MP4060—TRIAC Dimmable PFC, PSC LED Controller for 200-265VAC LEDs

MP4060 Rev. 1.0

www.MonolithicPower.com

16

5/27/2015

MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

© 2015 MPS. All Rights Reserved.

OPERATION

The MP4060 is a TRIAC-dimmable primary-side

control, offline LED controller designed for high-

performance LED lighting. The MP4060 controls

accurately the LED current using the real-current

control

method

based

on

primary-side

information. The adaptive dimmer type detection

and phase-cut-based dimming control provide

good dimmer compatibility and a deep dimming

range. Also, it achieves a high power factor to

eliminate noise pollution on the AC line. The

integrated VCC charging circuitry achieves fast

start-up without any perceptible delay. The

integrated thermal current foldback function can

prolong the lifetime of the LED. With a duty ratio

that varies with the dimming cycle, DIM easily

supports color temperature and brightness

control for warm sunset dimming application.

Boundary-Conduction Mode

rectified input voltage applied on the primary-side

inductor (Lm) makes the primary current through

Lm increase linearly from zero to the peak value

energy stored in Lm forces the secondary-side

rectifier diode to turn on, and the inductor current

decreases linearly from the peak value to zero.

turn on

0

Inductor

current

Figure 2—Boundary-conduction mode

When the current decreases to zero, the voltage

drop on the main MOSFET drain-to-source falls

and oscillates. The oscillation frequency is

determined by the primary-side inductor and the

combined parasitic capacitances. The resonance

is reflected on the auxiliary winding (see Figure

2).

The zero-current detector generates the external

MOSFET turn-on signal when the ZCD voltage

and ensures the MOSFET turns on at a relatively

low voltage (see Figure 3).

+

Vcc

ZCD

Auxiliary Winding

Figure 3—Zero-current detector

As a result, there are incredibly small primary

switching-on losses and no secondary-diode

reverse-recovery losses. This ensures high

efficiency and low EMI noise.

Real-Current Control

The

proprietary

real-current–control

method

allows the MP4060 to control the secondary-side

LED current based on primary-side information.

The output LED mean current can be calculated

approximately with Equation (1):

⋅

≈

⋅

REF

o

s

NV

I

2R

(1)

Where:

N is the turn ratio of the primary side to the

secondary side,

0.414), and

MOSFET source and GND.