3.4 I/O Connection
CA5350
3-10
3.4.1 Connection of optical sensor, etc. (photodiode)
Ensure to place the sensor in a shied BOX.
(1) No-bias type sensor
シールドBOX
同軸ケーブル
CURRENT
INPUT
CA5350
雑音を最小にするには
ケーブルを最短にします
INVERTING
BIAS
OUTPUT
Figure 3-8 Connection of sensor without bias type
(2) Reverse bias type sensor
シールドBOX
同軸ケーブル
CURRENT
INPUT
CA5350
INVERTING
BIAS
OUTPUT
C0
近づけて配線
Figure 3-9 Connection of reverse bias type sensor
Keeping the DC bias voltage setting in
CA5350
is minus (0V or less) will apply reverse
bias (plus to cathode, minus to anode) to the sensor shown in
“Figure 3-9 Connection of
reverse bias type sensor
”
.
C0
in
“Figure 3-9 Connection of reverse bias type sensor”
is the capacitor for
bypassing the noise from outside, and use the capacitor with sufficiently large
electrostatic capacitance when it is needed(for example: about 0.1µF).
Arrange the current input and bias output cable keeping it flat as much as possible. If
the loop area formed with two cables become large, electromagnetic induction noise due
to external magnetic flux will easily occur.
External DC voltage source can also be used as the bias voltage source for sensor. In
that case, use sufficiently stable and low noise DC power.
When using a sensor with large dark current, it may cause the saturation of
CA5350
. It
allows cancelling the dark current and getting larger gain by using current suppression
function.
For the current suppression
“4.2 Cancelling the dark current of sensor”
Shield BOX
For minimizing the noise,
Make the cable as short as possible
Coaxial cable
Shield BOX
Shield BOX
Coaxial cable
As near as possible
