EYE on NPI - Richtek RT6160A Buck-Boost Converter with I²C Interface

Adafruit Industries

This week's EYE ON NPI will make you say "Yeee-haww", to the buckin'-and-boostin' bronco known as the Richtek RT6160A Buck-Boost Converter with I²C Interface (https://www.digikey.com/en/product-highlight/r/richtek/rt6160a-buck-boost-converter). The RT6160A is a high-efficiency, single-inductor, synchronous buck-boost converter that can provide up to 3 Amps of current to a dynamically-configurable voltage from 2.025V to 5.2V. With an amazing 2uA quiescent current, this chip lets you add an advanced power supply for the price of an LDO that will let you design with the smallest possible battery. We're big fans of Richtek for low quiescent power supply chips - our favorite 3.3V LDO is the RT9080-33 (https://www.digikey.com/en/products/detail/richtek-usa-inc/RT9080-33GJ5/6161634) which can provide up to 600mA with a 0.5V dropout, and a really nice 4uA quiescent current. This is great for deep-sleep wireless projects where you've got a chip with ultra-low power snooze modes, like the ESP32 - we were able to get down to 10.5 uA in deep sleep thanks to the RT9080! (https://learn.adafruit.com/adafruit-itsybitsy-esp32/low-power-use). Compare that to the AP2112K which we used to use, has a quiescent current of 55uA. However, the RT9080 is a LDO fixed at 3.3V@600mA - and of course, LDOs have that dropout which translates to power lost. If you want to sip every last Coulomb out of the battery on hand, you'll need a DC/DC converter. Usually we see a buck converter - since you are converting from a Lithium Polymer battery, you'll have 3.7V nominal, 4.2V peak voltage and maybe you'll buck that down to 3V. If you want to really get the best possible range of performance, you can go with a buck boost (https://en.wikipedia.org/wiki/Buck%E2%80%93boost_converter). That way you can buck down from 3.4-4.2V and then as the battery starts drooping, the chip switches into a boost mode to cover the 2.7V~3.2V range. The RT6160A is a Buck-Boost converter that seems well designed for battery-powered projects, with an input and output range of about 2 to 5V. The default output is 3.3V and you can 'select' between two voltages by toggling a GPIO pin. This makes it easy to adjust the desired voltage and then swap from 'high' to 'low' voltages without an I2C command. Why would you want two voltages? Well, you could use 3.3V or greater for when you want the best performance from a radio, then drop down to 2.5V when the radio isn't on and you want to reduce both the conversion current and also reduce your chip quiescent current: most microcontrollers will use lower current at lower voltages since they are not pushing around as much current onto the internal logic FETs. Combine this with a microcontroller's dynamic clock frequency configuration and you've got a simple system to squeeze more current out of your battery. And usually you have to 'spend' a lot of current to run the DC/DC converter, but this chip has an amazing 2uA quiescent current - lower than most LDOs we've used, and amazing for an up-to-3A output device. If you want to have the lowest quiescent, highest-flexibility power management chip in your next design, the Richtek RT6160A Buck-Boost Converter with I²C Interface (https://www.digikey.com/short/hv7fm4nt) is an excellent choice: Richtek really know their power supplies and they keep it nice and simple so you can get to integration instantly. Best of all, DigiKey has the RT6160A (https://www.digikey.com/short/hv7fm4nt) in stock right now, for immediate shipment, and $1.32 by the reel! All you need is some ceramic caps and an inductor. For fast testing in your application, there are also some EVB_RT6160AWSC (https://www.digikey.com/short/0p80hqvj) eval boards in stock. Order today and you can be waving your cowboy hat in celebration by tomorrow afternoon.