AK9844A Datasheet, PDF (7/17 Pages) Asahi Kasei Microsystems – 4Kbit EEPROM with 4ch 8bit D/A Converter

ASAHI KASEI
[AK9844A]
„ Power Down Function
There are the power down mode and the normal mode in AK9844A. When the AK9844A is in
power down mode, the outputs of D/A are "High impedance" and the DAC section is in the standby
mode and the power consumption of the AK9844A is decreased.
The power down mode of AK9844A can be determined by the control of the PD pin or the
PDEN/PDDS instructions.
When the PD pin is low level, the AK9844A is in power down mode. When the PD pin is high level,
the state of the AK9844A can be determined by PDEN/PDDS instructions. When the PD pin is
High level and the PDEN instruction is executed, the AK9844A becomes the power down mode.
Once the AK9844A becomes the power down mode, the AK9844A is in the power down mode until
the PDDS instruction is executed. When the PDDS instruction is executed, the AK9844A becomes
the normal mode.
If the CS pin is High level in the power down mode, the EEPROM section also becomes the standby
mode and the AK9844A becomes the lower power-down mode.
The relation between the PD pin and the PDEN/PDDS instructions is showed on Table 3. The
relation between the power down mode and the DAC/EEPROM section is showed on Table 4. The
state at the time AK9844A is powered up is showed on Table 5.
PD pin
Low level
High level
instruction
PDEN
PDDS
PDEN
PDDS
mode
power down mode
power down mode
normal mode
Table 3. Relation between the PD pin and the PDEN/PDDS instructions
State
normal mode
power down mode1
power down mode2
CS pin="L"
CS pin="H"
DAC section
normal mode
standby mode
standby mode
EEPROM section
normal mode
normal mode
standby mode
Table 4. Relation between the power down mode and the DAC/EEPROM section
Condition at the time AK9844A is powered on
PD pin="L"
CS pin="L"
CS pin="H"
PD pin="H"
State
power down mode1
power down mode2
normal mode
Table 5. State at the time AK9844A is powered up
„ Precautions for use
1) Output voltage of D/A converter at the time the AK9844A is powered up
At the time the AK9844A is powered up, the D/A converters output "VREF/2" until the instruction
or AUTO READ is executed.
2) Power Supply Decoupling
On the boards, decoupling capacitors(0.1µF) between power supply pins(VCC,VREF1,VREF2)
and GND should be located as near as possible to the part.
DAD05E-00
-7-
2005/03