AK9844A Datasheet, PDF (5/17 Pages) Asahi Kasei Microsystems – 4Kbit EEPROM with 4ch 8bit D/A Converter

ASAHI KASEI
[AK9844A]
„ Output of D/A converter
The AK9844A includes 4 channel, 8bit D/A converter. The output voltage ranges for AO0 and AO1
are set by the VREF1 pin and the output voltage ranges for AO2 and AO3 are set by the VREF2 pin.
The output voltage can be set by the READ or WRITE instruction.
When the DAC register block is specified in the WRITE instruction, the output voltage for the
specified D/A converter is set. When the WRITE instruction is executed in case that the PROTECT
pin is "H" and the programming state is enabled, the output voltage for the specified D/A converter is
set and the specified address in the DAC register block in EEPROM is written with the data
specified in the instruction.
When the WRITE instruction is executed in case that the PROTECT pin is "H" and the programming
state is disabled, the output voltage for the specified D/A converter is set and the specified address
in the DAC register block in EEPROM is not written with the data specified in the instruction. When
the WRITE instruction is executed in case that the PROTECT pin is "L", the output voltage for the
specified D/A converter is not set and the specified address in the DAC register block in EEPROM is
not written with the data specified in the instruction. The relation between the WRITE instruction
and the DAC register block is showed on the Table 2.
When the DAC register block is specified in the READ instruction, the output voltage for the
specified D/A converter is set by the data which is stored in the DAC register block in EEPROM, and
the DO pin outputs the data in the specified address.
Execution of the READ instruction is independent of the PROTECT pin and the programming state.
PROTECT
pin
"H"
"L"
Programming
State
DAC register block
(EEPROM section)
Output of DAC
(D/A Converter section)
Enable
The specified address in the
DAC register block is written
with the data specified in the
instruction.
The output voltage for the
specified D/A converter is set
by the data specified in the
instruction.
Disable
Enable
Disable
The data in the DAC register
section does not change.
The output of the DAC does
not change.
Table 2. Relation between the WRITE instruction and the DAC register block
○ AUTO READ Function
When VCC is applied to the AK9844A, the data on EEPROM are read out and loaded at a time to
each corresponding D/A (4 channels total) automatically, starting from AO0 to AO3 in ascending
order. Then each D/A analog output is settled to pre-determined value.
If the CS pin goes to "H" and then goes to "L" after "power-up" with the PROTECT pin and the CS
pin left "L", AUTO READ cycle is initiated. After the CS pin goes to "L", 4 channel D/A outputs are
settled to pre-determined value within 2ms.
In AUTO READ cycle, the SK pin and the DI pin become "don't care" and the serial data do not
output.
If the WREN instruction is executed after AUTO READ cycle is completed, programming into the
memory block on the internal EEPROM is enabled.
DAD05E-00
-5-
2005/03