t
t
TSLW1401
EXTENDED TEMPERATURE
128
y
1 LINEAR SENSOR ARRAY WITH HOLD
TAOS024A – JUNE 2001
D
D
D
D
D
D
D
D
Optical Glass Window
128
×
1 Sensor-Element Organization
400 Dots-Per-Inch (DPI) Sensor Pitch
High Linearity and Uniformity
for 256 Gray-Scale (8-Bit) Applications
Output Referenced to Ground
Low Image Lag . . . 0.5% Typ
Operation to 2 MHz
Single 5-V Supply
(TOP VIEW)
SI
CLK
AO
V
DD
1
2
3
4
8
7
6
5
GND
GND
GND
GND
Description
The TSLW1401 linear sensor array consists of a 128
×
1 array of photodiodes, associated charge amplifier
circuitry, and a pixel data-hold function that provides simultaneous-integration start and stop times for all pixels.
The pixels measure 63.5
µm
(H) by 55.5
µm
(W) with 63.5-µm center-to-center spacing and 8-µm spacing
between pixels. Operation is simplified by internal control logic that requires only a serial-input (SI) signal and
a clock.
Functional Block Diagram
Pixel 1
Integrator
Reset
Pixel
2
Pixel
3
Pixel
128
Analog
Bus
Output
Amplifier
Sample/
Output
3
AO
R
L
(External
Load)
V
DD
4
_
+
6,7
Switch Control Logic
GND
Hold
Q1
Q2
Q3
Q128
Gain
Trim
CLK
SI
2
1
128-Bit Shift Register
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Texas Advanced Optoelectronic Solutions Inc.
800 Jupiter Road, Suite 205
S
Plano, TX 75074
S
(972) 673-0759
t
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Copyright
E
2001, TAOS Inc.
1
TSLW1401
EXTENDED TEMPERATURE
128
y
1 LINEAR SENSOR ARRAY WITH HOLD
TAOS024A – JUNE 2001
Terminal Functions
TERMINAL
NAME
AO
CLK
GND
SI
V
DD
NO.
3
2
5,6,7,8
1
4
Analog output.
Clock. The clock controls charge transfer, pixel output, and reset.
Ground (substrate). All voltages are referenced to the substrate.
Serial input. SI defines the start of the data-out sequence.
Supply voltage. Supply voltage for both analog and digital circuits.
DESCRIPTION
Detailed Description
The sensor consists of 128 photodiodes arranged in a linear array. Light energy impinging on a photodiode
generates photocurrent, which is integrated by the active integration circuitry associated with that pixel.
During the integration period, a sampling capacitor connects to the output of the integrator through an analog
switch. The amount of charge accumulated at each pixel is directly proportional to the light intensity and the
integration time.
The output and reset of the integrators is controlled by a 128-bit shift register and reset logic. An output cycle
is initiated by clocking in a logic 1 on SI. For proper operation, after meeting the minimum hold time condition,
SI must go low before the next rising edge of the clock. An internal signal, called Hold, is generated from the
rising edge of SI and transmitted to analog switches in the pixel circuit. This causes all 128 sampling capacitors
to be disconnected from their respective integrators and starts an integrator reset period. As the SI pulse is
clocked through the shift register, the charge stored on the sampling capacitors is sequentially connected to a
charge-coupled output amplifier that generates a voltage on analog output AO. Simultaneously, during the first
18 clock cycles, all pixel integrators are reset, and the next integration cycle begins on the 19th clock. On the
129th clock rising edge, the SI pulse is clocked out of the shift register and the analog output AO assumes a
high impedance state. Note that this 129th clock pulse is required to terminate the output of the 128th pixel, and
return the internal logic to a known state. A subsequent SI pulse may be presented as early as the 130th clock
pulse, thereby initiating another pixel output cycle.
AO is driven by a source follower that requires an external pulldown resistor. When the output is not in the output
phase, it is in a high-impedance state. The output is nominally 0 V for no light input and 2 V for a nominal
white-level output.
The voltage developed at analog output (AO) is given by:
V
out
= V
drk
+ (R
e
) (E
e
)(t
int
)
where:
V
out
V
drk
R
e
E
e
t
int
is the analog output voltage for white condition
is the analog output voltage for dark condition
is the device responsivity for a given wavelength of light given in V/(
µJ/cm
2)
is the incident irradiance in
µW/cm
2
is integration time in seconds
The TSL1401 is intended for use in a wide variety of applications, including: image scanning, mark and code
reading, optical character recognition (OCR) and contact imaging, edge detection and positioning, and optical
linear and rotary encoding.
Copyright
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2001, TAOS Inc.
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TSLW1401
EXTENDED TEMPERATURE
128
y
1 LINEAR SENSOR ARRAY WITH HOLD
TAOS024A – JUNE 2001
Absolute Maximum Ratings
†
Supply voltage range, V
DD
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to 6 V
Input voltage range, V
I
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to V
DD
+ 0.3V
Input clamp current, I
IK
(V
I
< 0) or (V
I
> V
DD
) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –20 mA to 20 mA
Output clamp current, I
OK
(V
O
< 0 or V
O
> V
DD
) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –25 mA to 25 mA
Voltage range applied to any output in the high impedance or power-off state, V
O
. . . –0.3 V to V
DD
+ 0.3 V
Continuous output current, I
O
(V
O
= 0 to V
DD
) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –25 mA to 25 mA
Continuous current through V
DD
or GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –40 mA to 40 mA
Analog output current range, I
O
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –25 mA to 25 mA
Operating free-air temperature range, T
A
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –25°C to 115°C
Storage temperature range, T
stg
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to 125°C
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260°C
†
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “Recommended Operating Conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
Recommended Operating Conditions (see Figure 1 and Figure 2)
MIN
Supply voltage, V
DD
Input voltage, V
I
High-level input voltage, V
IH
Low-level input voltage, V
IL
Wavelength of light source,
λ
Clock frequency, f
clock
Sensor integration time, t
int
Setup time, serial input, t
su(SI)
Hold time, serial input, t
h(SI)
(see Note 1)
Operating free-air temperature, T
A
NOTE 1: SI must go low before the rising edge of the next clock pulse.
4.5
0
2
0
400
5
0.0645
20
0
–25
115
NOM
5
MAX
5.5
V
DD
V
DD
0.8
1000
2000
100
UNIT
V
V
V
V
nm
kHz
ms
ns
ns
°C
CLK
SI
Internal
Reset
18 Clock Cycles
Integration
Not Integrating
Integrating
129 Clock Cycles
AO
Hi-Z
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ÎÎÎÎÎÎÎÎ ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎ ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
Hi-Z
Figure 1. Timing Waveforms
t
Copyright
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2001, TAOS Inc.
t
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TSLW1401
EXTENDED TEMPERATURE
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1 LINEAR SENSOR ARRAY WITH HOLD
TAOS024A – JUNE 2001
Electrical Characteristics at f
clock
= 1 MHz, V
DD
= 5 V, T
A
= 25°C,
λ
p
= 565 nm, t
int
= 5 ms,
R
L
= 330
Ω,
E
e
= 15
µW/cm
2
(unless otherwise noted) (see Note 2)
PARAMETER
V
out
V
drk
PRNU
Analog output voltage (white, average over 128 pixels)
Analog output voltage (dark, average over 128 pixels)
Pixel response nonuniformity
Nonlinearity of analog output voltage
Output noise voltage
R
e
V
sat
SE
DSNU
IL
I
DD
I
IH
I
IL
C
i
Responsivity
Analog output saturation voltage
Saturation exposure
Dark signal nonuniformity
Image lag
Supply current
High-level input current
Low-level input current
Input capacitance
V
I
= V
DD
V
I
= 0
5
See Note 6
All pixels
All except pixel 1
See Note 8
See Notes 3 & 4
See Note 4
See Note 5
19
3
TEST CONDITIONS
E
e
= 15
µW/cm
2
,
t
int
= 5 ms,
MIN
1.6
0
TYP
2
0.1
±4%
±0.4%
1
25
3.5
136
0.08
0.017
0.5%
2.5
4
1
1
mA
µA
µA
pF
0.120
0.035
V
32
MAX
2.4
0.2
±7.5%
FS
mVrms
V/
(µJ/cm
2
)
V
nJ/cm
2
UNIT
V
V
λ
p
= 565 nm
see Note 2
λ
p
= 565 nm
λ
p
= 565 nm
See Note 7
See Note 7
88
NOTES: 2. The array is uniformly illuminated with a diffused LED source having a peak wavelength of 565 nm.
3. PRNU is the maximum difference between the voltage from any single pixel and the average output voltage from all pixels of the
device under test when the array is uniformly illuminated at the white irradiance level. PRNU includes DSNU.
4. Nonlinearity is defined as the maximum deviation from a best-fit straight line over the dark-to-white irradiance levels, as a percent
of analog output voltage (white).
5. RMS noise is the standard deviation of a single-pixel output under constant illumination as observed over a 5-second period.
6. Minimum saturation exposure is calculated using the minimum V
sat
, the maximum V
drk
, and the maximum R
e
.
7. DSNU is the difference between the maximum and minimum output voltage in the absence of illumination.
8. Image lag is a residual signal left in a pixel from a previous exposure. It is defined as a percent of white-level signal remaining after
a pixel is exposed to a white condition followed by a dark condition:
IL
+
V out (IL)
*
V drk
V out (white)
*
V drk
100
Timing Requirements (see Figure 1 and Figure 2)
MIN
t
su(SI)
t
h(SI)
t
w
t
r
, t
f
Setup time, serial input (see Note 9)
Hold time, serial input (see Note 9 and Note 10)
Pulse duration, clock high or low
Input transition (rise and fall) time
20
0
50
0
500
NOM
MAX
UNIT
ns
ns
ns
ns
NOTES: 9. Input pulses have the following characteristics: t
r
= 6 ns, t
f
= 6 ns.
10. SI must go low before the rising edge of the next clock pulse.
Dynamic Characteristics over recommended ranges of supply voltage and operating free-air
temperature (see Figure 2)
PARAMETER
t
s
Analog output settling time to
±1%
TEST CONDITIONS
R
L
= 330
Ω,
C
L
= 50 pF
MIN
TYP
350
MAX
UNIT
ns
Copyright
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2001, TAOS Inc.
t
www.taosinc.com
4
t
TSLW1401
EXTENDED TEMPERATURE
128
y
1 LINEAR SENSOR ARRAY WITH HOLD
TAOS024A – JUNE 2001
t
w
CLK
t
su(SI)
SI
1
2
128
129
2.5 V
5V
0V
5V
0V
50%
t
h(SI)
t
s
AO
t
s
Pixel 1
Pixel 128
Figure 2. Operational Waveforms
TYPICAL CHARACTERISTICS
PHOTODIODE SPECTRAL RESPONSIVITY
1
T
A
= 25°C
0.8
Normalized Responsivity
0.6
0.4
0.2
0
300
400
500
600
700
800
900
1000 1100
λ
– Wavelength – nm
Figure 3
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2001, TAOS Inc.
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