DATEL DMS-EB-RMS Datasheet

Actual Size

®®

R1

R2

R3

U2

12

1

C4

1

SG4

SG3

U1

PS1

J1

U3

JP1

J6

2

C2

C1

C5

J4

TB1

J5

SG1SG2

J2

J3

1

23 456

11

10

9

8

7

DMS-EB-RMS

AC-to-RMS Con v e rter

Application Board for

Purchase on-line at www .datel.com

Features

••

•

Displays true rms values of ac inputs

••

••

•

±0.5% accuracy for DMS-30PC-0

••

or DMS-30LCD-0-5

••

•

±2% accuracy for DMS-30PC-1

••

or DMS-30LCD-1-5

••

•

Also works with DMS-40PC/LCD meters

••

(see Ap Note 11)

Functional Specifications

(TA = +25°C, VCC = +5V)

Vac Measurement Range:

±200mV meters 0 to 199.9Vac
±2V meters 0 to 750Vac

Conversion Accuracy:

0-200Vac ±0.5%
0-750Vac ±2%

Crest Factors

3, maximum

Input Frequency Range

40Hz to 2kHz

Primary Operating Power

+5V (±5%)

Current Consumption (Board only)

+0.5mA typ., +1mA max.

Operating Temperature Range

0 to +60°C

Storage Temperature Range

–20 to +75°C

Humidity

0 to 95%, non-condensing

Dimensions

2.02" (51.31mm)W x 0.83" (21.08mm)H

Ordering Information

DMS-EB-RMS AC-to-RMS conversion
DMS-BZL1 Bezel assembly

DMS-BZL2 Bezel assembly with

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

DATEL makes no representation that the use of its products in the circuits described herein, or the use of other technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained

herein do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without notice. The DATEL logo is a registered DATEL, Inc. trademark.

board

sealing gasket

Tec hnical Notes

Description: The DMS-EB-RMS board allows the true rms value of ac signals to be displayed

on 5V -powered DMS-30PC/LCD digital voltmeters . The meter/board combination has an input
range of 0-750Vac with ±2V meters (1V ac resolution) or 0-199.9V ac with ±200mV meters
(0.1Vac resolution). A built-in scre w-terminal block reliably interfaces signal and po wer
connections. The DMS-EB-RMS now accommodates user-installed modifications such as
input-scaling resistors and isolated +5V dc/dc converters.

Power and Safety Precautions: The DMS-EB-RMS’s A C HI and AC LOW inputs are not
electrically isolated from its 5V supply (AC LOW is connected directly to 5V RETURN).
When measuring any input signal which is derived from ac power mains, a dedicated (i.e.,
it only powers the DMS-EB-RMS), transformer-isolated +5V supply, with a minimum 1kV
breakdown rating, must be used to power the DMS-EB-RMS board/meter combination.
When measuring ac power mains inputs, never connect the DMS-EB-RMS’s 5V RETURN
to chassis/earth ground anywhere in the system. Failing to follow these instructions could
defeat any safety grounding and will place the system +5V power supply, and all its
associated circuitry, at dangerously ele vated ac-line potentials. In many applications, the
DMS-EB-RMS installation is required to meet
electrical code requirements. To ensure

safe operation, the DMS-EB-RMS board
should only be installed and serviced by
technically-qualified personnel. See DMS

Application Note 11 for more details.

(–) INPUT LO

(+) INPUT HI

REF. OUT

REF. IN

DMS-30PC/LCD Meters

C1 100µF

+

5

CAV

12

11

10

9

8

7

SG4

6

OUT

7

+V

8

COM

TB1

Figure 1. DMS-EB-RMS Schematic Diagram

AC HI

S

U1

J1

C2

10µF

1

–V

S

CF

V

IN

CC

+

R1

988kR2988k

JP1

3

AC LOW

4

3

2

1

C4

2.2µF

R3

1.98k

56

+5V

+

5V Return

5

V

6

LV

7

OSC

8

V+

J4

U3

1

V

IN

V

GND

4

OUT

CAP–

C5

3

GND

2.2µF

U2

Q

3

OUT

2

+

2

CAP+

1

BOOST

J5

PS1

Q

2

4

+V

IN

+V

DC/DC

3

–V

OUT

–V

1

J6

Components are user-supplied

Q

and not part of the standard product.

+5V SUPPLY

1

2

5V RETURN

3

SG1

DP3

4

SG2

DP2

5

SG3

DP1

6

DS-0398A 1/98