LTC2487_15 datasheet(21/34 Pages) LINER

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LTC2487

2487ff

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Figure 6. Conversion Sequence

Figure 7. Consecutive Reading with the Same Input/Configuration

Table 6. Address Assignment

CA1

CA0

ADDRESS

LOW

0010100

LOW

HIGH

0010110

LOW

FLOAT

0010101

HIGH

LOW

0100110

HIGH

0110100

HIGH

FLOAT

0100111

FLOAT

LOW

0010111

FLOAT

HIGH

0100101

FLOAT

0100100

ACK

DATA

DATA TRANSFERRING

7-BIT ADDRESS

R/W

2487 F06

CONVERSION

SLEEP

DATA INPUT/OUTPUT

7-BIT ADDRESS

ACK

READ

2487 F07

CONVERSION

ADDRESS

SLEEP

DATA OUTPUT

DATA INPUT

SLEEP

Operation Sequence

The LTC2487 acts as a transmitter or receiver, as shown

in Figure 6. The device may be programmed to perform

several functions. These include input channel selection,

measure the internal temperature, selecting the line fre-

quency rejection (50Hz, 60Hz, or simultaneous 50Hz and

60Hz), a 2x speed mode and gain.

Continuous Read

Inapplicationswheretheinputchannel/configurationdoes

not need to change for each cycle, the conversion can be

continuously performed and read without a write cycle

(see Figure 7). The configuration/input channel remains

unchanged from the last value written into the device. If

the device has not been written to since power up, the

configuration is set to the default value. At the end of a

read operation, a new conversion automatically begins.

At the conclusion of the conversion cycle, the next result

may be read using the method described above. If the

conversion cycle is not concluded and a valid address

selects the device, the LTC2487 generates a NAK signal

indicating the conversion cycle is in progress.

Continuous Read/Write

Once the conversion cycle is concluded, the LTC2487 can

be written to and then read from using the Repeated Start

(Sr) command.

Figure 8 shows a cycle which begins with a data Write, a

repeated Start, followed by a Read and concluded with a

Stop command. The following conversion begins after all

24 bits are read out of the device or after a Stop command.

Thefollowingconversionwillbeperformedusingthenewly

programmed data. In cases where the same speed (1x/2x

mode), rejection frequency (50Hz, 60Hz, 50Hz and 60Hz)

and gain is used but the channel is changed, a Stop or

Repeated Start may be issued after the first byte (channel

selection data) is written into the device.

Discarding a Conversion Result and Initiating a New

Conversion with Optional Write

At the conclusion of a conversion cycle, a write cycle

can be initiated. Once the write cycle is acknowledged, a

Stop command will start a new conversion. If a new input

channel or conversion configuration is required, this data

APPLICATIONS INFORMATION

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