The HI-8425 is a combined 8-channel discrete-to-digital sensor and quad low side driver fabricated with Silicon-on-Insulator (SOI) technology for robust latch-up free operation. Sense detection can either be GND/Open or Supply/Open as configured by the SNSE_SEL pin. Supply/Open sensing is also referred to as 28V/Open sensing. The sensing circuit window comparator thresholds can be fixed at the internal programmed values or can be set externally at the HI_SET and LO_SET pins, as selected by the nTHS_SEL pin. The digital SENSE outputs can be tri-stated by taking the nOE pin high. The VWET pin is available for optional application of a voltage higher than the logic supply to provide wetting current to Ground side relay contacts. If the Ground offset is small, then the wetting source will automatically be provided from VLOGIC without connecting VWET.
All sense inputs are internally lightning protected to DO160G, Section 22, Cat AZ, BZ and ZZ without external components.
The HI-8425 also offers four low side switches each capable of sinking 200 mA of current. Each switch transistor is controlled by its own digital input pin and is fully fault protected. Over-current conditions, such as a short circuit, are detected and inhibited while signaling the fault condition at the corresponding logic output. These four FAULT outputs are also available in a combined OR output. The outputs are fully protected from transients when driving relays.
The HI-8426 is a smaller, reduced pin version of the HI-8425 and is available in a 32-pin PQFP or 5mm x 5mm QFN. It has all the features of the HI-8425 except the individual fault detection outputs, tri-state pin selection and fixed internal thresholds.
Interface to the digital subsystem is simple CMOS logic inputs and outputs. The logic pins are compatible with 5V or 3.3V logic allowing direct connection to a wide range of microcontrollers or FPGAs.
Features
- 8-channel Selectable Sense Operation, GND/Open or 28V/Open
- Selectable Thresholds and Hysteresis
- Sense Detection Range 2V to 21V
- Logic Operation from 3.0V to 5.5V
- Lightning Protected Sense Inputs
- Airbus ABD0100H compliant
- 4 Low-Side 200 mA Drivers
- 4.5 Ohm On Resistance
- Over-Current Fault Detection Signaled by Logic Output
- Max Power Dissipation Automatically Limited by Fault Protection
- Diode Clamps for Discharging Inductive Loads
- Robust CMOS Silicon-on-Insulator (SOI) technology
- Industrial & extended temperature ranges available
Applications
- Avionics discrete sensing applications
- Avionics low-side driver applications (e.g. indicator lamps and relays)