MCP4728 Microchip Technology Inc., MCP4728 Datasheet - Page 35

• Manufacturer Part Number: MCP4728
• Description: 12-bit, Quad Digital-to-analog Converter With Eeprom Memory
• Manufacturer: Microchip Technology Inc.

5.6.1
The Fast Write command is used to update the input
DAC registers from channels A to D sequentially. The
EEPROM data is not affected by this command. This
command is called “Fast Write” because it updates the
input registers with only limited data bits. Only the
Power-Down mode selection bits (PD1 and PD0) and
12 bits of DAC input data are writable.
The input register is updated at the acknowledge pulse
of each channel’s last data byte.
example of the Fast Write command.
Updating Analog Outputs:
a.
b.
c.
© 2009 Microchip Technology Inc.
Note 1: UDAC bit is not used in this command.
When the LDAC pin is “High” before the last byte
of the channel D, all analog outputs are updated
simultaneously by bringing down the LDAC pin
to “Low” any time.
If the command starts with the LDAC pin “Low”,
the channel’s analog output is updated at the
falling edge of the acknowledge clock pulse of
the channel’s last byte.
Send the General Call Software Update
command: This command updates all channels
simultaneously.
FAST WRITE COMMAND
(C2=0, C1=0, C0=X, X = DON’T
CARE)
Figure 5-7
shows an
5.6.2
This command is used to write DAC input register, one
at a time. The EEPROM data is not affected by this
command.
The DAC selection bits (DAC1, DAC0) select the DAC
channel to write. Only a selected channel is affected.
Repeated bytes are used to write more multiple DAC
registers.
The D11 - D0 bits in the third and fourth bytes are the
DAC input data of the selected DAC channel. Bytes 2 -
4 can be repeated for the other channels.
shows an example of the Multi-Write command.
Updating Analog Outputs:
The analog outputs can be updated by one of the
following events after the falling edge of the
acknowledge clock pulse of the 4th byte.
a.
b.
c.
Note 1: The UDAC bit can be used effectively to
When the LDAC pin or UDAC bit is “Low”.
If UDAC bit is “High”, bringing down the LDAC
pin to “Low” any time.
By sending the General Call Software Update
command.
MULTI-WRITE COMMAND: WRITE
DAC INPUT REGISTERS
(C2=0, C1=1, C0=0; W1=0, W0=0)
upload the input register to the output
register, but it affects only a selected
channel only, while the LDAC pin and
General Call Software Update command
affect all channels.
MCP4728
DS22187A-page 35
Figure 5-8