DATEL DMS-20PC Service Manual

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®®

DMS-20PC Series

3½ Digit, LED Displa y

Actual Size

Features

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Lowest-cost LED meters

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Subminiature size:

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1.38" x 0.88" x 0.48"
35mm x 22mm x 12mm

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Large (0.37"/9.4mm) LED display

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Choice of 5 LED colors

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High-intensity or low-power (7mA) red

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LED's optional

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Epoxy-encapsulated, 12-pin DIP package

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with built-in color filter and bezel

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4 differential input voltage ranges

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Factory calibrated, ±1 count accuracy

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Single +5V power supply

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User-selectable decimal point placement

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DISPLAY ENABLE function for

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"power-down" mode

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DISPLAY TEST and HOLD (optional)

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functions

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0 to +60°C temperature range

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Low-Cost, Subminiature

Digital Panel Voltmeters

DMS-20PC Series, 3½ Digit, LED Display, Digital Panel Voltmeters combine a
precision A/D converter; a factory-trimmed, highly stable, voltage reference; and a
large (0.37"/9.4mm), easy-to-read LED display in a single package that is only
slightly larger than the display itself. Displays are offered in either red, orange,
amber, yellow or green colors. High-intensity and low-power (35mW total) red LED's
are also optional.

These low-cost meters are fully self-contained and fully functional. Their
subminiature (1.38" x 0.88" x 0.48"), epoxy-encapsulated cases incorporate built-in
color filters and bezels; are moisture and vibration proof; and function well in the
harshest environments. Their 12-pin, dual-in-line configuration offers component-like,
plug-in convenience and maximum versatility. Operating temperature range is 0 to
+60°C.

The meters come with one of four, differential, input voltage ranges: ±200mV, ±2V
±20V or ±200V. Input impedance is a minimum 800kΩ. CMRR is typically 86dB (dc
to 60Hz), and CMV is ±2V. Input over voltage protection (on the non-inverting input)
is ±250V. Devices are fully calibrated at the factory to an accuracy of ±1 count
(±0.05% of full scale range) and never require calibration or adjustment.

A DISPLAY ENABLE function permits the display to be disabled for "power­down" operation. All models have a DISPLAY TEST function. Standard red LED
models offer an optional DISPLAY HOLD function.

Small size, low cost and adjustment-free reliability make the DMS-20PC Series
the best choice for all your 3½ digit, LED, DPM applications.

DC/DC

0 Vdc

+5V

–5V

CONVERTER

DATA

A/D

1

909k

12

11

11

R1

10

V+

2

»

R2

+2.0V

0.01
µF

V–

+5V

2

Only used on ±200mV (-0) and ±2V (-1) models.

3

Pin 9 is DISPLAY TEST on all but eight models. On those models

-H option), it is DISPLAY HOLD.

(–) INPUT LO

(+) INPUT HI

ANALOG
COMMON

9

DISPLAY
TEST/HOLD

8

REFERENCE OUT

7

REFERENCE IN

3

+5V SUPPLY

DISPLAY

ENABLE

5V RETURN

DP 3

DP 2

DP 1

1

2

3

4

5

6

1

R2 is not used on ± 2 00 mV (-0) models or ±2V (-1) mode ls .
R2 = 100k on ±20V (-2) models and 9.1k on ±200V (-3) models.

CONVERTER

Figure 1. DMS-20PC Series Simplified Schematic

DATEL, Inc., Mansfield, MA 02048 (USA) • Tel: [phone] Fax: [phone] • E-mail: [e-mail] • Internet: www.datel.com

DMS-20PC

3½ DIGIT, LED DISPLAY DIGITAL PANEL VOLTMETERS

Performance/Functional Specifications

Typical at TA = +25°C and supply voltage = +5V using the single-ended input circuit,
unless otherwise noted.

Analog Inputs Min. Typ. Max. Units
Full Scale Input Range:

DMS-20PC-0 -- ±200 -- m V
DMS-20PC-1 -- ±2 -- Volts
DMS-20PC-2 -- ±20 -- Volts
DMS-20PC-3 -- ±200 -- Volts

Input Impedance:

DMS-20PC-0, -1 100 1000 -- M
DMS-20PC-2, -3 0.8 1 -- M

Overvoltage Protection
Common Mode Voltage Range -- -- ±2 Volts
CMRR (dc to 60Hz) -- 86 -- dB
Control Inputs ➁ ➂
Decimal Point Placement (Pins 4-6) Tie to pin 3 to activate
Display Test (Pin 9) Tie to pin 1 to activate all segments
Display Hold (Pin 9)
Performance
Sampling Rate 2.5 samples per second
Accuracy (3 minute warm-up):

DMS-20PC-0 (VIN = +0.19V) -- ±1 ±3 Counts
DMS-20PC-1 (VIN = +1.9V) -- ±1 ±3 Counts
DMS-20PC-2 (VIN = +19V) -- ±2 ±3 Counts
DMS-20PC-3 (VIN = +190V) -- ±2 ±3 Counts

Zero Reading (VIN = 0 Volts) "–001" "000" "001"
Temperature Drift (0 to +60°C) -- ±0.2 ±0.4 Cnts/°C
Power Supply Requirements
Supply Voltage + 4.75 +5.00 +5.25 Volts
Supply Current:

DMS-20PC-X-RS -- +60 +90 mA
DMS-20PC-X-RL -- +7 +12 mA
DMS-20PC-X-AS -- +90 +120 mA
DMS-20PC-X-GS -- +90 +120 mA
DMS-20PC-X-OS -- +90 +120 mA
DMS-20PC-X-YS -- +90 +120 mA
DMS-20PC-X-RS-H -- +60 +90 mA
DMS-20PC-X-GS-H -- +90 +120 mA
DMS-20PC-X-RH -- + 6 0 +90 mA

Display
Display Type and Size 3½ Digit LED, 0.37"/9.4mm high
Polarity Indication Autopolarity ("–" for negative VIN)
Overrange Indication "–1___" for negative VIN

Physical/Environmental
Operating Temperature 0--+60°C
Storage Temperature –40 -- +75 °C
Humidity (Non-condensing) 0 -- 95 %
Case Material Polycarbonate
Weight 0.4 ounces (11 grams)

➀

Applies for transient or continuous overvoltages applied to (+) INPUT HI (pin 11)
with (–) INPUT LO (pin 12) properly connected. Pin 12 is not overvoltage protected
(see Figure 1). Voltages applied to pin 12 should not exceed the supply voltage.

➁

See Technical Notes.

➂

The DISPLAY HOLD function is optional on standard red and green LED models only.
See Ordering Information.

➀

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-- -- ±250 Volts

Tie to pin 1 to hold last reading

"1___" for positive VIN

Ordering Information

DMS-20PC-1- RS

Input Range:

0 = ±200mV

Ω
Ω

1 = ±2V
2 = ±20V
3 = ±200V

LED Color:

AS = Standard Amber
GS = Standard Green
OS = Standard Orange
RS = Standard Red

Accessories:

DMS-20-CP Panel cutout punch
DMS-BZL3 DMS-20 bezel assembly
DMS-BZL4 DMS-20 bezel assembly with sealing gasket
DMS-EB2 Application/evaluation board with standard

MOLEX connector, decimal point solder pads
and attenuation resistor pads.

A panel-mount retaining clip is supplied with each model.

Leave blank for standard
models.
Add -H for DISPLAY
HOLD option (available on
standard red and green
LED models only).

YS = Standard Yellow
RH = High-Intensity Red
RL = Low-Power Red

Order on-line at www.datel.com

T echnical Notes

1. REFERENCE OUTPUT (Pin 8) and INPUT (Pin 7): Pin 8 is a

precision reference actively trimmed at the factory. In normal
operation, pin 8 must be tied to pin 7 to achieve all listed accuracy
and drift specifications.

2. ANALOG COMMON (Pin 10): This pin is connected to an internal,
low-noise, "relative" ground. It is used in certain differential and
"floating" measurements as described in the Applications section
of this data sheet and Ap Note 3 of the DATEL Panel Meter Catalog.

Pin 10 should not be connected to pin 3 (5V RETURN) or to
your system’s analog ground.

3. Decimal Point Placement: The location of the decimal point is

user-selectable, and the decimal point control pins (DP1-DP3) are
active low functions. Select the appropriate decimal point by tying
the appropriate pin (pin 4, 5 or 6) to pin 3 (5V RETURN). Unused
decimal point location pins should be left open.

Hard wiring is preferable, however, you can use logic gates to
exercise dynamic control over the location of the decimal point if the
following drive conditions are met:

Model Applied "0" Voltage Load Current*
DMS-20PC-X-RL +0.05V max. 0.7mA max.
All Others +0.4V max. 6mA max.

* The driving gates must be able to sink this much current

OL) with a logic "0" output.

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