Longer Battery Life for Tomorrows Design Challenges

TI Ensures Ultra-low IQ Power Management

“ As we increasingly rely on smaller, smarter and more connected devices, the demand for power grows faster than ever”, stated Mike Beckman, VP and General Manager, Linear Power, of Texas Instruments during a press conference in Munich in September. “As we hold power – literally – in the palm of our hands, we need devices with longer battery life. This demand for longer battery life requires low quiescent current (IQ).”

Low IQ plays a key role in extending battery and shelf life, enabling more functionality, increasing system life and reducing system cost. In brief: two factors drive the demand for low IQ:

• Power systems that operate with batteries, e.g. medical devices, need low standby power to preserve battery life and provide better user experience;

• non-portable electronics, like meters, need more accurate end-of-service detection and maximum standby energy efficiency.

Texas Instruments introduced low IQ power innovations, that can fuel engineers´ solutions to the challenges below.

 

Ultra-LDO Linear Voltage Regulator

The TPS7A02 is TI´s new ultra-low-power low-dropout (LDO) linear voltage regulator with the industry’s lowest quiescent current (IQ) of sub-25 nA — one-tenth that of competing ultra-small devices. The new regulator features low IQ control at light loads even in dropout conditions, allowing engineers to at least double the battery life of their applications. In addition, it provides a best-in-class transient response for faster wake-up, improving application response times and dynamic performance. The small solution footprint helps engineers design smaller, lighter, more efficient products quickly by reducing power supply solution size, and its common industry packages allow for pin-to-pin drop-in replacement in existing designs.

 

Figure 1: The TPS7A02 is TI´s new ultra-low-power low-dropout (LDO), linear voltage regulator.

 

The TPS7A02 helps engineers solve critical design challenges in many power-sensitive, high-precision and low-power applications such as in the grid infrastructure, building automation, medical equipment and wearables markets. The device joins TI’s portfolio of low-IQ LDO linear regulators that enable designers to prolong system life. By implementing the TPS7A02 with other ultra-low IQ devices — such as TI’s family of ultra-low-power MSP430 MCUs, the SimpleLink CC2642R MCU, the TLV8802 nano power OpAmp, or the TMP1075 low-power temperature sensor — engineers can further optimize battery life and performance in their systems.

 

Key Features and Benefits of the TPS7A02

Extended application run times, longer system lifetime: The TPS7A02’s ultra-low IQ control at light loads allows engineers to at least double the battery life for applications using standard battery chemistry, such as lithium-ion. For example, by using the TPS7A02 in wireless video doorbell and security camera designs, engineers can achieve 24 months or more of battery life (up to four times the industry standard). In addition, the TPS7A02’s ultra-low shutdown IQ of 3nA can extend battery shelf life by as much as five times in portable medical and wearable applications compared to competing devices.

Faster wake-up, better dynamic performance: The TPS7A02 can settle in less than 5µs for 1-to-50-mA load transients – half the time of competing devices – enabling engineers to design applications with shorter response times and better dynamic performance. With the ability to quickly respond to rapidly changing loads while providing minimal variation in output voltage, the TPS7A02 can benefit high-precision, low-power applications such as wireless IoT and portable medical devices, which require clean power to accurately acquire signals from around the body.

Smaller solution footprint, faster time to market: The TPS7A02 automatically transitions from an IQ-saving, low-load state to a high load, fast-transient state without the need for any external circuitry or components. As a result, engineers can use the TPS7A02 to shrink the solution size by 70%, adding more functionality to their designs in space-constrained applications or lowering system costs by using smaller boards.

Pre-production samples of the TPS7A02 are now available in an X2SON package measuring 1mm by 1mm. A 5-pin SOT-23 package measuring 2.9mm by 1.6mm will become available later this year, and a 4-pin DSBGA package (0.65 by 0.65mm) will become available in early 2020.

 

60-nA I Q Buck Converter Shrinks Solution Size

The new ultra-low-power switching regulator TPS62840, a synchronous step-down converter, features the industry’s lowest operating quiescent current (IQ) at 60nA – 1/3 that of the nearest competitive device. It delivers a very high light-load efficiency of 80% at 1µA load, which can enable designers to extend the battery life of their systems or use fewer or smaller batteries to shrink their overall power supply solution size and reduce cost. Additionally, the new DC/DC converter’s wide VIN range of 1.8V to 6.5V supports a variety of battery chemistries and configurations.

These features plus its selectable functions enable the TPS62840 to help engineers solve critical design challenges in many battery-powered, always-ON industrial and personal electronics applications – including narrow-band IoT, grid infrastructure equipment and wearables – that require more flexibility, an extended wireless range, improved accuracy, and reduced EMI. The TPS62840 joins TI’s portfolio of highly integrated, low-IQ DC/DC converters that enable designers to maximize power delivery in the smallest possible solution size.

 

Figure 2: Synchronous step-down converter, features the industry’s lowest operating quiescent current

 

Key Features and Benefits of the TPS62840

Longer battery life, very high light-load efficiency: A lower IQ draw delivers longer battery life for systems with very light loads (less than 100µA), and those operating primarily in standby/ship mode (not switching). The low IQ of the TPS62840 enables its 80% efficiency at a 1-µA load, which is up to 30% better than competitive devices. Selectable modes enhance performance, lower overall cost: The TPS62840’s selectable mode and stop functions improve noise performance and reduce signal distortion. These benefits can help lower the solution cost because designers can achieve system requirements without using more expensive precision signal-chain components, sensors or radio solutions to perform the same functions. The mode pin allows for continuous conduction mode, also called forced PWM mode, to improve ripple or noise performance and lessen the impact on transmissions in sensitive radio-frequency applications.

The stop pin turns OFF all switching to reduce EMI or ripple and minimizes distortions passed to precision signal-chain, measurement, sensors or wireless connectivity components.

Smaller solution size: Engineers can use the new switching regulator to cut their battery count in half or use smaller batteries in their design. For example, designers can save up to 16,980mm3 using four AAAs instead of four AAs.

Flexible VIN broadens applications: The TPS62840’s wide range of 1.8VIN-6.5VIN accommodates multiple battery chemistries and configurations, such as two lithium manganese dioxide (2s-LiMnO2) cells in series, single-cell lithium thionyl chloride (1xLiSOCL2), four-cell and two-cell alkaline, and lithium polymer (Li-Po).

Pre-production samples of the TPS62840 are now available in the following packages: 8-pin SON, measuring 1.5mm by 2.0mm; 6-pin WCSP, measuring 0.97mm by 1.47mm. An 8-pin thermally enhanced package (HVSSOP), measuring 3mm by 5mm, will become available later this year.

 

New Battery Charger Increases Battery Capacity

At the same event, Samuel Wong, Product Line Manager, Battery Management Systems, introduced a new switching battery charger IC that supports a termination current of 20mA. The three-in-one switching boost converter achieves the lowest quiescent current for small medical and personal electronics applications. Compared to competing devices, which typically support a termination current higher than 60mA, the new BQ25619 enables a 7% higher battery capacity and longer run time. The charger delivers three-in-one boost converter integration and ultra-fast charging, too, offering 95% efficiency at a 4.6V and 0.5A output. Additionally, with the industry’s lowest quiescent current, the new charger can double the shelf life of ready-to-use electronics.

The BQ25619 charger helps engineers design more efficiently for small medical and personal electronics applications such as hearing aids, earbuds and wireless charging cases, IP network cameras, patient monitoring devices and personal care applications.

 

Figure 3: An ultra-low termination current of 20mA increases battery capacity and run time by up to 7%.

 

Key Features and Benefits of the BQ25619

The industry’s lowest termination current for switching chargers: An ultra-low termination current of 20mA increases battery capacity and run time by up to 7%. The BQ25619’s settable top-off timer further increases run time, enabling users to charge their devices less frequently.

Best-in-class low quiescent current: The BQ25619 reduces battery leakage down to 6µA in ship mode, which conserves battery energy to double the shelf life for the device. While in battery-only operation, the device consumes only 10µA, to support standby systems.

Three-in-one boost converter integration: The BQ25619 includes integrated charge, boost converter and voltage protection to support efficient design for space-constrained applications and eliminate the external inductor required by previous-generation charger ICs. Due to its integrated bidirectional buck or boost topology, the BQ25619’s charging and discharging capabilities require just a single power device.

The BQ25619, available now, expands TI’s portfolio of industry-leading battery-charger solutions, offering single- and multicell switchmode chargers for high-capacity batteries, as well as linear chargers with high integration to extend battery run time and reduce total solution size. Offered in a 24-pin wafer WQFN package, the charger is priced at USD1.45 in 1,000-unit quantities. The 30-pin BQ25618, with similar features, will be offered in a smaller WCSP in the third quarter of 2019.

 

About the Author

Roland R. Ackermann has been a technology journalist since 1957, covering electronics, engineering and manufacturing/automation. He has been a freelance journalist 1996, publishing work in Elektronik Journal, was editor in chief of Electronik Embedded System and verlagsweltMAGAZIN, and also wrote numerous articles in German and English publications and newspapers. He was a regular column writer in E&E Faszination Elektronik and is now a correspondent for Bodo's Power Systems. Ackermann holds talks at international venues, moderates panel discussions, and organizes events.