Datasheet
FS1015
Air Velocity Sensor Module

The FS1015 mass air velocity module measures theair velocity using the thermo-transfer (calorimetric)
principle.
The FS1015 offers key advantages over resistorbased flow solutions. The sensor uses thermopile
sensing, which provides an excellent signal-to-noise
ratio. The sensor comprises a “solid” thermal
isolation technology and silicon-carbide coating toprotect it from abrasive wear and provides
robustness and long-term reliability.
The FS1015 design allows it to be mounted in a
vertical or horizontal position.

Features■

Robust “solid” isolation technology■

Resistant to vibration and pressure shock■

Analog output■

Supply voltage: 5V■

Module operating temperature range: -20°C to+85°C

Applications■

HVAC and air control systems■

Data center and servers■

Air filtration and collection systems■

Laminar flow control systems

Figure 1. FS1015 Air Velocity Module

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FS1015 Datasheet

Contents
1.

2.

Pin Information .............................................................................................................................................. 3
1.1

Pin Assignments .................................................................................................................................... 3

1.2

Pin Descriptions ..................................................................................................................................... 3

Specifications................................................................................................................................................. 4
2.1

Absolute Maximum Ratings ................................................................................................................... 4

2.2

Recommended Operating Conditions ................................................................................................... 4

2.3

Electrical Characteristics ....................................................................................................................... 4

3.

Typical Flow Graphs ...................................................................................................................................... 54.

I2C Sensor Interface ...................................................................................................................................... 7
4.1

Sensor Slave Address ........................................................................................................................... 7

4.2

I2C Communication ............................................................................................................................... 7

4.3

Digital Output Measurements ................................................................................................................ 8

4.4

Calculating Checksum ........................................................................................................................... 8

5.

Package Outline Drawings............................................................................................................................ 96.

Ordering Information ..................................................................................................................................... 9

7.

Revision History .......................................................................................................................................... 10

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1. Pin Information
1.1

Pin Assignments

Figure 2. Pin Assignments1.2

Pin Descriptions

Pin Number

Pin Name

1

VIN

Supply voltage

2

GNDGround

3

VOUTAnalog Output

4SDA

Serial Data5

SCL

Serial Clock

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2. Specifications
2.1

Absolute Maximum Ratings

The absolute maximum ratings are stress ratings only. Stresses greater than those listed below can cause
permanent damage to the device. Functional operation of the FS1015 at absolute maximum ratings is not
implied. Exposure to absolute maximum rating conditions may affect device reliability.
Table 1. Absolute Maximum Ratings
SymbolParameter

VIN

Supply Voltage

TSTOR

Storage Temperature

2.2Conditions

Minimum-20

Maximum

Unit

5.5

V85°C

Recommended Operating Conditions

The FS1015 is optimized for operating at 5V in room temperature. A regulated 5V supply voltage must be used
to conform to the output curves provided. Variations in the supply voltage will result in a slightly different outputcurve.
Table 2. Recommended Operating Conditions
SymbolParameter

VIN

Supply Voltage

TAMB

Ambient Operating Temperature

2.3

Minimum

TypicalMaximum

5.0-20Unit
V85°CMaximumUnit

Electrical Characteristics
Table 3. Electrical Characteristics

SymbolParameter

IVIN

Current Consumption

FAIR

Air Flow Range

Conditions

Minimum

Typical22mA

FS1015-1005

07.23

FS1015-1015

015

meter/sec

VAOUT

Analog Voltage Output

Min to Max of Flow Range

0.5

4.5

V

VDOUT

Digital Output

Min to Max of Flow Range

409

3686

CountsEAIR

Flow Accuracy

At 25°C

tRESP

Response TimefSCL

SCL Clock Frequency

VIL

I2C Input Logic Low Threshold

VIH

I2C Input Logic High ThresholdVOL

I2C Output Logic Low Threshold1.

5% ofF.S.[1]125ms400

kHz

0.3VDD or
1.5

V

0.7VDD or 3

V
0.4

V

F.S: Full scale flow range.

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FS1015 Datasheet

3. Typical Flow Graphs

Figure 3. FS1015-1005 Air Velocity Curve

Air Velocity (meter/sec)

Analog Output (Volt)

Digital Output (Count)

00.50

409

1

1.12

915

2

1.86

1522

3

2.52

2066

4

3.08

2523

5

3.55

2908

6

3.98

3256

7

4.363572

7.23

4.50

3686

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FS1015 Datasheet

Figure 4. FS1015-1015 Air Velocity Curve

Air Velocity (meter/sec)

Analog Output (Volt)

Digital Output (Count)

00.50

409

10.95

760

2

1.48

1203

31.95

1597

42.33

1908

5

2.67

2187

6

2.94

2400

7

3.21

2629

8

3.43

2801

9

3.67

3006

10

3.88

3178

11

4.04

3309

13

4.34

3563

15

4.50

3686

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FS1015 Datasheet

4. I2C Sensor Interface
The FS1015 includes a digital I2C two-wire interface with a bidirectional data line (SDA) and a clock line (SCL).
The two lines are open drain and connected to the supply voltage using two pull-up resistors (Rp). The FS1015
operates as a slave device on the I2C bus with support for 100kHz and 400kHz bit rates.
Vdd

I2C MAINMASTERSDA

Rp

Rp

I2C
SLAVE

SCL

Figure 5. I2C Master-Slave Configuration

The recommended pull-up resistor (Rp) values depend on the system implementation, but a value between
2.2kΩ and 10kΩ can be used.
The capacitive load on both SDA and SCL should be the same, therefore, the signal lengths should be similar toavoid asymmetry.

4.1Sensor Slave Address

The FS1015 default I2C address is 50HEX. The device will respond only to this 7-bit address.

4.2

I2C Communication

The START condition is used to initiate I2C communication by the master. The sensor transmission is initiatedwhen the master sends a 0 START bit (S). A HIGH-to-LOW transition on the SDA line while the SCL is HIGH
indicates the beginning of a transmission.
The STOP condition is used to stop I2C communication by the master. The transmission is terminated when themaster sends a 1 STOP bit (P). A LOW-to-HIGH transition on the SDA line while the SCL is HIGH indicates theend of a transmission.
All transfers consist of 8 bits and a response bit: 0 for Acknowledge (ACK) or 1 for Not Acknowledge (NACK).
After the ACK is received, another data byte can be transferred or the communication can be stopped with aSTOP bit.
The master expects an ACK back from the slave after each byte is transmitted. The slave pulls the SDA low toindicate that it has received a byte and then it frees the I2C bus again. If the slave does not initiate an ACK, thenit will consider it a NACK.
Data on the SDA line is always sampled on the rising edge of the SCL line and must remain stable while SCL is
HIGH to prevent false START or STOP conditions.
START Condition
SCL

STOP Condition
SCLSTARTSDASTOPSDA

Figure 6. START and STOP Condition Waveform

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4.3

Digital Output Measurements

The FS1015 continuously measures during operation. The data is sent in byte packages. Each byte is followedby an ACK from the slave. The most significant bit (MSB) is transmitted first.
To read the data, the following command is sent to the FS1015.
After the START bit, the master device sends the 7-bit slave address followed by an eighth bit = 1 (READ). TheREAD bit indicates a transmission from the FS1015 (slave) to master (see Figure 7).
The checksum used for data integrity is returned from the FS1015 followed by the two bytes of flow data.
The flow data is a 12-bit integer. Only the least significant four bits in the high byte are valid (see Figure 8).

S

61Byte543210010000Device Slave Address (0x50), [6:0]R (1)AFigure 7. Flow Data Read Command

7610A

7Byte 265432
1Sensor Flow Data, High Byte [3:0]0A

77Byte 465432
1
Generic Checksum Data [7:0]0A

7Byte 565432
1
Generic Checksum Data [7:0]0AP

5Byte 1432Checksum [7:0]

Byte 365432
1Sensor Flow Data, Low Byte [7:0]0A

Figure 8. Flow Data from FS1015

4.4SSTART Condition

RREAD ModeP

STOP Condition

AAcknowledge (ACK)Calculating ChecksumThe checksum used for data integrity is the 2’s complement (negative) of the 256-modulo (8-bit) sum of the databytes (does not include I2C address).
Figure 8 shows the 5 bytes read:
Example:Byte 1, 0xCC (Checksum)
Byte 2, 0x01
Byte 3, 0x99
Byte 4, 0x01 or 0x00
Byte 5, 0x99 or 0x00

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FS1015 Datasheet

The 256-modulo (8-bit) sum is calculated as:(EQ) 1

𝑠𝑠𝑠𝑠𝑠𝑠 = 0𝑥𝑥01 + 0𝑥𝑥99 + 0𝑥𝑥01 + 0𝑥𝑥99 = 0𝑥𝑥134

Validating the data payload is done by calculating the sum and adding it to the checksum. If the result is 0x00
then the data is valid.
(EQ) 2𝑐𝑐ℎ𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒 + 𝑠𝑠𝑠𝑠𝑠𝑠 = 0𝑥𝑥𝑥𝑥𝑥𝑥 + 0𝑥𝑥134 = 0𝑥𝑥00

5. Package Outline Drawings

Figure 9. Package Outline Drawings

6. Ordering Information
Part Number

Package Description

Carrier Type

Temperature Range

FS1015-1005

0 to 7 m/sec air velocity module

Box-20°C to +85°C

FS1015-1015

0 to 15 m/sec air velocity module

Box

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FS1015 Datasheet

7. Revision History
RevisionDate

1.00

Jun 2, 2022

R36DS0008EU0100 Rev.1.00
Jun 2, 2022

Description
Initial release.

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