Substituting the values result in:

RB = 23.437k

RA = RB x (220V / 14V -1)

RA = 396.34k

Standard resistor values of 100k

are chosen for R1 and

180k

for R2. The value of Rtrim is chosen to cover ±20% of

RA. The values in the resistor ladder are used so that the

resistor value halves with the next value. This results in using

only two values in the E96 resistor range.

Resistors R15 and R16 (figure 3) define the current level into

the current sense inputs of the SA2102D. The PM2102DP

meter can be used with most available shunts. The

explanation in this text is given for a 625µ

shunt with an I

of

80A and 50mV at I

. To ensure proper current sensing it is

advisable to use a shunt that will give a voltage drop of at least

20mV at rated conditions. The resistor values are calculated

for an input of 16µA

on the current sense inputs at rated

conditions. The design equation is as follows:

R15 = R16 = (I / 16µA) x R

/ 2

I = Line current

R

= Shunt value

Also see the section on

.

T

W

W

W

W

W

W

CURRENT SENSE INPUT

REFERENCE VOLTAGE

MA

X

MA

X

RM S

LSH

L

SH

DESIGN EXAMPLES

he on chip reference current is derived from a 47k

resistor

sames

RM2102DSE

3/16

Figure 2: Voltage divider circuit and Resistive Calibration Network

http://www.sames.co.za

connected between pin 3 of the device and VSS.

Analog Ground (GND)

The GND pin of the SA2102D is connected to the live phase,

which is halfway between V and V .

The PM2102DP meter can be connected directly to live and

neutral at terminals 3 and 4 on the meter-box. These terminals

are internally connected to J1 on the PCB. The current must be

connected to terminals 1 and 2 on the meter-box, which is

internally connected to J2.

DD

SS

PM2102DP METER SETUP

External Connectors

PRELIMINARY

R1

R2

R4

R5

R6

R7

R10

R11

R12

R13

J3

J4

J5

J6

J7

J8

J9

J10

NEUTRAL

LIVE IN

R14

RB

R18

RA

LIVE IN

LIVE OUT

Shunt

R15

R16

IIN

IIP

Figure 3: Current sensing using a shunt

Opto-isolated

Pulse output

Current In

Current out

Live

Neutral

12345

6

1+

2

3-

4

Counter

Figure 4: Current and mains voltage connection diagram