Philips pm2521 - Page 119

130
OQ0063
PROGRAMMABLE
CURRENT SOURCE Specification
of the inputs and
outputs of the
000063
ST2485
1
rs
C
Cs
c
1
rc
c
Vss
C
C
.clock C
C.clockc
RNG
B
C
V
OUTc
C
COMP,
c
00
0063
18
1
^
0
1
rp
Cs
1
Rx
GNO
Vdd
RNG A
RNG
C
-Vin
+Vin
/
Pin
no.
1
2
3
4
5
6
7
8
g
10
11
12
13
14
15
16
17
18
Name
Description
Irs
Ref.
current adjustment
Cs Smoothing
Capacitor
Ire
1
Ref.
Common
Vss Supply
C
clock
C clock
RNG B
Range B
V out
Output voltage
C comp
C.
Compensation
-i-Vin
-t-
input
—Vin
—
input
RNG
C
Range
C
RNG
A
Range
A
Vdd
Supply
GND
GROUND,^
1 out
Cs
Irp
With Rs the
output current
can be adjusted.
Smoothing
capacitor for
the
switched currents.
Common
connection of
Rs and
Rp.
Negative
supply voltage.
Capacitor
for the
clock-oscillator.
Range
information
(see
12,
13).
Output of the
compensation
amplifier.
Compensation
capacitor for the
compensation
amplifier.
+
and
—
input
of the
compensation/protection
amplifier.
Compensation:
With the ampifier the
current
consumption of
the ADC
is
compensated
during 12
measurements.
Protection:
With the
amplifier also the
leak current through
the
protection
diodes during 12
measurements
is compensated.
Together with
signal
RNG B the signals
determine the
digital
range
information
from the jUP.
Range
Measuring
current
RNG A RNG
B RNG
C
1
kl2
1mA
1 1
1
10
kl2
100
A
0
0
0
100
kl2
10
M
A
1
0
0
1Ml2
1
M
A
0 1
0
10M12
100
nA
1
1 0
Positive
supply
voltage.
Supply
zero
^
Output current.
Smoothing
capacitor.
With
Rp
the
temperature-coefficient
of
the reference current
is
determined.