Honeywell IPT User manual

Honeywell Integrated Pressure Transducer
IPT User’s Manual

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ADS-14152 Rev. 7/16
Customer Service Email: [e-mail]
www.pressuresensing.com
No part of this manual may be reproduced or transmitted in any form or by any means, electronic or mechanical, including
photocopying and recording, for any purpose, without the express written permission of Honeywell, Inc.
Honeywell reserves the right to make changes to improve reliability, function or design. Honeywell does not assume any
liability arising out of the application or use of any product or circuit described herein; neither does it convey any license
under its patent rights nor the rights of others.

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IPT User’s Manual Contents
1 Introduction.....................................................................................................................................................4
1.1 Overview..................................................................................................................................................4
2 Specifications.................................................................................................................................................4
2.1 Block Diagram .........................................................................................................................................4
2.2 Specifications/Performance .....................................................................................................................5
2.3 Outline/Dimensions (inches)....................................................................................................................6
2.4 Electrical Connections .............................................................................................................................7
2.4.1 Connector.........................................................................................................................................7
3 Operation........................................................................................................................................................8
3.1 Commands and Format...........................................................................................................................8
3.1.1 Initialization.......................................................................................................................................8
3.1.2 Normal Operation (Polling)..............................................................................................................10
3.1.3 Other Modes...................................................................................................................................11
3.2 Correction Algorithms ............................................................................................................................12
3.2.1 Pressure .........................................................................................................................................12
3.2.1.1 Algorithm #1.................................................................................................................................12
3.2.1.1.1 Horner’s Method, Algorithm #1..................................................................................................12
3.2.1.2 Algorithm #2.................................................................................................................................13
3.2.1.2.1 Horner’s Method, Algorithm #2..................................................................................................13
3.2.2 Pressure Sensor Temperature........................................................................................................14
3.2.2.1 Algorithm......................................................................................................................................14
3.2.2.1.1 Horner’s Method........................................................................................................................14
3.3 EEPROM Storage..................................................................................................................................15
3.3.1 EEPROM Format............................................................................................................................15
3.3.2 Contents .........................................................................................................................................15
4 Installation Recommendations......................................................................................................................19
4.1 Installation Examples.........................................................................................................................19
4.1.1 Flexible Tubing and Double-wire Hose Clamps..........................................................................19
4.1.2 Static Radial O-ring Seals ..........................................................................................................20
4.1.3 Static Radial and Face O-ring Seals...........................................................................................20
5 Marking ........................................................................................................................................................20
6 Fletcher Checksum.......................................................................................................................................21
6.1 Calculation.............................................................................................................................................21

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Sensor
-- Temperature --
Op-Amp
3.3V Output
LDO Regulator
256 X 8 EEPROM
SPI Serial
Connector
3.3V Analog and
Digital Supply
4-12V
-- Pressure --
Op-Amp 24-bit ADC, SPI
18+ ENOB @ 250 sps
+ P.S.
DIN
SCLK
CS_ADC_P
CS_EE
GND
16-bit ADC, SPI
~16 ENOB @ 20 sps
CS_ADC_T
DOUT/RDY
1 Introduction
1.1 Overview
The Honeywell IPT provides high accuracy pressure data in an industry standard SPI digital format. The core
of the IPT is a proven Honeywell silicon piezo-resistive pressure sensor with both pressure and temperature
sensitive elements. The IPT is both small and lightweight and can be easily integrated into a wide variety of
applications that require high performance in a small package.
Applying coefficients stored in the on-board EEPROM to normalized IPT pressure and temperature output
yields accurate pressure readings over a -40 to 85°C compensated temperature range.
2 Specifications
2.1 Block Diagram

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2.2 Specifications/Performance
Total Error Band(1)
±0.04%FS absolute
±0.10%FS gauge, differential
±0.20%FS 1 psi gauge
Supply Voltage
4 to 12 VDC
Current Consumption
6 mA typical, 7.5 mA max
Operating Temperature Range
-40 to 85°C (-40 to 185°F)
Storage Temperature Range
-55 to 125°C (-67 to 257°F)
Sample Rate
See section 3.1.2
Long Term Stability
0.025%FS max per year typical
Pressure Ranges/Type
20, 50 psia
1, 2, 5, 10, 20 psig
1, 2, 5, 10, 20 psid
Pressure Units
PSI (2)
Media Compatibility
Non-condensing, non-corrosive,
non-combustible gases
Weight (3)
~ 8.0 grams (absolute)
~ 9.7 grams (gauge, differential)
Size
See section 2.3 (3)
Interface
3.3V SPI (mode 1,1)(4)
SCLK ≤5 MHz
Output
24-bit pressure value
16-bit temperature value
256 x 8 EEPROM configuration
Overpressure
3X FS
Burst Pressure
3X FS
Humidity Sensitivity of Pressure Ports
DO-160E, Section 6.0, category A (5)
Electromagnetic Immunity/Emissions
(6)
Mechanical Shock
DO-160E Section 7.0, Category A,
Figure 7.2, Operational Standard
Thermal Variation
Storage Temperature Cycling per
JESD22-104, Section 5.0: -55°C to
+125°C,
Vibration
DO-160E Section 8, Category H,
Aircraft Type 2, Aircraft Zones 1 & 2.
ESD
Class 3A, Table III, MIL-STD-883G,
Method 3015.7, section 3.4
RoHS Compliant (2011/65/EU)
Yes
(1) Total Error is the sum of worst case linearity, repeatability, hysteresis, thermal effects, and calibration errors over the operating
temperature range. Accuracy is only achieved after applying the correction coefficients and algorithm as shown in section 3.2. (FS =
Full Scale) For total error calculations of differential units, “Full Scale” is the pressure difference between the minimum and maximum
pressures. For example, full scale for a 1 psid PPT is 2 psi (-1 to +1 psi).
(2) After applying the correction coefficients stored in EEPROM, the resultant pressure reading is expressed in PSI (pounds per square
inch).
(3) Not including any mounting hardware. Dimensions in section 2.3 do not include Humiseal 1A33 conformal coating which is typically
applied to the PWB assembly at a thickness of 1-3 mils.
(4) Operation with a digital interface > 3.3V can damage the IPT and cause shifts in the ADC output.
(5) IPT electronics require protection from humidity.
(6) IPT requires shielding from EMI.

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2.3 Outline/Dimensions (inches)

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2.4 Electrical Connections
2.4.1 Connector
2mm, 2x4 Low Profile Bottom & Top-Entry Connector, Samtec P/N CLT-104-02-L-D-A-K-TR
Connector centered on circuit board and aligned with mounting holes.
Compatible Samtec mating connectors: TMM, MMT, TW, TMMH, MTMM

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3 Operation
3.1 Commands and Format
3.1.1 Initialization
The IPT piezo-resistive pressure sensing die contains two bridge circuits; one for pressure, one for
temperature. The IPT provides two serial (SPI-compatible) Analog-to-Digital Converters (ADCs), one
for each of these data channels. The pressure channel uses a 24-bit ADC from Analog Devices, P/N
AD7799. The temperature channel uses a 16-bit ADC from Analog Devices, P/N AD7790. After
applying power to the IPT and before obtaining data, each data channel needs to be initialized.
As per the manufacturer’s data sheets, the SPI serial clock for each ADC should be ≤5 MHz. During
reads and writes to the ADC’s as detailed below, the appropriate chip-select line must be brought low
(CS_P or CS_T).
3.1.1.1 Pressure Channel
The pressure channel ADC is controlled and configured via a number of on-chip registers. ALL
communication to the pressure channel ADC starts with a write operation to the 8-bit write-only
communication register.
Initializing the pressure channel ADC requires writing data to a sequence of four registers; the
Communication register, the Mode register, the Communication register, and the Configuration
register.
3.1.1.1.1 Communication Register
Sending 0x10 to the Communication register tells the ADC the following write will be to
the 16-bit Configuration register.
3.1.1.1.2 Configuration Register
Sending 0x1020to the Configuration register sets the ADC’s gain and buffering.
3.1.1.1.3 Communication Register
Sending 0x08 to the Communication register tells the ADC the following write will be to
the 16-bit Mode register.
3.1.1.1.4 Mode Register
Sending 0x3001 to the Mode register places the ADC into a single conversion mode
and sets the update rate, fADC to 470 Hz.
From the AD7799 manufacturer’s datasheet:
“When single-conversion mode is selected, the ADC powers up and performs a single
conversion. The oscillator requires 1 ms to power up and settle. The ADC then performs
the conversion, which takes a time of 2/fADC [4.26 ms]. The conversion result is placed in
the data register, RDY goes low, and the ADC returns to power-down mode. The
conversion remains in the data register and RDY remains active (low) until the data is
read or another conversion is performed.”

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3.1.1.1.5 Reading
Note: after initialization is complete, reading the Configuration and Mode Registers is
recommended to ensure they have been set as desired. See the AD7799 manufacturer’s
datasheet for information regarding reads of the Configuration and Mode registers.
3.1.1.2 Temperature Channel
The temperature channel ADC is controlled and configured via a number of on-chip registers.
ALL communication to the temperature channel ADC starts with a write operation to the 8-bit
write-only Communication register.
Initializing the temperature channel ADC requires writing data to a sequence of four registers;
the Communication register, the Mode register, the Communication register, and the Filter
register.
3.1.1.2.1 Communication Register
Sending 0x20 to the communication register tells the ADC the following write will be to
the 8-bit Filter register.
3.1.1.2.2 Filter Register
Sending 0x03 to the Filter register sets the ADC’s update rate (fADC) to 20 Hz.
3.1.1.2.3 Communication Register
Sending 0x10 to the Communication register tells the ADC the following write will be to
the 8-bit Mode register.
3.1.1.2.4 Mode Register
Sending 0x80 to the Mode register places the ADC into a single conversion mode.
From the AD7790 manufacturer’s datasheet:
“When single conversion mode is selected, the ADC powers up and performs a single
conversion, which occurs after a period 2/fADC [100 ms]. The conversion result in placed
in the data register, RDY goes low, and the ADC returns to power-down mode. The
conversion remains in the data register and RDY remains active (low) until the data is
read or another conversion is performed.”
3.1.1.2.5 Reading
Note: after initialization is complete, reading the Filter and Mode registers is
recommended to ensure they have been set as desired. See the AD7790 manufacturer’s
datasheet for information regarding reads of the Filter and Mode registers.

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3.1.2 Normal Operation (Polling)
3.1.2.1 Pressure Channel
After initializing the Mode register per section 3.1.1.2, a new 24-bit pressure value will be available in ~
5.26 ms (1 ms settle time + 4.26 ms conversion).
The pressure conversion remains in the data register and DOUT/ RDY remains active (low) until the
data is read or another conversion is performed.
The process of reading the conversion and reconfiguring the ADC for single conversion mode requires
repeated cycling through the following steps:
1. Wait > 5.26 ms for the conversion to complete, and/or monitor the status of the
DOUT/ RDY line.
2. Send 0x58to the Communications register to indicate a subsequent read of the 24-bit
Data register.
3. Send 24 clock cycles to read the 24-bit Data register.
4. Send 0x08 to the Communications register to indicate a subsequent write to the 16-bit
Mode register.
5. Send 0x3001 to the Mode register to place the ADC into a single conversion mode and
set the update rate to 470 Hz.
6. Repeat
3.1.2.1 Temperature Channel
After initializing the Mode register per section 3.1.1.1, a new 16-bit temperature value will be available
in ~ 100 ms. (As temperature is generally a more slowly changing input than pressure, and has a
modest impact on the pressure output, this conversion rate should be adequate for most applications.)
The temperature conversion remains in the data register and DOUT/ RDY remains active (low) until
the data is read or another conversion is performed.
The process of reading the conversion and reconfiguring the ADC for single conversion mode requires
repeated cycling through the following steps:
1. Wait 100 ms for the conversion to complete and/or monitor the status of the
DOUT/ RDY line.
2. Send 0x38to the Communications register to indicate a subsequent read of the 16-bit
Data register.
3. Send 16 clock cycles to read the 16-bit Data register.
4. Send 0x10 to the Communications register to indicate a subsequent write to the 8-bit
Mode register.
5. Send 0x80 to the Mode register to place the ADC into a single conversion mode.
6. Repeat