PM9105AF

sames

5/10

The values of these resistors should be calculated as follows:

Phase 1:

R

Phase 2:

R

Phase 3:

R

Where I

LX

=

Secondary CT current at rated conditions.

R

=

Termination resistors of the three current transformers.

R

R

for Phase 3. The values should be selected so that the input currents into the voltage

sense inputs (virtual ground) is set to 14

µA at nominal line voltage. Capacitors C1,

C2 and C3 are for decoupling and phase compensation.

R

With R

optimum conditions are set. P

Any changes to R

∆R = +5%, ∆FOUT =

+10%).

XTAL is a colour burst TV crystal (f = 3.5795 MHz) for the oscillator. The oscillator

frequency is divided down to 1.7897 MHz on-chip to supply the digital circuitry and

the A/D converters.