FS2012 Series Datasheet

© 2018 Integrated Device Technology, Inc.

6

August 24, 2018

6. Functional Description

The FS2012 digital flow sensor accurately measures the mass flow rate of a liquid or gaseous medium across the sensor using the calorimetric

principle.

The MEMS flow sensor comprises a resistive heater and two clusters of thermocouples (thermopiles), each positioned symmetrically upstream

and downstream of the heater. The thermopile output changes according to the rate of flow, and it is proportional to the amount of heat sensed

from the heater.

7. I2C Sensor Interface

The FS2012 operates as a slave device via the digital I2C compatible communication protocol bus with support for 100kHz and 400kHz bit

rates. To accommodate multiple devices, the protocol uses two bi-directional open-drain lines: a Serial Data Line (SDA) and a Serial Clock Line

(SCL). Pull-up resistors to VDD are required. Several slave devices can share the bus, and multiple master devices on the same bus are

supported. If two or more masters attempt to initiate a data transfer simultaneously, an arbitration scheme is employed with a single master

always winning the arbitration. Note that it is not necessary to specify one device as the master in a system; any device that transmits a START

bit and a slave address becomes the master for the duration of that transfer.

7.1 Sensor Slave Address

7.2 Data Read

The FS2012 is programmed to continuously output data to the I2C bus.



Number of bytes to read out: 2



First returned byte: MSB



Second returned byte: LSB

8. Calculating Flow Sensor Output

The entire output of the FS2012 is 2 bytes. The flow rate for gas and liquid parts is calculated as follows:

Output Data



Number of bytes to read out: 2



First returned byte: MSB



Second returned byte: LSB

Gas Part Configurations (-NG ending for part code number)



Conversion to SLPM



Flow in SLPM = [(MSB << 8) + LSB] / 1000

Liquid Part Configurations (-LQ ending for part code number)



Conversion to SCCM



Flow in SCCM = [(MSB << 8) + LSB] / 10