Welcome to the training on TruStability™ HSC Series Silicon Pressure Sensors from Honeywell. This training module will introduce HSC and SSC series silicon pressure sensors, the key features and applications.
Piezoresistance of a semiconductor can be described as a change in resistance caused by an applied strain of the diaphragm. Thus, solid-state resistors can be used as pressure sensors, much like wire strain gages, but with several important differences and advantages. The high sensitivity, or gage factor, is perhaps 100 times that of wire strain gages. Piezoresistors are implanted into a silicon medium, and the implanted resistors are integrated into the silicon force-sensing member. Silicon is an ideal material for receiving the applied force. It is a perfect crystal and does not become permanently stretched. After being strained, it returns to the original shape. Silicon wafers are better than metal for pressure-sensing diaphragms, and silicon has extremely good elasticity within its operating range. Silicon diaphragms normally fail only by rupturing. These pressure sensors offer state of the art benefits of hybrid IC devices, including compactness, ruggedness, and reliability.
Each Honeywell solid-state pressure sensor is developed around a square silicon chip with an integral sensing diaphragm and four piezoresistors. Pressure applied on the diaphragm causes it to flex, changing the resistance, which results in a low-level output voltage proportional to pressure. The sensing resistors are connected as a four active element bridge for best linearity and sensitivity. Gold pads attached to the silicon chip surface provide connection to the piezoresistors, and serve as pads for bonding of wire leads. The thin diaphragm is formed by chemically etching a square cavity into the surface opposite the piezoresistors.
The new TruStability™ Silicon Pressure Sensor offer different accuracies and compensated temperature ranges that address specific segment needs. These devices offer customers three key benefits; Stability: These sensors are the most stable silicon pressure sensors available; Accuracy: They are designed to provide an extremely tight accuracy specification; and Flexibility: Their modular and flexible design offer customers a variety of package styles and options, all with the same industry-leading performance specifications.
The TruStability silicon pressure sensors include HSC and SSC series. HSC stands for high accuracy silicon ceramic and SSC for standard accuracy silicon ceramic. The HSC Series is designed to provide a ±1 % total error band specification and the SSC Series provides a ±2 % total error band specification. Despite their small size, both series are temperature compensated, calibrated, and provide an amplified signal, typically allowing the customer to remove the components associated with signal conditioning from the PCB to increase space and reduce costs often associated with those components. Both Series offer the option of analog or digital outputs. Digital ASIC output in either I 2 C or SPI protocols from digital sensors accelerates performance through reduced conversion requirements and the convenience of direct interface to microprocessors or microcontrollers.
These pressure sensors are designed to be used in a diversity of applications. They are ideal for applications requiring precise measurement of pressure, where the benefits of repeatability, low hysteresis, and long-term stability are important. In medical equipment, where accuracy is often critical, solid-state pressure sensors are used in airflow meters, kidney dialysis, handheld blood pressure monitors, oxygen concentrators, ventilators, and Respiratory machines. In industrial applications, the broad sensing capabilities and ruggedness of these pressure sensors are well suited for use in barometry, flow calibrators, HVAC, and pneumatic controls.
HSC and SSC series sensors measure absolute, differential and gage pressure. The absolute versions have an internal vacuum reference and an output value proportional to absolute pressure. Differential versions allow application of pressure to either side of the sensing diaphragm. Gage and compound versions are referenced to atmospheric pressure and provide an output proportional to pressure variations from atmosphere. Note that the output type defines which protocol the sensor uses to communicate.
Here list some key parameters to help you roughly evaluate these sensors. Both series look similar, but the total error band, compensated temperature range, and response time is slightly different. The compensated temperature range is the temperature range over which the sensor will produce an output proportional to pressure within the specified performance limits. Obviously, SSC series has wider range. The maximum deviation from the ideal transfer function over the entire compensated temperature and pressure range is called total error band. These errors are caused by offset, full scale span, pressure non-linearity, pressure hysteresis, repeatability, etc. We can see from the table, the HSC series has higher accuracy. If your application is more sensitive to response time, then the HSC is a better solution than the SSC.
The part number simplify referencing the HSC and SSC series based on their package, pressure port configuration, pressure range, output type, transfer function, and supply voltage. The figure gives you the order guide.
Hemodialysis machine treatments replace some kidney functions by removing waste and fluid from the bloodstream via diffusion and osmosis of solutes and fluid across a semipermeable dialysis membrane. Here shows the simplified block diagram of a hemodialysis system. The HSC and SSC pressure sensors are designed to is designed to provide enhanced reliability and may be used to obtain a direct, in-line continuous dialysate and venous pressure measurement in the dialysis membrane without interrupting flow.
Thank you for taking the time to view this presentation on “ TruStability™ HSC Series Silicon Pressure Sensors ” . If you would like to learn more or go on to purchase some of these devices, you may either click on the part list link, or simply call our sales hotline. For more technical information you may either visit the Honeywell Sensing and Control site, or if you would prefer to speak to someone live, please call our hotline number, or even use our ‘live chat’ online facility. You may visit Element 14 e-community to post your questions.
TruStability™ HSC & SSC Series Silicon Pressure Sensors
Introduction <ul><li>Purpose </li></ul><ul><ul><li>To introduce HSC and SSC series silicon pressure sensors, its key features and applications. </li></ul></ul><ul><li>Outline </li></ul><ul><ul><li>Silicon pressure sensors basics </li></ul></ul><ul><ul><li>HSC & SSC series overview </li></ul></ul><ul><ul><li>Key features </li></ul></ul><ul><ul><li>Part numbering </li></ul></ul><ul><ul><li>Application example </li></ul></ul><ul><li>Content </li></ul><ul><ul><li>12 pages </li></ul></ul>
Silicon Pressure Sensors Basics <ul><li>Gage factor 100 times greater than wire strain gages </li></ul><ul><li>Piezoresistors implanted into silicon medium </li></ul><ul><li>Integrated into silicon force-sensing member </li></ul><ul><li>Perfect crystal, returns to original shape </li></ul><ul><li>Better than metal for pressure-sensing diaphragms </li></ul><ul><li>Extremely good elasticity </li></ul><ul><li>Fail only by rupturing </li></ul><ul><li>Compact, rugged, reliable </li></ul>
Honeywell Silicon Pressure Sensor Structure <ul><li>Square silicon chip </li></ul><ul><ul><li>Integral sensing diaphragm </li></ul></ul><ul><ul><li>Four piezoresistors </li></ul></ul><ul><li>Diaphragm flexes under pressure </li></ul><ul><ul><li>Resistance changes </li></ul></ul><ul><ul><li>Low-level output voltage proportional to pressure </li></ul></ul><ul><li>Gold pads connect silicon chip surface to piezoresistors </li></ul><ul><li>Wire leads bond to gold pads </li></ul><ul><li>Diaphragm formed by etching square cavity </li></ul>
Why TruStability ™? <ul><li>Helps prevent drift over time or from temperature and humidity extremes </li></ul><ul><li>Eliminates the customer's need to calibrate after mounting to the PCB, and also the need for the end-user to calibrate the device </li></ul><ul><li>Temperature compensated and calibrated to provide an extremely tight accuracy specification </li></ul><ul><li>Modular and flexible design offers a wide variety of package styles and options, all with the same industry-leading performance specifications </li></ul>Accuracy Stability Flexibilty
HSC & SSC Overview <ul><li>Industry leading long-term stability </li></ul><ul><li>Extremely tight accuracy of ±0.25 % FSS BFSL </li></ul><ul><li>Low operating voltage </li></ul><ul><li>Extremely low power consumption </li></ul><ul><li>Ratiometric 12-bit analog output </li></ul><ul><li>Virtually insensitive to mounting direction </li></ul><ul><li>Internal diagnostic functions increase system reliability </li></ul><ul><li>Absolute, differential, gage, and compound types </li></ul><ul><li>Custom calibration available </li></ul><ul><li>Various pressure port options </li></ul><ul><li>RoHS compliant </li></ul>
Types of Pressure Sensor Measurement <ul><li>Absolute (Port 2) </li></ul><ul><ul><li>Port 2 sealed at zero atmospheres </li></ul></ul><ul><ul><li>Pressure applied to P1 port </li></ul></ul><ul><ul><li>Pressure deflects diaphragm, producing voltage change </li></ul></ul><ul><li>Differential (Port1 – Port2) </li></ul><ul><ul><li>Difference between two pressure </li></ul></ul><ul><ul><li>Pressure applied to both ports </li></ul></ul><ul><ul><li>Change in differential leads to change in voltage </li></ul></ul><ul><li>Gage (P2 – Atmospheric Pressure) </li></ul><ul><ul><li>Ambient atmospheric pressure used as reference </li></ul></ul><ul><ul><li>P1 port vented to atmospheric pressure </li></ul></ul><ul><ul><li>Measured pressure applied to P2 port </li></ul></ul>
Key Parameters HSC SSC Pressure range 1psi to 150psi 1psi to 150psi Accuracy ± 0.25% FSS BFSL ± 0.25% FSS BFSL Total Error Band ± 1% FSS ± 2% FSS Compensated Temperature Range 0 º C ~ 50 º C -25 º C ~ 85 º C Output Accuracy 12 bit 12 bit Response Time 0.46ms 1ms
Part Numbering HSC M RN N 001BG 2 A 5 Series Package M: SMT D: DIP Pressure Port NN : flat covers AN : Axial, single port RN : Radial, single port RR : Radial, dual port on same side DR : Radial, dual port on both side Diagnostics D : Diagnostics N : No diagnostics Pressure Range Output Type A : Analog voltage S : SIP 2 : I 2 C, 0x28 3 : I 2 C, 0x23 4 : I2C, 0x48 5 : I2C, 0x58 6 : I2C, 0x68 7 : I2C, 0x78 Supply Voltage 3 : 3.3V 5 : 5V Transfer Function A : 10% to 90% of Vsupply B : 5% to 95% of Vsupply
Additional Resource <ul><li>For ordering HSC & SSC Pressure Sensors, please click the part list or </li></ul><ul><li>Call our sales hotline </li></ul><ul><li>For more product information go to </li></ul><ul><ul><li>http://sensing.honeywell.com/index.cfm?Ne=2308&ci_id=154348&N=3383&la_id=1 </li></ul></ul><ul><li>Visit Element 14 to post your question </li></ul><ul><ul><li> www.element-14.com </li></ul></ul><ul><li>For additional inquires contact our technical service hotline or even use our “Live Technical Chat” online facility </li></ul>Newark 1 Farnell Newark 2