Datasheet
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DAC8571
SLAS373A – DECEMBER 2002 – REVISED JULY 2003
master generates a 9
th
SCL pulse and monitors the state of the SDA line during the high period of this 9th clock
cycle (master leaves the SDA line high). The SDA line being pulled low by the receiver during the high period of
9
th
clock cycle is called an acknowledge signal. If the master receives an acknowledge signal, it knows that a
DAC8571 successfully matched the address the master sent. Upon the receipt of this acknowledge, the master
knows that the high-speed communication link with a DAC8571 has been established and more data could be
sent. The master continues by sending a control byte, C<7:0>, which sets DAC8571 operation mode. After
sending the control byte, master expects an acknowledge. Upon the receipt of an acknowledge, the master
sends a most significant byte, M<7:0> that represents the eight most significant bits of DAC8571's 16-bit
digital-to-analog conversion data. Upon the receipt of the M<7:0>, DAC8571 sends an acknowledge. After
receiving the acknowledge, the master sends a least significant byte, L<7:0>, that represents the eight least
significant bits of DAC8571's 16-bit conversion data. After receiving the L<7:0>, the DAC8571 sends an
acknowledge. At the falling edge of the acknowledge signal following the L<0>, DAC8571 performs a digital to
analog conversion, depending on the operational mode. For further DAC updates, the master can keep repeating
M<7:0> and L<7:0> sequences, expecting an acknowledge after each byte. After the required number of digital
to analog conversions is complete, the master can break the communication link with DAC8571 by pulling the
SDA line from low to high while SCL line is high. This is called a stop condition. A stop condition brings the bus
back to idle (SDA and SCL both high). A stop condition indicates that communication with a device (DAC8571)
has ended. All devices on the bus including DAC8571 then await a new start condition followed by a matching
address byte. DAC8571 stays at its current state upon the receipt of a stop condition. A stop condition during the
high-speed mode also indicates the end of the high-speed mode. Table 3 demonstrates the sequence of events
that should occur while a master transmitter is writing to DAC8571 in I
2
C high-speed mode.
Table 3. Master Transmitter Writes to Slave Receiver in High-Speed Mode
HS Mode Write Sequence-Data Input
Transmitter MSB 6 5 4 3 2 1 LSB Comment
Master Start Begin sequence
(1)
Master 0 0 0 0 1 X X X HS mode master code
No device may acknowledge HS
NONE Not Acknowledge
master code
Master Repeated Start
Master 1 0 0 1 1 A0 0 R/ W Write addressing (LSB = 0)
DAC8571 DAC8571 Acknowledges
Master 0 0 Load 1 Load 0 0 Brcsel 0 PD0 Control byte (PD0=0)
DAC8571 DAC8571 Acknowledges
Master D15 D14 D13 D12 D11 D10 D9 D8 Writing dataword, high byte
DAC8571 DAC8571 Acknowledges
Master D7 D6 D5 D4 D3 D2 D1 D0 Writing dataword, low byte
DAC8571 DAC8571 Acknowledges
Master Stop or Repeated Start
(2)
Done
(1) High-byte, low-byte sequences can repeat
(2) Use repeated start to secure bus operation and loop back to the stage of write addressing for next Write.
17