HF81
X Capacitor Bleeder
The Future of Analog IC Technology
DESCRIPTION
HF81 is an innovative two-terminal IC that
automatically discharges an X capacitor while
eliminating power losses and allowing power
supplies to comply with safety standards.
The HF81 acts as a smart high-voltage switch
when placed in series with discharge resistors
(alternatively bleed resistors). In the presence
of an AC voltage, the HF81 blocks current flow
in the safety discharge resistors to reduce the
power loss in these components to zero at 230
VAC. When disconnected from the AC voltage,
the HF81 automatically and safely discharges
the X capacitor by closing the circuit through
the bleed resistors and directing the energy
away from the exposed AC plug.
Table 1: Component Selection Range for HF81
Total X Capacitance
100nf to 5μF
Total X
Capacitance
≤500nF
750nF
1μF
1.5μF
2μF
2.5μF
3.5μF
5μF
Total Series Resistance
1.5MΩ to 150kΩ
Total Series
Resistance
1.5MΩ
1MΩ
780kΩ
480kΩ
360kΩ
300kΩ
200kΩ
150kΩ
Power
Saving
(2)
66mW
86mW
142mW
191mW
230mW
347mW
464mW
FEATURES
Disconnect series discharge resistors from
L-N when AC voltage is applied
Connect series discharge resistors with L-N
to discharge the X capacitor when AC
voltage is unplugged
Supplied by AC voltage directly and doesn’t
need external bias
Meets safety standards for use before or
after input fuse
No external ground pin leads to high
common mode surge immunity
1000V internal JFET inside leads to high
differential surge immunity
>4mm creepage on package and PCB
Compliant to IEC 60950-1
AC/DC converters with X capacitors larger
than 0.1μF
All converters requiring ultra-low no-load
consumption and low standby power
Appliances requiring EuP Lot 6 compliance
Appliances requiring Energy Star V2.0
White Goods (For example, Dishwasher,
Washing Machine, Air-Conditioner and etc.)
Server Power, Telecom Power, ATX Power
APPLICATIONS
Table 2: Typical Component Recommendation
(1)
PN
HF81
Notes:
1) The recommended values are calculated based on a 0.75s
RC time constant to meet safety requirement considering
tolerance. They may vary in applications.
2) The values are calculated at Vin=265Vac
All MPS parts are lead-free and adhere to the RoHS directive. For MPS green
status, please visit MPS website under Quality Assurance. “MPS” and “The
Future of Analog IC Technology” are Registered Trademarks of Monolithic
Power Systems, Inc.
HF81 Rev. 1.15
9/22/2017
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2017 MPS. All Rights Reserved.
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