Pro-Wave Electronics Corp. Tel: 886-2-22465101 Fax: 886-2-22465105 E-mail: [email protected] URL: http://www.prowave.com.tw Ultrasonic Sonar Ranging IC - PW0268 Features: z z z z z z z SSOP20 z Operating Voltage: 6 – 10Vdc single source Operating Frequency: broadband output ranging up to 250KHz Variable R/C Oscillator: compensates for transducer resonate frequency drift due to temperature. High Gain Amplifier: varies with time over 32 steps Integrated Band Pass Filter: reduces external component count Bi-direction I/O Pin: simplifies the control function for transmitting a pulse and receiving an echo An adjustable System Clock: enables the control of, the number of pulses transmitted, the slope of the variable gain amplifier, and the pulse repetition rate. The PW0268 IC is suitable for use in car reversing aids, electronic tape measures and other sonar ranging applications. Description: The PW-0268 ultrasonic sonar ranging IC is ideally suited for echo ranging systems. This chip has many design features to enhance its performance and ease of use in this application. The externally tunable RC Oscillator automatically tracks and compensates for the shift of the resonate frequency of the transducer due to temperature changes. The Fix Gain Preamplifier can be tailored to compensate for varying transducer sensitivities. The 32-step Time Controlled Variable Gain Amplifier slope can be modified by adjusting the frequency of the system clock. An onboard Comparator converts the analog signal of the returning echo to a TTL level digital signal for use with an external microprocessor. The integrated Band Pass Filters can be adjusted for custom applications by changing a few external components. The frequency of the System Clock can be adjusted to control other operating parameters of the chip including the transmit pulse width and sample rate. The I_O pin, (pin 1) is a bi-direction pin and is designed as an open collector connection with an internal pull high resistor. When the I_O pin is being pulled low by an external transistor, the RC oscillator generates a tone burst signal at DRIVER_0 (pin 11), the output driver stage for the transducer. After the transmit pulse, the I_O pin, (pin 1) will again go low if a valid echo signal is detected. The reflected echo signal is presented to the first stage pre-amplifier through ECHO (pin 10). The gain of pre-amplifier can be adjusted to accommodate transducers with varying sensitivities by changing an external resistor between ECHO (pin 10) and GR_I (pin 9). The 32 steps time controlled variable gain amplifier input TCG_I (pin7) and output TCG_O (pin 6) is synchronized to start incrementing at the end of control pulse signal I-O, (pin 1) and is reset at the beginning of the next control pulse. Only a few passive components are needed for the active band pass filter. There are two stages, a low pass, LP_I (pin 5) and LP_O (pin 4) and upper band pass, HP_I (pin 3) to HP_O (pin 2). The center frequency and bandwidth of the filter are chosen based on the type of ultrasonic transducer being used and the specific application. The amplified echo signal after being filtered is routed to a comparator, which shapes and coverts the analog echo signal into digital signal outputted at I_O (pin 1) for further µP handling. The unique temperature compensating Ultrasonic R/C Oscillator circuitry tracks the resonant frequency drift of the transducer that is causes by environment temperature changes. Simply adding dual diodes and one resistor between DRIVER_O (pin 11) and Ftrace (pin 12) is all that is needed to complete this function. 1 Pro-Wave Electronics Corp. Tel: 886-2-22465101 Fax: 886-2-22465105 E-mail: [email protected] URL: http://www.prowave.com.tw Block Diagram Vref Vcc Vreg GND 20 19 18 17 CLK ORC3 16 15 System Clock 4V Regulator ORC2 ORC1 Ftrace 14 13 12 Driver_O 11 Sensor Driver Ultrasonic R/C Oscillator Auto Frequency Tracking Timer High-Speed Comparator Control Center 32 Steps TCG Amp Band-pass Filter Fixed Gain Amp 1st Pre-Amp 1 2 3 4 5 6 7 8 9 10 I_O HP_O HP_I LP_O LP_I TCG_O TCG_I GR_O GR_I ECHO Pin Assignment 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 PW0268 I_O HP_O HP_I LP_O LP_I TCG_O TCG_I GR_O GR_I ECHO 2 Vref Vcc Vreg GND CLK ORC3 ORC2 ORC1 Ftrace Driver_O Pro-Wave Electronics Corp. Tel: 886-2-22465101 Fax: 886-2-22465105 E-mail: [email protected] URL: http://www.prowave.com.tw Specifications: Unless otherwise specified, all data measured under Vcc = 9V, F = 40KHz Parameter Symbol Condition Min. Supply Voltage Vcc Vreg = 4V 5.5 Supply Current Icc Vcc = 6 ~ 10V 8 Regulated Voltage Vreg Vcc = 6 ~ 10V 3.8 Stability of Vreg Vlr Vcc = 6 ~ 10V , ± 3% -3.0 Reference Voltage Vcc = 6 ~10V , Vref 0.4 RL>2KΩ Op-Amp Slew Rate SR Vin = 3Vpp 5 Comparator Trigger Tcomp Over Vref 300 Level System Clock R=33KΩ，C=22pF CLKf 610 Frequency System Clock CLKr 0.001 Frequency Range Ultrasonic Oscillation R=5.6K，C=1000pF Foscf 38 Frequency Ultrasonic Oscillation Foscr 0.001 Frequency Range 2nd Amp Gain GR 29 Time Controlled Gain Min(1x, 0dB) -1 TCGain Amplifier Max(58x, 35.2dB) 34 Bandwidth of 2nd Amp GRbw Gain = 50dB 150 Idrv Driver_O Driving Current Isink Driver_O I_OVIH Input Voltage Level I_OVIL 0.15 Output Voltage Level I_OVOH I_OVOL 0 Input Low Level I_OIOL Current I_O Internal Pull Up Rup 3.5 Resistance Absolute Maximum Ratings Description Supply Voltage Operation Temperature Storage Temperature Symbol Vcc Topr Tstg Condition Typ. 11 4 0 Max. 11 14 5 +3.0 Unit V mA V % 0.44 0.5 Vreg - - V/µS 350 400 mV 660 710 KHz - 1500 KHz 40 42 KHz - 500 KHz 30 0 35 170 20 -20 0.3 0.2 0.9 0.05 31 +1 36 200 40 -80 0.4 1 - dB dB dB KHz mA -10 -20 mA 5 6.5 KΩ Vcc Vcc Min. Max. Unit 0 12 V ℃ -40 +85 ℃ -65 +150 I_O，Vcc -0.3 Vcc+0.3 V Max. Pin Input Voltage Vimax Others -0.3 Vreg+0.3 Max. Input Current Iimax * -10 +10 mA *To prevent latch up, the instantaneous input current should be no large than 100mA for each pins. 3 Pro-Wave Electronics Corp. Tel: 886-2-22465101 Fax: 886-2-22465105 E-mail: [email protected] URL: http://www.prowave.com.tw Pins Description: Pin 1 2 3 4 5 6 7 8 Name I_O HP_O HP_I LP_O LP_I TCG_O TCG_I GR_O Description Input/Output High pass filter output High pass filter input Low pass filter output Low pass filter input Time controlled gain output Time controlled gain input External adjustable gain output 9 10 GR_I ECHO External adjustable gain input Receiving echo input Pin Name Description 11 Driver_O Transducer driving output 12 Ftrace Frequency tracing input 13 ORC1 RC oscillator: terminal 1 14 ORC2 RC oscillator: terminal 2 15 ORC3 RC oscillator: terminal 3 16 CLK System clock 17 GND Ground 18 Vreg Regulated voltage for internal analogue devices 19 Vcc Power supply 20 Vref Reference voltage output Application Circuit: for car reversing aids (values should be changed for other applications) Vref Vcc 400EP14D BAV99 Vref Vcc C2 47K 100u Vcc 100u 3 2 1 3 2 1 D1 1K C1 R1 22p 220u D2 3 1 20K 2 4 IFT R2 Vref R3 100u Vcc 3 2 1 100 Vreg R4 Ultrasonic Transducer BSS123 660KHZ 20 19 18 17 16 15 14 13 12 11 6.8K PW0268 MMBT3904 10K Echo High Level Pulse MCU 1 2 3 4 5 6 2200p 2.7K 7 8 10 4.7K 10n 680p 680p 470p 39K BAV99 13K 4.7K 470p Vref 9 Vref Vref 4 Pro-Wave Electronics Corp. Tel: 886-2-22465101 Fax: 886-2-22465105 E-mail: [email protected] URL: http://www.prowave.com.tw Application Note The circuit shown on page 4 is a typical circuit for car reversing aids. The RC Oscillator generates a tone burst when a low level pulse is applied to the I_O pin, (pin 1). To accommodate tolerance variations of transducers during manufacturing, a 1K-ohm variable resistor (R1) is provided to trim the output operating frequency. The range of adjustment is from 38.0 – 42.0 KHz. and allows for a better match of the drive signal to the resonate frequency of the transducer. The active burst number (number of pulses transmitted) is controlled by the pulse width of the low level signal applied to the I_O pin, (pin 1). The tone burst output, Driver_O (pin 11), drives the transducer through a MOSFET transistor and impedance matching transformer IFT. The inductance in the secondary winding of the transformer is designed to tune out the reactance of the parallel capacitance of the transducer. The high output voltage of the tone burst is snubbed by two diodes and the returning echo signal is passed on to the first stage pre-amplifier. The signal is then passed on to the second stage fix gain amplifier and finally to the third stage 32-step time controlled variable gain amplifier. The gain of the pre-amplifier should be properly set to meet the sensitivity needs of the transducer and application requirements. The center frequency of band-pass filter should be chosen to exactly match the frequency of the RC Oscillator and considerations for the width of pass-band filter should be made based on actual application requirements. If the amplified echo signal from the output of the band pass filter exceeds 0.35V + Vref, the comparator will output a low pulse to the I_O pin, (pin 1). The width of the low level pulse is proportional to the echo signal strength. The above description is summarized in the signal timing charts illustrated below. MCU output: H: 1ms/Div., V: 2.0V/Div. The RC oscillator will be enabled in the duration of input pulse. The maximum pulse width is 396/F and any time longer than this upper limit will be ignored. Driver_O (Pin 11): H: 1ms/Div., V: 2.0V/Div. The next input pulse will be ignored if the pulse repetition rate is shorter than 9900/F + pulse width. F: Frequency of system clock Transducer Oscillation: H: 1ms/Div., V: 50V/Div. HP_O (Pin 2): H: 1ms/Div., V: 2.0V/Div. Output at Pin 1 I_O: H: 1ms/Div., V: 5.0V/Div. 5 Pro-Wave Electronics Corp. Tel: 886-2-22465101 Fax: 886-2-22465105 E-mail: [email protected] URL: http://www.prowave.com.tw The resonate frequency of ultrasonic piezo transducers varies in an inversely proportional relationship to temperature. The lower the temperature, the higher the resonate frequency, the higher the temperature the lower the resonate frequency. This property of piezo transducers may cause a mismatch between transducer and drive signal with changes in ambient temperature and reduces efficiency of the system when the frequency of the drive circuit remains constant and does not track the resonate frequency shift of the transducer. Therefore it is desirable to have the output frequency of the drive source track the resonate frequency of the transducer with changes in ambient temperature. The Auto Frequency Tracking circuitry between Ftrace, (pin 12), and Drive_O, (pin 11) is used to accomplish this task. The voltage change at Ftrace (pin 11) varies in proportion to the forward bias voltage change across diodes D1, D2. This change is caused by the negative temperature coefficient of the diodes and the ratio of the resistor circuit R2/R3. A lower temperature increases the voltage drop across the diodes. This intern accelerates the charge rate of an internal integrator circuit controlling the R/C Oscillator, ORC3, (pin15). The net result is the adjustment to the R/C Oscillator increases the resonate frequency of the output, Drive_O, (pin11). Conversely, a higher temperature decreases the voltage drop across the diodes. This slows the charge rate of the internal integrator circuit controlling the R/C Oscillator. The net result of this adjustment is to decrease the resonate frequency of the output Drive_O, (pin 11). Choose values for the components R1, R2, R3 and C1 that will best track the characteristic resonate frequency shift curves due to temperature for a specific transducer. Recommended values for the following transducers are listed below. Used Transducer 400EP14D 400EP18A 235AC130 R1(Ohm) 3,300 3,300 2,000 R2(Ohm) 1,500 1,500 0 R3(Ohm) 511 604 2,100 C1(pF) 2,200 2,200 220 For a fixed output of 40KHz at Drive_O (pin 11) simply remove D1, D2 and R2 and set R1 = 4,500 Ohm, C1 = 2,200 pF, and R3 = 511 Ohm. The system clock CLK (pin 16) controls the maximum input pulse width, the slope of time controlled gain amplifier and pulse repetition rate. For example, as illustrated in the block diagram, if the system clock is set to 660KHz (C2: 22pF, R4: 47K Ohm), then: (1) The maximum input pulse width is 396/F = 396/660K = 0.6 ms and any duration longer than 0.6ms will be ignored. (2) The step duration of the 32 step time controlled gain amplifier is equal to 220/F = 0.333 ms, starting from the end of the pulse on the I_O pin, (pin 1). (3) The minimum pulse repetition rate is 9900/F + pulse width = 9900/F + 0.5 ms (20 bursts of 40KHz) = 9900/660K + 0.5 = 15.5 ms. For long distance measurements of 18 meters (one way distance), the system clock should be set as follows: Min. Pulse Repetition Rate = 9900/F + 0.75 = 166 mS Frequency of System Clock F = 60 KHz (30 bursts of 40KHz) For additional information about an 18-meter tape measure circuit, please consult with the factory. 6 Pro-Wave Electronics Corp. Tel: 886-2-22465101 Fax: 886-2-22465105 E-mail: [email protected] URL: http://www.prowave.com.tw Time Controlled Gain Amplifier 40 35 30 Gain (dB) 25 20 15 10 5 0 0 5 10 15 20 25 30 35 Steps The time controlled gain amplifier is stepping up once the input pulse falling. The time duration can be calculated as: T = 220/F F: Frequency of System Clock 7 Pro-Wave Electronics Corp. Tel: 886-2-22465101 Fax: 886-2-22465105 E-mail: [email protected] URL: http://www.prowave.com.tw Package and Dimensions: 20 Pins, SSOP (150mil) 8 Pro-Wave Electronics Corp. Tel: 886-2-22465101 Fax: 886-2-22465105 E-mail: [email protected] URL: http://www.prowave.com.tw 9 Pro-Wave Electronics Corp. Tel: 886-2-22465101 Fax: 886-2-22465105 E-mail: [email protected] URL: http://www.prowave.com.tw Symbol A A1 A2 b b1 c c1 D E E1 e L L1 L2 R R1 θ θ1 θ2 aaa bbb ccc ddd eee Min. 0.053 0.004 0.049 0.008 0.008 0.006 0.006 Nom. Max. 0.069 0.010 0.065 0.012 0.010 0.011 0.010 0.008 0.009 0.341 BSC 0.236 BSC 0.154 BSC 0.025 BAS 0.016 0.050 0.041 REF 0.010 BAS 0.003 0.003 0° 8° 5° 15° 0° 0.004 0.008 0.004 0.007 0.004 10 - Pro-Wave Electronics Corp. Tel: 886-2-22465101 Fax: 886-2-22465105 E-mail: [email protected] URL: http://www.prowave.com.tw Notes: 1. 2. 3. 4. 5. 6. 7. 8. 9. Dimensioning and tolerancing per ANSI Y14.5M-1982. Dimensions in inches (angles in degrees) Dimension D does not include mold flash, protrusions or gate burrs. Mold flash, protrusions or gate burrs shall not exceed 0.006” per end. Dimension E1 does not include interlead flash or protrusions. Interlead flash or protrusions shall not exceed “0.006” per side. D1 and E1 dimensions are determined at datum H. The package top may be smaller than the package bottom. Dimensions D and E1 are determined at the outermost extremes of the plastic body exclusive of mold flash, tie bar burrs, gate burrs and interlead flash, but including any mismatch between the top and bottom of the plastic. Datum A and B to be determined at datum H. N is the maximum number of terminal position. (N=20) The dimensions apply to the flat section of the lead between 0.004 to 0.010 inches from the lead tip. Dimension b does not include dambar protrusion. Allowable dambar protrusion shall be 0.004” total in excess of b dimension at maximum material condition. The dambar can not be located on the lower radius of the foot. Refer to JEDEC MO-137 variation AD. JEDEC is the registered trademark of JEDEC SOLID STATE TECHNOLOGY ASSOCIATION Copyright © 2004 Pro-Wave Electronics Corp. 9/15/2004 11 Sonar Ranging Module The SRM400 is a sonar ranging module utilizing our new developed Sonar Ranging IC, PW-0268, which can work with all our PT or EP type transducers. SRM400 provides as a shortcut to develop car reversing systems or some other distance measurement systems for design engineers who are not very familiar with analog circuit and/or the operation of ultrasonic transducers. By using this module engineers can focus firstly on the other fields of digital circuit and software designs as well as some other mechanical issues. After first stage then you can either design your own analog circuit based on the module construction or consult with factory for making your own module for your special needs. Features: z z z z z z z z Operating Voltage: 6 – 10Vdc single source Operating Frequency: broadband output ranging up to 250KHz Built-in variable RC oscillator matching transducers with different frequencies High Gain Amplifier: varies with time over 32 steps Integrated Band Pass Filter: reduces external component count, Bi-direction I/O Pin: simplifies the control function for transmitting a pulse and receiving an echo An adjustable System Clock: enables the control of, the number of pulses transmitted, the slope of the variable gain amplifier, and the pulse repetition rate Board size: 27.9 * 18 mm (L*W) SRM400 Specification: Operation voltage Operation current Oscillation frequency Amplifier gain Pre-Amplifier 2nd Stage Amplifier Time controlled 32 steps main amplifier Bandpass filter DC6 - 10V <20 mA ＠DC10V Variable RC oscillator 14 dB 30 dB 35 dB max. Fc: 38 KHz Bandwidth: 20KHz Insertion loss: 1 dB 130Vpp; pulse width 0.5ms Driving voltage (no load) Bi-directional I/O Input signal Open collector pull low Output 0..05*Vcc to 0.9*Vcc digital echo signals Measuring distance 25 – 150 cm SRM400 includes: 1. Module board 2. 400EP14D enclosed type transducer of asymmetrical beam patterns, see detail specification of 400EP14D. 3. Detail electrical schematic S. Square Enterprise Company Limited Pro-Wave Electronics Corporation P.O. Box 1-70 Chung Ho, Taiwan, ROC; E-mail: [email protected]; Tel: 886-2-22465101(5 lines), 22459774; Fax: 886-2-22465105 http://www.s2.com.tw ; http://www.prowave.com.tw Sonar Ranging Module SRM400 Electronic Circuit Diagram Vref Vcc BAV99 Vref Vcc Vreg Test "C" 3 100 2200p 1 220u 1K User Side 47K 100u Vcc 100u 22p 3 2 1 3 2 1 3 2 1 4 IFT 3.3K 1.5K 100u 400EP14D Vref 511 Vcc 20K 2 BSS123 Ultrasonic Transducer 660KHZ 20 19 17 18 16 14 15 13 12 11 Test "B" 6.8K PW0268 MMBT3904 10K 1 2 3 5 6 2200p 2.7K Echo High Level Pulse 7 8 9 10n 33K 680p 680p BAV99 13K Test "A" Test "E" 10 4.7K 10n Test "F" MCU 4 4.7K Test "D" 470p Vref Vref Vref Waveforms at different test points: works with transducer model 400EP14D against a hard target of size of 20cmL*20cmW*1cmT at distance of 50cm “B” Point: Tone bursts Signal “A” Point: Control Pulse (from MCU) H: 0.5ms/div V: 5V/div “C” Point: Transducer loading H: 0.5ms/div V: 50V/div “E” Point: Main 32 Steps TCG Amplifier H: 0.5ms/div V: 1V/div Refer to PW-0268 Sonar Ranging IC for detail information. H: 0.5ms/div V: 5V/div “D” Point: 1st Pre-Amplifier H: 0.5ms/div V: 20mV/div “F” Point: Digital Echo signal Output H: 0.5ms/div V: 5V/div Quartz Crystals & Matching Transformers Miniature Tuning Fork Quartz Crystals Specification Model Nominal Number Frequency Hz S40000 40,000 S32768 32,768 Tolerance at 25 C PPM ±60 ±20 Temperature Load Series Shunt Drive Stability –10 C to +70 C Capacitance Resistance Capacitance Level pF Ohm pF mW PPM 12.5 35,000 2.3 0.001 ±45 12.5 35,000 2.3 0.001 ±30 Matching Transformers 3 4 2 1 6 Specification Parts Number Operating Frequency Variable Inductance (min.) Unloaded Q (min.) Turn Ratio Matching Transducer K4000001 40.0 KHz 10.6 mH± 6% 70 1:10 400EP14D K4000002 40.0 KHz 10.6 mH± 6% 100 1:10 400EP14D (Temperature Compensated Type K4000003 40.0 KHz 10.6 mH± 6% 25 1:10 235SR130 K4000004 40.0 KHz 10.6 mH± 6% 47 1:10 400EP18A S. Square Enterprise Company Limited Pro-Wave Electronics Corporation P.O. Box 1-70 Chung Ho, Taiwan, ROC;E-mail: [email protected];Tel: 886-2-22465101(5 lines), 22459774;Fax: 886-2-22465105 http://www.s2.com.tw ; http://www.prowave.com.tw