Datasheet

DocID023432 Rev 4 9/40

LED2000 Functional description

5 Functional description

The LED2000 device is based on a “peak current mode” architecture with fixed frequency

control. As a consequence, the intersection between the error amplifier output and the

sensed inductor current generates the control signal to drive the power switch.

The main internal blocks shown in the block diagram in Figure 3 are:

 High-side and low-side embedded power element for synchronous rectification

 A fully integrated sawtooth oscillator with a typical frequency of 850 kHz

 A transconductance error amplifier

 A high-side current sense amplifier to track the inductor current

 A pulse width modulator (PWM) comparator and the circuitry necessary to drive the

internal power element

 The soft-start circuitry to decrease the inrush current at power-up

 The current limitation circuit based on the pulse-by-pulse current protection with

frequency divider

 The dimming circuitry for output current PWM

 The thermal protection function circuitry.

Figure 3. LED2000 block diagram

WSNIVANIV

OSC

E/A

DRIVER

DMD

OTP

MOSFET

CONTROL

LOGIC

REGULATOR

DIMMING

I_ SENSE

COMP

PWM

OCP

REF

0.1V

SOFT-START

Vsum

OCP

UVLO

Vdrv

I2V

SENSE

GNDP

GNDADIMFB

AM12894v1