TSPR1A170100 Spreeta Liquid Sensor Microcomponents Technology Center Analytical Sensors Analytical Sensors SLYS009B – MARCH 2000 D D D D D D D Real-Time Sensing Quantitative Analysis† Internal Fault Detection† On-Board Factory Set Calibration Robust Affordable Packaging Small and Lightweight Variety of Applications – Refractometry – Diagnostics – Quality Control – Distributed Process Control Sensing Surface SpreetaTM The Texas Instruments (TI) TSPR1A170100 Spreetat liquid analytical sensor allows you to measure the refractive index of liquids that come in contact with the sensing surface. This measurement is obtained using an ultrasensitive physical principle known as surface plasmon resonance (SPR). Electrical connections are made via pins that protrude from the bottom of the device. The pin configuration is similar to a standard 16-pin dual in-line device. The following sections provide detailed information. functional block diagram 11 Anode Cathode 16 15 VDD 4K I 2C Serial EEPROM LED 128 X 1 Pixel Detector Clock Start 5 3 14 7,8 SDA SCL Output 128-Bit Shift Register 13 6 Ground Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. † When used in conjunction with processor board and Spreeta software I2C is a trademark of Philips Corporation. Spreeta is a trademark of Texas Instruments. Copyright 1999, Texas Instruments Incorporated PRODUCT PREVIEW information concerns products in the formative or design phase of development. Characteristic data and other specifications are design goals. Texas Instruments reserves the right to change or discontinue these products without notice. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 1 ADVANCE INFORMATION description TSPR1A170100 Spreeta Liquid Sensor Microcomponents Technology Center Analytical Sensors SLYS009B – MARCH 2000 Terminal Functions TERMINAL ADVANCE INFORMATION NO. NAME I/O DESCRIPTION 1 NC No internal connection 2 NC 3 SDA 4 NC 5 CLOCK 6 GROUND 7 OUTPUT O SPR information output (analog) (See Note 1) 8 OUTPUT O SPR information output (analog) (See Note 1) No internal connection I/O Read/Write calibration data No internal connection I Clocks the measurement and output cycles Device ground 9 NC No internal connection 10 NC No internal connection 11 VDD Device power 12 NC No internal connection 13 START I Initiates output cycle and internal reset 14 SCL I Clocks calibration data out or data in 15 C O LED cathode 16 A I LED anode NOTES: 1. Pins 7 and 8 are connected together internally. detailed description t The Spreeta sensor uses a physical principle called surface plasmon resonance (SPR) to measure the refractive index of liquids in contact with the sensing surface. The sensor consists of a light-emitting diode (LED), a sensing surface, and a light detector integrated into a unique optical package. Electrical connections are made to the sensor via pins at the bottom of the device. Detailed information on surface plasmon resonance can be found at http://www.ti.com/spreeta. When a liquid comes in contact with the sensing surface and the appropriate signals are applied to the pins, the sensor provides an output that corresponds with the refractive index of the liquid. The output of the Spreeta sensor is a series of analog voltages, one per clock pulse, from which the refractive index of the liquid is derived when the voltages are digitized and processed with the proper algorithm. t t The TSPR1A170100 Spreeta liquid sensor has a dynamic range of 1.320 to 1.368 refractive index units (RIU) with a resolution of 5 X 10–6 RIU. The physical dimensions of the Spreeta are shown in Figure 13 on page 14. t sensor operation t See the functional block diagram and Figure 1 for this discussion. Using the Spreeta sensor to measure the refractive index of a liquid requires the proper application of signals to the pins. See Figure 1 for a diagram of the measurement cycle. A pulse is applied to the START pin. On the subsequent positive edge of the CLOCK, the start pulse is clocked into the internal shift register initiating a reset cycle. Simultaneously, the data output cycle begins and the first data bit is presented to the OUTPUT pin. Data presented to the OUTPUT pin will always be data collected during the previous measurement cycle. An additional 127 clock pulses are required to complete the data output cycle. With each clock pulse during the data output cycle a new data bit is presented to the OUTPUT pin. One additional clock pulse, (129th) is required to end the data output cycle and clear the internal shift register. 2 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TSPR1A170100 Spreeta Liquid Sensor Microcomponents Technology Center Analytical Sensors SLYS009B – MARCH 2000 Master Clock Start Reset Cycle 18 Clock Cycles ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ 129 Clock Pulses Measurement Cycle LED On Hi–Z Hi–Z Not Measuring Measuring LED Off LED On Figure 1. Timing Waveforms The reset cycle continues for the first 18 clock pulses of the data output cycle. It is important that the start pulse go low before the second clock pulse in the data output cycle. Having more than one start pulse in the internal shift register is an illegal condition. After the 18th clock pulse, the reset cycle is complete and the measurement cycle begins. The measurement cycle continues until the next start pulse is clocked into the internal shift register. The minimum time allowed for the measurement cycle is 111 clock cycles (129 – 18 clock pulses). After the 129th clock pulse of the data output cycle, the Clock may continue to run or be stopped. The measurement cycle continues with or without the presence of the Clock until the next start pulse is clocked into the internal shift register. To measure a refractive index, the LED must be illuminated during the measurement cycle, although not necessarily for the entire measurement cycle. An external current-limiting resistor should be used to ensure that the LED does not experience excessive currents. The output data consists of 128 bits of analog data from a charge mode linear array detector. The output voltage of each bit is a product of the measurement time and the LED illumination. The output voltage of each bit has a range of 100 mV (when the LED is off and the sensor is in a completely dark environment) to 3 V. The measurement cycle should be adjusted so that the average output voltage level of all 128 bits is 2.5 V with the LED illuminated, the sensor in a dark environment, and with no liquid on the sensing surface. Texas Instruments offers the TSPREVM-0001 Evaluation Module, which provides the control, interface electronics, and software to operate the Spreeta sensor from a desktop PC or laptop computer. Developers interested in getting started with Spreeta sensing can find information about the EVM at the Spreeta web site. t t POST OFFICE BOX 655303 t • DALLAS, TEXAS 75265 3 ADVANCE INFORMATION Data Output Cycle TSPR1A170100 Spreeta Liquid Sensor Microcomponents Technology Center Analytical Sensors SLYS009B – MARCH 2000 t sensor. Figure 2 illustrates operational waveforms for the Spreeta tw 1 Clock 2 128 1 129 2 129 2.5 V 5V 0V tsu 1 Output Cycle 50% Start 5V Output Cycle 0V th ts ts ADVANCE INFORMATION Output Figure 2. Operational Waveforms absolute maximum ratings† Supply voltage, VDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V Digital input voltage range, VI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 0.6 V to VDD+1.0 V Digital input current range, II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 20 mA to 20 mA Operating free-air temperature range, TA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0_C to 70_C Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 25_C to 85_C Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260_C † Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. recommended operating conditions, TA = 25°C (unless otherwise noted) (see Figure 2 and Figure 1) General Supply voltage, VDD High-level input voltage, VIH Low-level input voltage, VIL MIN NOM MAX UNIT 4.5 5.0 5.5 V VDD × 0.7 0 VDD × 0.3 V 20 270 mA V Measurement And Output Cycle Peak forward current, IPK (See Note 2) LED forward voltage at 20 mA dc, Vf 1.7 V Average power dissipation PD(AVG) (See Note 3) 50 mW tw ns 2000 kHz Start pulse setup time, tsu(ss) 0 Start pulse, hold time, th(ss) (See Note 2) 20 Clock frequency, fCLOCK 5 ns 25 NOTE 2: An external current-limiting resistor is required to avoid damaging the LED with excess currents. NOTE 3: The current-limiting resistor should be selected to limit the current based upon the selected duty cycle. 4 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TSPR1A170100 Spreeta Liquid Sensor Microcomponents Technology Center Analytical Sensors SLYS009B – MARCH 2000 performance characteristics at TA = 25°C (unless otherwise noted) (see Note 4) PARAMETER TEST CONDITIONS MIN TBD 1.320 Refractive Index Range Resolution NOM 5× TBD MAX UNIT 1.368 RIU 10–6 RIU NOTES: 4. Actual resolution varies depending upon the analog-to-digital (A/D) converter and algorithm used. active-sensing region The active-sensing region is an area of thin gold film that is actively used in liquid sensing. It is approximately 14.0 mm long by 1.0 mm wide on the face of the sensor (see Figure 3). 2.5 mm Sensing Surface Active Sensing Region TSPR1A170100 t Sensor Active Sensing Region Figure 3. Spreeta calibration data read/write t The TSPR1A170100 Spreeta sensor has been factory tested and calibrated. The initial factory-set calibration data is stored on-board the sensor in a 4K I2C serial EEPROM. See Table 4 on page 12 for a description of the data stored on the memory chip. The following sections describe how to access the stored data and how to write new data to the memory. functional description The memory device protocol supports a bidirectional 2-wire bus and data transmission protocol. bus characteristics Bus timing data is shown in Figure 4 and Figure 5. Data transfer may be initiated only when the bus is not busy. During data transfer, the data line must remain stable whenever the clock line is high. A change in the data line while the clock line is high is interpreted as a Start or Stop condition. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 5 ADVANCE INFORMATION 14 mm TSPR1A170100 Spreeta Liquid Sensor Microcomponents Technology Center Analytical Sensors SLYS009B – MARCH 2000 SCL tsu:sta tsu:sto thd:sta SDA Stop Start Figure 4. Bus Timing Start/Stop tf ADVANCE INFORMATION tr thigh tlow SCL tsu:sta thd:sta tsu:dat thd:dat tsu:sto SDA IN ÌÌÌÌÌÌÌÌ ÌÌÌÌÌÌÌÌ taa SDA OUT tbuf thd:sta taa Figure 5. Bus Timing Data 6 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TSPR1A170100 Spreeta Liquid Sensor Microcomponents Technology Center Analytical Sensors SLYS009B – MARCH 2000 bus characteristics (continued) Calibration storage characteristics are listed in Table 1. Table 1. Calibration Storage Characteristics SYMBOL MIN MAX UNITS COMMENTS Clock frequency fCLK – 100 kHz Clock high time tHIGH 4000 – ns Clock low time tLOW 4700 – ns Clock rise time tr – 1000 ns Clock fall time tf – 300 ns Start condition hold time tHD:STA 4000 – ns After this period, the first clock pulse is generated. Start condition setup time tSU:STA 4700 – ns Only relevant for repeated start condition Data input hold time tHD:DAT 0 – ns Data input setup time tSU:DAT 250 – ns Stop condition setup time tSU:STO 4000 – ns tAA – 3500 ns See Note tBUF 4700 – ns Time the bus must be free before a new transmission can start tOF – 250 ns See Note 1, CB ≤ 100 pF Output valid from clock Bus free time Output fall time from VIH min to VIL max Write cycle time tWR – 10 ms Byte or page mode NOTES: 5. As a transmitter, the device must provide an internal minimum delay time to bridge the undefined region (minimum 300 ns) of the falling edge of SCL. This is to avoid unintended generation of Start or Stop conditions. bus conditions Figure 6 illustrates the bus conditions. The bus is considered not busy when both data and clock lines are high. A Start condition occurs when a high-to-low transition occurs on the SDA line while the SCL line is high. A Stop condition occurs when a low-to-high transition occurs on the SDA line while the SCL line is high. Each data transfer is initiated with a Start condition and terminated with a Stop condition. Data is valid after a Start condition when the data is stable during a high period of the clock cycle. After receiving an address or data word, the memory acknowledges by responding with a zero on the ninth clock pulse. start data transfer (B) A high to low transition of the SDA line while the clock (SCL) is high determines a Start condition. All commands must be preceded by a Start condition. stop data transfer (C) A low to high transition of the SDA line while the clock (SCL) is high determines a Stop condition. All operations must be ended with a Stop condition. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 7 ADVANCE INFORMATION PARAMETER TSPR1A170100 Spreeta Liquid Sensor Microcomponents Technology Center Analytical Sensors SLYS009B – MARCH 2000 (A) (B) (D) (D) (C) (A) SCL SDA Start Condition Address or Acknowledge Valid Data Allowed To Change Stop Condition Figure 6. Bus Conditions data valid (D) ADVANCE INFORMATION The state of the data line represents valid data when, after a Start condition, the data line is stable for the duration of the high period of the clock signal. The data on the line must be changed during the low period of the clock signal. There is one clock pulse per bit of data. Each data transfer is initiated with a Start condition and terminated with a Stop condition. The number of the data bytes transferred between the Start and Stop conditions is determined by the master device and is theoretically unlimited, although only the last 16 bits are stored during a write operation. When an overwrite does occur, it replaces data in a first-in first-out (FIFO) manner. 8 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TSPR1A170100 Spreeta Liquid Sensor Microcomponents Technology Center Analytical Sensors SLYS009B – MARCH 2000 bus characteristics (continued) acknowledge Each receiving device, when addressed, must generate an acknowledge after the reception of each byte. The master device must generate an extra clock pulse, which is associated with this acknowledge bit. NOTE: The 24LC04B device does not generate any acknowledge bits if an internal programming cycle is in progress. The device that acknowledges must pull down the SDA line during the acknowledge clock pulse in such a way that the SDA line is stable low during the high period of the acknowledge-related clock pulse. Setup and hold times must be taken into account. A master device must signal an end of data to the slave by not generating an acknowledge bit on the last byte that has been clocked out of the slave. In this case, the slave must leave the data line high to enable the master device to generate the Stop condition. The first byte sent after the Start condition must be the control byte. This 8-bit word is required to address the memory device. See Figure 7 and Table 2 for this discussion. The first four most significant bits (MSB) are the control code and they must always be 1010. The next two bits are don’t care bits. The last bit of the control byte defines the operation as read (if set to 1) or write (if set to 0). Start Read/Write 1 MSB 0 1 0 Required X X X R/W Ack Don’t Care LSB Figure 7. Control Byte Allocation Table 2. Control Byte Operation BLOCK SELECT R/W Read OPERATION 1010 CONTROL CODE Block address 1 Write 1010 Block address 0 write operations Byte write and page write operations are described here. byte write After a Start condition, a control byte with the R/W bit set to 0 is sent, which indicates to the memory device that a byte with a word address will follow after it has generated an acknowledge bit during the ninth clock cycle. The next byte transmitted is the word address and it is written into the address pointer of the memory device. After receiving another acknowledge signal from the memory device, the data word may be written into the addressed memory location. The memory device acknowledges again, and the master generates a Stop condition, which initiates the internal write cycle. During this time, the memory device does not generate acknowledge signals (See Figure 8). POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 9 ADVANCE INFORMATION device addressing TSPR1A170100 Spreeta Liquid Sensor Microcomponents Technology Center Analytical Sensors SLYS009B – MARCH 2000 Bus Activity Master Start SDA Line Control Byte Word Address Stop Data S P Bus Activity ACK ACK ACK Figure 8. Byte Write ADVANCE INFORMATION page write To perform page write, the write control byte, word address, and first data byte are transmitted to the memory device in the same way as in a byte write. But, instead of generating a Stop condition, up to 16 data bytes are transmitted to the memory device, which temporarily stores them in the on-chip page buffer and writes them into the memory after receiving a Stop condition. After the receipt of each word, the four low-order address pointer bits are internally incremented by one. The high-order seven bits of the word address remain constant. if the memory device receives more than 16 words before generating the stop condition, the address counter rolls over and the previously received data is overwritten. As with the byte write operation, when the Stop condition is received, an internal write cycle begins (see Figure 9). Bus Activity Master SDA Line Start Control Byte Word Address (n) Data n+1 Data n Data n+15 S Stop P Bus Activity ACK ACK ACK ACK ACK Figure 9. Page Write read operations Read operations are initiated in the same way as write operations with the exception that the R/W bit of the control byte is set to 1. There are three basic types of read operations: current address read, random read, and sequential read. current address read The memory device contains an address counter that maintains the address of the last word accessed, internally incremented by one. Therefore, if the previous access (either a read or write operation) was to address n, the next current address read operation would access data from address n + 1. Upon receipt of the address with the R/W bit set to one, the memory device issues an acknowledge (ACK) and transmits the 8-bit data word. (see Figure 10). Bus Activity Master SDA Line Start Control Byte Data n S Bus Activity P ACK Figure 10. Current Address Read 10 Stop POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 NO ACK TSPR1A170100 Spreeta Liquid Sensor Microcomponents Technology Center Analytical Sensors SLYS009B – MARCH 2000 random read Random read operations allow you to access any memory location in a random manner. To perform this type of read operation, you must first set the word address. This is done by sending the word address to the sensor as part of a write operation. After the word address is sent, you generate a Start condition following the acknowledge. This terminates the write operation, but only after the internal address pointer is set. Then, you issue the control byte again, but with the R/W bit set to one. The memory device then issues an acknowledge and transmits the 8-bit data word. You then generate a Stop condition, and the memory device discontinues transmission (see Figure 11). Bus Activity Master Start SDA Line Control Byte Word Address (n) S Start Control Byte Data (n) Stop S Bus Activity ACK P ACK ACK NO ACK sequential read Sequential read operations are initiated in the same way as random read operations except that after the memory device transmits the first data byte, you issue an acknowledge instead of a Stop condition. This directs the memory device to transmit the next sequentially addressed 8-bit word (see Figure 12). Bus Activity Master Control Byte Data n Data n + 1 Data n + 2 Data n + X P SDA Line Bus Activity Stop ACK ACK ACK ACK NO ACK Figure 12. Sequential Read To provide sequential reads, the memory device contains an internal address pointer that is incremented by one at the completion of each operation. This address pointer allows the entire memory contents to be serially read during one operation. Table 3 describes the memory map contents. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 11 ADVANCE INFORMATION Figure 11. Random Read TSPR1A170100 Spreeta Liquid Sensor Microcomponents Technology Center Analytical Sensors SLYS009B – MARCH 2000 Table 4. Memory Map ADVANCE INFORMATION MEMORY BLOCK DESCRIPTION # BYTES 1 Air reference raw data 256 2 Factory use only 5 2 Spreeta model number 10 2 Chip ID number—Date code and serial number 2 # BITS 2048 START BYTE EXAMPLE 1 128 pixels; 16 bits per pixel 40 257 N/A 80 262 TSPR1A170100 20 160 272 12/31/2001, sensor #0 to 1,000,000,000 10 bytes + 10 bytes LED setting (See Note 6) 1 8 292 0 to 15 2 Sensor integration time (See Note 7) 1 8 293 0 to 15 2 Factory use only 1 8 294 N/A 1 Moment level 1 8 295 0 to 255 2 Factory set calibration point 1 4 32 296 TBD 2 Factory set calibration point 2 4 32 300 TBD 2 Factory set calibration point 3 4 32 304 TBD 2 User calibration point 1 4 32 308 TBD 2 User calibration point 2 4 32 312 TBD 2 User calibration point 3 4 32 316 TBD NOTES: 6. LED setting starts with 1 = 32-mA peak and follows a slope of approximately 0.0161 times N, which is 0.0017 mA, where N is the LED setting number. There is no internal current limit; hence, this number is for reference only. NOTES: 7. Sensor integration time is the optimal time for achieving an average of 2.5 volts for all 128 pixels at a given LED setting. This number is for reference only. care, handling, and cleaning t The Spreeta sensor is sensitive to high voltages, such as those produced by static electrical discharges. Normal handling is generally not a problem if you are properly grounded prior to handling the sensor. t Because the Spreeta sensing region that sustains the surface plasmon resonance is only a few hundred angstroms thick, handling of this surface must be done with care to avoid scratching and damaging it. t The integrated nature of the Spreeta sensor makes it rugged and shock resistant, but damage to the sensor can result from excessive bending of the pins, dropping the sensor, and exposure to excessive temperature changes. 12 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TSPR1A170100 Spreeta Liquid Sensor Microcomponents Technology Center Analytical Sensors SLYS009B – MARCH 2000 ADDITIONAL INFORMATION t liquid sensor and its components, see the Spreetat website at: For details on the TI Spreeta http://www.ti.com/spreeta t This website expands on the operation and application of the Spreeta liquid sensor, provides access to important documentation, and explains how you can order a Spreeta Evaluation Kit. t If you have questions or comments, please contact us through our website feedback form or email us at: ADVANCE INFORMATION [email protected] POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 13 TSPR1A170100 Spreeta Liquid Sensor Microcomponents Technology Center Analytical Sensors SLYS009B – MARCH 2000 MECHANICAL INFORMATION 0.316 [8,03] 1.093 1.139 [28,92] 0.962 .962 [24,44] ADVANCE INFORMATION SpreetaTM Pin 1 0.236 [5,99] 0.100 [2,54] 0.300 [7,62] 0.404 [10,24] 0.531 [13,49] 1.630 [41,40] Sensing Surface TSPR1A170100 Pin 1 0.200 Nom Figure 13. Spreeta 14 t Sensor Dimensions POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. Customers are responsible for their applications using TI components. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. TI’s publication of information regarding any third party’s products or services does not constitute TI’s approval, warranty or endorsement thereof. Copyright 2000, Texas Instruments Incorporated