EYE on NPI: Richtek RT4539 36 V I²C Controlled 6-Channel WLED Driver #EYEonNPI #Digikey @DigiKey @Adafruit

This week’s EYE ON NPI (video) is a bright-eyed and bushy-tailed go-getter, who can juggle multiple tasks at once: it’s the Richtek RT4539 36 V I²C Controlled 6-Channel WLED Driver!

This chip can do it all: it’s a boost converter, it’s a calibrated constant-current sink, it’s a PWM controller, it’s a gamma-corrector, and it’s got I2C for controlling all the settings. It’s designed for use in laptop or tablet backlight control, and all the little extras that were designed in make it excellent for other sorts of lighting drives – just cause it says it’s for white LEDs doesn’t mean you have to only use it for that purpose!

The first feature of this chip is the boost converter. Since most LED backlights (and even some large LED clusters) have the LEDs in series to keep them current balanced, we often need to boost the battery voltage up to 20V+, this chip can go up to 36V output from 2.7 to 24V input – which means it can handle up to 10 LEDs at 3.3V forward drops, and still have a little headroom.

The boost FET switch is internal so only an inductor and diode are required. Since this is a constant-current chip, the output voltage will fluctuate as necessary to support the current draw needed. The booster frequency can be adjusted over I2C to balance flickering/beat frequencies and efficiency vs low power usage.

The second feature is the constant current string driver. As mentioned, large backlights try to string LEDs together to balance the current, but once you get past about 3-5″ diagonal, there’s usually more than one string. So now you want to make sure each string is balanced. Inside are comparator/differential drivers that use matched transistors and resistors with current mirroring setup to make sure you get the same exact current through each string.

The third feature of the RT4539 is the PWM driver. Yes you can reduce the current through the strings but its easier to get a wide range of brightness values by keeping a constant current and then PWMing the output sink drivers. It’s normal to see linear PWM drivers: where you can go from 0-255, say for 8-bit control and that translates to a linear duty cycle.

This chip goes above-and-beyond and provides an exponential “gamma corrected” output control curve if desired. This gives a more natural and useful brightness curve where there’s more granularity at low brightness values, often used for night modes.

The fourth (and final?) feature to highlight is that all of the settings for the capabilities are available over I2C! From the booster frequency to sink current, to the PWM style and duty cycles to extras like smooth dimming transition features, there’s a register map for easy configuration and adjustment, making his chip trivial to integrate into any design with a microcontroller or microcomputer.

The Richtek RT4539 is super-duper new, so it’s not yet available for purchase on Digi-Key’s website – keep an eye out for when this chip becomes available or contact your Digi-Key sales rep and they’ll be able to wrangle you some samples!

See on Digi-Key here.

Catch up with Richtek Technologies on YouTube


Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.

Join 35,000+ makers on Adafruit’s Discord channels and be part of the community! http://adafru.it/discord

Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.

Join us every Wednesday night at 8pm ET for Ask an Engineer!

Follow Adafruit on Instagram for top secret new products, behinds the scenes and more https://www.instagram.com/adafruit/

CircuitPython – The easiest way to program microcontrollers – CircuitPython.org


Maker Business — How (some) chips get made

Wearables — Sample code is your new best friend

Electronics — Solder braid quick fix

Python for Microcontrollers — Python on Microcontrollers Newsletter: Mu 1.2.0 Released, WSL Out of Beta and so much more! #CircuitPython @micropython @ThePSF @Raspberry_Pi

Adafruit IoT Monthly — Jellyfish Lanterns, Matter 1.0, and more!

Microsoft MakeCode — MakeCode Thank You!

EYE on NPI — Maxim’s Himalaya uSLIC Step-Down Power Module #EyeOnNPI @maximintegrated @digikey

New Products – Adafruit Industries – Makers, hackers, artists, designers and engineers! — JP’s Product Pick of the Week 11/22/22 EyeSPI Breakout @adafruit @johnedgarpark #adafruit #newproductpick

Get the only spam-free daily newsletter about wearables, running a "maker business", electronic tips and more! Subscribe at AdafruitDaily.com !



No Comments

No comments yet.

Sorry, the comment form is closed at this time.