ICHAUS WG1S

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.