ACS704 Allegro Micro Systems, Inc., ACS704 Datasheet - Page 16

• Manufacturer Part Number: ACS704
• Manufacturer: Allegro Micro Systems, Inc.

Transient Common-Mode Voltage Rejection in the ACS704
ACS704ELC005-DS, Rev. 7
In order to quantify transient common-mode voltage rejection for the ACS704, a device was soldered onto a printed
circuit board. A 0.1 μF bypass capacitor and a 5 V dc power supply were connected between VCC and GND (pins 8 and
5) for this device. A 10 kΩ load resistor and a 0.01 μF capacitor were connected in parallel between the VOUT pin and
the GND pin of the device (pins 7 and 5).
A function generator was connected between the primary current conductor (pins 1 thru 4) and the GND pin of
the device (pin 5). This function generator was configured to generate a 10 V peak (20 V peak-to-peak) sine
wave between pins 1-4 and pin 5. Note that the sinusoidal stimulus was applied such that no electrical current
would flow through the copper conductor composed of pins 1-4 of this device.
The frequency of this sine wave was varied from 60 Hz to 5 MHz in discrete steps. At each frequency, the
statistics feature of an oscilloscope was used to measure the voltage variations (noise) on the ACS704 output
in mV (peak to peak). The noise was measured both before and after the application of the stimulus. Transient
common-mode voltage rejection as a function of frequency is shown in the following figure.
ACS704 Schematic Diagram of the Circuit used to Measure Transient Rejection
–30
–35
–40
–45
–50
–55
–60
freq=variable
V
OUT
V
=20VPP
OUT
=0V
V1
0.06
1
Frequency of 20 V Peak-to-Peak Stimulus
1
2
3
4
ACS704ELC-005
Applications Information
10
I
P
100
300
8
7
6
5
600
Output
C3
C=0.01µF
800
R=10kΩ
R0
C=0.1µF
1000 3000 5000
C0
(kHz)
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
Ground
Vcc
VDC=5V
GND
V0
16