AD7147A-1ACBZ-RL Analog Devices Inc, AD7147A-1ACBZ-RL Datasheet - Page 13

• Manufacturer Part Number: AD7147A-1ACBZ-RL
• Description: CAPACITANCE TO DIGITAL CONVERTER
• Manufacturer: Analog Devices Inc
• Series: CapTouch™r
• Type: Capacitive Sensor Controllerr

Specifications of AD7147A-1ACBZ-RL

• Resolution (bits): 16 b
• Data Interface: I²C, Serial
• Voltage Supply Source: Single Supply
• Voltage - Supply: 2.6 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 25-WLCSP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Sampling Rate (per Second): -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Full Power Mode
In full power mode, all sections of the AD7147A remain fully
powered and converting at all times. While a sensor is being
touched, the AD7147A processes the sensor data. If no sensor is
touched, the AD7147A measures the ambient capacitance level
and uses this data for the on-chip compensation routines. In full
power mode, the AD7147A converts at a constant rate. See the
CDC Conversion Sequence Time section for more information.
Low Power Mode
When AD7147A is in low power mode, the POWER_MODE
bits are set to 10 upon device initialization. If the external
sensors are not touched, the AD7147A reduces its conversion
frequency, thereby greatly reducing its power consumption.
The part remains in a reduced power state while the sensors are
not touched. The AD7147A performs a conversion after a delay
defined by the LP_CONV_DELAY bits, and it uses this data to
update the compensation logic and check if the sensors are active.
The LP_CONV_DELAY bits set the delay between conversions
to 200 ms, 400 ms, 600 ms, or 800 ms.
In low power mode, the total current consumption of the
AD7147A is an average of the current used during a conversion
and the current used while the AD7147A is waiting for the next
conversion to begin. For example, when LP_CONV_DELAY
CONVERSION SEQUENCE
UPDATE COMPENSATION
EVERY LP_CONV_DELAY
LOGIC DATA PATH
Figure 22. Low Power Mode Operation, AD7147A
NO
AND INITIALIZATION
POWER_MODE = 10
AD7147A SETUP
TO SENSOR?
PROXIMITY
USER IN
Rev. B | Page 13 of 68
YES
CONVERSION SEQUENCE
YES
EVERY 9ms, 18ms, OR
36ms FOR SENSOR
PROXIMITY TIMER
is 400 ms, the AD7147A typically uses 0.85 mA of current for
36 ms and 14 μA of current for 400 ms during the conversion
interval. (Note that these conversion timings can be altered
through the register settings. See the CDC Conversion Sequence
Time section for more information.)
The time for the AD7147A to transition from a full power state
to a reduced power state after the user stops touching the external
sensors is configurable. The PWR_DOWN_TIMEOUT bits in
the Ambient Compensation Control 0 register (AMB_COMP_
CTRL0, Address 0x002) control the time delay before the
AD7147A transitions to the reduced power state after the user
stops touching the sensors.
Low Latency from Touch to Response
In low power mode, the AD7147A remains in a low power state
until proximity is detected on any one of the external sensors.
When proximity is detected, the AD7147A begins a conversion
sequence every 36 ms, or 18 ms, or 9 ms to read back data from
the sensors. The latency between first touch and AD7147A
response is greatly reduced compared to the AD7147 because
the part is already in a full power state by the time the user
touches the sensor.
TO SENSOR?
COUNTDOWN
READBACK
PROXIMITY
USER IN
NO
TIMEOUT
AD7147A