Download Power Supply Testing

Pixel Power Supply Response Measurement
Lalith Perera - Univ. of Iowa
Carlos Florez , Simon Kwan, Charles Newsom, Christian Veelken
• Response of the CAEN power supply to transient
currents
• Response of the power supply to remote shut
down.
8/11/2006 FPIX TB meeting
L. Perera
1
CAEN Power supply overview
•
•
•
•
SY2527 system mainframe
• Can install six A1676A branch control
cards
A1676A branch control card
–
Controls one E4000 crate
E4000 crate
–
Accommodates 8 power modules
CAEN E4603 power module
–
Each unit has two independent power
units
• Two low voltages 2.5V, 1.75V
(remotely sensed voltage control, up
to 6V at the supply)
• Two high voltages.
8/11/2006 FPIX TB meeting
L. Perera
2
Objective
• Preliminary testing to get familiar with using the power supply with
the MSC cable for the system test
• Make sure that power supply meet system requirements and behave
well with remote sensing:
– Current fluctuations changes the voltage drop across the supply
cable resulting fluctuating voltage at the load.
scope
48V
CAEN
A4603
Cable ~40m
Load
CAEN
SY2527
8/11/2006 FPIX TB meeting
Pulse generator
L. Perera
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CMS pixel power cable (MSC)
• We used a 40m length of MSC cable
• Six 4mm2 cables for LV
– 4 for 2.5 V
– 2 for 1.75
• Resistance of each cable 0.005W/m
• Cables for sense wires and HV
8/11/2006 FPIX TB meeting
L. Perera
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switching
transistors
Jumper
switches
resistor
elements
Test Load
• Six resistors ~1.6W (connected through
jumper switches - up to 8A current)
Test Setup
8/11/2006 FPIX TB meeting
• Two 0.1W connected through switching
transistors (FET) (2A pulse current)
L. Perera
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Results
voltage at
the load
pulse current
control pulse
2.5V
1.75V
• No observed oscillations
• Voltage drops by ~ 0.5V when load change by 2A.
• recovery time of the power supply
– 2.5V ~50 ms, 1.75V 100 ms
• There are small (50mV) spikes at ~ 80kHz likely to be coming from
from switching in the power supply
8/11/2006 FPIX TB meeting
L. Perera
6
response to 1ms pulse
after adding 13mF capacitor
•Voltage fluctuation can be lowered by adding decoupling
capacitors near the load
•However in the real detector load is distributed, so capacitors at
each ROC should take care of the fluctuation
8/11/2006 FPIX TB meeting
L. Perera
7
Remote Shut Down
• CAEN power supply is controlled by the DCS computer so
can be turned on/off through DCS. It is software controlled so
would to be too slow for an emergency shut down.
There are two control inputs to SY2527 to turn
off all channels.
•KILL: input for a TTL/NIM signal
“ The KILL input signal, sent through the
relevant connector, allows to switch the channels off
at the maximum rate available, regardless of the
Ramp-Down or other parameters.”
•INTERLOCK: close/open circuit input
“The INTERLOCK condition allows to switch
off simultaneously all the channels, similar to the
KILL command”
8/11/2006 FPIX TB meeting
L. Perera
8
Shut Down Response Time Measurement
5v
KILL
Pulse generator
power supply
load
scope
Test setup to measure KILL response time
From PLC
relay
INTERLOCK
power supply
load
scope
Test setup to measure INTERLOCK response time
8/11/2006 FPIX TB meeting
L. Perera
9
Results: KILL
KILL
Power Digital
Response
time
Power Ana.
68ms
40ms
18ms
36ms
96ms
27ms
Response time to KILL changes from few ms to ~100ms
8/11/2006 FPIX TB meeting
L. Perera
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INTERLOCK Response Time
INTERLOCK
36ms
Power Digital
42ms
68ms
Power Ana.
•Measured INTERLOCK response time is tens of ms and varies
•It could be that both KILL and INTERLOCK is activated by
software
So depending on where it occurs in the control loop of the
power supply it gives a different response time.
This needs to be verified with CAEN.
8/11/2006 FPIX TB meeting
L. Perera
11
Conclusions
•
Power supply behaves well to transient currents with the
CMS MSC cable. No oscillations observed.
•
Remote sensing time constant of the supply voltage is about
25 ms.
•
There are two remote hardware shut down modes
(INTERLOCK, KILL) available. Both have response times in
the order of tens of ms
8/11/2006 FPIX TB meeting
L. Perera
12