SA9105F
5.
Pulse Output Signals
The calculated power is divided down to a pulse rate of 64Hz, for rated conditions
on both FOUT1 and FOUT2.
The format of the pulse output signal, which provides power/energy and direction
information, is the only difference between the signals on FOUT1 and FOUT2.
The direction of the energy flow is defined by the mark/space ratio on FOUT1, while
the pulse width defines the direction on FOUT2.
Positive Energy Flow
Negative Energy Flow
Wave form on FOUT1
Wave form on FOUT2
t pp
m
m
m
m
t pp
t pn
m
m
t pn
m
m
t pp = 1.1ms
t pn = 3.4ms
Wave form on DIR
DR-00950
An integrated anticreep function ensures no metering at zero line currents.
The formula for calculating the Output Frequency (f) is given below:
FOSC
(I
I1
I
V1
) + (I
I2
I
V2
) + (I
I3
I
V3
)
f = 11.16 * FOUTX *
*
3.58MHz
3 * I
R2
Where FOUTX
FOSC
I
I1
, I
I2
, I
I3
I
R
= Nominal rated frequency (64Hz)
= Oscillator frequency (2MHz ...... 4MHz)
= Input currents for current sensor inputs (16µA at rated line current)
= Reference current (typically 50µA)
I
V1
, I
V2
, I
V3
= Input currents for voltage sensor inputs (14µA at rated line voltage)
TYPICAL APPLICATION
In the Application Circuit (Figure 1), the components required for a three phase power
metering application are shown. Terminated current transformers are used for current
sensing.
The most important external components for the SA9105F integrated circuit are:
sames
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SAMES [ SAMES ]
