TSL1401CS
128
×
1 LINEAR SENSOR ARRAY WITH HOLD
TAOS036A - AUGUST 2003
1
The
LUMENOLOGY
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r
r
Copyright
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2003, TAOS Inc.
www.taosinc.com
D
128
×
1 Sensor-Element Organization
D
400 Dots-Per-Inch (DPI) Sensor Pitch
D
High Linearity and Uniformity
D
Wide Dynamic Range . . . 4000:1 (72 dB)
D
Output Referenced to Ground
D
Low Image Lag . . . 0.5% Typ
D
Operation to 8 MHz
D
Single 3-V to 5-V Supply
D
Rail-to-Rail Output Swing (AO)
D
No External Load Resistor Required
Description
The TSL1401CS 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
µ
m (H) by 55.5
µ
m (W) with 63.5-
µ
m center-to-
center spacing and 8-
µ
m spacing between pixels.
Operation is simplified by internal control logic that
requires only a serial-input (SI) signal and a clock.
Functional Block Diagram
1
3
SI
CLK
128-Bit Shift Register
Q128
Switch Control Logic
Integrator
Reset
_
+
Pixel 1
Pixel
2
Pixel
128
Pixel
3
Sample/
Output
Analog
Bus
Q3
Q2
Q1
Hold
2
SO
7
Output
Buffer
Gain
Trim
V
DD
AO
GND
4, 5
8
6
r
r
Texas Advanced Optoelectronic Solutions Inc.
800 Jupiter Road, Suite 205
S
Plano, TX 75074
S
(972) 673-0759
HOLD 2
GND 4
AO 6
V
DD
8
(TOP VIEW)
1 SI
3 CLK
5 GND
7 SO
TSL1401CS
128
×
1 LINEAR SENSOR ARRAY WITH HOLD
TAOS036A - AUGUST 2003
2
r
r
Copyright
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2003, TAOS Inc.
The
LUMENOLOGY
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Terminal Functions
TERMINAL
DESCRIPTION
NAME
NO.
DESCRIPTION
AO
6
Analog output
CLK
3
Clock. The clock controls charge transfer, pixel output, and reset.
GND
4, 5
Ground (substrate). All voltages are referenced to the substrate.
HOLD
2
Hold signal. HOLD freezes the result of a 128 pixel scan.
SI
1
Serial input. SI defines the start of the data-out sequence.
SO
7
Serial output. SO provides a signal to drive the SI input of another device
for cascading or as an end-of-data indication.
V
DD
8
Supply voltage. Supply voltage for both analog and digital circuits.
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. The signal called Hold is normally connected to SI. Then,
the rising edge of SI causes a HOLD condition. 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 an op amp-type output that does not require an external pull-down resistor. This design allows a rail-to-rail
output voltage swing.
With V
DD
= 5 V, the output is nominally 0 V for no light input, 2 V for normal white level, and 4.8 V
for saturation light level.
When the device is not in the output phase, AO is in a high-impedance state.
The voltage developed at analog output (AO) is given by:
V
out
= V
drk
+ (R
e
) (E
e
)(t
int
)
where:
V
out
is the analog output voltage for white condition
V
drk
is the analog output voltage for dark condition
R
e
is the device responsivity for a given wavelength of light given in V/(
µ
J/cm
2
)
E
e
is the incident irradiance in
µ
W/cm
2
t
int
is integration time in seconds
A 0.1
µ
F bypass capacitor should be connected between V
DD
and ground as close as possible to the device.
The TSL1401CS 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.
TSL1401CS
128
×
1 LINEAR SENSOR ARRAY WITH HOLD
TAOS036A - AUGUST 2003
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LUMENOLOGY
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Company
r
r
Copyright
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2003, TAOS Inc.
www.taosinc.com
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
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maximum light exposure at 638 nm
5 mJ/cm
2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating free-air temperature range, T
A
-40
°
C to 100
°
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range, T
stg
- 40
°
C to 100
°
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Solder reflow temperature, case exposed 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
NOM
MAX
UNIT
Supply voltage, V
DD
3
5
5.5
V
Input voltage, V
I
0
V
DD
V
High-level input voltage, V
IH
2
V
DD
V
Low-level input voltage, V
IL
0
0.8
V
Wavelength of light source,
400
1000
nm
Clock frequency, f
clock
5
8000
kHz
Sensor integration time, t
int
(see Note 1)
0.016
100
ms
Setup time, serial input, t
su(SI)
20
ns
Hold time, serial input, t
h(SI)
(see Note 2)
0
ns
Operating free-air temperature, T
A
-40
85
°
C
NOTES: 1. This time does not include the 18 clock cycles for setup, which would consume an additional 0.002 mS of device integrate and read
time.
2. SI must go low before the rising edge of the next clock pulse.
TSL1401CS
128
×
1 LINEAR SENSOR ARRAY WITH HOLD
TAOS036A - AUGUST 2003
4
r
r
Copyright
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2003, TAOS Inc.
The
LUMENOLOGY
r
Company
www.taosinc.com
Electrical Characteristics at f
clock
= 1 MHz, V
DD
= 5 V, T
A
= 25
°
C,
p
= 640 nm, t
int
= 5 ms,
R
L
= 330
, E
e
= 11
µ
W/cm
2
(unless otherwise noted) (see Note 3 and Note 4)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
V
out
Analog output voltage (white, average over 128 pixels)
1.6
2
2.4
V
V
drk
Analog output voltage (dark, average over 128 pixels)
E
e
= 0
0
0.1
0.2
V
PRNU
Pixel response nonuniformity
See Note 5
±
4%
±
10%
Nonlinearity of analog output voltage
See Note 6
±
0.4%
FS
Output noise voltage
See Note 7
1
mVrms
R
e
Responsivity
See Note 8
25
35
44
V/
(µ
J/cm
2
)
V
Analog output saturation voltage
V
DD
= 5 V, R
L
= 330
4.5
4.8
V
V
sat
Analog output saturation voltage
V
DD
= 3 V, R
L
= 330
2.5
2.8
V
SE
Saturation exposure
V
DD
= 5 V, See Note 9
136
nJ/cm
2
SE
Saturation exposure
V
DD
= 3 V, See Note 9
78
nJ/cm
2
DSNU
Dark signal nonuniformity
All pixels, E
e
= 0
See Note 10
0.02
0.05
V
IL
Image lag
See Note 11
0.5%
I
Supply current
V
DD
= 5 V, E
e
= 0
2.8
4.5
mA
I
DD
Supply current
V
DD
= 3 V, E
e
= 0
2.6
4.5
mA
V
IH
High-level input voltage
2
V
V
IL
Low-level input voltage
0.8
V
I
IH
High-level input current
V
I
= V
DD
1
µ
A
I
IL
Low-level input current
V
I
= 0
1
µ
A
C
i
Input capacitance
5
pF
NOTES: 3. The array is uniformly illuminated with a diffused LED source having a peak wavelength of 640 nm.
4. All measurements made with a 0.1
µ
F capacitor connected between V
DD
and ground.
5. 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.
6. 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).
7. RMS noise is the standard deviation of a single-pixel output under constant illumination as observed over a 5-second period.
8. R
e(min)
= [V
out(min)
- V
drk(max)
]
÷
(E
e
×
t
int
)
9. SE(min) = [V
sat(min)
- V
drk(min)
]
×
E
e
×
t
int
)
÷
[V
out(max)
- V
drk(min)
]
10. DSNU is the difference between the maximum and minimum output voltage for all pixels in the absence of illumination.
11. 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
NOM
MAX
UNIT
t
su(SI)
Setup time, serial input (see Note 12)
20
ns
t
h(SI)
Hold time, serial input (see Note 11 and Note 13)
0
ns
t
w
Pulse duration, clock high or low
50
ns
t
r
, t
f
Input transition (rise and fall) time
0
500
ns
NOTES: 12. Input pulses have the following characteristics: t
r
= 6 ns, t
f
= 6 ns.
13. SI must go low before the rising edge of the next clock pulse.
TSL1401CS
128
×
1 LINEAR SENSOR ARRAY WITH HOLD
TAOS036A - AUGUST 2003
5
The
LUMENOLOGY
r
Company
r
r
Copyright
E
2003, TAOS Inc.
www.taosinc.com
Dynamic Characteristics over recommended ranges of supply voltage and operating free-air
temperature (see Figures 3 and 4)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
t
s
Analog output settling time to
±
1%
R
L
= 330
,
C
L
= 10 pF
120
ns
TYPICAL CHARACTERISTICS
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎ
18 Clock Cycles
129 Clock Cycles
CLK
SI
AO
Internal
Reset
Integration
Hi-Z
Hi-Z
Not Integrating
Integrating
Figure 1. Timing Waveforms
50%
AO
SI
CLK
Pixel 128
t
s
0 V
0 V
5 V
2.5 V
t
h(SI)
5 V
t
su(SI)
t
w
1
2
128
129
t
s
Pixel 1
Figure 2. Operational Waveforms
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