HR2000 — FLUORESCENT LAMP HB DRIVER WITH PFC

HR2000 Rev. 1.0

www.MonolithicPower.com

14

2/20/2013

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

© 2013 MPS. All Rights Reserved.

FUNCTIONAL DESCRIPTION

HR2000 includes Half-bridge part and PFC part.

Half-bridge part

In the typical application, the half-bridge can be

defined to two basic states: Oscillating state and

None-oscillating state.

Non oscillating state:

In non-oscillating state, IC stops to work. There

are 4 sub-states:

Start up state;

Fault state;

VCC under voltage state;

Over temperature protection (OTP) state

Start-up state

When Vcc<Vcc(reset), HR2000 will get into Start-

up state.

Initially, the IC can be supplied from the outside

resistor such as R207 in Figure1.

All internal circuit is reset in this state.

In this state, CP/EOL, Pre/FT, FC pin are

discharged by the internal switches.

Fault state

There are two conditions resulting in Fault state.

The first one is before Vvcc>Vvcc(reset), if

VPreFT>Vfault(reset), then IC will not start up.

The second one is after Pre/FT pin’s detection

function is active in all oscillating sub-states,

HR2000 will get into Fault state if Pre/FT pin

voltage VPreFT>Vfault(ref) & low side drive is

high.

The following items will affect Pre/FT pin in

oscillation state.

The voltage detected by the sample circuit such

as C211, C212, C213, D202, R204, R205 in Fig1.

In

EOL

protection

and

Capacitive

Mode

protection, a current source Ifault(ch) will charge

the capacitor at this pin such as C213 in Fig1.

In PFC VO-low state a current source Ifault(disch)

will discharge C213.

Before Vvcc>Vvcc(reset), this pin will be detected.

If VPreFT>Vfault(reset), IC will not start up.

VCC under voltage state

There is a hysteresis for Vcc detection. When

power

on,

HR2000

begin’s

to

work

after

Vvcc>Vvcc(start). If Vvcc<Vvcc(low) & low side

drive is high in oscillation state, the device will

get into VCC under voltage state.

OTP state

The temperature is monitor by IC internal circuit.

If detected temperature is higher than Thigh, then

IC will get into non-oscillation state. When

temperature is lower than Tlow, the oscillation is

enabled again.

Oscillating State

After start-up state, once the VCC pin gets to the

level VCC(start), IC begins to work.

In oscillating state, there are 3 sub-states:

Preheat state;

Ignition state;

Burn state;

Half-bridge oscillator

The oscillating frequency is programmed by the

capacitor on CT pin. The capacitor on CT pin is

charged by internal current source which is

related to REF pin resistor and FC pin voltage

which is voltage controlled current source for CT

pin. The waveform of CT pin is saw-tooth and its

frequency is twice of the half-bridge operating

frequency. There is a dead time between UG and

LG for ensuring their non-overlap operating. The

dead time is defined by REF resistor.

FC pin controls the operating frequency directly.

Higher Vfc results in a lower frequency.