Datasheet

ACHS-7124/7125 Data Sheet
Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 3 kV
RMS
Isolation and
Low-Resistance Current Conductor
Broadcom ACHS-7124-7125-DS101
13
Definition of Electrical Characteristics
The ACHS-7124/7125 product series is a Hall-Effect current
sensor that outputs an analog voltage proportional to the
magnetic field intensity caused by the current flowing
through the input primary conductor. Without magnetic field
the output voltage is half of the supply voltage. The sensor
can detect both DC and AC current.
Ratiometric Output
The output voltage of the ACHS-7124/7125 series is
ratiometric or proportional to the supply voltage. The
sensitivity (Sens) of the device and the quiescent output
voltage changes when there is a change in the supply
voltage (V
DD
). For example, for ACHS-7125 when the V
DD
is increased by +10% from 5V to 5.5V, the quiescent output
voltage will change from 2.5V to 2.75V and the sensitivity
also changes from 40 mV/A to 44 mV/A.
Sensitivity
The output sensitivity (Sens) is the ratio of the output
voltage (V
OUT
) over the input current (I
P
) flowing through the
primary conductor. It is expressed in mV/A. When an
applied current flows through the input primary conductor, it
generates a magnetic field that the Hall IC converts into a
voltage. The proportional voltage is provided by the Hall IC,
which is programmed in the factory for accuracy after
packaging. The output voltage has a positive slope when an
increasing current flows through the pins 1 and 2 to pins 3
and 4. Sensitivity Error (E
SENS
) is the difference between
the measured Sensitivity and the Ideal Sensitivity
expressed as a percentage (%).
Nonlinearity
Nonlinearity is defined as half of the peak-to-peak output
deviation from the best-fit line (BFL), expressed as a
percentage of the full-scale output voltage. The full-scale
output voltage is the product of the sensitivity (Sens) and full
scale input current (I
P
).
[(Max
Δ from BFL – Min Δ from BFL) / 2]
NL (%) =
×100%
Sens × full scale I
P
Figure 11: Nonlinearity Calculation
Zero Current Output Voltage
This is the output voltage of ACHS-7124/7125 when the
primary current is zero. Zero current output voltage is half of
the supply voltage (V
DD
/ 2).
Zero Current Output Error
This the voltage difference between the measured output
voltage and the ideal output voltage (V
DD
/ 2) when there is
no input current to the device.
Total Output Error
Total output error in percentage is the difference between
the measured output voltage at maximum input current
(I
PMAX
) and the ideal output voltage at I
PMAX
divided by the
ideal output voltage at I
PMAX
.
Measured V
OUT
@ I
PMAX
– Ideal V
OUT
@ I
PMAX
Error (%) =
× 100%
Ideal V
OUT
@ I
PMAX
Power-on Time
This is the time required for the internal circuitry of the
device to be ready during the ramping of the supply voltage.
Power on time is defined as the finite time required for the
output voltage to settle after the supply voltage reached its
recommended operating voltage.