LUPA-1300(2007) View Datasheet(PDF) - Cypress Semiconductor
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LUPA-1300 Datasheet PDF : 32 Pages
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LUPA-1300
charge or discharge the load capacitance to obtain a higher
pixel rate.
To avoid variations on the supply voltage to be seen on the
output signal, a special module to stabilize the power supply
is required. This module that requires an additional supply
voltage (Vstable) allows variation on the supply voltage Voo
without being seen on the output signal.
One can also choose to have a passive load of chip instead of
the active output stage load. This deteriorates the linearity of
the output stages, but decreases the power dissipation, as the
dissipation in the load is external.
Frame rate and windowing
Frame rate calculation
The frame period of the LUPA-1300 sensor can be calculated
as follows:
Frame period = FOT + (Nr.Lns* (RBT + pixel period * Nr. Pxs/16)
with:
FOT: Frame Overhead Time = 1 us.
Nr. Lns: Number of Lines read out each frame (Y).
Nr. Pxs: Number of pixels read out each line (X).
RBT: Row blanking time = 200 ns (nominal; can be further reduced).
Pixel period: clock_x period/2 (both rising and falling edge are active edges).
- Example 1 read out of the full resolution at nominal speed (40 MHz pixel rate):
Frame period = 5 us + (1024 * (200 ns + 25 ns * 1280/16) = 2.25 ms => 444 fps.
- Example 2 read out of 800x600 at nominal speed (40 MHz pixel rate):
Frame period = 5 us + (600 * (200 ns + 25 ns * 800/16) = 871 us => 1148 fps.
- Example 3 read out of 640x480 at nominal speed (40 MHz pixel rate):
Frame period = 5 us + (480 * (200 ns + 25 ns * 640/16) = 577 us => 1733 fps.
- Example 4 read out of the full resolution at nominal speed (40 MHz pixel rate) with reduced overhead time:
Frame period = 5 us + (1024 * (100 ns + 25 ns * 1280/16) = 2.15 ms => 465 fps.
X-Y addressing and windowing
The pixel array is readout by means of programmable X and
Y shift registers. The pixel array is scanned line-by-line and
column-by-column. The starting point in X and Y is defined
individually for each register and is determined by the address
downloaded by the Serial-Parallel Interface (SPI). Both
registers work in the same way. A sync pulse that sets the
address pointer to the starting address of each register,
initializes them. A clock pulse for the x- and y-shift register
shifts the pointer individually and makes sure that the
sequential selection of the lines and columns is correct.
Temperature reference circuits
Temperature diode
The most commonly used temperature measurement is
monitoring of the junction voltage of a diode, therefore we also
added a temperature diode to measure the temperature of the
silicon die. This diode junction voltage is generated by a
"small", forward biased, constant current flow (in between 10
and 100 µA).
This junction voltage has a nearly linear relationship with the
temperature of the die with a typical sensitivity of about 430°C
per volt (2.3 mV per °C) for silicon junctions.
Temperature module
On the same image sensor we have foreseen a module to
verify the temperature on chip and the variation of the output
voltage (dark level of the pixel array) due to a temperature
variation. This module contains a copy of the complete signal
path, including a blind pixel, the column amplifiers and an
output stage. It DC response may serve a temperature
calibration for the real signal. The temperature functionality is
given in Figure 7. Between room temperature and 60oC we
see a voltage variation of about 0.5 mV.
Due to different applied supply voltages, as there are: Vreset,
Vmem, Vpix an offset between the output voltage of the
temperature sensor and the output of a black signal of the pixel
array can occur. Depending on the working conditions of the
image sensor one can fine-tune the temperature module with
its voltage supply. In case one has a 6V signal for reset and a
4-6V signal for Vmem, a supply voltage of 5.5V for the temper-
ature sensor will result in a closer match between this temper-
ature sensor and the black level of the image sensor.
Changing the supply voltage of the temperature sensor results
only in a shift of the output voltage therefore the supply voltage
of the temperature module can be tuned to make the output of
the module equal to the dark signal of the pixel array at a
certain working temperature.
Note
7. The LUPA-1300 is designed to drive a capacitive load, not a resistive. When one wants to transport the output signals over long distances (more than 1 inch),
make sure to place buffers on the outputs with high input impedances (preferably >1Mohms). This is necessary because the output impedance of the LUPA-1300
is between 200-300 ohms typically.
Document Number: 38-05711 Rev. *C
Page 10 of 32
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