DSDXL Series Digital pressure transducers FEATURES GENERAL DESCRIPTION The DSDXL series offers a digital interface on a very cost-effective basis. This family is fully calibrated and temperature compensated using an on-board ASIC. These sensors are intended for use with non-corrosive, non-ionic working fluids such as air and dry gases. · 0...±5, 0...±10, 0...10 "H2O differential/gage · Digital readout via I2C-bus · Precision ASIC conditioning · Temperature compensated · Non-ratiometric output The DSDXL010D4R device is available to measure gage pressure from 0...10 "H2O. APPLICATIONS The DSDXL...4D devices are available to measure differential pressures from 0...±5 "H 2 O (DSDXL005D4D) to 0...±10 "H 2 O (DSDXL010D4D). Differential devices allow application of pressure to either side of the sensing diaphragm and can be used for gage or differential measurements. · Medical instrumentation · HVAC controls · Pneumatic controls All DSDXL devices are accurate to within ±2.5 %FSS. The devices are characterized for operation from a single 5 V supply. The sensor is designed and manufactured according to standards laid down in ISO 9001. ELECTRICAL CONNECTION +Vs N/C Note: 6 1 5 7 DSDXL 2 8 4 N/C July 2007 / 588 SCL SDA 220 nF Pin 2 is an internal device connection and should be connected to ground with a 15 nF capacitor. It is important to place the capacitors as close to the pins as possible! IC 15 nF 3 A capacitor of 220 nF is required between +Vs and GND. Pins 4, 6 and 8 are internal device connections and should not be connected for any reason! GND 1/6 www.sensortechnics.com DSDXL Series Digital pressure transducers PRESSURE SENSOR CHARACTERISTICS Environmental specifications Maximum ratings Supply voltage VS Output current Sink Source 2 mA (max.) 2 mA (max.) Lead temperature (2 - 4 sec.) 250°C Common mode pressure 50 psi Caution! Temperature ranges Compensated Operating Storage 4.75 V to 5.25 VDC max. 6.50 VDC 0 to +85°C -20 to +105°C -40 to +125°C Vibration: 10 g at 20 - 2000 Hz Shock: 50 g for 11 ms The sensor is not reverse polarity protected. Incorrect applications of excitation voltage or ground to the wrong pin can cause electrical failure. Application of supply voltage above the maximum can cause electrical failure. PERFORMANCE CHARACTERISTICS (VS = 5.0 VDC, TA = 25°C) Part number Pressure range D S D X L005D 4D 0...±5 D S D X L010D 4D 0...±10 D S D X L010D 4R 0...10 Burst pressure1 3 "H2O 3 3 Sensitivity (typ.) 328 p si 164 328 counts/ "H2O Specification notes: 1. If maximum burst pressure is exceeded, even momentarily, the package may leak or burst, or the pressure sensing die may fracture. 2. Span is the algebraic difference between the output signal for the highest and lowest specified pressure. 3. Total accuracy is the combined error from offset and span calibration, linearity, pressure hysteresis, and temperature effects. Linearity is the measured deviation based on a straight line. Hysteresis is the maximum output difference at any point within the operating pressure range for increasing and decreasing pressure. Calibration errors include the deviation of offset and full scale from nominal values. 4. Delay time between sampling and signal change at the output. 5. The smallest change in the output voltage, given any change in pressure. July 2007 / 588 2/6 www.sensortechnics.com DSDXL Series Digital pressure transducers PERFORMANCE CHARACTERISTICS The output signal is not ratiometric to the supply voltage (VS = 5.0 VDC, TA = 25°C) DSDXL...D4D Characteristics Zero pressure offset Min. Typ. Max. 1966 2048 2130 Full scale span (FSS)2 Units 3276 counts Output at max. specified pressure 3604 3686 3768 at min. specified pressure 327 410 492 Total accuracy (0 to 85°C)3 ±2.5 Sample rate 100 Response delay4 2.73 %FSS Hz 14.11 ms Startup time (power up to 1st result) 40 Quantization step5 3 counts Current consumption 6 mA DSDXL010D4R Characteristics Zero pressure offset Min. Typ. Max. 327 410 492 Full scale span (FSS)2 Full scale output counts 3277 3604 3686 Total accuracy (0 to 85°C)3 3768 ±2.5 Sample rate 100 Response delay4 2.73 Units %FSS Hz 14.11 ms Startup time (power up to 1st result) 40 Quantization step5 3 counts Current consumption 6 mA July 2007 / 588 3/6 www.sensortechnics.com DSDXL Series Digital pressure transducers INTRODUCTION The DSDXL is capable to generate a digital output signal. It runs a cyclic program, which will store a corrected 12-bit sensor value about every 10 ms within the output registers of the internal ASIC. In order to use the pressure transducer for digital signal readout, the device should be connected to a bidirectional I²C-bus. STOP condition (P): LOW to HIGH transition of SDA line while clock (SCL) is HIGH determines STOP condition. STOP conditions are always generated by the master. More than one request for the current pressure value can be transmitted without generation of intermediate STOP condition. DATA valid (D): State of data line represents valid data when, after START condition, data line is stable for duration of HIGH period of clock signal. Data on line must be changed during LOW period of clock signal. There is one clock pulse per bit of data. According to the I²C-bus communication specification, the bus is controlled by a master device, which generates the clock signal, controls the bus access and generates START and STOP conditions. The DSDXL is designed to work as a slave, hence it will only respond to requests from a master device. Acknowledge (A): Data is transferred in pieces of 8 bits (1 byte) on serial bus, MSB first. After each byte receiving device – whether master or slave – is obliged to pull data line LOW as acknowledge for reception of data. Master must generate an extra clock pulse for this purpose. When acknowledge is missed, slave transmitter becomes inactive. It is on master either to send last command again or to generate STOP condition in that case. The I²C-bus master-slave concept requires a unique address for each device. The DSDXL has a hard coded slave address (1111000xb), therefore it is not possible to access more than one DSDXL on the same I²C-bus line. DIGITAL I2C INTERFACE Slave address: Each device connected to the bus has a unique slave address. After generating a START condition, the master has to transmit the slave address for the DSDXL with a READ command: $F1. The DSDXL must not be accessed with a WRITE command ($F0) as the correct function of the device can not be guaranteed in this case (note: a power-down power-up change will force the sensor to use factory data again). The DSDXL complies with the following protocol (FIG. I): Bus not busy: During idle periods both data line (SDA) and clock line (SCL) remain HIGH. START condition (S): HIGH to LOW transition of SDA line while clock (SCL) is HIGH is interpreted as START condition. START conditions are always generated by the master. Each request for the current pressure value must be initiated with a START. DATA operation: The DSDXL starts to send 2 data bytes containing the current pressure value placed in the output registers. SCL SDA START condition Data valid 1 S Slave Address R/W A Data allowed to change Data Byte 1 A STOP condition Data Byte 2 S Slave Address Read out of pressure value generated by master generated by slave P Next command S = START condition Data Byte 1 = High Byte (MSB first) A = Acknowledge Data Byte 2 = Low Byte (LSB last) P = STOP condition FIGURE I: I²C-BUS Protocol of DSDXL July 2007 / 588 4/6 www.sensortechnics.com DSDXL Series Digital pressure transducers I2C INTERFACE PARAMETERS Parameter Symbol Input high level Input low level Output low level Pull up current Load capacitance SDA SCL clock frequency Bus free time between STOP and START condition Hold time (repeated) START condition LOW period of SCL HIGH period of SCL Setup time repeated START condition Data hold time Data setup time Rise time of both SDA and SCL Fall time of both SDA and SCL Setup time for STOP condition Input filter spike suppression Conditions Min. Typ. 90 0 (open drain, IOL = -4 mA) (pins SCL and SDA) Max. 100 10 10 20 400 100 5 Unit % of Vs µA pF kHz FSC L --- tBUF 4.7 µs 4.0 µs tLOW tHIGH 4.7 4.0 µs µs tSU.STA 4.7 µs tHD.DAT tSU.DAT 0 250 ns ns tR --- 300 ns tF --- 300 ns tSU.STO 4 to first clock pulse tHD.STA tSP tSU;DAT µs sp i ke s o n S D A o r S C L o f that length are suppressed tHD;DAT 50 tSU;STA tHD;STA tR tSU;STO tBUF tHD;STA ns tF SCL SDA tHIGH tLOW SCL SDA FIGURE II: Timing characteristics of the I2C interface July 2007 / 588 5/6 www.sensortechnics.com DSDXL Series Digital pressure transducers ELECTRICAL CONNECTIONS Vs (pin 1) identifier Note: Pins 4, 6 and 8 are internal device connections and should not be connected for any reason. +Vs IC GND N/C SCL N/C SDA N/C Pin 2 is an internal device connection and should be connected to ground with a 15 nF capacitor. PHYSICAL DIMENSIONS 1.27 typ (0.050 typ) 16.89 (0.665) 7.87 typ (0.310 typ) 13.97 (0.550) 3.63 (0.143) High pressure port 2.29 (0.090) 3.38 (0.133) 8.13 8.89 (0.350) (0.320) 8.26 typ (.325 typ) 1.78 (0.070) 16.64 ±0.64 (0.655 ±0.025) third angle projection Low pressure port 0.51 typ (0.02 typ) 2.54 typ (0.100 typ) 4.5 (0.177) dimensions in mm (inches) ORDERING INFORMATION Pressure range Differential/Gage 0...±5 "H2O D S D X L005D 4D 0...±10 "H2O D S D X L010D 4D 0...10 "H2O D S D X L010D 4R Other pressure ranges or calibrations are available on request Sensortechnics reserves the right to make changes to any products herein. Sensortechnics 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. July 2007 / 588 6/6 www.sensortechnics.com