MPRB-16 / 32(Data sheet V1.1_01)

16 / 32 channel preamplifier
with individual bias supply andtemperature compensation forAvalanche Photo Diodes

mesytec MPRB-16 is a 16 channel charge sensitive preamplifier with integrated bias
voltage generators. The device is remote controllable via mesytec control bus, which allows to adjust the 16 bias voltages individually for each channel in 100 mV steps, up to600 V. It is designed to operate and read out arrays of avalanche photo diodes or strip detectors. A temperature sensor can be connected and allows the MPRB-16 to compensate
the APD gain drift with temperature by adapting the bias voltage with temperature. Allparameters can be set and read back via mesytec control bus.
Features:•••16 channel low noise charge
sensitive preamplifiers
Sensitivity selectable in two steps
by switch and RC Pulser input
Differential or unipolar signaloutput

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Bias supply can be adjusted byremote control
Bias adjustable for each channel insteps of 0.1 V
Maximum bias 600 V
Push button for ramp up and downof bias voltages
Also available as stacked
32 channel amplifier
With and without mounting latchesmesytec GmbH & Co. KG
Wernher-von-Braun-Str. 1, D-85640 Putzbrunn, Germany
phone: +49 - 89 / 456007-30 fax: +49 - 89 / 456007-39
info@mesytec.com - www.mesytec.com

MPRB-16 / 32

16 / 32 channel preamplifier

Technical Data
Bias voltage

Temperature compensation

Prefilter: 50 MΩ
Stability: 100 ppm/ °C (slope = 128, temp sensor
not connected)

The sensor can be connected at the SubD-25 input
connector. It occupies the position
which is usually used for the guard ring bias. So
all mesytec cable sets allow to connect the sensor
at the detector site between the guard ring pin andanalog ground (neighbour pin)

Maximum voltage difference between
channels: 300 V
When set value difference is larger, the channels
with too low voltage are increased.
So lowest channel voltage is: highest channel voltage –300 V.

Sensor type: NTC thermistor, Epcos B57861S502-F40 (5 kΩ @ 25 °C, B = 3988)

Power consumption with MPR-16-300+6 V–6 V+12V

130 mA–70 mA
80 mASize

55 x 105 x 171 mm

Offset slope adjustment (via RC) for modules withpositive bias:
Slope parameter = 0:
voltage is increased by 1.79V /°C
Slope parameter = 128:
slope about 0
Slope parameter = 255:
voltage is decreased by 1.79V /°C
For the MPRB-16-P device (positive bias voltage)
the theoretical slope parameter setting for
LAAPDs (0.78 V/ °C) is 128 - 56 = 72;
The optimum value measured for large area APDs
is 68 (= 0.84 V/ °C).

mesytec GmbH & Co. KG
Wernher-von-Braun-Str. 1, D-85640 Putzbrunn, Germany
phone: +49 - 89 / 456007-30 fax: +49 - 89 / 456007-39
info@mesytec.com - www.mesytec.com

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MPRB-16 / 32

16 / 32 channel preamplifier

Remote control

The module is controled via mesytec control bus.

Power updefault
0set voltage : 6000 = 600 V (steps of 100 mV)
000000000000000

Addr

Function

0123456789101112131415

Voltage0

Voltage 15

R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W

16

Sum current

RCurrent of all channels. 0 nA = 2048
1 nA per channel

17Pre-voltage

R

Voltage of main generator, for factory use only

18temperature

R

21
22

Error_code
Temp_slope

R
R/W

128

23

Temp_offset

R/W

128

24

Ramp
up/down

R/W

025

Voltage limit R/W

6000

26

Preamp_range R/W

031

Firmware revision

xxxx

R

Temp sensor ADC value
Typically 2048 @ 26 °C, increases by 61 channels
per °C (@reg 23 = 128)
16 bit err for 16 channels
0..255 128 → slope is 00..255 128 → offset for about 26 °C
correct ADC temperature reading to 2048 at typicaloperating temperature.
At this point correction of bias voltage is 0,change of slope parameter has no effect.
1 = up, 0 = down
Maximum allowed voltage
When channel voltage limited → error_ code register is set, Error LED lights up
0 = coded by front panel switch
1 = high range (low sensitivity)
2 = low range (high sensitivity)// not implemented !!
shows 4 digit firmware revision in BCD format

mesytec GmbH & Co. KG
Wernher-von-Braun-Str. 1, D-85640 Putzbrunn, Germanyphone: +49 - 89 / 456007-30 fax: +49 - 89 / 456007-39
info@mesytec.com - www.mesytec.com

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MPRB-16 / 32

16 / 32 channel preamplifier

Temperature Adjustment, Temperature reading

A value proportional to the temperature can be read from register 18 "temperature".
It is possible (but not essential) to adjust a temperature offset via register 23 "Temp offset".
When the temperature is shifted via offset register to a reading value of 2048, the output voltage correction
value is 0. When the temperature gets different to this calibration value, the output voltage is corrected,depending on temperature difference and Temp_slope.

Offset correction of temperature reading

Set register 23 to 128 . (mid position)
Read temperature register 18
Calculate:

temp_offset_val = 128 + (temperature - 2048) / 7

Write temp_offset_val to register 23.
Read temperature register 18, it should now have a value of about 2048

mesytec GmbH & Co. KG
Wernher-von-Braun-Str. 1, D-85640 Putzbrunn, Germany
phone: +49 - 89 / 456007-30 fax: +49 - 89 / 456007-39
info@mesytec.com - www.mesytec.com

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