February 2016

DocID028931 Rev 1

1/7

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STEVAL-IHT008V1

Low standby loss front-end with inrush current limitation and

insulated AC switch control

Data brief

Features



Fully electronic solution without the need for

an inrush current limiter resistor and bulky

by-pass electromechanical relay



DC bus disconnection at standby to reduce

loss below 0.3 W



Inrush current compliant with IEC61000-3-3



Operation allowed with PFC (continuous or

discontinuous)



EN 55015, IEC 61000-4-11 compliant



Criteria A @ 2 kV IEC 61000-4-5 and @ 4

kV IEC 61000-4-4



Insulated control of AC switches used to

drive AC loads for residential appliances



RoHS compliant

Description

The STEVAL-IHT008V1 evaluation board limits

the inrush current charging a DC bus capacitor

so that it is compliant with the IEC 61000-3-3

standard. This inrush current is based on a soft-

start procedure for the rectifier bridge achieved

with a Triac added in series with the mains line,

which is controlled through progressive phase-

control during the startup phase.

This solution drastically reduces standby losses

as the DC bus can be totally disconnected from

the AC mains when it is not required. The DC bus

is easily turned off by turning off the series Triac,

without needing an additional relay to open the

circuit in standby.

Steady-state losses are also reduced because

NTC resistors, traditionally used to limit inrush

current, are not required; nor are the

corresponding relays to bypass them.

This board also demonstrates that AC loads can

be driven with an isolated easy-to-design solution

by using the same power supply as the whole

system and some opto-transistors which control

the AC switches.