LTC2995 datasheet(73/90 Pages) AD

73 / 90 page

LTM2985

Rev. 0

For more information www.analog.com

Table Lookup Mode

For table-driven output mode, the channel assignment

word's 1st two bytes are 0xF200 for differential readings

and 0xF600 for single-ended. The 12 least significant bits

APPLICATIONS INFORMATION

containlengthandpointerinformationforthecustomtable

data. When the LTM2985 is configured for table-driven

output data, it will take the voltage value from the ADC

and perform a table lookup. The result format of the table

lookup will be a 24-bit signed integer along with the error

status byte.

Table 78. Direct ADC Table Format

ADDRESS

BYTE 0

BYTE 1

BYTE 2

BYTE 3

BYTE 4

BYTE 5

0x250 + 6 • Start Address

Table Entry #1 (mV)

Table Entry #1 (Integer Value)

0x250 + 6 • Start Address + 6

Table Entry #2 (mV)

Table Entry #2 (Integer Value)

0x250 + 6 • Start Address + 12

Table Entry #3 (mV)

Table Entry #3 (Integer Value)

•

Max Address = 0x3CA

Table Entry #64 (mV)

Table Entry #64 (Integer Value)

Table 77. Direct ADC Table Lookup Fault Data Byte

BIT

FAULT

DESCRIPTION

D31

Sensor Hard Fault

VADC < –1.75 • VREF/2 or VADC > 1.75 • VREF/2

D30

Range Hard Fault

VADC < –1.75 • VREF/2 or VADC > 1.75 • VREF/2

D29

Not Used

D28

Not Used

D27

Soft Above

VADC > Last Table Point Voltage

D26

Soft Below

VADC < Second Table Point (P1) Voltage

D25

Soft Range

VADC < –1.125 • VREF/2 or VADC > 1.125 • VREF/2

D24

Result Valid (Always 1)

Table 76. Direct ADC Table Lookup Result Format

START ADDRESS

START ADDRESS + 1

START ADDRESS + 2

START ADDRESS + 3

(END ADDRESS)

D31

D30 D29 D28 D27

D26

D25

D24

D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

Fault Data

SIGN MSB

LSB

Sensor

Hard

Fault

Range

Hard

Fault

NA NA Soft

Above

Soft

Below

Soft

Range

Valid

Always

Table Lookup Result – Signed Integer

LTC2995 Datasheet(PDF) 73 Page - Analog Devices

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