CONNECTION DIAGRAM

BASIC CONFIGURATION

Tel: +44 (0)20 7380 8167 Fax: +44 (0)20 7874 1908 http://www.anders.co.uk

APPLICATION CIRCUITS

MULTI-RANGE DC VOLTAGE MEASUREMENT

For multi-range, use a 2 pole,

4 way rotary switch. 1 pole for

range select and the other to

connect the appropriate

decimal point to XBP.

DC CURRENT MEASUREMENT

It is important to note the power

dissipation in the shunt and choose

resistor rating accordingly

Vs

Ω

EXAMPLES

2

2

Current

200mA

1

Ω

0.04W

2A

0.1

Ω

0.4W

MULTI-RANGE DC CURRENT MEASUREMENT

For multi-range, use a 2 pole,

5 way rotary switch. 1 pole for

range select and the other to

connect the appropriate

decimal point to XBP.

DC VOLTAGE RATIO MEASUREMENT

To determine the ratio between two

voltages apply the inputs as shown.

V2

X 1000

Over range occurs when

V1

V1

To achieve a zero display reading

for a non-zero voltage input,

apply the offset voltage between

COM and INLO.

For a positive offset apply a

Positive signal to INLO w.r.t.

COM.

Apply the input signal between

INHI and COM

.

DC VOLTAGE OFFSET

The OEM22/24L is designed for 9/5V supply. Incorrect

supply polarity will destroy the module immediately. It is

ready for general use when connected as in figure 1, for

9V supply. For 5V supply, the module must be calibrated

before use as follows. Connect as in figure 2, apply

100mV to the inputs, from a calibrated source and adjust

VR1 until the display reads 1000.

The input range is 0-200mV. Over-range is indicated by

blanking the three least significant digits and displaying a

"1" in the most significant digit.

For 9V operation it is recommended to power from a 9V

battery. The inputs are intended to float with respect to the

supply but if they do not float they must be no closer than

1.5V from either VDD or VSS (VDD-1.5V and VSS+1.5V).

See the circuits for non-floating inputs below.

The low BAT voltage can be set adjusting VR2 but it is not

recommended to operate with a supply voltage below 7V.

USER INSTRUCTIONS

All annunciators are connected to BP for suppression

purposes. To light up, cut the trace between the selected

annunciator pad and BP track and then link with solder

the annunciator pad to the XBP pad next to it.

For 5V operation, INLO must be connected to TST for

non-floating inputs (as fig. 2) and to the analogue common

pin COM for floating inputs. The low BAT annunciator

needs to be turned of by adjusting VR2.

Where a single 5V supply is not

suitable but you must connect your

input signal ground to the module

supply ground, then either of these two

non-floating input circuits can be used.

Note that the module is set in the 9V

supply mode.

NON FLOATING INPUTS (a)

NON FLOATING INPUTS (b)

Using the formulae choose resistors to

ensure the analogue inputs are no

closer than 1.5V from either VDD or

VSS (VDD-1.5V or VSS+1.5V)

DC VOLTAGE MEASUREMENT

To measure voltages greater than 200mV

an attenuator is required.

R1+R2

EXAMPLES

Display

R1

R2

2V

1.999V

199.9mV 1M

Ω 110KΩ

10V 1500rpm

150mV

1M

Ω

15K

Ω

R2

The input impedance becomes R1+R2. Choose accurate stable

resistors. Typically, R1=1M

Ω. 9MΩ is a practical upper limit.

Revision 8 17/011/04