Datasheet

read and an acknowledge clock. The master has control
of the SCL line but the MAX5395 takes over the SDA
line. The final byte in the frame contains the register data
readback followed by a STOP condition. If additional
bytes beyond those required to read back the requested
data are provided, the MAX5395 will continue to read
back ones.
The wiper register and the configuration register are
the only two registers that support readback (Table 2).
Readback of all other registers is not supported and
results in the readback of ones.
D[7:0]: Wiper position
QP: Charge pump status, 1 is enabled, 0 is disabled.
HSW: H terminal switch status, 0 is closed, 1 is open
WSW: W terminal switch status, 0 is closed, 1 is open
LSW: L terminal switch status, 0 is closed, 1 is open
TSEL[1:0]: Tap select, 00- wiper is at contents of wiper
register, 01 – wiper is at 0x00, 10 – wiper is at 0x80, 11 –
wiper is at 0xFF.
General Call Support
The MAX5395 supports software reset through general
call address 0x00 followed by R/W = 0, followed by 0x06
data. A software reset of the MAX5395 will return the part
to the power-on default conditions. The MAX5395 will
ACK the general call address and any command byte fol-
lowing, but will not support any general call features other
than software reset.
Figure 6. Standard I
2
C Register Read Sequence
Table 2. I
2
C READ Command Byte Summary
REGISTER COMMAND BYTE DATA BYTE
C7 C6 C5 C4 C3 C2 C1 C0 D7 D6 D5 D4 D3 D2 D1 D0
WIPER 0 0 0 0 0 0 0 0 D7 D6 D5 D4 D3 D2 D1 D0
CONFIG 1 0 0 0 0 0 0 0 QP 0 0 HSW LSW WSW TSEL[1:0]
0 1 0 1 0 A1 A0 W 0 D D D D D D D D ~A1 0 1 0A A A1 A0 R ASEE REGISTER OPTIONSSDA
START STOP
WRITE ADDRESS
BYTE #1: I
2
C SLAVE ADDRESS
WRITE COMMAND
BYTE #2: COMMAND BYTE
READ ADDREESS
BYTE #3: I
2
C SLAVE ADDRESS
READ DATA
BYTE #4: DATA BYTE B[7:0]
REPEATED
START
SCL
ACK. GENERATED BY MAX5395L/
MAX5395M/MAX5395N
ACK. GENERATED BY I
2
C MASTER
MAX5395 Single, 256-Tap Volatile, I
2
C, Low-Voltage Linear
Taper Digital Potentiometer
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