H Low Current Bar Code Digitizer IC Technical Data HBCC-0500 Features • Compatible with HP Bar Code Sensors – HBCC-1570 - 0.013 in. 0.33 mm - HBCC-1580 - 0.007 in. 0.185 mm - HBCC-1590 - 0.005 in. 0.13 mm • Ambient Light Rejection > 100 K Lux • Accurate Digitizing of a Wide Range of Bar Code Labels Description The Hewlett-Packard Low Current Bar Code Digitizer IC allows designers to incorporate the high ambient light rejection and low power consumption features of the HBCS-AXXX/TXXX wands into their own bar code circuitry. The HBCC-0500 is packaged in a 24 pin SOIC plastic package. output of different sensor “bins” is equalized by varying the amplitude of the LED drive current. The sensor output has two components; DC due to ambient light, and AC from the bar code label. Photocurrent from the sensor is amplified and high pass filtered to remove the ambient light signal. The AC component is amplified and sent to an AM detector to recover the bar code information. The recovered bar code signal is low pass filtered to eliminate the 30 kHz carrier. The signal is input to a digitizer consisting of positive and negative Block Diagram SENSOR LED DRIVER Theory of Operation The digitizer IC uses the techniques in US Patent 4,682,015 to reduce power consumption and sensitivity to ambient light. Power is reduced by pulsing the LED every 33 microseconds with a 1 microsecond pulse. The 5964-1563E peak detectors and a comparator. The comparator threshold is generated from the peak detectors using a resistor ladder. This threshold, along with the current bar code signal, is input to a comparator. The output of the comparator drives an external output transistor. AM DETECTOR AMPLIFIER HIGH PASS FILTER LOW PASS FILTER DIGITIZER AMPLIFIER OUTPUT 4-33 Sensor Pinout Pinout RPER 1 24 LEDD RPWD 2 23 GND CTIM 3 22 LPFO VCC 4 21 LPFI AGND 5 20 IWSR EMIN 6 19 CMPO PREO 7 18 CTHR VCCA 8 17 CMPI PPKD 9 16 NPKD PRBP 10 15 PSTI PSTB 11 14 CMPA ACMP 12 13 AMDT HBCC-0500 Sensor Marking Sensors are marked with an eight digit code, the last digit being the “bin” number. The bin number is used to determine the bin resistor, Rb, using the Bin Table. 8 1 7 2 6 3 5 4 TOP VIEW Function LED Anode LED Cathode Detector Anode Detector Cathode Parts List Pin # 6 2 8 1 Pin Description Mnemonic RPER RPWD CTIM VCC AGND EMIN PREO VCCA PPKD PRBP PSTB ACMP AMDT CMPA PSTI NPKD CMPI CTHR CMPO IWSR LPFI LPFO GND LEDD Description Timer Period Timer Pulse Width Timer Capacitor Filtered Power Analog Ground Preamp Emitter Input Preamp Output Analog Power Positive Peak Detector Preamp Bias Point Postamp Bypass Compensation Cap AM Detector Compensation Cap Postamp Input Negative Peak Detector Comparator Input Comparator Threshold Comparator Output White State Return Current Low Pass Filter Input Low Pass Filter Output Ground LED Drive Bin Table Bin # 1 2 3 4 5 6 7 4-34 1570, 1580 Rb Ω 8.2 11 15 18 24 30 36 1590 Rb Ω 22 27 36 47 56 75 91 Quantity 1 1 1 1 1 1 2 1 2 2 1 2 1 1 1 2 1 1 1 1 1 2 1 1 4 3 1 Part Sensor HBCC-0500 1N4148 2N3904 2N4403 2N5088 39 Ω 9.1 kΩ 20 kΩ 56 kΩ 390 kΩ 470 kΩ 680 kΩ 1.3 MΩ 2.0 MΩ 6.8 MΩ Bin resistor Rb 12 pF 75 pF 330 pF 680 pF 1.0 nF 2.2 nF 8.2 nF 0.1 µF 0.22 µF 0.47 µF Optional Parts List Quantity 1 1 1 2 1 1 1 1 1 Part 1N4148 2N5088 2N3904 10 kΩ 220 kΩ 1.0 MΩ 2.0 MΩ 3.3 nF 1.0 µF 3. A 1.0 µF ceramic cap may be used in place of the 0.47 µF cap. 4. Place the 0.22 µF cap attached to pins 4 and 23 close to the IC. 5. Use a single point ground close to pin 23. Recommended Schematic Shown is the recommended schematic for the HBCC-0500. Here are some construction tips. 1. Place the sensor, 2N4403, bin resistor, and the 0.47 µF cap close to each other to minimize loop area. 2. If the 0.47 µF cap is tantalum, its ESR must be used in series with Rb to determine the correct value for Rb. Options There are four options on the recommended schematic. 1. Output pull up resistor 2. Inverted output 3. Black state return 4. Threshold adjust Pull Up Resistor The 10 kΩ pull up resistor on the standard or inverted output transistor is optional. If the transistor is driving a cable, the resistor should be on the far end of the cable. Schematic +5 V Rb Ω 2N4403 24 LEDD +5 V 39 Ω 39 Ω 0.47 µF 0.22 µF LED ANODE 6 LED CATHODE 2 8.2 nF DETECTOR CATHODE 1 8 DETECTOR ANODE SENSOR 680 KΩ 10 KΩ (OPTIONAL) OUTPUT CMPI 17 0.22 µF 23 GND LPFO 22 AMDT 13 15 7 6 2N5088 5 470 KΩ PSTI 21 PREO HBCC- LPFI 0500 EMIN CMPA 14 ACMP 12 AGND IWSR 20 1 RPER V A 8 CC 9.1 KΩ 6.8 MΩ 20 KΩ 56 KΩ 2.2 nF 330 pF NC 0.22 µF 16 CTHR NPKD 18 470 KΩ 390 KΩ 1N4148 INVERTED OUTPUT (OPTIONAL) 12 pF 0.1 µF 1 nF +5 V 10 KΩ (OPTIONAL) INVERTED OUTPUT 680 pF 56 KΩ 0.1 µF 0.1 µF 9 PPKD 2N3904 2.0 MΩ PRBP 10 PSTB 11 2 RPWD 75 pF 3 CTIM +5 V 20 KΩ CMPO 19 4 V CC 0.1 µF +5 V 3.3 nF 1.0 MΩ 220 KΩ 2N5088 2.0 MΩ 1.3 MΩ 1.0 pF 1N4148 1 nF BLACK STATE RETURN (OPTIONAL) 4-35 Inverted Output The standard output of the HBCC-0500 is high when the sensor is looking at black bars, and low when the sensor is looking at white spaces. If inverted output is needed, add the extra circuitry in the inverted output block. Make sure that the 10 kΩ pull up resistor on the normal output transistor is loaded. Black State Return The HBCC-0500 normally returns to the white state 100 milliseconds after the last transition. The extra circuitry forces the black state after a time out period set by the 1.0 µF cap. The normal time out period is about 1.5 seconds. If a longer time is needed, increase the values of the 1.0 µF and the 3.3 nF caps. The ratio of values should be no more than 300:1. its option, replace products that prove to be defective in material or workmanship under proper use during the warranty period. Threshold Adjustment NO OTHER WARRANTIES ARE EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. HEWLETT-PACKARD IS NOT LIABLE FOR CONSEQUENTIAL DAMAGES. The standard circuit uses a threshold designed for most bar codes. If the bar codes to be read consistently have narrow bars that are lighter than the wide bars, then the 470 kΩ and the 390 kΩ resistors attached to pin 18 should be swapped. Warranty and Service HP Digitizer ICs are warranted for a period of one year after purchase covering defects in material and workmanship. Hewlett-Packard will repair or, at Recommended Operating Conditions Parameter Scan Velocity Edge Contrast VCC Ambient Temperature Ambient Light Min. 7.6 (3) 40 4.5 -20 Max. 76 (30) 6.0 +65 100,000 Units cm/sec (in/sec) % V °C Lux Notes 1 2 3 Notes: 1. Narrow element width = 0.19 mm (0.0075 in.). 2. Contrast is defined as Rw - Rb, where Rw is the reflectance of the spaces in Rb is the reflectance of the bars, measured at the sensor wavelength (655 or 820 nm). 100% reflectance is barium sulfate. 3. Power supply ripple and noise should be less than 100 mV peak to peak. Electrical Characteristics Parameter Symbol Typical Supply Current, IC and Sensor ICC 2.7 High Level Output Current IOH Low Level Output Voltage VOL Output Rise Time tr 4.5 Output Fall Time tf 0.3 Wake Up Time tw 50 Max. 4.0 1.0 0.4 20 20 200 Units mA µA V µs µs ms Notes 4 4 5 Notes: 4. Rise and fall time will be dependent upon the capacitance of the cable. 5. Wake up time is defined as the time from initial power turn on until the circuit is digitizing bar codes within data sheet limits. 4-36 For additional warranty or service information, please contact your local Hewlett-Packard sales representative or authorized distributor.