Description
The EVL400W-80PL demonstration board is a 12 V - 400 W converter, tailored to
the typical specifications of an AC/DC adapter with wide input mains range, very low
power consumption at light load and good average efficiency.
It is composed by a motherboard mounting the high voltage power devices, the
primary control board mounting the IC controllers L4985A and L6699 and the
secondary control board for the synchronous rectification.
The architecture is based on a two-stage approach: a front-end PFC pre-regulator
based on a CCM (Continuous Conduction Mode) boost PFC controller using the
L4985A, and a downstream LLC resonant half-bridge converter, designed around the
L6699.
At the secondary side, synchronous rectification is implemented by means of the
SRK2001 that assures a very high rectification efficiency with a reduction in the size
of the heatsink required.
The PFC section uses the L4985A, a peak current-mode PFC controller for boost
converter with a proprietary multiplier “emulator” which, in addition to the innovative
THD optimizers, guarantees very low Total Harmonic Distortion (THD) performance in
all operating conditions.
The device operates in quasi-fixed frequency in all operating conditions thanks to a
proprietary off-time modulator and includes the high voltage startup block with the
circuitry to discharge the X-capacitors of the EMI filter.
This level of integration allows a low-component count solution for boost PFC preregulators.
The LLC section uses the L6699, a double-ended controller specific to seriesresonant
half-bridge topology. The output voltage regulation is obtained by
modulating the operating frequency.
The main focus of this demonstration board is the light-load efficiency, achieved
through the burst mode function of both PFC and LLC controllers with the selfadaptive
deadtime of the L6699, modulated by the internal logic according to the
half-bridge node transition times, which allows the maximization of the transformer
magnetizing inductance, reducing the primary current at light load operation.

Features
• Universal input mains voltage range: from 90 Vac to 264 Vac – frequency from
45 to 65 Hz
• Output voltage: 12 V at 33 A continuous operation
• Overall efficiency at full load: > 89%, according to ENERGY STAR® 6.1 limit for
computer and compliant with 80Plus PLATINUM level
• Average efficiency: > 89%, according to European CoC ver. 5 Tier 2 for
external power supplies
• Efficiency at 250 mW > 50%, compliant to EuP lot 6 Tier 2 limit for household
and office equipment
• No load mains consumption: < 150 mW at 230 Vac, below European CoC ver.
5 Tier 2 limit for external power supplies
• Mains harmonics: meets EN-61000-3-2 Class-D and JEITA-MITI Class-D
• EMI: according to EN55022 Class-B
• Safety: meets EN60950 standards
• RoHS compliant