HI-8470(2013) Ver la hoja de datos (PDF) - Holt Integrated Circuits

Número de pieza

componentes Descripción

fabricante

HI-8470
(Rev.:2013)

16-Channel Discrete-to-Digital Sensor with ARINC 429 Transmitter

Holt Integrated Circuits 

HI-8470

FUNCTIONAL DESCRIPTION

OVERVIEW

The HI-8470 has 16 Sense channels that are individually

programmed for either GND/OPEN or SUPPLY/OPEN de-

tection. The programming of each channel is set by strapping

the appropriate SEL pin. There are 16 SENSE INPUT pins

(SI15:0) with 16 corresponding SEL strap pins (SEL15:0).

The window comparator for detecting the state of the SENSE

INPUT is offered with a choice of either standard internal

voltage thresholds or, by option pins, the thresholds can be

supplied externally. The choice of standard internal or exter-

nal thresholds is selectable for each of the two sense func-

tions, GND/OPEN and VOLTAGE/OPEN. If an external op-

tion is chosen, there are two pins for each function to input a

HIGH or LOW level for thresholds. It is possible to set either

of the external thresholds to logic levels such that a particular

SEL option can function as digital state detection.

The HI-8470 has an onboard ARINC 429 transmitter. An on-

chip DC-DC converter provides 3.3V-only operation, or ex-

ternal +6V and -6V power supplies may be connected. This

selection is controlled by the voltage provided at the VDD

pin.

The discrete sense pins and line driver outputs are lightning

protected to RTCA/DO-160G, Section 22 Level 3 Pin

Injection Test Waveform Set A (3 & 4), Set B (3 & 5A) and Set

Z (3 & 5B) without the use of any external components.

Logic and digital inputs and outputs operate from the

VLOGIC supply.

A 1MHz clock must be provided at the CLKIN pin to operate

the ARINC 429 transmitter. The Master Reset (MR) pin is

ORed with an on-chip Power On Reset (POR).

The SPEED pin selects the speed of the ARINC 429 trans-

mission.

When set from logic 0 to logic 1, the TXENB input pin trig-

gers ARINC 429 word transmission. The ARINC 429 trans-

mitter is disabled when TXENB is held at logic 0. When

TXENB is held at logic 1, periodic ARINC 429 word trans-

mission occurs at a fixed interval programmed by eight

input pins TMR7:0. When the TMR7:0 value ranges from 1

to 255 decimal, the word re-transmit interval equals TMR

value x 10 milliseconds, or 10 to 2,550 ms.

Unique case:

When TMR7:0 equals zero, the ARINC 429 word re-

transmission interval depends on the state of the SPEED

input pin: For SPEED equals 0 (low-speed, 12.5Kb/s) the

shortest interval is 2.88 ms when TMR7:0 equals 0. For

SPEED equals 1 (high-speed, 100 Kb/s) the shortest re-

transmission interval is 360 us when TMR7:0 equals 0.

After a detected Power On Reset, transmission is disabled

for 500 ms to prevent spurious and possibly erroneous

data.

The sense data for each of the 16 channels is transmitted

directly in an ARINC 429 word. The label value is set by the

eight Label input pins (LBL7:0). 2 pins (BIT9 and BIT10)

configure the transmitted ARINC 429 SD bits. To allow

additional flexibility, the last five bits of the ARINC 429 word

are configured by the five BIT31:27 pins. Bits 11 through

26 of the ARINC 429 transmission have 16 bits of data

mapped from the SENSE INPUT detections. The 32nd bit

is odd parity. Note that the five bits of data set by the

BIT31:27 pins could alternatively be used for detection and

transmission of logic levels within the system.

Two pins (TEST1 and TEST0) provide a means of self test.

If TEST0 is taken high, all comparator inputs are forced to

ground and if TEST1 is taken high, all comparator inputs

are forced high. If both self test inputs are high, the result is

an alternating pattern with SI0 comparator input forcing a

high input, Si1 forcing a ground input, etc.

HOLT INTEGRATED CIRCUITS

6

Share Link: