1. Low Voltage Supply and Regulation
Henryk Palka, IFJ Krakow, DEPFET-Belle II meeting MPI, March 08, 2010
Low Voltage Supply and Regulation

2. Low voltages for DEPFET
Henryk Palka, IFJ Krakow, DEPFET-Belle II meeting MPI, March 08, 2010
Low voltages for DEPFET
18 voltage lines x 40 half-ladders = 720 PS output channels
1) Can be prohibitive in price (100’s k€)
2) PSs 20-30m away from the ladders
 difficult (imposible?) to regulate voltage drop at the PS
in 2.3A lines
R= 5mΩ/m * 30m [10 mm2 cable]
+ 1.72*10-8 Ωm *0.5 m/(17*10-6 m *3.48*10-3 m)
= 150 mΩ mΩ = 295 mΩ
ΔV = 2.3A * 0.295Ω = 0.68 V (at V0=1.8V)
→ voltage regulators needed, near to the ladder
then the number of PS output channels/half-ladder can be reduced, naively to 4 (+2.5V, +3.0V,+20V, -20V),
in practice to several channels

3. Below Vmin of existing radhard regulators. Use voltage dividers?
Henryk Palka, IFJ Krakow, DEPFET-Belle II meeting MPI, March 08, 2010
VDDA
VDDD
VDDIO
VJTAG
VDDIO
VDDC
PS 3V, 5A
REFIN
AMPLOW
PS 2.5V, 2A
Below Vmin of existing radhard
regulators. Use voltage dividers?
Vclear_on
Vbulk
Vgate_off
Vclear_off
Vsource
Vccg
Vgate_on
Vguard ?
PS 20V, 0.5A
PS -20V, 0.5A
Static voltages, need any regulation?
(fixed voltages with no sensing?)

4. Henryk Palka, IFJ Krakow, DEPFET-Belle II meeting MPI, March 08, 2010
DEPFET Voltages

5. Where to place the regulators:
Henryk Palka, IFJ Krakow, DEPFET-Belle II meeting MPI, March 08, 2010
Where to place the regulators:
x 40
Power unit
(rack)
Dock
DHH
Half-module
~0.5m
~20m
~2m
regulators?
regulators?
space?
Regulators placed at Docks:
-add less than 7% to overall resistance
do not heat up the region which is already critical for cooling
Less radiation hazard (the level O(108 n/cm2/yr) ?)

6. Use radiation tested regulators?
Henryk Palka, IFJ Krakow, DEPFET-Belle II meeting MPI, March 08, 2010
Use radiation tested regulators?
Plain regulators are chip and available in all varieties
Radiation tested are few:
RHL4913A (STM) used in ATLAS, regulates down to 1.22 V, Imax=2A (3A in SMD package)
LM117 (NS) used in CMS, min Vout=1.23V, Imax=0.8A
RH1086 (Linear Tech.), used in Alice, CMS (?)
min Vout=1.23V, Imax=1.5A
- MIC5209 (Micrel) min Vout=1.24V, Imax=0.5A
5950RH (M.S.Kennedy) min Vout=2.5V, Imax=5A
AN1081 (Int. Rectifier) min Vout=1.26V, Imax=3A
None goes below 1.2 V
Availability is another concern

7. RHFL4913A: VIN = 3 - 12 V VOUT = 1.2 – 9 V Vd = ~1V
Henryk Palka, IFJ Krakow, DEPFET-Belle II meeting MPI, March 08, 2010
RHFL4913A:
~5% of IL
goes into
sense wire
Rsense important!
ATLAS: remote sensing, protection:
over- voltage, current,
temperature
Monitoring
CAN Bus
VIN = V
VOUT = 1.2 – 9 V
Vd = ~1V
Pmax = 15 W (~ VIN/VOUT)
Occupies ~ 3.0 cm2 (+external)
Some experience at the Institute in using
this chip for ATLAS TRT regulator board
(Bartek Kisielewski)
Test board to study how it works for
Belle II conditions
More coll. needed to form a critical mass

8. - voltages to be regulated by dedicated circuity
Henryk Palka, IFJ Krakow, DEPFET-Belle II meeting MPI, March 08, 2010
Conclusions
We ought to define
- voltages to be regulated by dedicated circuity
(mix of PS regulated and custom regulated? Nightmare?)
- needed accuracy of the regulation and load currents ranges
- which of the supply lines are current source/current sink
- fix resistivity of the lines
- which protocol for controls (GPIB, CANBus,…)