LTC1290 datasheet(17/28 Pages) LINER

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LTC1290

APPLICATI

I FOR ATIO

8051 Code

MNEMONIC

COMMENTS

MOV P1,#02H

Bit 1 Port 1 Set as Input

CLR P1.3

SCLK Goes Low

SETB P1.4

CS Goes High

CONT

MOV A,#0EH

DIN Word for LTC1290

CLR P1.4

CS Goes Low

MOV R4,#08H

Load Counter

NOP

Delay for Deglitcher

LOOP

MOV C,P1.1

Read Data Bit Into Carry

RLC A

Rotate Data Bit Into ACC

MOV P1.2,C

Output DIN Bit to LTC1290

SETB P1.3

SCLK Goes High

CLR P1.3

SCLK Goes Low

DJNZ R4,LOOP

Next Bit

MOV R2,A

Store MSBs in R2

MOV C,P1.1

Read Data Bit Into Carry

CLR A

Clear ACC

RLC A

Rotate Data Bit Into ACC

SETB P1.3

SCLK Goes High

CLR P1.3

SCLK Goes Low

MOV C,P1.1

Read Data Bit Into Carry

RLC A

Rotate Data Bit Into ACC

SETB P1.3

SCLK Goes High

CLR P1.3

SCLK Goes Low

MOV C,P1.1

Read Data Bit Into Carry

RLC A

Rotate Data Bit Into ACC

SETB P1.3

SCLK Goes High

CLR P1.3

SCLK Goes Low

MOV C, P1.1

Read Data Bit Into Carry

RRC A

Rotate Right Into ACC

RRC A

Rotate Right Into ACC

RRC A

Rotate Right Into ACC

RRC A

Rotate Right Into ACC

MOV R3,A

Store LSBs in R3

SETB P1.3

SCLK Goes High

CLR P1.3

SCLK Goes Low

SETB P1.4

CS Goes High

MOV R5,#0BH

Load Counter

DELAY

DJNZ R5,DELAY

Go to Delay if Not Done

8 CHANNELS

3-WIRE SERIAL

INTERFACE TO OTHER

PERIPHERALS OR LTC1290s

OUTPUT PORT

SERIAL DATA

MPU

LTC1290 F05

LTC1290

Sharing the Serial Interface

The LTC1290 can share the same 3-wire serial interface

with other perpheral components or other LTC1290s (see

Figure 5). In this case, the CS signals decide which

LTC1290 is being addressed by the MPU.

ANALOG CONSIDERATIONS

1. Grounding

The LTC1290 should be used with an analog ground plane

and single point grounding techniques.

AGND (Pin 11) should be tied directly to this ground plane.

DGND (Pin 10) can also be tied directly to this ground

plane because minimal digital noise is generated within

the chip itself.

VCC (Pin 20) should be bypassed to the ground plane with

a 22

µF tantalum with leads as short as possible. V– (Pin

12) should be bypassed with a 0.1

µF ceramic disk. For

single supply applications, V – can be tied to the ground

plane.

It is also recommended that REF – (Pin 13) and COM (Pin

9) be tied directly to the ground plane. All analog inputs

should be referenced directly to the single point ground.

Digital inputs and outputs should be shielded from and/or

routed away from the reference and analog circuitry.

Figure 5. Several LTC1290s Sharing One 3-Wire Serial Interface

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