5/16

Combining the two equations gives:

(RA+RB)/230V=RB/14V

Values for resistors R4 = 10 , R5 = 24k and R6 = 1M is

chosen.

Substituting the values result in:

RB = 23.437k

RA=RBx(230V/14V–1)

RA = 361.607k .

Standard resistor values of R1, R2, R3 and R4 are chosen to

be 120k , 120k , 120k and 10 .

The capacitor C4 is used to compensate for phase shift

between the voltage sense inputs and the current sense inputs

of the device, in cases where CTs with phase errors are used.

The phase shift caused by the CT may be corrected by

inserting a capacitor in the voltage divider circuit. To

compensate for a phase shift of 0.18 degrees the capacitor

value is calculated as follows:

C=1/(2x x Mains frequency x R5 x tan (Phase shift angle))

C=1/(2x x50x1M tan (0.18 degrees ))

C = 1.013µF

The VREF pin of the SA9607 is connected to a resistor that

determines the on chip bias current. The PM9607AP module is

set up for the SA9607M, so the bias resistor is made up of

resistor R17 and trimpot P1 in series. The multi turn trimpot P1

may be varied for precise calibration.

Calibration of the bias current is not necessary when using the

SA9607P as device calibration is loaded from the external

EEPROM.

The GND pin of the SA9607 is connected to the neutral phase,

which is halfway between VDD and VSS. Note that supply

bypass capacitors C1 and C2 are positioned as close as

possible to the supply pins of the device, and connected to a

solid ground plane.

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W

W

W

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p

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Reference Voltage VREF

Ground GND

sames

PM9607AP

Protection

A MOV together with R4 protects the transformer and the

voltage divider circuit against voltage transients.

Common mode and asymmetrical transients are attenuated

by the current setting resistors R8, R9 R10 and R11.

The PM9607AP module uses a transformer based power

supply to ensure flexibility for different counter drive

configurations. The maximum current that can be drawn by

the circuit is as follows:

The average power consumption of the module is usually less.

The current indicated in table 2 is worst-case peak pulse

current. The normal operating current of the module is closer

to 15mA. A 78LC05-voltage regulator is used to regulate the

voltage from the transformer. Two resistors R18 and R19

generate the analog ground voltage for the SA9607. The

SA9607 operates between 5 Volt and 0 Volt with its GND pin

connected to mid-rail.

POWER SUPPLY

Table 4: Maximum peak current drawn by components on

the module

Source

SA9607M/P IC

DIR LED

SEL1 LED

ELT LED

Pulse LED

Counter

GND ref

EEPROM

Total

Max current

5

5

5

5

5

11

3

2

41

Unit

mA

mA

mA

mA

mA

mA

mA

mA

mA

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