iC-WG 14-BIT DIFFERENTIAL SCANNING OPTO ENCODER FEATURES APPLICATIONS ♦ 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 ♦ 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 R2 50Ω VCC 14 VCC 1 GND DR + - DSR (REF.) LED 8 LED LGND 9 AMPLIFIER VCC 1.2V R1 50kΩ 7 RSR 6 RGND CSR + - 5..25V VCC LED-CURRENT CONTROL AMPLIFIER P C2 100nF 11 CONTROL + NERR 10 R3 10kΩ ERROR + VCC N MONITOR IMP n.c. IMN n.c. A0 28 IP0 3 IN0 2 A1 IP1 IN1 27 5 4 A2 26 A3 ..13 25..15 IM1 n.c. TRACK POSITION VCC COMPARATOR AMPLIFIER P PUSH-PULL OUTPUT N TRACK 0 P N TRACK 1 (see TRACK 0) VCC COMPARATOR AMPLIFIER P PUSH-PULL OUTPUT N TRACK 2 P N (see TRACK 2) 12 TIP iC-WG 13 TIN TEST BIAS BLCC WGC2 1.2V TRACK 3..13 VCC AMPLIFIER MONITOR ©1999 Rev B0 iC-Haus GmbH Integrated Circuits Am Kuemmerling 18, D-55294 Bodenheim 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 Function GND IN0 IP0 IN1 IP1 RGND RSR LED LGND NERR CSR TIP TIN VCC A13 A12 .. A0 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. Unit Min. Max. G001 VCC Supply Voltage 0 21 G301 V(A) Voltage at Outputs A0..13 0 VCC G302 I(A) Current in Outputs A0..13 -3 3 mA G501 I(IM1) Current in Monitor Output IM1 -1 1 mA G601 I(TIP) I(TIN) Current in TIP, TIN -1 1 mA G701 I(RSR) Current in RSR -1 0.1 mA G702 I(RGND) Current in RGND -5 5 mA G703 I(LED) Current in LED 0 3 mA G704 I(LED -LGND) Current in LED to LGND 0 150 mA G705 I(LGND) Current in LGND -3 3 mA G706 V(CSR) Voltage at CSR 0 VCC G707 I(CSR) Current in CSR -1 1 mA G802 I(IPi) I(INi) Current in Analog Outputs IP0, IN0, IP1, IN1 -1 3 mA G902 I(IMP) I(IMN) Current in Monitor Outputs IMP, IMN -1 1 mA 0 30 V 2 kV 125 °C V(A)< 0V or V(A)> VCC V(LED)> VCC LED and NERR open GA01 V(NERR) Voltage at NERR LGND at GND E001 Vd() ESD Susceptibility at all Pins MIL-STD 883, Method 3015, HBM, 100pF discharged through 1.5kΩ TG1 Tj Junction Temperature TG2 Ts Storage Temperature -30 V see package specification THERMAL DATA Operating Conditions: VCC= 4.5..20V Item Symbol Parameter Conditions Ta Operating Ambient Temperature Range see package specification Fig. Unit Min. T1 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. Typ. Max. 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 Fig. Unit Min. Typ. Max. Total Device 001 VCC Permissible Supply Voltage 002 I(VCC) Supply Current in VCC, Outputs A0..13 hi 4.5 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 3.0 -20 27 85 125 see above, VCC= 20V 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 3.3 6.0 Cut-off Frequency, tracks 0..13 sinusoidal waveform, I(DP0..13)= 3..30nA I(DN0..13)= 30..3nA 005 tp(D-A) Switch Delay see No. 004 006 fo Cut-off Frequency, tracks 0..13 sinusoidal waveform, I(DP0..13)= 6..60nA I(DN0..13)= 60..6nA 007 tp(D-A) Switch Delay see No. 006 mA mA mA mA mA 14.6 mA mA mA mA mA 25.5 mA mA mA mA mA 38.5 mA mA mA mA mA 11.7 12.8 13.6 13.8 6.8 -20 27 85 125 004 fo 10.7 6.4 6.7 7.0 7.4 -20 27 85 125 see above, VCC= 20V V 5.4 5.9 6.2 6.2 -20 27 85 125 003 I(VCC) 20 14.6 16.3 17.0 17.4 100 kHz 2.5 200 µs kHz 1.5 µs Photodiodes DP0..13, DN0..13, DSR, DMP, DMN, DM1 008 S(λ)max Spectral Sensitivity λ= 850nm 009 λar Range of Spectral Sensitivity Se(λar)= 0.1×S(λ)max 0.5 500 A/W 1050 nm Photodiodes and Amplifiers with Analog Outputs, track 0 and 1 0.2 × 0.3 801 Aph(D) Radiant Sensitive Area 802 I(D) Permissible Photocurrent 803 Ierr Error Current at Photodiodes 804 CM() Common Mode DPi to DNi 805 CR() Current Gain I(IPi) / I(DPi), I(INi) / I(DNi) V(IPi,INi)= 1V..VCC, I(DPi,DNi)= 3..90nA 806 CR() Current Gain I(IPi) / I(DPi), I(INi) / I(DNi) VCC= 5V, V(IPi,INi)= 2V, I(DPi,DNi)= 30nA 807 TC(CR) Temperature Coefficient of Current Gain CR Tj< 90°C 808 I0(IPi) I0(INi) Analog Output Leakage Current V(IPi,INi)= 1V..VCC, I(DPi,DNi)= 0 -20 27 85 125 0.85 90 nA 4.7 3.6 3.2 15.5 20 15 15 25 nA nA nA nA 1 1.15 600 27 mm² 900 740 -0.03 %/K 10 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 Fig. Unit Min. Typ. 80 Max. Photodiodes and Amplifiers with Analog Outputs, track 0 and 1 (continued) 809 fo(IPi) fo(INi) Analog Output Cut-off Frequency R(VCC/IPi, VCC/INi)= 50kΩ, CL(IPi,INi)= 30pF 50 kHz 810 fo(IPi) fo(INi) Analog Output Cut-off Frequency V(IPi,INi)= constant, sinussoidal waveform, I(DPi)= 3..30nA, I(DNi)= 30..3nA 100 kHz 811 fo(IPi) fo(INi) Analog Output Cut-off Frequency V(IPi,INi)= constant, sinussoidal waveform, I(DPi)= 6..60nA, I(DNi)= 60..6nA 200 kHz Photodiodes and Amplifiers, tracks 2 to 13 101 Aph(D) Radiant Sensitive Area 102 I(D) Permissible Photocurrent 103 Ierr Error Current at Photodiodes 104 CM() Common Mode DPi to DNi 0.2 × 0.3 mm² 90 nA 4.7 3.6 3.2 15.5 20 15 15 25 nA nA nA nA 0.85 1 1.15 8 11 14 % 0.9 V V V V V 1.0 V V V V V 0.4 V V V V V -1.5 mA -20 27 85 125 Difference Comparators, tracks 0..13 201 Hys Hysteresis refered to [I(DPi) + I(DNi)] /2 I(DPi, DNi)= 3..30nA Push-Pull Outputs A0..13 301 Vs()hi Saturation Voltage hi Vs()hi= VCC -V(); I()= -40µA -20 27 85 125 0.79 0.69 0.58 0.51 -20 27 85 125 0.9 0.83 0.74 0.68 -20 27 85 125 0.21 0.22 0.25 0.27 Vs()hi= VCC -V(); I()= -400µA 302 Vs()lo Saturation Voltage lo I()= 1.6mA 303 Isc()hi Short-Circuit Current hi V()= 0V..VCC-1V -7 -4.6 304 Isc()lo Short-Circuit Current lo V()= 0.4V..VCC 1.8 7.3 305 SRhi Slew-Rate hi CL()= 30pF 24 306 SRlo Slew-Rate lo CL()= 30pF 27 13 mA 130 V/µs V/µs 330 V/µs V/µs 61 50 27 115 307 Vc()hi Clamp Voltage hi Vc()hi= V() -VCC; I()= 3mA 0.4 1.5 V 308 Vc()lo Clamp Voltage lo I()= -3mA -1.5 -0.4 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 Fig. Unit Min. Typ. Max. 400 1100 1600 2 14 100 µA 1.9 2.4 2.7 V 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) test aid active, I(TIP,TIN)= 2..200µA 602 It() Pull-Down Current at TIP, TIN; Test Aid Turn-on Threshold V(TIP,TIN)= 0.5V 603 V(TIP), V(TIN) Voltage at TIP, TIN test aid active; I(TIP)= 2..200µA and I(TIN)= 100µA, or I(TIP)= 100µA and I(TIN)= 2..200µA LED Current Control and Reference Photodiode DSR 0.15 × 0.665 701 Aph (DSR) Radiant Sensitive Area 702 I(DSR) Permissible Photocurrent in DSR 703 I(LED) Permissible Current in LED 704 Vs(LED /LGND) Saturation Voltage at LED vs. LGND I(LED)= 80mA, I(RSR)> 10µA, V(CSR)= VCC, V(LGND)= 0..1V 705 V(RSR) Voltage at RSR R(RSR/RGND)= 10..150kΩ 1.0 706 CR() Current Ratio I(RSR) / I(CSR) R(RSR)= 10..150kΩ, V(CSR)= 0V 5.3 707 CR() Current Ratio I(RSR) / I(DSR) closed LED Control, I(DSR)= 20..200nA; VCC= 5V 0 0 -20 27 85 125 Current Gain I(LED) / I(RSR) 709 R(LGND) Resistance at LGND control loop open, LGND at GND, V(LED)> 1.5V, V(CSR)= VCC V(LGND)= 0..2V nA 80 mA 1.2 V V V V V 1.22 1.5 V 10 13 340 660 450 430 420 415 220 -20 27 85 125 708 CG() 200 0.84 0.76 0.67 0.60 -20 27 85 125 see above, VCC= 20V mm² 540 370 350 345 340 15000 0.6 1.0 1.6 kΩ 0.27 0.4 V 15 27 mA 10 µA Control Monitor NERR A01 Vs()lo Saturation Voltage lo LGND at GND, I(NERR)= 3.2mA A02 Isc()lo Short-Circuit Current lo V(NERR)= VCC A03 I0() Collector Off-State Current NERR= off, V(NERR)= 25V 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 Fig. Unit Min. Typ. Max. Monitor Photodiode DM1 with Amplifier (not available in standard BLCC package) 501 Aph (DM1) Radiant Sensitive Area 502 Ierr Error Current at Photodiode DM1 503 CR() Current Gain I(IM1) / I(DM1) 504 fo Cut-off Frequency 0.1 × 0.1 -20 27 85 125 I(DM1)= 2..20nA, V(IM1)= 0..VCC-1V; VCC= 5V VCC= 20V 3000 4000 sinusoidal waveform, I(DM1)= 2..20nA mm² 1 1 1 3.5 5 5 5 10 5500 8900 10000 24000 100 nA nA nA nA Hz Track Position Monitor, Photodiodes DMP und DMN (not available in standard BLCC package) 0.125 × 0.530 901 Aph (DMP, DMN) Radiant Sensitive Area 902 Ierr Error Current at Photodiodes DMP, DMN 903 CR() Current Gain I(IMP) / I(DMP), I(IMN) / I(DMN) I(DMP,DMN)= 2..20nA, V(IMP,IMN)= 0..VCC-1V; VCC= 5V VCC= 20V Cut-off Frequency sinusoidal waveform, I(DMP,DMN)= 2..20nA 904 fo -20 27 85 125 3000 4000 100 mm² 3 3 3 15 20 15 15 25 5500 8900 10000 24000 nA nA nA nA Hz 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 iC-WG iC-WG BLCC WGC2 iC-WG with reticle WG1R BLCC WGC2 WG1S Code Disc (13-bit Gray) Order designation iC-WG Chip iC-WG BLCC WGC2 iC-WG BLCC WGC2 +WG1R WG1S 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.