consumption. Designing with the device is simply a matter of selecting the appropriate external resistor values for the X capacitor value being used to achieve the necessary time-constant.
Safety tests However, X capacitor discharge ICs have to be robust so they will not fail even under extreme conditions. This is why the IEC committee was so keen to ensure that proper testing provisions were included for these capacitors when it produced the IEC 62368-1 safety standard. Although vital and mandatory, this certification can
be difficult to achieve with some design techniques, such as using a flyback controller integrated with X capacitor discharge functions, where the designer is forced into using a complicated discharge path. The tests in the standard require the discharge function to happen even in the event of a single fault. Therefore, in this case with the discharge passing through many different components, system reliability is negatively impacted since if just one of those components fails then the discharge cannot happen safely. CapZero-2 ICs address this issue, as devices still
permit a discharge even if there is a fault. The parts have passed severe 8 KV line surges and the devices have been designed with pin redundancy so that even in the case of pin opens or shorts, they will still provide a safe discharge for the X capacitor energy. This allows power supplies to comply with IEC 62368-1, the over- arching safety standard which covers a broad segment of energy-using equipment, and which replaces IEC 60950 for IT equipment and IEC 60065 for television, video and audio equipment. The IEC 62368-1 safety standard was
approved and implemented last year and will become mandatory in 2019. Tests that must be passed include a 120 hour120- hour high humidity test. This is carried out at +40 ˚C and a relative humidity of 93 percent. Other tests include 100 positive and 100 negative impulses of severe line surge. These are done between the line and neutral using a capacitor with the largest capacitance and a resistor with the smallest resistance, and then repeated with a capacitor with the smallest capacitance and a resistor with the largest resistance as recommended by the manufacturer. The time between any two impulses must not be less than one second. Next, 110 percent of the rated AC voltage is applied for two and a half minutes and then the circuit is subjected to 10,000 cycles of power on and off. Again, this is performed using a capacitor with the smallest capacitance and a resistor with the largest resistance, and then repeated with a capacitor with the smallest capacitance and a resistor with the largest resistance as specified by the manufacturer. The power on and off cycle time is not less than one second.
Summary With the introduction of the CapZero-2 ICs, power supply designers only need to qualify one part number for all their X capacitor discharge IC applications. This increases design flexibility and speeds time-to-market while reducing the resources required to qualify devices. Because CapZero-2 devices are safety-certified to CB and Nemko requirements, developers do not need to perform a separate safety test on the X capacitor discharge circuit of the power supply.
igbt drivers
www.power.com SCALE-iDriver™ Family Single-Channel Gate Driver ICs with Reinforced Isolation
• 2.5 A, 5 A, 8 A output current devices • Drives 1200 V IGBTs and MOSFETs up to 110 kW • Revolutionary FluxLink™ communication technology • Low profile with 9.5 mm creepage and reinforced isolation
SCALE-iDriver
Primary-Side Logic
IN Output VIN VCC VVCC GND VEE COM PI-7949-072616 FluxLink GL Fault SO GH VISO VTOT
Secondary-Side Logic
VCE VGXX
January 2017
www.electronicscomponentsworld.com
/
www.electronicsproductionworld.com
EIU 17
+ -
+ -
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30
