us Bar Measurement
OUTLINE TPC low voltage distribution scheme Digital current variation

Test Setup Measurements
preliminary
results Conclusion
J. Baechler, C. Engster, L. Musa 2
15 April 2003
Luciano Musa
121 FEE Cards
TPC Low Voltage Distribution Scheme
115A max
115A max
115A max
DIGITAL
ANALOGUE
DIGITAL
Bus Bar pair
(positive + return line)
Bus Bar pair
40m
Wiener power supplies
Analogue
4.0
60
60
100
Digital
3.3
133
194
200
Voltage
on load
(V)
I stdby
(A)
I max
(A)
Bus bar
Section
(mm2)
Bus Bar
description
TPC endplate
What is the
transient
response of the
bus bar?
R = 2 x 6.8 m
: '
V = 816mV
R = 2 x 3.4 m
: '
V = 1.32V
L ~ 11
P
H 3
15 April 2003
Luciano Musa
Regulator
100 µF
1 µF
Power Supply
10 × 100 nF
ALTRO
Current Consumption during Trigger
0
50
100
150
200
Time (µs)
C
u
r
r
e
n
t
(
a
.u
.)
4
P
s peaking time
Standby power
(15A /
P
s)
60A
Dynamic Digital Current Consumption
3.3V
2.5V 4
15 April 2003
Luciano Musa
Regulator
100 µF
1 µF
Power Supply
10 × 100 nF
ALTRO
Current Consumption during Trigger
0
50
100
150
200
Time (µs)
C
u
r
r
e
n
t
(
a
.u
.)
100
P
s peaking time
Standby power
Dynamic Digital Current Consumption
(0.6A /
P
s)
60A
3.3V
2.5V 5
15 April 2003
Luciano Musa
C
R
Test Configurations
Configuration A:
R =
f
C=0
Configuration B:
R=25m
:
C=0;
Configuration C:
R=25m
:
C=70mF
Configuration D:
R =
f
C=70mF
Test setup
I
Load
time
'
I
T
High
40m
Wiener
PL500
)
160mm
2
multi-strand copper bar
Electronic Load
HP6050A 6050B
V
PS
V
Load
I
h=1cm = 2.1
u
10
-8
:
m
L = 11
P
H 6
15 April 2003
Luciano Musa
62.6V
0.8ms
680mV
'
I (A)
Freq (Hz)
'
T
HIGH
(ms)
Slew rate (A/
P
s)
60
100
4 10
Test Parameters
Measurement 1 (configuration A )
A sudden interruption of the current can damage the Front End Cards ! 7
15 April 2003
Luciano Musa
'
I (A)
Freq (Hz)
'
T
HIGH
(ms)
Slew rate (A/
P
s)
41.6 100 4
10
Test Parameters
A current swing of 41.6A produces
a transient voltage of ~1.8V
480mV
1.28V
0.78V
Measurement 2 (configuration B )
W
L/R ~

ms
Voltage drop across the bar for a current
swing of 60A '
V low load (dc)
0.90 V '
V high load (dc)
1.32 V '
V (transient)
3.40 V 8
15 April 2003
Luciano Musa
'
I (A)
Freq (Hz)
'
T
HIGH
(ms)
Slew rate (A/
P
s)
41.6 100 4
10
1000 0.1

Test Parameters
70mF in parallel to the electronic load assorbes the large transient spikes
Measurements 3 (configuration C )
0.95V
0.30V
A
B
A
B
B
A
ALICE TPC conditions 9
15 April 2003
Luciano Musa
'
I (A)
Freq (Hz)
'
T
HIGH
(ms)
Slew rate (A/
P
s)
60 10 40
10
Test Parameters
Measurements 4 (configuration D )
2V 10
15 April 2003
Luciano Musa
'
I (A)
Freq (Hz)
'
T
HIGH
(ms)
Slew rate (A/
P
s)
60 100 4
10
1000 0.1

Test Parameters
A
B
B
A
A
B
3.3V
2.5V
100
P
s
Measurements 5 (configuration A + sense wire )
The sensing feedback is not fast enough to react to the load variations
ALICE TPC conditions 11
15 April 2003
Luciano Musa
Measurements 6 (configuration C + sense wire )
'
I (A)
Freq (Hz)
'
T
HIGH
(ms)
Slew rate (A/
P
s)
41.6 100 4
10
Test Parameters
1.2V
The sensing feedback is not fast enough to react to the load variations 12
15 April 2003
Luciano Musa
220mV
100
P
s
Measurements 7 (configuration C + sense wire )
'
I (A)
Freq (Hz)
'
T
HIGH
(ms)
Slew rate (A/
P
s)
41.6 1000 0.1
10
Test Parameters
The sensing feedback is not fast enough to react to the load variations
C = 100mF 13
15 April 2003
Luciano Musa
Summary and Conclusions
‰
The distribution of the Analogue Voltage (static load) does not pose any
problem
‰
The distribution of the Digital Voltage (dynamic load) requires the insertion
of protection capacitors
‰
The protection capacitors have to be very close to the front-end cards
‰
The long term reliability of large-value capacitors (10mF) has to be verified!
Configuration
Voltage (digital)
Voltage drop
Required Voltage
on load
across bus bar
at the source
No CAP
~3.4V
~6.7V
70mF CAP
~1.2V
~4.5V
3.3V 14
15 April 2003
Luciano Musa
TPC SECTOR TEST 15
15 April 2003
Luciano Musa
TPC SECTOR TEST