AK4185 AKM [Asahi Kasei Microsystems], AK4185 Datasheet - Page 17

• Manufacturer Part Number: AK4185
• Manufacturer: AKM [Asahi Kasei Microsystems]

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To fix the internal register, send the control command when first power up. It initiates all registers such as PD0 bit and
sequence register. The sequence is that 1) Power On with CSN= “H” or “L” then CSN = “H”. 2) Send control command
after CSN = “L”. 3) CSN = “H” again. Once sending command to fix the internal register after first power up, the state of
the AK4185 is held on the same condition as last command issued.
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Power-down and pen interrupt function are controlled by PD0 bit. In order to achieve minimum current, it is
recommended to set PD0 bit = “0” for automatic power down of the A/D converter after A/D conversion. It is possible to
reduce the variation in data by setting PD0 = “1” during measurements. A/D converter keeps power up after every
measurement complete.
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The AK4185 supports sleep mode that puts touch panel to open state and disables pen interrupt function, effective for
reducing power consumption caused by unnecessary pen touch.
The AK4185 changes to sleep mode when the micro-controller writes to SLEEP1-0 bits of AK4185’s register. After
writing the sleep command, this sleep mode starts when the CSN pin is “H”. The AK4185 returns to normal operation out
of sleep mode when the CSN pin is “L” and receives the normal control command.
MS0954-E-00
Power-down Control
Sleep Mode
Power on Sequence
PD0
0
1
SLEEP[1:0]
Auto Power-down Mode
ADC ON Mode
00
01
10
11
A/D converter is automatically powered up at the start of the conversion, and powered down
automatically at the end of the conversion. The AK4185 is always powered down at this mode if CSN
= “H”. All touch screen driver switches except YN or BL switch are turned off and relative pins are
open state. Only YN or BL driver switch is turned ON and forced to VSS in this case. PEN interrupt
function is enabled except when in the sampling time and conversion time.
A/D converter is always powered up while CSN = “L”. If X-axis or Y-axis is selected as analog input,
touch screen driver switches are always turned ON and the current flows through the touch plate if
CSN = “L”. This is effective if more settling time is required to suppress the electrical bouncing of
touch plate. If CSN = “H”, A/D converter is always powered down and touch screen driver switches
are always off. (Only YN or BL driver switch is turned ON and forced to VSS.) And while CSN =
“H”, PEN interrupt function is enabled. When CSN state sets from “H” to “L”, the input channel and
driver switches is set to the last setting.
Normal Operation
Normal Operation
Normal Operation
PENIRQN
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CSN = “L”
Table 13. Power-down Control
Normal Operation
Normal Operation
Normal Operation
Touch Panel
Table 14. Sleep Mode
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Function
Normal Operation
(PENIRQN=Hi-z)
(PENIRQN=H)
PENIRQN
Disable
Disable
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CSN = “H”
Normal Operation
Touch Panel
Open
Open
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[AK4185]
2008/05