Buck-boost converter developed for wearables and IoT

21st December 2023
Mick Elliott

The MAX77837 from Analog Devices (ADI) is an extremely small nanoPower buck-boost converter optimised for single-cell battery chemistries used in wearable and Internet of Things (IoT) applications.

It is in stock at authorised distributor DigiKey

The converter operates on an input supply between 1.8 V to 5.5 V. Output voltages between 1.8 V to 5.2 V are set through resistors connected to two hardware control pins. The IC can operate in continuous conduction mode (CCM), skip mode, and a low-power mode to ensure high efficiency over a wide load current range.

In addition, the IC features an ultra-low quiescent current (IQ) of 430 nA (typical) and a shutdown current of 10 nA (typical), making it ideal for battery-powered applications requiring a long standby time.

The MAX77837 offers two unique hardware control pins, SEL1 and SEL2. The resistor connected at SEL1 (RSEL1) selects a predefined combination of two output voltages between 1.8 V to 5.2 V, OUT1 and OUT2. The resistor connected at SEL2 (RSEL2) allows two different configurations of switch current limit at 1050 mA and 400 mA to optimise external component size, enable or disable dynamic voltage scaling (DVS) function, and select either hiccup or latch-off mode during a hard short event.

RSEL2 can also configure the startup voltage as OUT1 or OUT2, and the DVS function can change the output voltage from a lower VOUT to a higher VOUT as required without powering down the part.

The MAX77837 is available in both a 1.84 mm x 1.03 mm, 8-bump wafer-level package (WLP) with a bump pitch of 0.4 mm and a 2.5 mm x 2.0 mm, 8-lead flip chip QFN package (FC2QFN).

The MAX77837EVKIT evaluation kit (EV kit) is a fully assembled and tested printed circuit board (PCB) demonstrating the MAX77837 nanoPower buck-boost converter. The EV kit has an input range of 1.8 V to 5.5 V, with a switch current limit of 1.05 A.

Features include:

  • Peak efficiency of 95% (5.5 VIN, 3.8 VOUT)
  • 430 nA typical quiescent current
  • 10 nA shutdown current
  • Protections
    • Input undervoltage lockout (UVLO)
    • Overcurrent protection (OCP)
    • Thermal shutdown

Applications cover LPWAN SoC companion power solution, IoT and wearable applications, asset trackers and smart meters

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