HOLT INTEGRATED CIRCUITS

3

PIN

FUNCTION

DESCRIPTION

VLOGIC

Supply

3.3V Power Supply for both sensors and logic.

VWET<0-3>

Supply

Optional inputs to supply relay wetting current to sense lines in GND/Open

operation. Each of the 4 banks of 8 inputs has a VWETn pin. 50K

to GND.

Ω

SENSE<31:0>

Discrete Input

4 banks of 8 discrete inputs programmable through the SPI to be either

GND/Open or Supply/Open.

The type of input is programmed by bank, PSEN<3:0> bits. “0” makes the

bank GND/Open sensors, “1” makes the bank SUPPLY/Open sensors

The status of the inputs SENSE<31:0> are stored in SO<31:0>

See SPI section for programming and reading sensors.

GND

Supply

0V Ground for Sensor and Logic.

SCK

Digital Input

SPI Clock.

nCS

Digital Input

SPI Chip Select, Active Low, internal 30K

pull-up.

Ω

SI

Digital Input

SPI serial data input, internal 30K

pull-down.

Ω

SO

Digital Output

SPI serial data output.

nMR

Digital Input

Master Reset, Active Low, internal 30K

pull-up.

Ω

HI-8436

PIN DESCRIPTIONS

OP Code

R/W

# Data

Bytes

DESCRIPTION

0x02

W

1

Write Control Register

0x04

W

1

Write Program Sense Banks Register, PSEN<3:0>, to program SENSE Inputs

0x3A

W

2

Write GND/Open Threshold Center Value and Hysteresis

0x3C

W

2

Write Supply/Open Threshold Center Value and Hysteresis

0x1E

W

1

Write Test Mode Data Register

0x82

R

1

Read Control Register

0x84

R

1

Read Program Sense Banks Register, to read programmed bank type

0xBA

R

2

Read GND/Open Threshold Center Value and Hysteresis

0xBC

R

2

Read Supply/Open Threshold Center Value and Hysteresis

0x9E

R

1

Read Test Mode Data Register

0x90

R

1

Read Bank 0, SOUT Register, SO<7:0>, status of SENSE<7:0> Inputs

0x92

R

1

Read Bank 1, SOUT Register, SO<15:8>, status of SENSE<15:8> Inputs

0x94

R

1

Read Bank 2, SOUT Register, SO<23:16>, status of SENSE<23:16> Inputs

0x96

R

1

Read Bank 3, SOUT Register, SO<31:24>, status of SENSE<31:24> Inputs

0xF8

R

4

Read All Banks, SOUT Register, SO<31:0>, status of SENSE<31:0> Inputs

SPI COMMANDS

Table 2.

Table 1.