AMC6821 Datasheet, PDF (8/54 Pages) Burr-Brown (TI) – Analog Monitor and Control Circuit

AMC6821
SBAS386C – MAY 2006 – REVISED JULY 2007
SMBUS INTERFACE
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The AMC6821 communicates through the serial system management bus (SMBus). The AMC6821 is connected
to this bus as a slave device, under the control of a bus master. The AMC6821 has a 7-bit serial bus address
that is programmable by properly connecting the address pins A0 and A1. Table 2 shows the selection of the
AMC6821 slave address. The address selection pins should be either tied directly to V_DD or GND. For the NC
condition, they should be unconnected with minimum trace capacitance. Note that the address is checked only
on a reset or power-up condition.
Table 2. AMC6821 Address Select⁽¹⁾
A0
GND
NC
V_DD
GND
NC
V_DD
GND
NC
V_DD
A1
GND
GND
GND
NC
NC
NC
V_DD
V_DD
V_DD
ADDRESS
0011000
0011010
0011001
0101100
0101110
0101101
1001100
1001110
1001101
(1) NC = No connection.
Communication Protocols
The AMC6821 employs four standard SMBus protocols: the send byte, receive byte, write byte, and read byte.
All other operations result in undefined results. Repeated start is not allowed during the read bit.
Table 3. Send Byte
S
SLAVE ADDRESS
WR
ACK
7-bit AMC6821 slave address
COMMAND
8-bit register address
ACK
P
S = start condition; P = stop condition; shaded = slave to master; unshaded = master to slave; WR = write (bit value of 0).
Table 4. Receive Byte
S
SLAVE ADDRESS
RD
ACK
DATA
NACK
P
7-bit AMC6821 slave address
8-bit data from the register selected
previously
S = start condition; P = stop condition; shaded = slave to master; unshaded = master to slave; RD = read (bit value of 1); NACK = not
acknowledged.
S
SLAVE ADDRESS
WR
7-bit AMC6821 slave address
ACK
Table 5. Write Byte
COMMAND
8-bit register address
ACK
DATA
ACK
P
8-bit data written to register
S = start condition; P = stop condition; shaded = slave to master; unshaded = master to slave; WR = write (bit value of 0).
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