for improved reliability and component and space saving
• Industrial and extended temperature ranges
• Burn-in available

 

Applications

• Sense analog input levels compliant to Airbus ABD0100H specification in 28V aircraft systems
• Sense low threshold levels in the 0 to 5V range in CMOS or TTL applications
• Sense analog input levels in 5V aircraft systems such as MIL-STD-1760 address line or similar discrete voltages