AK9844 Datasheet, PDF (7/17 Pages) Asahi Kasei Microsystems – 4Kbit EEPROM with 4ch 8bit D/A Converter

ASAHI KASEI
[AK9844]
„ Power Down Function
There are the power down mode and the normal mode in AK9844. When the AK9844 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 AK9844 is decreased.
The power down mode of AK9844 can be determined by the control of the PD pin or the PDEN/ PDDS
instructions.
When the PD pin is low level, the AK9844 is in power down mode. When the PD pin is high level, the state of
the AK9844 can be determined by PDEN/PDDS instructions. When the PD pin is High level and the PDEN
instruction is executed, the AK9844 becomes the power down mode. Once the AK9844 becomes the power
down mode, the AK9844 is in the power down mode until the PDDS instruction is executed. When the PDDS
instruction is executed, the AK9844 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 AK9844 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 AK9844 is
powered up is showed on table.5.
PD pin
instruction
mode
Low level
PDEN
power down mode
PDDS
High level
PDEN
power down mode
PDDS
normal mode
Table.3 Relation between the PD pin and the PDEN/PDDS instructions
State
DAC section
EEPROM section
normal mode
normal mode
normal mode
power down mode1 CSpin=L
standby mode
normal mode
power down mode2 CSpin=H
standby mode
standby mode
Table.4 Relation between the power down mode and the DAC/EEPROM section
Condition at the time AK9844 is powered on
State
PDpin = "L"
PDpin = "H"
CSpin=L power down mode1
CSpin=H power down mode2
normal mode
Table.5 State at the time AK9844 is powered up
„ Precautions for use
1) Output voltage of D/A converter at the time the AK9844 is powered up
At the time the AK9844 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(0.1uF) between power supply pins(VCC,VREF1,VREF2) and GND
should be located as near as possible to the part.
DAD02E-00
-7-
1999/05