RESET

STANDBY

ACTIVE

POR = L

Control command

POR

Control command

ends

POR = H

LP5522

SNVS488A – JUNE 2007 – REVISED MARCH 2013

www.ti.com

Modes of Operation

RESET In the reset mode all functions are off and all registers are reset to the default values. Reset is entered

always if internal Power On Reset (POR) is active. Power On Reset will activate during the device startup

or when the supply voltage VIN falls below 1.5V (typ.).

STANDBY: After Power On Reset device is in Standby mode. This is the low power consumption mode, when

all circuit functions are disabled.

ACTIVE: Once rising edge of CTRL signal is detected device goes into Active mode. In Active mode four sub

modes are present:

RUN: Run mode is divided into two sub modes depending on whether a blinking sequence is programmed into

memory or not.

Non-programmed mode: No blinking sequence programmed to memory. LED output follows CTRL input

Programmed mode: Blinking sequence programmed to memory. LED output follows the programmed blinking

sequence

RUN ONCE: In Run once mode, programmed blinking sequence is performed once and after that device

returns into Standby mode. Run once mode is available only if a blinking sequence is programmed into

memory.

TRAINING: In Training mode new blinking sequence can be programmed. LED output follows CTRL signal

during the programming

TSD: If chip temperature rises above 160°C (typ.) device goes into Thermal Shut Down (TSD) mode. In TSD

mode output is disabled but supporting functions are on.

LED Driver Operational Description

The LP5522 LED driver is constant current source. Current can be set with external resistor (RISET) so that the

current ratio between resistor and LED is 1:400. RISET current correlates to ISET reference voltage (VISET).

Consequently, current through LED can be adjusted using equation IOUT = 480/RISET.

Use of external resistor is optional. If external resistor is not connected, default output current is 5 mA. When

external resistor is not used ISET pin should be connected to VDD.

6

Submit Documentation Feedback

Copyright © 2007–2013, Texas Instruments Incorporated

Product Folder Links: LP5522