XIA XPPS User manual

User’s Manual
X-ray Preamplifier Power
Supply
Model XPPS
XIA LLC
31057 Genstar Rd.
Hayward, CA 94544 USA
Tel: [phone]; Fax: [phone]
http://www.xia.com
Information furnished by XIA LLC is believed to be accurate and reliable. However, no responsibility is
assumed by XIA for its use, nor for any infringements of patents or other rights of third parties which may
result from its use. No license is granted by implication or otherwise under any patent or patent rights of
XIA. XIA reserves the right to change specifications at any time without notice.
Copyright 2005 by XIA LLC Manual # XPPS-MAN-000.5
September 10, 2020

1 Overview
The Model XPPS X-ray Preamplifier Power Supply from
XIA provides low-noise linear DC power to run x-ray and gamma-ray
preamplifiers. The XPPS provides 24V and 12V on four industry-
standard DB-9 connectors, and is specifically designed to provide
power for multi-element x-ray detectors used at synchrotron beamlines.
The XPPS is designed to power 50 or more preamplifier channels,
based on the published preamplifier power needs for the most popular
detectors. The 12V supplies produce 5.1 amps each, while the 24V
supplies each produce 3.6 amps. Test points are available on the front
panel to measure the voltages. A thick ground strap is provided to make
a strong ground connection to the signal processing electronics in order
to reduce possible ground loop noise.
1.1 XPPS Features
Low noise, linear power supplies.
24V and 12V power for 50 or more preamplifiers.
12V at 5.1 amps each; 24V at 3.6 amps each.
Four front panel DB-9 outputs.
Front panel test points allow checking supply voltages.
Use with DXP modules to control ground loops and lower
noise.
Intended to be mounted close to detector array.
Eliminates noise pickup from long preamplifier signal cables.
Works with all common AC line voltages (100V, 120V, 220V,
240V)
Standalone 19”, rack mountable chassis (4U height, 16 inches
deep)

2 Application
The primary application for the XPPS is in detector array
systems using XIA’s DXP or DGF digital signal processors, where it
provides a source of clean, low noise linear power for the detector’s
preamplifiers. For synchrotron applications, the XPPS is intended to be
mounted in the x-ray hutch, close to the detector, along with the
processing electronics. This provides the following benefits. First, it
controls ground loops, which might arise if the DXP’s and
preamplifiers were powered from separate sources. Because the DXP
input signal is referenced to its local power supply ground, such ground
loop noise appears directly superimposed on the preamplifiers’ signals
and can seriously degrade energy resolution. Second, it allows the PXI
chassis (or CAMAC crate) containing the DXP’s or DGF’s to be placed
in close proximity to the detector array. This often allows the signal
cables from the preamplifiers to the DXP’s to be greatly shortened,
which in turn can significantly reduce their noise pickup from the
environment. This is particularly important in digitally noisy
environments or in the presence of strong radio-frequency signals, such
as in synchrotron applications. In the latter case, the PXI chassis can be
placed in the hutch and only digital control and data signals being sent
to the external control computer system.

3 Operation
The XPPS module is very simple to use. In most cases, all that
is needed is to connect the XPPS to AC power, and connect the
preamplifier cables, being mindful of connector and cable current
ratings. For best results, it may be necessary to also connect the ground
strap to the associated signal processing electronics in order to
eliminate ground loop noise. Prior to connecting the AC power, it is
necessary to select the proper input voltage on the AC power input
module on the rear of the unit; see below for instructions. In most
cases, the voltage will be set properly prior to shipment.
3.1 Connector Current Ratings
Note that the XPPS front-panel DB9 connectors are rated at 2
Amperes per pin. As a rule of thumb, each connector should carry no
more than 1.5 Amperes on any voltage, no more than 3 Amperes total.
Note: It is always safest to split the load between all four DB9
connectors.
Current per
Voltage
Total
Current
Recommendation
< 1.5 A
< 3.0 A
Use one or more DB9 connectors
< 3.0 A
< 6.0 A
Use two or more DB9 connectors
< 6.0 A
< 12.0 A
Use three or more DB9 connectors
> 6.0 A
> 12.0 A
Use all four DB9 connectors
For example, consider a 26-element detector system that
draws 100 mA on +/-12 V and 50 mA on +/-24 V. The current
required at +/-12V is 2.6 A, and the current required at +/-24 V is 1.3
A. The total current is 3.9 A. At a minimum, two DB9 connections
must be made, however, the best cabling solution would use all four
DB9 connections.
3.2 Preamplifier Connector Pinout
The female DB9 connectors on the XPPS conform to the
standard pinout for detector preamplifier power connections:
Pin
Description
1 and 2
Ground
4
+12V
6
-24V
7
+24V
9
-12V
3, 5 and 8
Unused