SA9602E
TYPICAL APPLICATION
퐼퐿
푅푆퐻
2
80퐴 250휇Ω
In Figure 6 the components required for a stand-alone power
metering application are shown. The application uses a shunt
resistor for the mains current sensing. The meter is designed
for 220V/80A IMAX operation. The most important external
components for the SA9602E integrated circuit are the
current sense resistors, the voltage sense resistors as well as
the bias setting resistor.
푅6 = 푅7 =
×
=
×
≈ 620Ω
16휇퐴
16휇퐴
2
Voltage Divider
The voltage divider is calculated for a voltage drop of 14V.
Equations for the voltage divider in Figure 6 are:
푅퐴 = 푅1 + 푅2 + 푅3
(
)
푅퐵 = 푅11 || 푅10 + 푃1
Bias Resistor
R12 defines all on-chip and reference currents. Optimum
conditions are set by using R12=24k. Device calibration is
done on the voltage input of the device.
Combining the two equations gives:
(
)
푅퐴 + 푅퐵
푅퐵
14
=
220ꢆ
Shunt Resistor
The voltage drop across the shunt resistor at rated current
should be at least 20mV. A shunt resistor with a value of
250μis chosen. The voltage drop across the shunt resistor
is therefore 25mV at rated conditions (IMAX). The maximum
power dissipation in the current sensor is:
A 5k trimpot will be used on the voltage channel for meter
calibration. The center position on the pot is used in the
calculations. Therefore P1=2.5k and values for resistors
R10=22kand R11=1M are chosen.
Substituting the values will result in RB=23.91k and
RA=352k. Therefore R1, R2 and R3 are chosen to be
120k.
푃 = 80퐴 ꢂ × 250휇Ω = 1.6푊
(
)
Current Sense Resistors
The resistors R6 and R7 define the current level into the
current sense inputs of the device. The resistor values are
selected for an input current of 16μARMS on the current inputs
of the SA9602E at rated conditions. According to the equation
described in the Current Sense Inputs section:
SPEC-3117 (REV. 5)
29-09-2017
6/10
SAMES [ SAMES ]
