Device description

LED6001

12/26

DocID025575 Rev 3

7

Device description

The LED6001 device is a LED driver that integrates a boost controller, a high-side current

sensing circuitry and a gate driver for an external dimming switch. It has been specifically

designed for driving a single string of high-brightness LEDs. The device can support boost,

floating buck-boost and SEPIC topologies in order to cover most of applications. A single

pin, PWMI, combines both the device enable and PWM dimming control functions.

The brightness of the LED string can be controlled through PWM modulation, analog control

of the output current level (by means of a dedicated pin) or a combination of the two.

7.1

Device supply

The LED6001 device integrates two low dropout linear regulators to derive the + 3.3 V (typ.)

main supply and the +5 V supply for the gate drivers. The VIN pin is the input terminal for

both linear regulators. Both the linear regulators are enabled when a PWM signal is applied

to the PMWI pin. If the PWMI pin is held low for more than 10 ms (min.), the shutdown mode

is automatically entered and both the LDOs are turned-off for minimum power consumption.

An undervoltage lockout (UVLO) protection is associated to each linear regulator: in case

the output voltage of LDO3 and VDR is below their respective nominal value, the device is

no allowed to operate and the XFAULT pin is tied low.

When an external +5 V rail is available, the related internal LDO can be bypassed by

connecting together the VIN and VDR pins: in this case the VDR pin is used as supply input.

7.2

Boost controller

7.2.1

Turn on and power-down sequences

The LED6001 is turned on and off by acting on the PWMI pin. This digital input combines

two functions at the same time: device turn on/off and PWM dimming control.

When a high pulse having a 100 µs (typ.) minimum duration appears at the PWMI pin, the

LDOs are turned on and, after the VDR has reached its nominal value, a soft-start sequence

on the boost controller takes place. The output voltage is smoothly increased by releasing in

steps the current limit of the boost converter within a fixed 3 ms (typ.) period, unless the

feedback voltage reaches 75% of the nominal value in advance.