7

LTC1392

MSB-First Data (MSBF = 1)

CS

START

SEL1 SEL0

SEL1 SEL0

MSBF

Hi-Z

Hi-Z

FILLED WITH ZEROS

B9

B8

B7

B6

B5

B4

B3

B2

B1

B0

CLK

CS

START

MSBF

Hi-Z

Hi-Z

LTC1392 • F01

FILLED WITH ZEROS

B9

B8

B7

B6

B5

B4

B3

B2

B1

B0

B1

B2

B3

B4

B5

B6

B7

B8

B9

CLK

Figure 1

temperature measurement or a 10

µs delay for other mea-

surements, followed by a 4-bit input word which config-

ures the LTC1392 for the current conversion. This data

three-state to an output pin. A null bit and the result of the

current conversion are serially transmitted on the falling

can be either MSB-first sequence or MSB-first sequence

followed by an LSB-first sequence. This provides easy

interface to MSB- or LSB-first serial ports. Bringing CS

high resets the LTC1392 for the next data exchange.

INPUT DATA WORD

Data transfer is initiated by a falling chip select (CS) signal.

After CS falls, the LTC1392 looks for a start bit. Once the

start bit is received, the next three bits are shifted into the

ignored until the next CS cycle. The four bits of the input

word are defined as follows:

BIT 3

BIT 2

BIT 1

BIT 0

Start

Select 1

Select 0

MSBF

Start Bit

goes low is the Start Bit. The Start Bit initiates the data

transfer and all leading zeros which precede this logical

one will be ignored. After the Start Bit is received the

remaining bits of the input word will be clocked in. Further

cycle.