Power and Battery Management Solutions for Hearables and Wearables

The DS2488 is a simple bridge device that with a single dedicated contact on each side of the bridge enables up to 512kbps pass-through communication, power delivery for battery charging, small message exchange, and state reporting between two microcontroller-based subsystems. An example application is true wireless stereo (TWS) earbuds containing a Bluetooth^® Audio SoC and the microcontroller operated case that holds and charges the earbuds. In this scenario, the DS2488 would reside in earbuds alongside the SoC, and the charge case microcontroller would communicate with the DS2488 from a single dedicated pin (see the Typical Application Circuit). All of this is enabled with the flexibility of Maxim's 1-Wire interface, which is used to operate each of the two independent I/O ports, IOA and IOB. To enable device operation between two connected controllers, each of these two DS2488 1-Wire interfaces has access to a 64-bit factory-programmed ROM ID, an 8-byte buffer to transmit small messages, and registers for device configuration, status, and control of three open-drain GPIO pins. Through a configuration setting a bidirectional, high-speed 512kbps pass-through mode is enabled, which enables large data transfers between the two connected microcontrollers.

For communication between IOA and IOB, the DS2488 has a maximum operating voltage of 3.63V. But to support a special mode of power delivery from the subsystem connected to the IOA side to the subsystem connected to the IOB side, the device is 5V tolerant and goes into the power delivery state when 4V to 5V (nom) is applied to IOA. In this mode, an additional DS2488 output pin is used to control an external transistor for power delivery to IOB-side electronics, such as a battery charger.

Applications

• Communication and Control Bridging
• Electronic Locks
• True Wireless Stereo Earbuds and Charger Box
• Wearable Devices

The MAX17260 is an ultra-low power fuel gauge IC which implements the Maxim ModelGauge^™ m5 algorithm. The IC monitors a single-cell battery pack and supports both high-side and low-side current sensing.

The ModelGauge m5 EZ algorithm makes fuel gauge implementation easy by eliminating battery characterization requirements and simplifying host software interaction. The algorithm provides tolerance against battery diversity for most lithium batteries and applications. The algorithm combines the short-term accuracy and linearity of a coulomb counter with the long-term stability of a voltage-based fuel gauge, along with temperature compensation to provide industry-leading fuel gauge accuracy. The IC automatically compensates for cell-aging, temperature, discharge rate, and provides accurate state-of-charge (SOC) in percentage (%) and remaining capacity in milliampere-hours (mAh) over a wide range of operating conditions. As the battery approaches the critical region near empty, the algorithm invokes a special correction mechanism that eliminates any error. The IC provides accurate estimation of time-to-empty and time-to-full and provides three methods for reporting the age of the battery: reduction in capacity, increase in battery resistance, and cycle odometer.

The IC provides precision measurements of current, voltage, and temperature. The temperature of the battery pack is measured using an internal temperature sensor or external thermistor. A 2-wire I²C interface provides access to data and control registers. The IC is available in tiny lead-free 0.4mm pitch, 1.5mm x 1.5mm, 9-pin WLP package and 3mm x 3mm, 14-pin TDFN package.

Design Solution: Choose a Fuel Gauge with the Right Current Sensing for Your Battery System ›

Applications

• Wearables, Smartwatches
• Tablets, 2-in-1 Laptops
• Bluetooth Headsets
• Health and Fitness Monitors
• Digital Still, Video, and Action Cameras
• Medical Devices
• Handheld Computers and Terminals
• Wireless Speakers
• Home and Building Automation, Sensors
• Portable Game Players
• Toys

The MAX17262 is an ultra-low power fuel-gauge IC which implements the Maxim ModelGauge™ m5 algorithm. The IC monitors a single-cell battery pack and supports internal current sensing. The IC provides best performance for batteries with 30mAhr to 6Ahr capacity.

The ModelGauge m5 EZ makes fuel-gauge implementation easy by eliminating battery characterization requirements and simplifying host software interaction.The ModelGauge m5 EZ robust algorithm provides tolerance against battery diversity for most lithium batteries and applications.

The ModelGauge m5 EZ algorithm combines the short-term accuracy and linearity of a coulomb counter with the long-term stability of a voltage-based fuel gauge, along with temperature compensation to provide industry-leading fuel-gauge accuracy. The IC automatically compensates for cell-aging, temperature, and discharge rate, and provides accurate state-of-charge (SOC) in percentage (%) and remaining capacity in milliampere-hours (mAh) over a wide range of operating conditions. As the battery approaches the critical region near empty, the ModelGauge m5 algorithm invokes a special correction mechanism that eliminates any error. The IC provides accurate estimation of time-to-empty and time-to-full and provides three methods for reporting the age of the battery: reduction in capacity, increase in battery re- sistance, and cycle odometer.

The IC provides precision measurements of current, voltage, and temperature. The temperature of the battery pack is measured using an internal temperature sensor or external thermistor. A 2-wire I²C interface provides access to data and control registers. The IC is available in a tiny lead-free 0.4mm pitch, 1.5mm x 1.5mm, 9-pin wafer-level package (WLP).

APPLICATIONS

• Bluetooth Headset Cases
• Handheld Computers and Terminals
• Health and Fitness Monitors
• Home and Building Automation, Sensors
• Medical Devices
• Toys
• Wearables and Smartwatches

The MAX17332 is a 35μA I_Q stand-alone charger, fuel gauge, protector, and battery internal self-discharge detection IC for 1-cell lithium-ion/polymer batteries. When a voltage source is present, the IC regulates charging by modulating the charge N-FET, using AccuCharge™charger technology. The IC regulates charge voltage, current, and FET temperature. Stand-alone charging is supported by flexible configuration in nonvolatile memory. The IC supports the following applications:

• Low-Power Charging
  • 1mA to 500mA directly from universal 5V USB
  • No USB identification/coordination needed
• High-Power Parallel Packs (>1000mA)
  • Independently charges parallel packs
  • Prevents cross-charging for parallel batteries
  • Coordinates external DC-DC with alerts
  • Minimizes dropout and heat
• Protection and Charging Control—pack or host side

The IC ideal diode circuit supports a quick response to system transients and adapter removal with low voltage drop across the CHG FET.

The IC uses the ModelGauge™ m5 EZ algorithm that combines the short-term accuracy and linearity of a coulomb counter with the long-term stability of a voltage-based fuel gauge to provide industry-leading accuracy. The IC automatically compensates for cell aging, temperature, and discharge rate while providing accurate state-of-charge (SOC) in milliampere-hours (mAh) or percentage (%) over a wide range of operating conditions.

The IC monitors the voltage, current, temperature, and state of the battery to provide protection against over/undervoltage, overcurrent, short-circuit, over/undertemperature and overcharge conditions, and internal self-discharge protection using external high-side N-FETs to ensure that the lithium-ion/polymer battery operates under safe conditions which prolongs the life of the battery.

APPLICATIONS

• USB PPS and Direct Charging
• Smart Batteries and Hybrid Supercap Batteries
• Dual Screen Smartphones, Tablets
• Hearables, Wearables, Smartwatches
• Medical Devices, Health, Fitness Monitors
• Handheld Radios, Computers, Accessories
• Home/Building Automation, Sensors, Cameras
• Parallel Battery AR/VR Systems

The MAX20343/MAX20344 is an ultra-low quiescent current, noninverting buck-boost converter with 1A current capability at 3.5V intended for applications that require long run times while also demanding bursts of high current. The device employs a unique control algorithm which seamlessly transitions between buck, buck-boost, and boost modes, minimizing discontinuities and subharmonics in the output voltage ripple. The low 1.9V input voltage for startup allows users to power the device from a variety of sources, and the near-zero minimum operating voltage gives the user the ability to extract as much as possible from their energy source. The MAX20343/MAX20344 has also been designed to keep inductance and output capacitance requirements as low as possible for space-constrained applications.

The MAX20343/MAX20344 is ideal for power in optical sensor applications as well as for powering radios in low power, wide area network (LPWAN) applications since in both cases noise must be minimal and efficiency must be high. For instance, the small light-load output voltage ripple allows a photoplethysmography (PPG) system to operate at low LED currents without interference. Additionally, seamless transitions between operating modes enables the use of dynamic voltage scaling (DVS) to minimize headroom on the LED and to save power in such systems. In applications where a low-power-density battery must be buffered by a super-capacitor to provide large LPWAN type bursts of current, the ultra-low operating voltage of the MAX20343/MAX20344 allows the user to extract as much energy as possible from the super capacitor. The low output inductance/capacitance requirement allows a small total solution size. For example in PPG systems, this provides the flexibility to place the MAX20343/MAX20344 on a remote optical module if overcrowding on the main PCB is an issue.

The MAX20343/MAX20344 is available with a highly configurable I²C serial interface or as a single-pin-enabled fixed-programming version. See Table 3 for specific device settings. MAX20343 operates over the -40°C to +85°C temperature range, is available in a 16-bump, 1.77mm x 2.01mm, 0.4mm pitch WLP package and a 12-pin, 2.50mm x 2.50mm, 0.5mm pitch FC2QFN package. MAX20344 operates over the -40°C to +125°C temperature range, and is available in a 12-pin, 2.50mm x 2.50mm, 0.5mm pitch FC2QFN package.

Applications

• Biometric Optical Sensing Including PPG
• Industrial Sensors
• IoT
• LPWAN (LTE/NB-IoT, LTE/Cat-M1)

The MAX2036 8-channel variable-gain amplifier (VGA) and programmable octal mixer array is designed for high linearity, high dynamic range, and low-noise performance targeting ultrasound imaging and Doppler applications. Each amplifier features differential inputs and outputs and a total gain range of 50dB (typ). In addition, the VGAs offer very low output-referred noise performance suitable for interfacing with 10-bit ADCs.

The MAX2036 VGA is optimized for less than ±0.5dB absolute gain error to ensure minimal channel-to-channel ultrasound beamforming focus error. The device's differential outputs are designed to directly drive ultrasound ADCs through an external passive anti-aliasing filter. A switchable clamp is also provided at each amplifier's output to limit the output signals, thereby preventing ADC overdrive or saturation.

Dynamic performance of the device is optimized to reduce distortion to support second-harmonic imaging. The device achieves a second-harmonic distortion specification of -62dBc at V_OUT = 1.5V_P-P and f_IN = 5MHz, and an ultrasound-specific* two-tone third-order intermodulation distortion specification of -52dBc at V_OUT = 1.5V_P-P and f_IN = 5MHz.

The MAX2036 also integrates an octal quadrature mixer array and programmable LO phase generators for a complete CW beamforming solution. The LO phase selection for each channel can be programmed using a digital serial interface and a single high-frequency clock or the LOs for each complex mixer pair can be directly driven using separate 4 x LO clocks. The serial interface is designed to allow multiple devices to be easily daisy-chained in order to minimize program interface wiring. The LO phase dividers can be programmed to allow 4, 8, or 16 quadrature phases. The input path of each CW mixer consists of a selectable lowpass filter for optimal CWD noise performance. The outputs of the mixers are summed into I and Q differential current outputs. The mixers and LO generators are designed to have exceptionally low noise performance of -155dBc/Hz at 1kHz offset from a 1.25MHz carrier.

The MAX2036 operates from a +5.0V power supply, consuming only 120mW/channel in VGA mode and 269mW/channel in normal power CW mode. A low-power CW mode is also available and consumes only 226mW/channel. The device is available in a lead-free 100-pin TQFP package (14mm x 14mm) with an exposed pad. Electrical performance is guaranteed over a 0°C to +70°C temperature range.

Applications

• Sonar
• Ultrasound Imaging

Applications

• Bluetooth Headphones, Hearables
• Wireless Speakers
• Fitness, Health, and Activity Monitors
• Wearables
• Safety and Security Monitors
• Sensor Nodes
• Portable Consumer Devices
• Internet of Things (IoT)

The MAX77787 is a standalone, 3.15A charger with integrated USB Type-C^® CC detection and reverse-boost capability. The fast-charge current and termination voltage is easily configured with resistors. The IC operates with an input voltage of 4.5V to 13.4V and has a maximum input current limit of 3A. The IC also implements the adaptive input current limit (AICL) function that regulates the input voltage by reducing input current to prevent the voltage of a weak adapter from collapsing or folding back.

The USB Type-C Configuration Channel (CC) detection pins on the IC enable automatic USB Type-C power source detection and input current limit configuration without any software control as soon as the USB plug is inserted. The IC also integrates BC1.2 and proprietary adapter detection using the D+ and D- pins.

The IC offers reverse-boost capability up to 5.1V, 1.5A, that can be enabled with the ENBST pin, also BYP reverse-boost that can be enabled with the ENBST and STBY pin combination. The STAT pin indicates charging status, while the INOKB pin indicates valid input voltage. Charging can be stopped by pulling the CHGENB pin low.

The IC is equipped with a Smart Power Selector™ and a battery true-disconnect FET to control the charging and discharging of the battery or isolate the battery in case of a fault. The IC supports Li-ion batteries with JEITA compliance. It also has another option that supports LiFePO₄ batteries with non-JEITA compliance. The IC comes in a 2.758mm x 2.758mm, 0.4mm pitch, 6 x 6 wafer-level package (WLP) making it suitable for low-cost PCB assembly.

Applications

• Mobile Point-of-Sale (mPOS) Terminals
• Portable Medical Devices
• Wireless Headphones
• GPS Trackers
• Charging Cradles for Wearable Devices
• Power Banks
• Mobile Routers