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New LEDs & LED Drivers Series from ROHM Semiconductor Provide High-Efficiency Design Solutions for Automotive Display Backlighting Applications

15th November 2011

ROHM Semiconductor GmbH

ES Admin

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ROHM Semiconductor unveiled its new high power, high brightness white chip LED SMLx family with reflector (PLCC2 & high heat radiation packages) for automotive backlighting applications. Today, the increased functionality of clusters, car audio & navigation, climate control, switches and LCD/TFT backlighting create a high demand for efficiency while also relying on constant light emission, power saving and stability. With its new LED and LED drivers line-ups ROHM addresses the specific needs of these advanced application areas.

Within the new SMLZ1xx, SMLKxx,SMLVxx & SMLXAxx LED family, designers can choose from a variety of top and side view package types, forward currents as well as luminous intensity (mcd). The emitted colours are cold white and warm white. Additionally, the new LEDs offer high heat radiation for operation at high temperature, maintenance of high power at high currents, as well as for superior device reliability and durability.

Key Features of SMLx LED family:
* Ultra-high-power white visual chip LED with reflector
* High heat dissipation package
* Package sizes: PLCC2&6 (t= 1.9mm), PSML2 (t= 0.6mm) and side view (t=2.15mm)
* Dissipation PD 111mW~ 675mW
* Forward current IFmax. 30mA~ 150mA
* Peak forward current IFP from 100 to 400mA
* Reverse voltage VR 5V
* Chromaticity 0.30,0.28~0.44,0.4@20mA~90mA,
* Luminous intensity (mcd) IV 1800@20mA, 2200@20mA, 5900(φv_typ 21lm) @90mA,10200 (φv_typ 30lm)
* Forward voltage VF(V) 3.2@20mA, 3.9@90mA
* Reverse current IR(µA) 10@5V
* Operating temperature range: -40° to +100°

With the development of its new BD81A04 LED driver series, ROHM is now able to provide a complete design solution for display backlighting. The new IC is a 4 channel 120mA/ch LED driver with an integrated buck-boost DC/DC constant current driver which can be used to drive various LEDs for efficient backlighting of a large range of displays or HuDs (Head-up Displays). Due to its unique topology it only requires one coil for buck-boost configuration and provides stable operation over a wide voltage range, significantly reducing design work and the number of required external components. In addition the BD81A04 integrates MOSFETs like the PWM current driver or the boost FET. This reduces the number of external components even further.

The advanced brightness control /dimming functions and the flexibility to combine fewer channels with higher output current round up the features of this device. For example, instead of using four channels with 120mA, it’s now possible to achieve 240mA via two channels. In order to ensure reliable operations all protection functions like the monitoring voltage, current, temperature or the short circuit detection function are implemented as well.

Key Features of BD81A04 LED Drivers:
* Correspond to Boost and Buck-boost (integrated Boost FET)
* Output current: Io max = 120mA
* Wide operating voltage range: 4.5 ~30V
* 4ch constant current output (current accuracy: 3%)
* PWM dimming control: 0.01 ~ 100%@100Hz with phase shift function
* UVLO circuit, OVP, TSD, OCP
* LED anode / cathode (SCP)
* LED open / short detection (short detection ON/OFF function)
* Oscillating frequency accuracy: +/- 5%
* Package: HTSSOP-B28 or VQFN028V5050

Availability
LED SMLx family: Samples and volume production are available
LED Driver BD81A04: samples are available; volume production will start Q2/2012
The new line-up is an ideal addition to ROHM’s line-up of standard, top-view, side-view and reverse-mount type LEDs and LED drivers for any kind of lighting applications.