Table of Contents
Advertisement
Trigger Input
Thi s sectio n i s on sche matic 5C .
I
t co n di t i o n s an extern ally
a
pplied trigger signa l.
External Trigger Signal
HP 811 OA Se r vice Guide
Th e external
T
r i gger si gnal enters t h rough J301 . Th e inpu t
imp edan ce
i
s swi tchabl e to either 50 Ω or α high imp edance in the
regi on
o
f 10 k Ω , u sing Q301, relay Κ301 and assoc iated comp o ne nts .
Comparator
U
301 i s α fast comp arator t hat shapes t he incoming trigger s ignal
a
n d sets i t to
E
C L le vel s . CR301 and C R 302
p
rovide inpu t overload
p
rotect i o n for
U
301 .
T
hresh old Generation
Th e thres hold at w hich
t
he
f
ast comp arator,
U
301 op erates, is set
by
t
he linear 8- bit
D
-Α converter U302 . The voltage ra nge of the
DAC
b
eing set by U 304 A
a
nd U304 D to
m
ake it comp atible wit h
U301 . Th e digital inform ation controllin g
U
301 can
b
e set on the
instrument by t he user, or sen t in on t he HP- ΙΒ in terface .
The differe nt i al
o
utput sign als
f
rom the differen t ial amplifier
U
301
are
p
assed to Q P 301 where th ey are combin ed and converted to
EE C L l e v el s and sent to the TIG ER IC .
TIG ER IC
Thi s secti on i s on sche matic 5D .
I
t contain s t h e TIGER IC and i ts associated circuitry. Th e TI GER
IC i s co ntrolled over th e DBI (in funct ional uni t 5Β ) .
U
402 i s α RAM IC that stores data for burst operation
o
f th e TIGER
IC . The data is receiv ed initially by t he DBI
a
nd
p
assed to t h e RAM
a
fter C MOS/ EC L convers i on in mul tipl exers U403 an d
U
404 . Th e
TIG ER IC addresses the RAM when data operat ion i s requi red .
Th e TIG ER IC h as 4 out puts:
1 . Ch annel 1
2 . Ch a nn el 2
3 . Strob e
4 .
T
rigger
Th ese are connected to the diagn ostic circuitry throug h R403 -
R
406 .
P
ower reg ul atio n is
p
rovided by U 405 (- F5
V)
and
U
406 (-5 V)
F
u nction al Descriptio n
7-
2 1
Advertisement
Table of Contents
