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ΗΡ 8110 Α Service Guide
Device
B
us Inte
r
face & Diagnostics
This section is on schematic 5Β .
7-20
Fu
nctional Desc
r
i
p
tion
Output Boards, depending on the options fitted in
the instrument .
5-TIGER
C
urrent Source
This controls the
p
eriod of the generated signals .
6-Trigger and-Strobe Outputs
These outputs are conditioned
b
efore
b
eing
m
ade
available at the output of t he instrument .
More detailed descriptions of
t
he functional units
f
ollow :
Power Filters
This section is on schematic 5Α .
I
t
p
rovides filtering and decoupling of the
p
ower supplies
n
eeded by
the P eriod B oard.
RF is decoupled by 4
n
etworks, each comprising 2 small-value
capacitors placed either side of an inductor wound on α
f
errite bead .
Ripple decoupling
i
s
p
rovided by
e
lectrolytic capacitors
f
ollowing the
RF decoupling networks .
Device
B
us Interface
This functional unit u ses α DBI (Device Bus Interface)
I
C to
communicate with the Microprocessor . This
I
C is driven serially,
buffered through U201 .
EEPR
O
M
Data
An EEPROM stores specific information
a
bout the
P
eriod
B
oard,
such as its serial number and calibration data. At switch-on the
Microprocessor compares its data with this EEPROM and if
d
ifferences show, uploads data
f
rom the EEPROM . In this w ay the
HP 8110Α
b
ecomes aware of
c
hanges in the instrument (for example
α
P
C B oard change) .
Diagnostics
The output
f
rom t he TIGER IC is received by the
I
SIS
I
C and
p
resented to
U
204, α
D
-Α converter . The output from
t
he
D
-Α
converter
i
s then scaled to
p
roduce
p
ositive-going outputs by U205
and U206, and passed to
U
207, an Α-D converter . The diagnostic
software can then
c
heck that the TIGER IC is working correctly.
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