SA9105F

sames

8/12

C

A/D converters. The typical value of C

560pF.

The actual values determine the signal to noise and stability performance. The tolerances

should be within ± 10%.

C

converters. The typical value of C

and larger than 5nF should be avoided.

Terminated current sensors (current transformers) are connected to the current sensor

inputs of the SA9105F through current setting resistors (R

The resistor values should be selected for an input current of 16

µA

at the rated line current.

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

=

Current transformer termination resistors for the three phases.

R

R

P

3. The values should be selected so that the input currents into the voltage sense inputs

(virtual ground) are set to 14

µA

are for decoupling and phase compensation.

R

conditions are set. R

to R

∆R = +5%, ∆f = +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.