Stand-Alone, 10-Channel, 10-Bit System Monitors

14

______________________________________________________________________________________

Clock pulses on SCLK shift data into DIN on the rising

edge of the SCLK and out of DOUT on the falling edge

of SCLK.

Data transfers require a logic low on CS. A high-to-low

transition of CS marks the beginning of a data transfer. A

logic high on CS at any time resets the serial interface.

See Figure 6 and the

Timing Characteristics table for

detailed serial-interface timing information.

Input Data Format

Serial communications always begin with an 8-bit com-

mand word, serially loaded from DIN. A high-to-low

transition on CS initiates the data input operation. The

command word and the subsequent data bytes (for

write operations) are clocked from DIN into the

MAX1153/MAX1154 on the rising edges of SCLK. The

first rising edge on SCLK, after CS goes low, clocks in

the MSB of the command word (see the

Command

Word section). The next seven rising edges on SCLK

complete the loading of the command word into the

internal command register. After the 8-bit command

word is entered, transfer 0 to 20 bytes of data, depend-

ing on the command. Table 2 shows the number of

data bytes for each command.

Output Data Format

Output data from the MAX1153/MAX1154 is clocked

onto DOUT on the falling edge of SCLK. Single-ended

and unipolar differential measurements are output in

straight binary MSB first, with two 8-bytes-per-conver-

sion result, with 2 sub-bits and the last 4 bits padded

with zeros. For temperature and bipolar differential volt-

age measurements, the output is two’s complement

binary in the same 2-byte format. The MSB of the out-

put data from a read command transitions at DOUT

after the falling edge of the 8th SCLK clock pulse fol-

lowing the CS high-to-low transition. Table 2 shows the

number of bytes to be read from DOUT for a given read

command.

Command Word

The command word (Table 1) controls all serial com-

munications and configuration of the MAX1153/

MAX1154, providing access to the 44 on-chip registers.

The first 4 MSBs of the command word specify the

command (Table 2), while the last 4 bits provide

address information.

The first rising edge on SCLK, after CS goes low, trans-

fers the command word MSB into DIN. The next seven

rising edges on SCLK shift the remaining 7 bits into the

internal command register (see the

Serial Digital

Interface section).

SCLK

DIN

DOUT

CS

Figure 6. Detailed Serial Interface Timing Diagram

Table 1. Command Word

B7 (MSB)

B6

B5

B4

B3

B2

B1

B0 (LSB)

Command B3

Command B2

Command B1

Command B0

Address B3

Address B2

Address B1

Address B0