Ammeter
Section
The
ammeter
section
converts
current
owing
into
to
corresponding
digital
data.
The
section
includes
an
I-V
converter
,
reference
current
source
,
and
the
Analog-to-Digital
Converter
.
I-V
Converter
.
Figure
4-5
shows
the
I-V
converter
block
diagram.
Figure
4-5.
I-V
Converter
Block
Diagram
The
I-V
Converter
is
essentially
an
integrator
composed
of
an
operational
amplier
and
a
capacitor
.
When
current
Ix
ows
into
the
integrator
,
the
current
charges
capacitor
C.
As
a
result,
the
integrator
outputs
a
negative
going
ramp
of
which
slope
is
0I
x
C
.
The
current
Ix
can
be
obtained
by
0C
1v
1t
,
where
1t
is
a
certain
time
interval,
and
1v
is
the
output
voltage
drop
for
this
interval.
Capacitor
C,
which
is
called
range
capacitor
,
determines
the
applicable
measurement
range
in
a
practical
integrator
.
Reference
Current
Source
.
The
Reference
Current
Source
is
an
internal
current
reference
,
which
provides
the
I-V
converter
with
some
sets
of
pre-dened
dc
currents
.
The
source
is
used
for
the
power-on
self
test
sequence
and
for
the
calibration
function.
T
roubleshooting
4-7
