OM5428T Hendon Semiconductors, OM5428T Datasheet - Page 9

• Manufacturer Part Number: OM5428T
• Description: Triacs 300mA Triac Phase Controller
• Manufacturer: Hendon Semiconductors

Specifications of OM5428T

• Product Category: Triacs
• Rohs: yes
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: SO-16
• Minimum Operating Temperature: - 40 C

10 IMPORTANT: ELECTRICAL SAFETY WARNING
OM5428 circuit is connected to the mains electrical supply
and operates at voltages which need to be protected by
proper enclosure and protective covering. Application
circuits for OM5428 should be designed to conform to
relevant standards (such as IEC 65, or Australian
Standards AS3100, AS3250 and AS3300), it should only
be used in a manner that ensures the appliance in which it
is used complies with all relevant national safety and other
Standards.
It is recommended that a printed circuit board using this
integrated circuit be mounted with non-conductive clips,
and positioned such that the minimum creepage distances
from the assembly to accessible metal parts, and between
high voltage points cannot be transgressed.
It should be noted that as there are Mains Voltages on the
circuit board adequate labelling should be attached to
warn service personnel, and others, that this danger
exists.
A control board assembly should be mounted, preferably
vertically, with sufficient free air flow across its surface to
prevent the heat dissipated in various components from
causing an unacceptable rise in the ambient temperature.
The triac also needs to have an adequate heatsink, as
exceeding its rated maximum junction temperature can
result in loss of control, unpredictable behaviour, and
possible dangerous conditions.
The board should be mounted in a place that is clean and
dry at all times, not subject to condensation or the
accumulation of dust and other contaminants.
11 APPLICATION INFORMATION
The reliability of modern triacs has given a strong impetus
to the introduction of electronic power control in industrial
as well as non-industrial areas. Because of the low cost of
these devices and simplification in trigger circuitry,
electronic power control now enjoys a host of applications
such as electronic household cookers, panel radiators,
fans, hobby tools, and even vacuum cleaners.
The general purpose trigger circuit OM5428, referred to as
a trigger module, supplies the pulses for gate triggering
triacs. This module is connected to the mains via a
dropping resistor hence removing the need for an
expensive external supply.
The OM5428 is an inexpensive, versatile trigger module
and, being a monolithic IC in 16-pin dual in-line package, it
2008 Jul 29, Revision 6.0
Phase Controller and Triac Triggering IC
8
takes up hardly any space at all. It is ideally suited for
applications such as:
1. Phase control: single phase control (full cycle).
2. Soft-start power controller.
3. On/off control: static switch.
4. Time proportional control: temperature and motor
5. Temperature dependent phase control for motor
Phase control is stepless control of output power by
varying the conduction angle of the triac, 180 degree
conduction corresponding to full output power. Step
changes in triac voltage and current during turn-on
give rise to RF interference. Appropriate RF
interference suppression methods need to be applied
for all phase triggered loads.
It should be noted that phase control is not permitted
for heating purposes.
Soft-start is a means of providing a controlled turn-on
of an electric motor, to eliminate the effect of high
starting torque. It is particularly useful in industrial
vacuum cleaner applications.
On/off control is a method of power control where
triggering should preferably occur symmetrically with
respect to the zero crossing of the triac current to avoid
RF interference. That is, triggering must start before
the current has dropped to the holding value, and must
continue until the current has risen again above the
latching level. Under these conditions radio
interference is kept at a minimum.
speed control.
Time proportional control is on/off control with a fixed
repetition rate of load switching. The system is called
time proportional because the power in the load
averaged over the repetition period is varied. This
system provides more accurate temperature control,
avoiding the overshoot which is inherent in on/off
control. Triggering conditions are the same as for
on/off control.
speed control.
Full phase control is realised over a narrow
temperature range of 25 degC or less using an NTC
thermistor temperature sensor and low power
Op-Amps. This configuration allows motor speed
control from 0 to 100% over narrow temperature
ranges by varying the triac conduction angle. Suitable
for applications such as building ventilation, coolant
pumping systems and wherever temperature is used
to control motor speed.
Product Specification
OM5428