Datasheet E522.80, E522.81, E522.82, E522.83 (Elmos) - 10

link to page 9 link to page 9 Triple 150mA Linear LED Controller E522.80/81/82/83 Production Data - May 5, 2017 To handle the high power that is typically generated in linear LED drivers, the 522.80/81/82/83 device family offers an ad- vanced power distribution feature. The channels current is regulated as a sum of currents in LEDxA and LEDxB. The priority output LEDxB drives the current as long as the voltage headroom allows to. Afterwards the bypass output LEDxA is activated to deliver the remaining current flow. This distribution of current allows to share some of the linear regulator power with the external Power-Shunt. „Figure 1. Power Management Example using a Channel of E522.8x at 120mA“ shows the basic power generation per channel in (as a function of VVS) - the LED load driven - the external power shunt, given for exemplary values R1=33Ω, R2=56Ω, R3=82Ω - the remaining power for this channel in E522.8x For calculation, this principle offers two points of “zero” power in E522.8x, one for the VVS,Z1 = VLED and a second “zero” power point at VVS,Z2 = VLED+ILED*RPOWERSHUNT. Beyond VVS,Z2 the power in E522.8x starts to increase linearly as for common linear LED driv- ers. At the voltage derating threshold VVS,DERATE the internal reference is reduced to 60% of nominal, thus the overall system power is reduced as shown to avoid excessive heat generation in case of e.g. load dump pulses. 5.3 IR Driver The interface IRx is used to configure the current in the according LEDxA/B channel. By connecting the IRx input to GND po- tential, the current flow in IRx is multiplied to LEDxA/B by a factor of typical 960:1. Digital dimming can be applied to IRx by setting VIRx > VIR,DIS. A simple option to control the current is to switch the GND connec- tion of RIRx by a micro controller port, thus ‘low’ level drives the current into IRx, the high level disables the according channel. Various factors influence the reference voltage driven to IR as an output. Details are illustrated in Figure 2. In nominal case (typical junction temperature, VENA > 3V) the internal reference is used. The lowest reference applied to the amplifier shown in Figure 2 is used to regulate VIR. ENA + ENABLE 1.2V - V V REF,NOM REF,HV VS Overvoltage ( V > V ) VS VS,DERATE Channel Current 250kΩ Reference + + + 250kΩ - IRX Internal VIR,DIS Temperature -100mV 6V Derating + Channel V Disable IR,DIS - Figure 2. IR Reference Generation Elmos Semiconductor AG reserves the right to change the detail specifications as may be required to permit improvements in the design of its products. Elmos Semiconductor AG Data Sheet QM-No.: 25DS0132E.03 10/25