TESTtz

ACS712
Fully Integrated, Hall Effect-Based Linear Current Sensor with
2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor
Definitions of Dynamic Response Characteristics
Propagation delay (t PROP ). The time required for the sensor
output to reflect a change in the primary current signal. Propagation
delay is attributed to inductive loading within the linear IC
package, as well as in the inductive loop formed by the primary
conductor geometry. Propagation delay can be considered as a
fixed time offset and may be compensated.
I (%)
90
0
Primary Current
Transducer Output
Propagation Time, t PROP
t
Response time (t RESPONSE ). The time interval between
a) when the primary current signal reaches 90% of its final
value, and b) when the sensor reaches 90% of its output
corresponding to the applied current.
I (%)
90
0
Primary Current
Transducer Output
Response Time, t RESPONSE
t
Rise time (t r ). The time interval between a) when the sensor
reaches 10% of its full scale value, and b) when it reaches 90%
of its full scale value. The rise time to a step response is used to
derive the bandwidth of the current sensor, in which ƒ(–3 dB) =
0.35 / t r . Both t r and t RESPONSE are detrimentally affected by eddy
current losses observed in the conductive IC ground plane.
I (%)
90
10
0
Primary Current
Transducer Output
Rise Time, t r
t
t PO (µs)
Power on Time versus External Filter Capacitance
200
180
160
I P =5 A
140
120
I
100
P =0 A
80
60
40
20
0
0 10 20 30 40 50
C F (nF)
Step Response
T A =25°C
Output (mV)
1000
Noise versus External Filter Capacitance
15 A
Excitation Signal
Noise (p-p) (mA)
100
10
t r (µs)
1
0.01 0.1 1 10 100 1000
C F (nF)
Rise Time versus External Filter Capacitance
1200
1000
800
600
}
400
200
Expanded in chart at right
0
0 100 200 300 400 500
C F (nF)
C F (nF)
t r (µs)
0 6.647
1 7.74
4.7 17.38
10 32.09087
22 68.15
47 88.18
100 291.26
220 623.02
470 1120
t r (µs)
Rise Time versus External Filter Capacitance
400
350
300
250
200
150
0
0 50 75 100 125 150
C F (nF)
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com