CS209A Proximity Detector The CS209A is a bipolar monolithic integrated circuit for use in metal detection/proximity sensing applications. The IC (see Figure 1) contains two on–chip current regulators, oscillator and low–level feedback circuitry, peak detection/demodulation circuit, a comparator and two complementary output stages. The oscillator, along with an external LC network, provides controlled oscillations where amplitude is highly dependent on the Q of the LC tank. During low Q conditions, a variable low–level feedback circuit provides drive to maintain oscillation. The peak demodulator senses the negative portion of the oscillator envelope and provides a demodulated waveform as input to the comparator. The comparator sets the states of the complementary outputs by comparing the input from the demodulator to an internal reference. External loads are required for the output pins. A transient suppression circuit is included to absorb negative transients at the tank circuit terminal. http://onsemi.com 8 DIP–8 N SUFFIX CASE 626 CS209A AWL YYWW 8 1 8 1 SO–8 D SUFFIX CASE 751 8 1 Features • Separate Current Regulator for Oscillator • Negative Transient Suppression • Variable Low–Level Feedback • Improved Performance Over Temperature • 6.0 mA Supply Current Consumption at VCC = 12 V • Output Current Sink Capability – 20 mA at 4.0 VCC – 100 mA at 24 VCC MARKING DIAGRAMS 209A ALYWX 1 14 SO–14 D SUFFIX CASE 751A 14 1 CS209A AWLYWW 1 A WL, L YY, Y WW, W = Assembly Location = Wafer Lot = Year = Work Week ORDERING INFORMATION Device Semiconductor Components Industries, LLC, 2001 April, 2001 – Rev. 2 1 Package Shipping CS209AYN8 DIP–8 50 Units/Rail CS209AYD8 SO–8 95 Units/Rail CS209AYDR8 SO–8 2500 Tape & Reel CS209AYD14 SO–14 55 Units/Rail CS209AYDR14 SO–14 2500 Tape & Reel Publication Order Number: CS209A/D CS209A PIN CONNECTIONS DIP–8 and SO–8 OSC 1 8 SO–14 1 TANK VCC GND OUT1 DEMOD OUT2 ∆VBE/R Current Regulator OSC TANK GND OUT1 NC OUT2 NC RF 14 NC RF VCC NC DEMOD NC NC VBE/R Current Regulator 300 µA VCC Oscillator OSC 4.8 kΩ 23.6 kΩ OSC Feedback OUT1 RF VCC Neg Transient Suppression OUT2 + COMP – DEMOD TANK GND DEMOD Figure 1. Block Diagram ABSOLUTE MAXIMUM RATINGS* Rating Value Unit Supply Voltage 24 V Power Dissipation (TA = 125°C) 200 mW Storage Temperature Range –55 to +165 °C Junction Temperature Range –40 to +150 °C 2.0 kV 260 peak 230 peak °C °C Electrostatic Discharge (except TANK pin) Lead Temperature Soldering: Wave Solder (through hole styles only) (Note 1.) Reflow (SMD style only) (Note 2.) 1. 10 second maximum. 2. 60 second maximum above 183°C. *The maximum package power dissipation must be observed. http://onsemi.com 2 CS209A ELECTRICAL CHARACTERISTICS: (–40°C ≤ TA ≤ +125°C, unless otherwise specified.) Characteristic Test Conditions Min Typ Max Unit Supply Current ICC VCC = 4.0 V VCC = 12 V VCC = 24 V – – – 3.5 6.0 11.0 6.0 11.6 20 mA mA mA TANK Current VCC = 20 V –550 –300 –100 µA Demodulator Charge Current VCC = 20 V –60 –30 –10 µA Output Leakage Current VCC = 24 V – 0.01 10 µA Output VSAT VCC = 4.0 V, IS = 20 mA VCC = 24 V, IS = 100 mA – – 60 200 200 500 mV mV Oscillator Bias VCC = 20 V 1.1 1.9 2.5 V Feedback Bias VCC = 20 V 1.1 1.9 2.5 V OSC – RF Bias VCC = 20 V –250 100 550 mV Protect Voltage ITANK = –10 mA –10 –8.9 –7.0 V Detect Threshold – 720 1440 1950 mV Release Threshold – 550 1200 1700 mV PACKAGE PIN DESCRIPTION PACKAGE PIN # DIP–8 & SO–8 SO–14 PIN SYMBOL FUNCTION 1 1 OSC Adjustable feedback resistor connected between OSC and RF sets detection range. 2 2 TANK Connects to parallel tank circuit. 3 3 GND Ground connection. 4 4 OUT1 Complementary open collector output; when OUT1 = LOW, metal is present. 5 6 OUT2 Complementary open collector output; when OUT2 = HIGH, metal is present. 6 10 DEMOD 7 12 VCC Supply voltage. 8 13 RF Adjustable feedback resistor connected between OSC and RF set detection range. – 5, 7, 8, 9, 11, 14 NC No connection. Input to comparator controlling OUT1 and OUT2. http://onsemi.com 3 CS209A TYPICAL PERFORMANCE CHARACTERISTICS 6.5 8 (VCC = 12 V, RLOAD = 1.0 kΩ) Switching Delay (µs) Switching Delay (µs) (T = 25°C, VCC = 12 V) 6 4 5.5 4.5 3.5 0.1 kΩ 2 2.5 0 4 8 12 16 20 –40 –20 0 20 40 60 80 100 Output Load (kΩ) Temperature (°C) Figure 2. Output Switching Delay vs. Output Load Figure 3. Output Switching Delay vs. Temperature Object Detected (T = 25°C, VCC = 12 V) 120 DEMOD (V) 1.75 1.5 Object Not Detected, L Unloaded 1.25 2.5 kΩ 5.0 kΩ 7.5 kΩ 12.5 kΩ 15 kΩ 17.5 kΩ 1.0 0.75 0 0.100 0.200 0.300 0.400 Distance To Object (in.) Figure 4. Demodulator Voltage vs. Distance for Different RF PRINCIPLE OF OPERATION The detection is performed as follows: A capacitor connected to DEMOD is charged via an internal 30 µA current source. This current, however, is diverted away from the capacitor in proportion to the negative bias generated by the tank at TANK. Charge is therefore removed from the capacitor tied to DEMOD on every negative half cycle of the resonant voltage. (See Figure 6) The voltage on the capacitor at DEMOD, a DC voltage with ripple, is then directly compared to an internal 1.44 V reference. When the internal comparator trips it turns on a transistor which places a 23.6 kΩ resistor in parallel to the 4.8 kΩ. The resulting reference then becomes approximately 1.2 V. This hysteresis is necessary for preventing false triggering. The CS209A is a metal detector circuit which operates on the principle of detecting a reduction in Q of an inductor when it is brought into close proximity of metal. The CS209A contains an oscillator set up by an external parallel resonant tank and a feedback resistor connected between OSC and RF. (See Figure 5.) The impedance of a parallel resonant tank is highest when the frequency of the source driving it is equal to the tank’s resonant frequency. In the CS209A the internal oscillator operates close to the resonant frequency of the tank circuit selected. As a metal object is brought close to the inductor, the amplitude of the voltage across the tank gradually begins to drop. When the envelope of the oscillation reaches a certain level, the IC causes the output stages to switch states. http://onsemi.com 4 CS209A VCC RL 1.0 kΩ OSC RL 1.0 kΩ 20 kΩ CS209A OUT1 RF OUT2 TANK GND DEMOD CDEMOD 2200 pF 4300 pF NORMALLY HI NORMALLY LO L: Core: Siemens B65531–D–R–33 52 Turns, 6 × 44 AWG, Litz Unserved Single Polyurethane L Figure 5. Test and Application Diagram VOUT1 VTANK VDEMOD VDEMOD Figure 6. Capacitor Ripple Figure 7. Output Pulse for an 8 Tooth Gear circuit is required to detect, assuming of course the Q of the tank is high enough to allow the object to be within the IC’s detection range. Then adjust the potentiometer to obtain a lower resistance while observing one of the CS209A outputs return to its normal state. (See Figure 5.) Readjust the potentiometer slowly toward a higher resistance until the outputs have switched to their tripped condition. Remove the metal and confirm that the outputs switch back to their normal state. Typically the maximum distance range the circuit is capable of detecting is around 0.3 inch. The higher the Q, the higher the detection distance. The feedback potentiometer connected between OSC and RF is adjusted to achieve a certain detection distance range. The larger the resistance the greater the trip–point distance. (See Figure 4.) Note that this is a plot representative of one particular set–up since detection distance is dependent on the Q of the tank. Note also from the graph that the capacitor voltage corresponding to the greatest detection distance has a higher residual voltage when the metal object is well outside the trip point. Higher values of feedback resistance for the same inductor Q will therefore eventually result in a latched–ON condition because the residual voltage will be higher than the comparator’s thresholds. As an example of how to set the detection range, place the metal object at the maximum distance from the inductor the http://onsemi.com 5 CS209A Commonly Encountered Metals For this application it is recommended to use a core which concentrates the magnetic field in only one direction. This is accomplished very well with a pot core half. The next step is to select a core material with low loss factor (inverse of Q). The loss factor can be represented by a resistance in series with the inductor which arises from core losses and is a function of frequency. The final step in obtaining a high Q inductor is the selection of wire size. The higher the frequency the faster the decrease in current density towards the center of the wire. Thus most of the current flow is concentrated on the surface of the wire resulting in a high AC resistance. LITZ wire is recommended for this application. Considering the many factors involved, it is also recommended to operate at a resonant frequency between 200 and 700 kHz. The formula commonly used to determine the Q for parallel resonant circuits is: QP Stainless Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . Carbon Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Copper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aluminum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Brass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.101″ 0.125″ 0.044″ 0.053″ 0.052″ Coins US Quarter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Canadian Quarter . . . . . . . . . . . . . . . . . . . . . . . . . . 1 German Mark . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Pound Sterling . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 Japanese Yen . . . . . . . . . . . . . . . . . . . . . . . . . . 100 Italian Lira . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.055″ 0.113″ 0.090″ 0.080″ 0.093″ 0.133″ Other 12 oz. soda can . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.087″ R 2fRL Note that the above is only a comparison among different metals and no attempt was made to achieve the greatest detection distance. A different type of application involves, for example, detecting the teeth of a rotating gear. For these applications the capacitor on DEMOD should not be selected too small (not below 1000 pF) where the ripple becomes too large and not too large (not greater than 0.01 µF) that the response time is too slow. Figure 6 for example shows the capacitor ripple only and Figure 7 shows the entire capacitor voltage and the output pulses for an 8–tooth gear rotating at about 2400 rpm using a 2200 pF capacitor on the DEMOD pin. Because the output stages go into hard saturation, a time interval is required to remove the stored base charge resulting in both outputs being low for approximately 3.0 µs. (See Figure 3.) where R is the effective resistance of the tank. The resistance component of the inductor consists primarily of core losses and “skin effect” or AC resistance. The resonant capacitor should be selected to resonate with the inductor within the frequency range recommended in order to yield the highest Q. The capacitor type should be selected to have low ESR: multilayer ceramic for example. Detection distances vary for different metals. Following are different detection distances for some selected metals and metal objects relative to one particular circuit set–up: http://onsemi.com 6 CS209A PACKAGE DIMENSIONS DIP–8 N SUFFIX CASE 626–05 ISSUE L 8 NOTES: 1. DIMENSION L TO CENTER OF LEAD WHEN FORMED PARALLEL. 2. PACKAGE CONTOUR OPTIONAL (ROUND OR SQUARE CORNERS). 3. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 5 –B– 1 4 DIM A B C D F G H J K L M N F –A– NOTE 2 L C J –T– MILLIMETERS MIN MAX 9.40 10.16 6.10 6.60 3.94 4.45 0.38 0.51 1.02 1.78 2.54 BSC 0.76 1.27 0.20 0.30 2.92 3.43 7.62 BSC --10 0.76 1.01 INCHES MIN MAX 0.370 0.400 0.240 0.260 0.155 0.175 0.015 0.020 0.040 0.070 0.100 BSC 0.030 0.050 0.008 0.012 0.115 0.135 0.300 BSC --10 0.030 0.040 N SEATING PLANE D M K G H 0.13 (0.005) M T A M B M SO–8 D SUFFIX CASE 751–07 ISSUE W –X– NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSION A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE. 5. DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D DIMENSION AT MAXIMUM MATERIAL CONDITION. A 8 5 0.25 (0.010) S B 1 M Y M 4 K –Y– G C N X 45 SEATING PLANE –Z– 0.10 (0.004) H M D 0.25 (0.010) M Z Y S X S http://onsemi.com 7 J DIM A B C D G H J K M N S MILLIMETERS MIN MAX 4.80 5.00 3.80 4.00 1.35 1.75 0.33 0.51 1.27 BSC 0.10 0.25 0.19 0.25 0.40 1.27 0 8 0.25 0.50 5.80 6.20 INCHES MIN MAX 0.189 0.197 0.150 0.157 0.053 0.069 0.013 0.020 0.050 BSC 0.004 0.010 0.007 0.010 0.016 0.050 0 8 0.010 0.020 0.228 0.244 CS209A SO–14 D SUFFIX CASE 751A–03 ISSUE F NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSIONS A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE. 5. DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D DIMENSION AT MAXIMUM MATERIAL CONDITION. –A– 14 8 –B– 1 P 7 PL 0.25 (0.010) 7 G M B M F R X 45 C –T– SEATING PLANE D 14 PL 0.25 (0.010) M J M K T B S A S DIM A B C D F G J K M P R MILLIMETERS MIN MAX 8.55 8.75 3.80 4.00 1.35 1.75 0.35 0.49 0.40 1.25 1.27 BSC 0.19 0.25 0.10 0.25 0 7 5.80 6.20 0.25 0.50 INCHES MIN MAX 0.337 0.344 0.150 0.157 0.054 0.068 0.014 0.019 0.016 0.049 0.050 BSC 0.008 0.009 0.004 0.009 0 7 0.228 0.244 0.010 0.019 PACKAGE THERMAL DATA Parameter DIP–8 SO–8 SO–14 Unit RΘJC Typical 52 45 30 °C/W RΘJA Typical 100 165 125 °C/W ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. 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