Issued April 1997
8105
31⁄2 DIGIT LCD DPM
Instruction Leaflet
DPM 125 RS stock no. 257-212
● Ultra compact
● 12.5mm Digits
● Ultra low power
● Snap-in bezel
A uniquely compact LCD DPM ideally suited for low or high volume applications
featuring an exceptionally large display in a sub-miniature package. The meter will plug
directly into a SIL socket or can be panel mounted using the snap-in bezel provided. The
low profile bezel incorporates a flat reverse printed window giving a superb appearance
that cannot be damaged or rubbed off by contact.
This DPM features Auto-zero, Auto-polarity, 200mV FSD, 12.5mm Digit height, Low
battery indication and logic selectable decimal points. On-card solder pads for essential
inter-connections make selection of the operating mode quick and easy with the
minimum of external wiring. Very low current consumption allows long battery life
making it especially useful in portable equipment.
48 (1.89)
a b
24 (0.94)
a. 1.5 (0.06)
b. 9.0 (0.35)
c. 5.0 (0.20)
d. 1.6 (0.06)
e. 4.0 (0.16)
g
h
40.5 (1.59)
Panel cut-out
45 x 22.2 (1.77 x 0.87)
i
Viewing Area display TEST mode
14 (0.55)
f
18.2 (0.72)
cde
RH0
RH1 (HOLD)
RL0
COM
IN LO
IN HI
V+
VTEST
DP3
DP2
DP1
20.4 (0.80)
38 (1.50)
f. 10.4 (0.41)
g. 7.5 (0.30)
h. 2.54 (0.10)
i. 0.5 (0.20)
-1888
31 (1.22)
00000
8105
PIN Functions
1.
2.
3.
4.
DP1.
DP2.
DP3.
TEST.
199.9
19.99
Connect to V+ to display required DP.
1,999
Connect to V+ to display segments as illustrated. It should not be operated
for more than a few seconds as the d.c. voltage applied to the LCD may
“burn” the display. This pin is normally at 5V below V+ and is the ground
for digital section of the meter. It can be used to power external logic up
to a maximum of 1mA.
5. V-.
Negative power supply.
6. V+.
Positive power supply.
7. IN HI.
Positive measuring input.
8. IN LO.
Negative measure input.
9. AN COM. The ground for the analogue section of the converter, held actively at 2.8V
(Nom) below V+. AN COM must not be allowed to sink excessive current
(>100µA) by connecting it directly to a higher voltage.
10. REF LO. Negative input for the reference voltage (can be connected to AN COM via
Link 3).
11. REF HI.
Positive input for reference voltage (connected via Link 1 to REF OUT).
12. REF OUT. Positive output from internal reference.
}
Circuit Diagram
PL1 6
V+
C1
R1
R8
7
IN HI
47n
180K
220n
C2
C3
1M
10n
8
IN LO
L2
9
COM
LS
11
10
REF LO
C5
47P
R4
R11
4
TEST
0R
V+
L1
RS
100K
IN LO
6 OBC2
180K 7
8 OBC1
TEST VS4
V+
POL
A1
B1
C1
D1
E1
F1
G1
A2
B2
C2
D2
E2
F2
G2
A3
B3
C3
DS
ES
F6
G3
AB
BP
27
12
11
10
9
15
13
14
19
18
17
16
21
20
32
30
23
31
22
25
24
29
26
28
7
24
23
21
20
19
25
22
28
27
17
16
14
1
28
3
2
12
11
10
4
5
8
15
R8
RS
10 3
13 4
9 10
1
DP1
2
1
199.
6
DP2
5
V+
19.99
8
DP3
9
3
1,999
6
R12
R13
R14
14
1M
1M
1M
11
1M
RCH
V+
LCD
LOW BAT
V+
12
R9
12
38
40
COM
42
C REF+
41 C REF44 REF HI
43
REF LO
4 OBC S
C4
100n
REF HI
35
INT
36 BUFF
37
A/Z
39
IN HI
IC2
13
SK
390K
R7
TR1
BCK1
1K5
V-
2
5
R10
120K
7
4
8105
Component Layout
R8 R11 C5 R4
R5
R7
R6
C4
R9
TR1
C3
R10
IC1
C2
IC2
R1
R3
C1
R12 R13 R14
Applications
Input scaling: Two resistors may be used to alter the full scale reading of the meter - See
table.
+
IN HI (7)
Ra
Rb
-
IN LO (8)
Required F.S.R.
2V
20V
200V
2000V
200µA
2mA
20mA
200mA
Ra
910K
1M
1M
1M
LINK
LINK
LINK
LINK
Rb
100K
10K
1K
100R
1K
100r
10R
1R
Analogue inputs
IN HI, IN LO and REF LO are different inputs. They respond only to the voltage across them
and not their voltage with respect to the power supply. However, no input must be higher
than 0.5V below V+ or lower than 1.0V above V -. If the power supply is floating with
respect to the circuit being monitored, connect IN LO and REF LO to AN COM for best
results. If there is any danger that an input may be taken beyond the power supply rails, a
series resistor MUST be fitted to limit the input current to less than 100µA.
Circuit connections
The DPM can be configured for any of the applications shown below. Interconnections can
be made by one of two methods:
1. Via the user’s conditioning PCB, terminating at the DPM edge connector.
2. Bridging solder across the appropriate solder pad links provided (see circuit
diagram).
Panel fitting
Fit the bezel to the front of the panel and then locate the meter into the bezel from behind.
Alternatively the meter and bezel may be assembled before fitting into the front of the
panel but care must be taken not to use excessive force.
3
8105
Link pad 3
510k
Cut link 1
11
IN HI
10
10k
7
V+
6
8
7
510k
5
V-
Link pad 3
In put
voltage
7
IN HI
8
5
VMeasuring a floating voltage
source of 200mV full
V+
6
IN HI
8
IN LO
7
In put
voltage
9
IN LO
IN LO
Link pad 3
V+
6
IN HI
8
IN HI
IN LO
5
Measuring the ratio of two
voltages.
Reading = 1000 V2/V1
COM
Offset
voltage
REF LO
V+
6
V-
Measuring a supply voltages.
(min 7.5V, max 15V).
In put
voltage
Link pad 2, 3
IN LO
8
7
V+
6
REF HI
10mF
5
VZero display when the applied
input is not zero, the offset
and input voltages should
be applied as shown.
Specification
2
+
4
V-
8
3
+
5 - +10mF 5
Measuring a single ended input reference to supply.
Note: 7660 is a +5V DC to -5V DC voltage converter.
See Semiconductors section of the RS catalogue
Min.
d
Accuracy (± 1 count)
Linerity
Sample rate
Temp Stability
Temp range
Supply voltage (V+ to V-)
Supply current
Max. d.c. input voltage
Input leakage current (Vin = 0V)
Low battery threshold
Typ.
Max.
Unit
0.05
0.1
±1
%
Count
per sec
ppm/¡C
¡C
V
µA
V
pA
V
3
100
0
7.5
9
150
1
7.5
50
15
±20
10
The information provided in RS technical literature is believed to be accurate and reliable; however, RS
Components assumes no responsibility for inaccuracies or omissions, or for the use of this information, and all use
of such information shall be entirely at the user’s own risk.
No responsibility is assumed by RS Components for any infringements of patents or other rights of third parties
which may result from its use.
Specifications shown in RS Components technical literature are subject to change without notice.
RS Components, PO Box 99, Corby, Northants, NN17 9RS Telephone: 01536 201234
An Electrocomponents Company
© RS Components 1997