AK9844 Datasheet, PDF (5/17 Pages) Asahi Kasei Microsystems – 4Kbit EEPROM with 4ch 8bit D/A Converter

ASAHI KASEI
[AK9844]
„ Output of D/A converter
The AK9844 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 Programming
DAC register block
Output of DAC
pin
State
(EEPROM Section)
(D/A Converter Section)
"H"
Enable
The specified address in the
The output voltage for the
DAC register block is written
specified D/A converter is
with the data specified in
set by the data specified
the instruction.
in the instruction.
Disable
The data in the DAC register
"L"
Enable
section does not change.
Disable
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 AK9844, 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.
DAD02E-00
-5-
1999/05