NXP Semiconductors Document Number: MC34845
Rev. 8.0, 8/2016
Data Sheet: Technical Data
Low cost six channel led backlight
34845
driver with integrated power supply
LED DRIVER
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.
98ASA00602D
PWM dimming is performed by applying a PWM input signal to the PWM pin
24-PIN QFN-EP
which modulates the LED channels directly. An Enable Pin (EN) provides for low
Applications
power standby. Alternatively, a single wire scheme selects power down when
PWM is connected to the Wake pin and held low.
PC notebooks
The integrated boost converter uses dynamic headroom control to automatically Netbooks
set the output voltage. There are three device versions for boost frequency;
GPS screens
34845C is 600 kHz, and the 34845D is 300 kHz. External compensation allows
Portable DVD players
the use of different inductor/ capacitor combinations.
Picture frames
The 34845 includes fault protection modes for LED short and open,
Smaller screen televisions
overtemperature, overcurrent and overvoltage errors. It features an internally
Industrial/instrumentation displays
fixed OVP value of 60 V (typical) which protects the device in the event of a failure
Health care device displays
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
34845
12V VIN
SWA
VDC1
SWB
VDC2
VOUT
PGNDB
COMP PGNDA
OVP
5V
EN
~ ~ ~ ~ ~ ~
~ ~ ~ ~ ~ ~
FAIL
PWM
CONTROL
CH1
UNIT WAKE
CH2
CH3
CH4
ISET
CH5
CH6
GND EP GND
Figure 1. 34845 simplified application diagram
2016 NXP B.V.1 Orderable parts
Table 1. Device variations
Boost switch current limit Switching frequency Slope compensation V
SLOPE
Temperature
(1)
I (A) f (kHz) (V/s)
BOOST_LIMIT S
Part number Package
(T )
A
Min. Typ. Max. Min. Typ. Max. Min. Typ. Max.
MC34845CEP 1.9 2.1 2.3 540 600 660 0.52
-40 to 85 C 24 QFN-EP - -
MC34845DEP 2.1 2.35 2.6 270 300 330 0.22
Notes
1. To order parts in Tape and Reel, add the R2 suffix to the part number.
34845
2 NXP Semiconductors