™
DESCRIPTION
Honeywell Zephyr™ Digital Airflow Sensors: HAF Series-High
Accuracy, provide a digital interface for reading airflow over the
specified full scale flow span and temperature range. Their
thermally isolated heater and temperature sensing elements
help these sensors provide a fast response to air or gas flow.
Zephyr sensors are designed to measure mass flow of air and
other non-corrosive gases. They are available in standard flow
ranges and are fully calibrated and temperature compensated
with an on-board Application Specific Integrated Circuit (ASIC).
The HAF Series is compensated over the temperature range of
0 C to 50 C [32 F to 122 F] and operates across a
temperature range of -20 C to 70 C [-4 F to 158 F]. The
state-of-the-art ASIC-based compensation provides digital (I2C)
outputs with a response time of 1 ms.
These sensors operate on the heat transfer principle to
measure mass airflow. They consist of a microbridge
Microelectronic and Microelectromechanical System (MEMS)
with temperature-sensitive resistors deposited with thin films of
platinum and silicon nitride. The MEMS sensing die is located
in a precise and calculated airflow channel to provide
repeatable flow response.
Zephyr sensors provide customers with enhanced reliability,
digital accuracy, repeatable measurements and the ability to
customize sensor options to meet many specific application
needs. The combination of rugged housings with a stable
substrate makes these products extremely robust. They are
designed and manufactured according to ISO 9001 standards.
FEATURES AND BENEFITS (
= competitive differentiator)
High ±2.5% accuracy allows for very precise airflow
measurement, often ideal for demanding applications with
high accuracy requirements
Full calibration and temperature compensation typically allow
customer to remove additional components associated with
signal conditioning from the PCB, reducing PCB size as well
as costs often associated with those components (e.g.,
acquisition, inventory, assembly)
Customizable for specific end-user needs
High sensitivity at very low flows allows a customer’s
application to detect presence or absence of airflow
High stability reduces errors due to thermal effects and null
shift to provide accurate readings over time, often eliminating
need for system calibration after PCB mount and periodically
over time
Low pressure drop typically improves patient comfort in
medical applications, and reduces noise and system wear on
other components such as motors and pumps
Linear output provides more intuitive sensor signal than the
raw output of basic airflow sensors, which can help reduce
production costs, design, and implementation time
Fast response time allows a customer's application to
respond quickly to airflow change, important in critical
medical (i.e., anesthesia) and industrial (i.e., fume hood)
applications
High 12-bit resolution increases ability to sense small airflow
changes, allowing customers to more precisely control their
application
Low 3.3 Vdc operating voltage option and low power
consumption allow for use in battery-driven and other
portable applications
ASIC-based I2C digital output compatibility eases integration
to microprocessors or microcontrollers, reducing PCB
complexity and component count
Bidirectional flow sensing capability eliminates the need for
two airflow sensors, helping to reduce production costs and
implementation time
Insensitivity to mounting orientation allows customer to
position sensor in most optimal point in the system,
eliminating concern for positional effects
Insensitivity to altitude eliminates customer-implemented
altitude adjustments in the system, easing integration and
reducing production costs by not having to purchase
additional sensors for altitude adjustments
Small size occupies less space on PCB, allowing easier fit
and potentially reducing production costs; PCB size may
also be reduced for easier fit into space-constrained
applications
RoHS-compliant materials meet Directive 2002/95/EC
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2 www.honeywell.com/sensing
POTENTIAL APPLICATIONS
Medical
Me
Anesthesia delivery machines
Ventricular assist devices (heart pumps)
Hospital diagnostics (spectrometry, gas chromatography)
Nebulizers
Oxygen concentrators
Patient monitoring systems (respiratory monitoring)
Sleep apnea machines
Spirometers
Ventilators
Industrial
I
n
Air-to-fuel ratio
Analytical instrumentation (spectrometry, chromatography)
Fuel cells
Gas leak detection
Gas meters
HVAC filters
VAV system on HVAC systems
Meteorolgy
Table 1: Absolute Maximum Ratings1
Characteristic Parameter CAUTION
IMPROPER USE
Do not use these products to sense liquid or
fluid flow.
Failure to comply with these instructions
may result in product damage.
Supply voltage -0.3 Vdc to 6.0 Vdc
Voltage on output pin -0.3 V to Vsupply
Storage temperature range -40 C to 125 C [-40 F to 257 F]
Maximum flow change 5.0 SLPM/s
Maximum common mode pressure 25 psi at 25 C [77 F]
Maximum flow 10 SLPM
Note 1: Absolute maximum ratings are the extreme limits that the device will withstand without damage to the device. However, the electrical and
mechanical characteristics are not guaranteed as the maximum limits (above recommended operating conditions) are approached, nor will the
device necessarily operate at absolute maximum ratings.
Table 2: Operating Characteristics
Characteristic Parameter Note
Supply voltage 3.3 Vdc 10%; 5.0 Vdc 10%
Supply current 16 mA max.
Power:
3.3 Vdc
5.0 Vdc
23 mW typ.
38 mW typ.
Operating temperature range -20 C to 70 C [-4 F to 158 F]
Compensated temperature range 0 C to 50 C [32 F to 122 F] 1
Accuracy:
forward flow
reverse flow
±0.25% FSS or ±2.5% of reading, whichever is greater
±0.25% FSS or ±9% of reading, whichever is greater
2, 4
Total error band:
forward flow:
reverse flow:
±0.25% FSS or ±4.5% of reading, whichever is greater
±0.25% FSS or ±9% of reading, whichever is greater
3, 4
Null accuracy ±0.02% FSS 4, 10
Response time 1 ms typ. 5
Resolution 12 bit min.
Start up time 17 ms 6
Warm up time 30 ms 7
Calibration media gaseous nitrogen 8
Bus standards I2C, fast mode (400 kHz) 9
Null stability ±0.01% FSS maximum deviation from null output after 1000 hours at 25 C
Reverse polarity protection no
Notes:
1. Custom and extended compensated temperature ranges are possible. Contact Honeywell for details.
2. Accuracy is the maximum deviation from the nominal digital output over the compensated flow range at a reference temperature of 25 C.
Errors include offset, span, non-linearity, hysteresis and non-repeatability (see Figure 3 for the Accuracy Error Band vs Flow).
3. Total error band includes all errors over the compensated flow range including all effects due to temperature over the compensated
temperature range (see Figure 4 for the Total Error Band).
4. Full Scale Span (FSS) is the algebraic difference between the digital output at the forward Full Scale (FS) flow and the digital output at the
reverse FS flow. Forward flow is defined as flow from P1 to P2 as shown in Figure 4. The references to mass flow (SCCM) refer to gas flows at
the standard conditions of 0
w
C and atmospheric pressure 760 (101.3 kPa).
5. Response time: time to electrically respond to any mass flow change at the microbridge airflow transducer (response time of the transducer
may be affected by the pneumatic interface).
6. Start-up time: time to first valid reading of serial number proceeding streaming 14-bit flow measurements.
7. Warm-up time: time to the first valid flow measurement after power is applied.
8. Default calibration media is dry nitrogen gas. Please contact Honeywell for other calibration options.
9. Refer to Honeywell Technical Note for I2C protocol information.
10. Null accuracy is the maximum deviation in output at 0 SCCM from the ideal transfer function over the compensated temperature range. This
includes offset errors, thermal airflow hysteresis and repeatability errors.
Honeywell Sensing and Control 3
Table 3. Environmental Characteristics
Characteristic Parameter
Humidity 0% to 95% RH, non-condensing
Shock 100 g, 11 ms
Vibration 15 g at 20 Hz to 2000 Hz
ESD Class 3B per MIL-STD 883G
Radiated immunity Level 3 from (80 MHz to 1000 MHz) per spec IEC61000-4-3
Table 4. Wetted Materials
Characteristic Parameter
Covers high temperature polymer
Substrate PCB
Adhesives epoxy
Electronic components silicon, gold
Compliance RoHS, WEEE
Table 5. Recommended Mounting and Implementation
Characteristic Parameter CAUTION
LARGE PARTICULATE DAMAGE
Use a 5-micron filter upstream of the sensor to
keep media flow through the sensor free of
condensing moisture and particulates. Large,
high-velocity particles or conductive particles
may damage the sensing element.
Failure to comply with these instructions
may result in product damage.
Mounting screw size 5-40
Mounting screw torque 0.68 N m [6 in-lb]
Tubing for long port style 70 durometer, size 0.125 inch inside
diameter, 0.250 inch outside diameter silicone
tubing
O-ring for short port style AS568A, Size 7, Silicone, Shore A 70
O-ring for long port style AS568A, Size 10, Silicone, Shore A 70
Filter recommendation 5-micron filter upstream of the sensor
Figure 1. Nomenclature and Order Guide
Example Catalog
Listing
HAFBLS0200C2AX5 =
High accuracy airflow
sensor, bidirectional
forward flow optimized,
long port style, snap
mount housing, 200
SCCM, digital I2C output
with 0X29 address, 10%
to 90% transfer function,
5.0 Vdc supply voltage.
Customer-specific
Requirements
Apart from the general
configuration required,
other customer-specific
requirements are also
possible. Please contact
Honeywell.
Note:
1. The Long Port Port Style with the Snap Mount Housing Style is not a valid configuration.
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4 www.honeywell.com/sensing
Figure 2. Nominal Digital Output Ideal Transfer Function
Digital Output Code = 16383 * [0.5 + 0.4 * (Flow Applied/Full
Scale Flow)]
Flow Applied = Full Scale Flow * [(Digital Output Code/16383)
- 0.5]/0.4
Figure 3. Accuracy Error Band Figure 4. Total Error Band
Figure 5. Long Port Style Flow vs Pressure
Flow
(SCCM)
Pressure Drop
(inches H
2
O)
-200 -0.019
-150 -0.013
-100 -0.007
-50 -0.001
00.000
50 0.005
100 0.010
150 0.016
200 0.022
Figure 6. Short Port Style Flow vs Pressure
Flow
(SCCM)
Pressure Drop
(inches H
2
O)
-200 -0.470
-150 -0.284
-100 -0.143
-50 -0.045
00.000
50 0.048
100 0.139
150 0.287
200 0.452
Honeywell Sensing and Control 5
Figure 7. Wave Solder Profile
020406080100
0
50
100
150
200
250
300
Time (s)
Temperature (°C)
Max. temp. = 243 °C
Max. temp. = 205 °C
Housing temp. (top of device)
Pin temp. (bottom of device)
Figure 8. Mounting Dimensions (For reference only: mm [in]). Additional port and housing styles available.
Long Port Style, Fastener Mount Short Port Style, Snap Mount
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9,(:(')5207(50,1$/6,'(
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3,0
[0.12]
2,00 TYP.
[0.079]
MODEL NUMBER
LOT CODE
10,3
[0.40]
10,00
[0.39]
3,50
[0.14]
6,50
[0.26]
19,90
[0.78]
6,35
[0.25]
28,80
[1.13]
36,00
[1.42]
7,20
[0.28]
12,70
[0.50]
AIRFLOW DIRECTION, PORT SIDE
2X DIA. 3,40
[0.13]
1,00
[0.04]
7,20
[0.28]
4X DIA. 0,812
[0.032]
7,20
[0.28]
18,00
[0.71]
36,00
[1.42]
2X DIA. 3,40
[0.134]
2X DIA. 5,35
[0.21]
;32576
7(50,1$/6,'(
6(1625)22735,17
9,(:(')5207(50,1$/6,'(
MODEL NUMBER
LOT CODE
19,90
[0.78]
6,35
[0.25]
28,80
[1.13]
12,70
[0.50]
10,3
[0.40]
2,50
[0.10]
4,80
[0.19]
3,3
[0.13]
2,00 TYP.
[0.079]
1,00
[0.04] 3,00
[0.12]
12,8
[0.50]
26,00
[1.02]
1,80
[0.071]
6,50
[0.26]
10,40
[0.41]
7,20
[0.28] 4,60
[0.18]
26,00
[1.024]
AIRFLOW DIRECTION, PORT SIDE
22,0
[0.866]
2X DIA. 2,2 [0.086] THRU
HOLES FOR MOUNTING
3,80
[0.150]
4,00
[0.157]
2X 2,50
[0.098]
2X 7,20
[0.28]
0,65
[0.026]
22,00
[0.87]
4X DIA. 0,812
[0.032]
DIA. 2,30
[0.09]
Pinout (digital function) 1 = SCL 2 = Vsupply 3 = ground 4 = SDA
