WG1S

iC-WG 14-BIT DIFFERENTIAL SCANNING OPTO ENCODER FEATURES ♦ Excellent matching and reliability due to monolithic construction with integrated photodiodes ♦ Short track pitch (600µm) ♦ Elimination of dark currents due to differential scanning ♦ Photocurrent amplifier with high cut-off frequency ♦ Current comparators with acurately tracked hysteresis ♦ Current-limited push-pull outputs ♦ Adjustable LED current control for constant receive power ♦ Integrated power driver for the transmit LED ♦ LED current monitor with error message output ♦ Integrated test aid1 ♦ Low power consumption ♦ Broad operating voltage range, from 4.5V to 20V ♦ Available as 28-pin BLCC or as chip ♦ Options: extended temperature range of -30..110°C, customized packages, reticle assembly, code disc APPLICATIONS ♦ Optical position decoding with 14-bit resolution based on the principle of differential scanning CHIP 2.97mm × 8.71mm BLOCK DIAGRAM 4.5..20V C1 100nF VCC 14 1 VCC GND DR DSR (REF.) AMPLIFIER VCC R2 50Ω LED + - 8 LED LGND 9 VCC 1.2V 7 R1 50kΩ RSR RGND + VCC CSR 11 C2 100nF 5..25V R3 10kΩ ERROR CONTROL 6 LED-CURRENT CONTROL AMPLIFIER + + NERR 10 VCC P N MONITOR TRACK POSITION VCC AMPLIFIER COMPARATOR PUSH-PULL OUTPUT IMP IMN n.c. n.c. 28 3 2 A0 P N IP0 IN0 TRACK 0 P N (see TRACK 0) TRACK 1 VCC PUSH-PULL OUTPUT A1 IP1 IN1 27 5 4 AMPLIFIER COMPARATOR A2 26 P N TRACK 2 P N (see TRACK 2) A3 ..13 25..15 TRACK 3..13 VCC AMPLIFIER 12 TIP 13 TIN iC-WG TEST BIAS 1.2V IM1 n.c. BLCC WGC2 MONITOR ©1999 iC-Haus GmbH Integrated Circuits Am Kuemmerling 18, D-55294 Bodenheim Rev B0 Tel +49-6135-9292-0 Fax +49-6135-9292-192 http://www.ichaus.com iC-WG 14-BIT DIFFERENTIAL SCANNING OPTO ENCODER Rev B0, Page 2/11 DESCRIPTION The iC-WG is an optoelectronic detector IC for linear and angle measuring systems, e.g. glass scales or rotary encoders. Monolithically integrated are photodiodes, amplifiers and comparators as well as TTL-compatible push-pull output drivers. All 14 tracks are differentially evaluated. An integrated LED current control with driver stage makes it possible to directly connect a transmit LED with series resistor and also guarantees a constant optical received power. The setpoint for the receive current is adjusted via an external resistor. If the LED current control deviates from its working range, this is indicated at the error message output. For the adjustment of a reticle the chip features two adjustment crosses and supplies the analog signals from three monitor photocurrent amplifiers. For exact radial alignment of the iC-WG (with reticle) to the code disk, two monitor photodiodes are arranged such that the track position can be checked (option, not available in the standard SMD package). Two test pins permit a complete electrical functional test of the IC not including the photodiodes. All push-pull and analog outputs are protected against ESD and short-circuits. The error message output NERR is also short-circuit-proof and due to it’s open-collector design bus capable. PAD DESCRIPTION Name GND IN0 IP0 IN1 IP1 RGND RSR LED LGND NERR CSR TIP TIN VCC A13 A12 .. A0 Function Ground Track N0 Analog Output (current sink) Track P0 Analog Output (current sink) Track N1 Analog Output (current sink) Track P1 Analog Output (current sink) Reference Ground for RSR circuitry LED Current Control Setup LED Driver Output LED Driver Power Ground Error Message Output, low active External capacitor for LED control Positive Test Aid Input Negative Test Aid Input +5 to +20V Supply Voltage Track 13 Push-Pull Output " " Track 0 Push-Pull Output iC-WG 14-BIT DIFFERENTIAL SCANNING OPTO ENCODER Rev B0, Page 3/11 CHIP LAYOUT dimensions in µm; chip size 2.97mm × 8.71mm iC-WG 14-BIT DIFFERENTIAL SCANNING OPTO ENCODER Rev B0, Page 4/11 ABSOLUTE MAXIMUM RATINGS Values beyond which damage may occur; device operation is not guaranteed. Item Symbol Parameter Conditions Fig. Min. G001 VCC G301 V(A) G302 I(A) G501 I(IM1) G601 I(TIP) I(TIN) G701 I(RSR) G702 I(RGND) G703 I(LED) G704 I(LED -LGND) G705 I(LGND) G706 V(CSR) G707 I(CSR) G802 I(IPi) I(INi) G902 I(IMP) I(IMN) Supply Voltage Voltage at Outputs A0..13 Current in Outputs A0..13 Current in Monitor Output IM1 Current in TIP, TIN Current in RSR Current in RGND Current in LED Current in LED to LGND Current in LGND Voltage at CSR Current in CSR Current in Analog Outputs IP0, IN0, IP1, IN1 Current in Monitor Outputs IMP, IMN LGND at GND MIL-STD 883, Method 3015, HBM, 100pF discharged through 1.5kΩ -30 see package specification LED and NERR open V(LED)> VCC V(A)< 0V or V(A)> VCC 0 0 -3 -1 -1 -1 -5 0 0 -3 0 -1 -1 -1 0 Max. 21 VCC 3 1 1 0.1 5 3 150 3 VCC 1 3 1 30 2 125 mA mA mA V kV °C mA mA mA mA mA mA mA mA V Unit GA01 V(NERR) Voltage at NERR E001 Vd() TG1 Tj TG2 Ts ESD Susceptibility at all Pins Junction Temperature Storage Temperature THERMAL DATA Operating Conditions: VCC= 4.5..20V Item Symbol Parameter Conditions Fig. Min. T1 Ta Operating Ambient Temperature Range see package specification Typ. Max. Unit All voltages are referenced to ground unless otherwise noted. All currents into the device pins are positive; all currents out of the device pins are negative. iC-WG 14-BIT DIFFERENTIAL SCANNING OPTO ENCODER Rev B0, Page 5/11 ELECTRICAL CHARACTERISTICS Operating Conditions: VCC= 4.5..20V, Tj= -20..125°C, unless otherwise noted Item Symbol Parameter Conditions Tj °C Total Device 001 VCC 002 I(VCC) Permissible Supply Voltage Supply Current in VCC, Outputs A0..13 hi LED control active: R(RSR/RGND)= 140kΩ, NERR=hi I(LED)≈ 8mA, I(A0..13)= 0; I(DP0..13)=30nA, I(DN0..13)=3nA, VCC= 5V see above, VCC= 20V -20 27 85 125 003 I(VCC) Supply Current in VCC, Outputs A0..13 lo LED control active: R(RSR/RGND)= 14kΩ, NERR=hi I(LED)≈ 80mA, I(A0..13)= 0; I(DP0..13)=3nA, I(DN0..13)=30nA, VCC= 5V see above, VCC= 20V -20 27 85 125 004 fo Cut-off Frequency, tracks 0..13 Switch Delay Cut-off Frequency, tracks 0..13 Switch Delay sinusoidal waveform, I(DP0..13)= 3..30nA I(DN0..13)= 30..3nA see No. 004 sinusoidal waveform, I(DP0..13)= 6..60nA I(DN0..13)= 60..6nA see No. 006 λ= 850nm Se(λar)= 0.1×S(λ)max 500 0.2 × 0.3 90 -20 27 85 125 0.85 V(IPi,INi)= 1V..VCC, I(DPi,DNi)= 3..90nA VCC= 5V, V(IPi,INi)= 2V, I(DPi,DNi)= 30nA Tj< 90°C V(IPi,INi)= 1V..VCC, I(DPi,DNi)= 0 27 600 4.7 3.6 3.2 15.5 1 20 15 15 25 1.15 900 200 100 6.0 -20 27 85 125 6.8 14.6 16.3 17.0 17.4 11.7 12.8 13.6 13.8 38.5 -20 27 85 125 3.3 6.4 6.7 7.0 7.4 25.5 4.5 3.0 5.4 5.9 6.2 6.2 14.6 20 10.7 V mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA kHz Fig. Min. Typ. Max. Unit 005 tp(D-A) 006 fo 2.5 µs kHz 007 tp(D-A) 008 S(λ)max 009 λar 1.5 µs Photodiodes DP0..13, DN0..13, DSR, DMP, DMN, DM1 Spectral Sensitivity Range of Spectral Sensitivity 0.5 1050 A/W nm Photodiodes and Amplifiers with Analog Outputs, track 0 and 1 801 Aph(D) 802 I(D) 803 Ierr Radiant Sensitive Area Permissible Photocurrent Error Current at Photodiodes mm² nA nA nA nA nA 804 CM() 805 CR() Common Mode DPi to DNi Current Gain I(IPi) / I(DPi), I(INi) / I(DNi) Current Gain I(IPi) / I(DPi), I(INi) / I(DNi) Temperature Coefficient of Current Gain CR Analog Output Leakage Current 806 CR() 740 807 TC(CR) 808 I0(IPi) I0(INi) -0.03 10 %/K µA iC-WG 14-BIT DIFFERENTIAL SCANNING OPTO ENCODER Rev B0, Page 6/11 ELECTRICAL CHARACTERISTICS Operating Conditions: VCC= 4.5..20V, Tj= -20..125°C, unless otherwise noted Item Symbol Parameter Conditions Tj °C Photodiodes and Amplifiers with Analog Outputs, track 0 and 1 (continued) 809 fo(IPi) fo(INi) 810 fo(IPi) fo(INi) 811 fo(IPi) fo(INi) Analog Output Cut-off Frequency R(VCC/IPi, VCC/INi)= 50kΩ, CL(IPi,INi)= 30pF Analog Output Cut-off Frequency V(IPi,INi)= constant, sinussoidal waveform, I(DPi)= 3..30nA, I(DNi)= 30..3nA Analog Output Cut-off Frequency V(IPi,INi)= constant, sinussoidal waveform, I(DPi)= 6..60nA, I(DNi)= 60..6nA 50 100 80 kHz kHz Fig. Min. Typ. Max. Unit 200 kHz Photodiodes and Amplifiers, tracks 2 to 13 101 Aph(D) 102 I(D) 103 Ierr Radiant Sensitive Area Permissible Photocurrent Error Current at Photodiodes -20 27 85 125 0.85 4.7 3.6 3.2 15.5 1 0.2 × 0.3 90 20 15 15 25 1.15 mm² nA nA nA nA nA 104 CM() Common Mode DPi to DNi Difference Comparators, tracks 0..13 201 Hys Hysteresis refered to [I(DPi) + I(DNi)] /2 I(DPi, DNi)= 3..30nA 8 11 14 % Push-Pull Outputs A0..13 301 Vs()hi Saturation Voltage hi Vs()hi= VCC -V(); I()= -40µA -20 27 85 125 Vs()hi= VCC -V(); I()= -400µA -20 27 85 125 302 Vs()lo Saturation Voltage lo I()= 1.6mA -20 27 85 125 303 Isc()hi 304 Isc()lo 305 SRhi 306 SRlo 307 Vc()hi 308 Vc()lo Short-Circuit Current hi Short-Circuit Current lo Slew-Rate hi Slew-Rate lo Clamp Voltage hi Clamp Voltage lo V()= 0V..VCC-1V V()= 0.4V..VCC CL()= 30pF 27 CL()= 30pF 27 Vc()hi= V() -VCC; I()= 3mA I()= -3mA 0.4 -1.5 50 115 1.5 -0.4 -7 1.8 24 61 330 0.21 0.22 0.25 0.27 -4.6 7.3 -1.5 13 130 0.9 0.83 0.74 0.68 0.4 0.79 0.69 0.58 0.51 1.0 0.9 V V V V V V V V V V V V V V V mA mA V/µs V/µs V/µs V/µs V V iC-WG 14-BIT DIFFERENTIAL SCANNING OPTO ENCODER Rev B0, Page 7/11 ELECTRICAL CHARACTERISTICS Operating Conditions: VCC= 4.5..20V, Tj= -20..125°C, unless otherwise noted Item Symbol Parameter Conditions Tj °C Test Aid TIP, TIN 601 CR(TIP), Current Ratio CR(TIN) I(TIP) / I(DPi,DMP,DR), I(TIN) / I(DNi,DMN,DSR), I(TIP) / I(DM1) 602 It() 603 V(TIP), V(TIN) Pull-Down Current at TIP, TIN; Test Aid Turn-on Threshold Voltage at TIP, TIN test aid active, I(TIP,TIN)= 2..200µA 400 1100 1600 Fig. Min. Typ. Max. Unit V(TIP,TIN)= 0.5V test aid active; I(TIP)= 2..200µA and I(TIN)= 100µA, or I(TIP)= 100µA and I(TIN)= 2..200µA 2 1.9 14 2.4 100 2.7 µA V LED Current Control and Reference Photodiode DSR 701 Aph (DSR) 702 I(DSR) 703 I(LED) 704 Vs(LED /LGND) Radiant Sensitive Area Permissible Photocurrent in DSR Permissible Current in LED Saturation Voltage at LED vs. LGND I(LED)= 80mA, I(RSR)> 10µA, V(CSR)= VCC, V(LGND)= 0..1V -20 27 85 125 1.0 5.3 340 -20 27 85 125 220 -20 27 85 125 708 CG() Current Gain I(LED) / I(RSR) control loop open, LGND at GND, V(LED)> 1.5V, V(CSR)= VCC V(LGND)= 0..2V 15000 0.6 1.0 1.6 kΩ 370 350 345 340 450 430 420 415 540 0 0 0.84 0.76 0.67 0.60 1.22 10 1.5 13 660 0.15 × 0.665 200 80 1.2 mm² nA mA V V V V V V 705 V(RSR) 706 CR() 707 CR() Voltage at RSR Current Ratio I(RSR) / I(CSR) Current Ratio I(RSR) / I(DSR) R(RSR/RGND)= 10..150kΩ R(RSR)= 10..150kΩ, V(CSR)= 0V closed LED Control, I(DSR)= 20..200nA; VCC= 5V see above, VCC= 20V 709 R(LGND) Resistance at LGND Control Monitor NERR A01 Vs()lo A02 Isc()lo A03 I0() Saturation Voltage lo Short-Circuit Current lo Collector Off-State Current LGND at GND, I(NERR)= 3.2mA V(NERR)= VCC NERR= off, V(NERR)= 25V 0.27 15 0.4 27 10 V mA µA iC-WG 14-BIT DIFFERENTIAL SCANNING OPTO ENCODER Rev B0, Page 8/11 ELECTRICAL CHARACTERISTICS Operating Conditions: VCC= 4.5..20V, Tj= -20..125°C, unless otherwise noted Item Symbol Parameter Conditions Tj °C Monitor Photodiode DM1 with Amplifier (not available in standard BLCC package) Fig. Min. Typ. Max. Unit 501 Aph (DM1) 502 Ierr Radiant Sensitive Area Error Current at Photodiode DM1 -20 27 85 125 I(DM1)= 2..20nA, V(IM1)= 0..VCC-1V; VCC= 5V VCC= 20V sinusoidal waveform, I(DM1)= 2..20nA 0.1 × 0.1 1 1 1 3.5 5 5 5 10 mm² nA nA nA nA 503 CR() Current Gain I(IM1) / I(DM1) 3000 4000 100 5500 8900 10000 24000 Hz 504 fo Cut-off Frequency Track Position Monitor, Photodiodes DMP und DMN (not available in standard BLCC package) 901 Aph (DMP, DMN) 902 Ierr Radiant Sensitive Area 0.125 × 0.530 mm² Error Current at Photodiodes DMP, DMN -20 27 85 125 I(DMP,DMN)= 2..20nA, V(IMP,IMN)= 0..VCC-1V; VCC= 5V VCC= 20V sinusoidal waveform, I(DMP,DMN)= 2..20nA 3 3 3 15 20 15 15 25 nA nA nA nA 903 CR() Current Gain I(IMP) / I(DMP), I(IMN) / I(DMN) Cut-off Frequency 3000 4000 100 5500 8900 10000 24000 Hz 904 fo iC-WG 14-BIT DIFFERENTIAL SCANNING OPTO ENCODER Rev B0, Page 9/11 DESCRIPTION OF FUNCTIONS LED Current Control The integrated LED current control with driver stage keeps the photocurrent of the reference photodiode DSR constant. Compensation is made for aging and dirt as well as for the decline in the efficiency of the transmit LED as the temperature rises. Figure 1: LED current control and control monitor The photocurrent in the reference photodiode DSR is amplified by the differential amplifier of the LED current control and output to the comparison point pin CSR via a current sink. Simultaneously the resistor R1 at pin RSR - the voltage at pin RSR is kept at a constant approx. 1.22V - supplies a reference current for the current source from VCC which also works on the comparison point, pin CSR. To compensate for the dark current of the reference diode and the amplifier input currents, the comparison point also receives the amplified current of compensation diode DR. If there is an optical feedback from the LED to the reference photodiode DSR, a voltage develops at pin CSR which is just high enough to satisfy the needs of the power driver for the required transmit current at pin LED. In this case the current ratio between I(RSR) and reference photodiode current I(DSR) is constant (electrical characteristics No.707). The current through resistor R1 is the setpoint for the control and presets the desired illuminance directly. The capacitor at pin CSR ensures the stability of the control. The value selected for it should be higher than 10nF; lower values for R1 require larger values for CSR, which also improve the power supply rejection for the control. A resistor in series with the transmit LED limits the current in the LED pin and establishes the operating limits of the control. The optical feedback between LED and reference photodiode should be so good that an LED current of less than 15mA develops at room temperature. Only then the power driver does have enough current reserve to also correct the declining efficiency of the LED for high temperatures too. If higher LED currents are required, the base of an external transistor can be connected to LGND to form a three-fold Darlington stage (increases the saturation voltage at error message output NERR). iC-WG 14-BIT DIFFERENTIAL SCANNING OPTO ENCODER Rev B0, Page 10/11 Control Monitor and Error Message Output The error message output NERR is used to signal a possible incorrect scanning due to illuminances which are too low or too high. The control monitor observes the potential at the CSR pin. Voltages which bring the power driver to saturation or off-state are recognized and indicated at the open collector output by NERR= low. If the series resistor for the LED limits the transmit current, this is indicated at NERR. Due to the principle of differential formation, however, the scanning is still guaranteed until the minimum brightness preset by the hysteresis of the comparators is achieved. As the illuminance declines, the cut-off frequency will initially drop without a faulty scanning developing in a static case (e.g. when code disk comes to standstill). Recognizing such faulty scanning necessitates an additional evaluating logic which constantly checks the code (check for unit-distance code in case of Gray code, parity check, etc.). APPLICATIONS INFORMATION Using the test aid The threshold current defined in electrical characteristic No.602 must be exceeded at both pins TIP and TIN simultaneously to activate the iC-WG’s built-in test aid. Once it has been activated, the test aid does not switch back to off-state until the current drops below approx. 1µA. A clamp circuit as shown in Figure 2 also prevents falling below the test aid turn-on threshold for a short time. The output polarity of the iC-WG is to be changed over with the switch. Figure 2: Wiring the test aid iC-WG 14-BIT DIFFERENTIAL SCANNING OPTO ENCODER Rev B0, Page 11/11 Track position monitor (not available in the standard BLCC28 package) If the code disk bears separate P/N tracks, the monitor diodes DMP and DMN can be used for radial alignment of chip with reticle. The reticle opening via DMP and DMN must be a whole-number multiple of the slot width for track 1. When the track position is correct, the analog outputs then exhibit signals equal in size and without AC components. Figure 3: Position monitoring with photodiodes DMP, DMN ORDERING INFORMATION Type Package Order designation iC-WG Chip iC-WG BLCC WGC2 iC-WG BLCC WGC2 +WG1R WG1S iC-WG iC-WG BLCC WGC2 iC-WG with reticle WG1R BLCC WGC2 WG1S Code Disc (13-bit Gray) For information about prices, terms of delivery, options for other case types, etc., please contact: iC-Haus GmbH Am Kuemmerling 18 D-55294 Bodenheim GERMANY Tel +49-6135-9292-0 Fax +49-6135-9292-192 http://www.ichaus.com This specification is for a newly developed product. iC-Haus therefore reserves the right to modify data without further notice. Please contact us to ascertain the current data. The data specified is intended solely for the purpose of product description and is not to be deemed guaranteed in a legal sense. Any claims for damage against us - regardless of the legal basis - are excluded unless we are guilty of premeditation or gross negligence. We do not assume any guarantee that the specified circuits or procedures are free of copyrights of third parties. Copying - even as an excerpt - is only permitted with the approval of the publisher and precise reference to source.