Ultra-low power, 3-output PMIC for wearables and small-battery applications

August 11, 2016 // By Graham Prophet
Maxim Integrated has posted details of its MAX77650/MAX77651 power management ICs that provide power regulation to wearable device designs, and to other systems with highly-constrained battery power supplies. With 3-way single-inductor/multiple output (SIMO), and charger circuitry for small Li+ batteries, they implement a highly-integrated battery charging and power solution.

Maxim cites possible applications in Bluetooth headphones/hearables; fitness, health, and activity monitors; Internet of Things (IoT); and other portable devices. Both devices feature a SIMO buck-boost regulator that provides three independently programmable power rails from a single inductor to minimize total solution size. A 150 mA LDO provides ripple rejection for audio and other noise-sensitive applications. A highly configurable linear charger supports a wide range of Li+ battery capacities and includes battery temperature monitoring for additional safety (JEITA).

The devices include other features such as current sinks for driving LED indicators and an analogue multiplexer that switches several internal voltage and current signals to an external node for monitoring with an external ADC. A bidirectional I²C interface allows for configuring and checking the status of the devices. An internal on/off controller provides a controlled startup sequence for the regulators and provides supervisory functionality when the devices are on. Factory programmable options allow the device to be tailored.

Features include integration of:

  • Smart Power Selector™ Li+/Li-poly charger
  • 3 output, buck-boost regulator
  • 150mA LDO
  • 3-channel current sink driver
  • Analogue MUX output for power monitoring

Low-power specifications incude: 0.3µA standby current, and 5.6 µA operating current (3 SIMO channels + LDO).

The charger, optimized for small battery size, offers:

  • Programmable fast-charge current from 7.5 mA to 300 mA
  • Programmable battery regulation voltage from 3.6V to 4.6V
  • Programmable termination current from 0.375 mA to 45 mA
  • JEITA battery temperature monitors adjust charge current and battery regulation voltage for safe charging

The IC comes in a 2.75 × 2.15 × 0.7mm, 30-pin, 0.4 mm-Pitch WLP, and can yield a total solution size of 28mm².

Maxim Integrated; www.maximintegrated.com/en/products/power/battery-management/MAX77650