ILA19002
V
t
FMO
t
MAINS
t
Due to comparator offset, the FMO low to high transition can be occur within a range as
shown above. The time between successive low to high transitions will be equal to the mains
voltage period.
TYPICAL APPLICATIONS
In the Application Circuits (Figures 1 and 2), the components required for power metering
applications, are shown.
In Figure 1 a shunt resistor is used for current sensing. In this application, the circuitry
requires a +2.5V, 0V, -2.5V DC supply.
In the case of Figure 2, when using a current transformer for current sensing, a +5V, 0V DC
supply is sufficient.
The most important external components for the ILA19002 integrated circuit are:
R
2
, R
1
and RSH are the resistors defining the current level into the current sense input. The
values should be selected for an input current of 16µA
RMS
into the ILA19002 at maximum line
current.
Values for RSH of less than 200µΩ should be avoided.
R
1
= R
2
= (I
L
/16µA)
RMS
* R
SH
/2
Where I
L
= Line current
RSH = Shunt resistor/termination resistor
R
3
, R
6
and R
4
set the current for the voltage sense input. The values should be selected so
that the input current into the voltage sense input (virtual ground) is set to 14µA
RMS
.
R
7
defines all on-chip bias and reference currents. With R
7
= 24kΩ, optimum conditions are
set. R
7
may be varied within ±10% for calibration purposes. Any change to R
7
will affect the
output quadratically (i.e.: R
7
= +5%, f
P
= +10%).
The formula for calculating the output frequency is given below:
I
⋅
I
FOSC
f
=
11.16
∗
FOUTX
∗
∗
I
2
V
3.58
MHz
I
R
Where FOUTX = Normal rated frequency (1160Hz)
FOSC = Oscillator frequency (2MHz ...... 4MHz)
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