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Unformatted text preview: ltra low noise of the A225, care should
be taken in circuit layout. The PC-25 Test Board may be used as an
example of appropriate layout technique. In general, ground plane
construction is recommended. Input and output lines should be kept well
separated and in most cases shielding will be necessary.
Particular attention should be paid to the detector ground connection
to avoid oscillation due to feedback. The supply voltage is internally
decoupled. While this is normally adequate, in some applications
external bypassing may be helpful.
To facilitate noise minimization in certain applications, two separate
ground connections are provided. Pin 4 is the ground connection for the
input stage and is also connected to the case. Pin 5 is ground for the
remainder of the circuit. In most applications Pin 4 and 5 may be
connected to the same ground (preferably a ground plane under the unit)
along with Pins 2,3,6,7,9,10 and 13.
The A225 may also be used in applications where the input from the
detector is positive by connecting Pin 5 (output ground) to a negative
supply voltage instead of ground. This voltage can range from 0 to -10 V.
A negative output pulse at Pin 8 will result from a positive input. The
dynamic range in this case will be approximately 0.5 Volts greater than
Pin 5. For example, with Pin 5 operated at -5 Volts, negative pulses of up
to 5.5 Volts amplitude can be obtained. This mode of operation will
result in increased operating current. The A225 is not specified in this
mode and critical parameters should be verified by the user. Temperature: -55 to +125 ºC Operational Temperature Stability: 0.02% / ºC at 25 ºC typical
±2% from -25 to +75 ºC Screening: Amptek High Reliability Power Supply Package: 14 pin hybrid DIP (metal) Radiation Resistance: 100k rad(Si) Warranty: One year While specifications are given for operation at +5 V, the characteristics of
the A225 are relatively unaffected by changes in supply voltage from +4
to +25 VDC. Parameters critical to a particular application should be
checked at the actual operating voltage. Test Board: PC-25 For more information visit www.amptek.com OPERATING NOTES (Continued)
In order to minimiz...
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- Fall '09