MAX5477_06 Datasheet, PDF (13/17 Pages) Maxim Integrated Products – Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers

Dual, 256-Tap, Nonvolatile, I²C-Interface,
Digital Potentiometers
SDA
SCL
DATA STABLE, CHANGE OF
DATA VALID DATA ALLOWED
Figure 5. Bit Transfer
START
CONDITION
SCL
1
2
SDA
Figure 6. Acknowledge
CLOCK PULSE FOR
ACKNOWLEDGMENT
8
9
NOT ACKNOWLEDGE
ACKNOWLEDGE
COMMAND BYTE IS STORED ON RECEIPT OF STOP CONDITION
ACKNOWLEDGE FROM
MAX5477/MAX5478/MAX5479
D15 D14 D13 D12 D11 D10 D9 D8
S
SLAVE ADDRESS
0A
COMMAND BYTE
AP
NOP/W
ACKNOWLEDGE FROM
MAX5477/MAX5478/MAX5479
Figure 7. Command Byte Received
HOW CONTROL BYTE AND DATA BYTE MAP INTO
MAX5477/MAX5478/MAX5479 REGISTERS
ACKNOWLEDGE FROM
MAX5477/MAX5478/MAX5479
ACKNOWLEDGE FROM
MAX5477/MAX5478/MAX5479
D15 D14 D13 D12 D11 D10 D9 D8
ACKNOWLEDGE FROM
MAX5477/MAX5478/MAX5479
D7 D6 D5 D4 D3 D2 D1 D0
S
SLAVE ADDRESS
0A
COMMAND BYTE
A
DATA BYTE
AP
NOP/W
Figure 8. Command and Single Data Byte Received
1 BYTE
3 bits in the slave address. Connect each address input
to V_DD or GND to set these 3 bits. Each device must
have a unique address to share a common bus.
Message Format for Writing
Write to the MAX5477/MAX5478/MAX5479 by transmit-
ting the device’s slave address with NOP/W (8th bit) set
to zero, followed by at least 1 byte of information
(Figure 7). The 1st byte of information is the command
byte. The bytes received after the command byte are
the data bytes. The 1st data byte goes into the internal
register of the MAX5477/MAX5478/MAX5479 as select-
ed by the command byte (Figure 8).
Command Byte
Use the command byte to select the source and desti-
nation of the wiper data (nonvolatile or volatile memory
registers) and swap data between nonvolatile and
volatile memory registers (see Table 3).
Command Descriptions
VREG: The data byte writes to the volatile memory reg-
ister and the wiper position updates with the data in the
volatile memory register.
NVREG: The data byte writes to the nonvolatile memory
register. The wiper position is unchanged.
NVREGxVREG: Data transfers from the nonvolatile
memory register to the volatile memory register (wiper
position updates).
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