Document Number: MC34845

Rev. 8.0, 8/2016

NXP Semiconductors

Data Sheet: Technical Data

© 2016 NXP B.V.

Low cost six channel led backlight

driver with integrated power supply

The 34845 series represents high efficiency LED drivers for use in backlighting

LCD displays from 10” to 17”. Operating from supplies of 5.0 V to 21 V, the 34845

series is capable of driving up to 16 LEDs in series in six separate strings. The

LED current tolerance in the six strings is within ±2% maximum and is set using

a resistor to GND.

PWM dimming is performed by applying a PWM input signal to the PWM pin

which modulates the LED channels directly. An Enable Pin (EN) provides for low

power standby. Alternatively, a single wire scheme selects power down when

PWM is connected to the Wake pin and held low.

The integrated boost converter uses dynamic headroom control to automatically

set the output voltage. There are three device versions for boost frequency;

34845C is 600 kHz, and the 34845D is 300 kHz. External compensation allows

the use of different inductor/ capacitor combinations.

The 34845 includes fault protection modes for LED short and open,

overtemperature, overcurrent and overvoltage errors. It features an internally

fixed OVP value of 60 V (typical) which protects the device in the event of a failure

in the externally programmed OVP. The OVP level can be set by using an

external resistor divider. This device is powered using SMARTMOS technology.

Features

• Input voltage of 5.0 V to 21 V

• Boost output voltage up to 60 V

•2.0 A integrated boost FET

• Fixed boost frequency - 300 kHz or 600 kHz

• OTP, OCP, UVLO fault detection

• LED short/open protection

• Programmable LED current between 3.0 mA and 30 mA

Figure 1. 34845 simplified application diagram

34845

LED DRIVER

98ASA00602D

24-PIN QFN-EP

12V

FAIL

PGNDB

34845

SWA

SWB

VOUT

PGNDA

CH1

CH2

CH3

CH4

CH5

CH6

EP

EN

PWM

ISET

VIN

VDC1

VDC2

COMP

WAKE

~~ ~~ ~~ ~~ ~~ ~~

OVP

GND

GND

CONTROL

UNIT

5V

Applications

• PC notebooks

• Netbooks

• GPS screens

• Portable DVD players

• Picture frames

• Smaller screen televisions

• Industrial/instrumentation displays

• Health care device displays