LTC1594CS datasheet(11/24 Pages) LINER

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LTC1594/LTC1598

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APPLICATIONS INFORMATION

Figure 2. LTC1594/LTC1598 Operating Sequence Example: All Channels Off

CLK

tCYC

Hi-Z

DOUT

CH0 TO

CH7

DIN

tCONV

Hi-Z

tsuCS

NULL

BIT

tOFF

D0N‘T CARE

ADCIN =

MUXOUT

COM = GND

1594/98 F02

DUMMY CONVERSION

CSMUX = CSADC = CS

break-before-make interval, tOPEN. After a delay of tON

(tOFF + tOPEN), the selected channel is switched on,

allowing the ADC in the chip to acquire input signal and

start the conversion (see Figures 1 and 2). After 1 null bit,

the result of the conversion is output on the DOUT line.

The selected channel remains on, until the next falling

edge of CS. At the end of the data exchange CS should be

brought high. This resets the LTC1594/LTC1598 and

initiates the next data exchange.

DIN1

DIN2

DOUT1

DOUT2

SHIFT MUX

ADDRESS IN

tSMPL + 1 NULL BIT

SHIFT A/D CONVERSION

RESULT OUT

1594/98 AI01

Break-Before-Make

The LTC1594/LTC1598 provide a break-before-make

interval from switching off all the channels simulta-

neously to switching on the next selected channel once

CS is pulled low. In other words, once CS is pulled low,

Data Transfer

The CLK synchronizes the data transfer with each bit

being transmitted on the falling CLK edge and captured

on the rising CLK edge in both transmitting and receiving

systems.

The LTC1594/LTC1598 first receive input data and then

transmit back the A/D conversion results (half duplex).

Because of the half duplex operation, DIN and DOUT may

be tied together allowing transmission over just 3 wires:

CS, CLK and DATA (DIN/DOUT).

Data transfer is initiated by a rising chip select (CS)

signal. After CS rises the input data on the DIN pin is

latched into a 4-bit register on the rising edge of the clock.

More than four input bits can be sent to the DIN pin

without problems, but only the last four bits clocked in

before CS falls will be stored into the 4-bit register. This

4-bit input data word will select the channel in the

multiplexer (see Input Data Word and Tables 1 and 2). To

ensure correct operation the CS must be pulled low

before the next rising edge of the clock.

Once the CS is pulled low, all channels are simulta-

neously switched off after a delay of tOFF to ensure a

LTC1594CS Datasheet(PDF) 11 Page - Linear Technology

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