Datasheet

Functional description LED5000
10/51 Doc ID 023951 Rev 1
4 Functional description
The LED5000 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:
● A fully integrated sawtooth oscillator with a typical frequency of 850 kHz
● A transconductance error amplifier
● An 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 dimming block to implement PWM dimming
● The inhibit block for standby operation
● The current limitation circuit based on the pulse-by-pulse current and the HICCUP
protection
● The bootstrap circuitry to drive the embedded N-MOS switch
● A circuit to implement the thermal protection function
Figure 3. LED5000 block diagram
VIN
OSC
E/A
DRIVER
DRIVER
DMD
MOSFET
CONTROL
LOGIC
REGULATOR
DIMMING
I_ SE NSE
COMP
COMP
OCP
REF
0. 1V
SOFTSTART
Vsum
Vc
OCP
UVLO
Vdrv_p
Vdrv_n
I2 V
R
SENSE
SW
GND
DIM
FB
COMP
INH
INH
AM13487v1