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