EARTH LEAKAGE CURRENT DETECTOR
M54128L/FP
MITSUBISHI <CONTROL / DRIVER IC>
PRECAUTIONS FOR APPLICATION
Note that the improvement examples in the following precautions
for application of M54128FP/L are merely examples.
1. VS applied voltage
(1) ls circuit current (clamp circuit characteristics of the
equivalent circuit) is as shown in TYPlCAL CHARAC-
TERISTICS figure 1 on page 9. Attention should be given to
the circuit current when designing the power supply circuit.
(2) Use of the lC by rectifying commercial power supply
a) As Vz, be sure to use zener diode of 12V or less (not
exceeding the absolute maximum rating of 15V).
b) At high temperatures, clamp voltage decreases and ls
increases. lncrease of ls will be restricted at Rs, however.
(3) lf normal DC power supply is used, use the lC at Vs=7to10V.
2. Resistor of IREF pin (R = 130kΩ)
Reference constant current source of the lC (for restraining
fluctuations in supply voltage characteristics and ambient
temperature characteristics).
Since this resistor determines the characteristics of each circuit,
use of high-precision resistor (±2%) is recommended.
3. Layout of printed circuit board
External noise (noise simulator etc.) may cause faulty operation
of the lC.
To improve the noise immunity, layout the printed circuit board
so that the wiring of the external C and R is made as short as
possible.
Special attention should be given to the wiring of the condensers
connected to Vs, Vcc and SCRT pins.
4. Be careful that the voltage of SCRT output pin does not
become lower than the GND level.
5. Change in sensitivity due to insulation deterioration
If the insulation of ZCT input pin from the high voltage part might
deteriorate, improvement might be expected by connecting a
resistor of about R=100kΩbetween VREF pin and GND.
It should be noted that the circuit current will increase at
I 2.7V/R (approx.).
6. Clamp diode of IBLI input pin
As shown in the equivalent circuit, it is made up of series resistor
(approx. 2kΩ) and seven stages of forward diode.
(1) At high temperatures, the drop in diode VFmay decrease
the clamp voltage of the pin. If the voltage approaches the
reference level of the comparator (2.4V) and current leaks
occur, the overvoltage detection level may slightly fluctuate.
Form the detection circuit as the figure below. It is
recommended that R1, R2and VZbe set as shown below.
(2) During excessive input, as shown above, setting should be
made so that the input pin voltage becomes 4.3V or lower
(to prevent the saturated comparator circuit from operating).
• VZ4.0V
=
• R1+ R2> 200kΩ
• Ω
R1x R2
R1+ R2
Commercial
power supply
RSVS
VZ
IC IBLI pin
Input R1
R2 VZ
=
< 7k