ADIS16220/PCBZ Analog Devices Inc, ADIS16220/PCBZ Datasheet - Page 8

• Manufacturer Part Number: ADIS16220/PCBZ
• Description: Vibration Sensor Evaluation Board
• Manufacturer: Analog Devices Inc
• Series: iSensor™r

Specifications of ADIS16220/PCBZ

• Silicon Manufacturer: Analog Devices
• Application Sub Type: Vibration Sensor
• Kit Application Type: Sensing - Motion / Vibration / Shock
• Silicon Core Number: ADIS16220
• Kit Contents: Board
• Sensor Type: Vibration, Accelerometer
• Sensing Range: ±70g
• Interface: SPI Serial
• Sensitivity: 19.073mg/LSB
• Voltage - Supply: 3.15 V ~ 3.6 V
• Embedded: No
• Utilized Ic / Part: ADIS16220
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADIS16220
THEORY OF OPERATION
The ADIS16220 is a wide-bandwidth, digital acceleration sensor
for vibration analysis. This sensing system collects data
autonomously and makes it available to any processor system
that supports a 4-wire serial peripheral interface (SPI).
SENSING ELEMENT
Digital vibration sensing in the ADIS16220 starts with a wide-
bandwidth MEMS accelerometer core that provides a linear
motion-to-electrical transducer function. Figure 6 provides a
basic physical diagram of the sensing element and its response
to linear acceleration. It uses a fixed frame and a moving frame
to form a differential capacitance network that responds to
linear acceleration. Tiny springs tether the moving frame to the
fixed frame and govern the relationship between acceleration
and physical displacement. A modulation signal on the moving
plate feeds through each capacitive path into the fixed frame
plates and into a demodulation circuit, which produces the
electrical signal that is proportional to the acceleration acting on
the device.
DATA SAMPLING AND PROCESSING
The analog acceleration signal feeds into an analog-to-digital
(ADC) converter stage, which passes digitized data into the
controller. The controller processes the acceleration data, stores
it in the capture buffer, and manages access to it using the
SPI/register user interface. Processing options include offset
adjustment, filtering, and checking for preset alarm conditions.
UNIT SENSING
CELL
PLATE
CAPACITORS
Figure 6. MEMS Sensor Diagram
MOVING
PLATE
ANCHOR
ANCHOR
FIXED
PLATES
MOVABLE
FRAME
UNIT
FORCING
CELL
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USER INTERFACE
SPI Interface
The user registers control operation and manage user access to
both sensor data and configuration inputs. Each 16-bit register
has its own unique bit assignment and has two addresses: one for
its upper byte and one for its lower byte. Table 8 provides a
memory map for each register, along with their function and
lower byte address. Each data collection and configuration
commands both use the SPI, which consists of four wires. The
chip select ( CS ) signal activates the SPI interface and the serial
clock (SCLK) synchronizes the serial data lines. Input commands
clock into the DIN pin, one bit at a time, on the SCLK rising
edge, and output data clocks out of the DOUT pin on the SCLK
falling edge. As a SPI slave device, the DOUT contents reflect
the information requested using a DIN command.
Dual Memory Structure
The user registers provide addressing for all input/output opera-
tions on the SPI interface. The control registers use a dual memory
structure. The SRAM controls operation while the part is on, and
facilitates all user configuration inputs. The flash memory pro-
vides nonvolatile storage for control registers that have flash
backup (see Table 8). Storing configuration data in the flash
memory requires a manual, flash update command (GLOB_
CMD[12] = 1, DIN = 0xBF10). When the device powers on or
resets, the flash memory contents load into the SRAM, and then
the device starts producing data according to the configuration
in the control registers.
SIGNALS
SENSOR
SENSOR
MEMS
TEMP
AIN
Figure 7. Simplified Sensor Signal Processing Diagram
(NO SPI ACCESS)
FLASH MEMORY
NONVOLATILE
Figure 8. SRAM and Flash Memory Diagram
CLOCK
ADC
CONTROLLER
START-UP
MANUAL
BACKUP
FLASH
RESET
CAPTURE
BUFFER
SPI ACCESS
VOLATILE
REGISTERS
REGISTERS
SRAM
CONTROL
OUTPUT