Can TI’s New DC-DC Converter Really Extend Battery by 50 Percent?September 05, 2020 by Jake Hertz
This week, Texas Instruments released a buck-boost converter with two heavy-hitter claims: that it extends battery life by 50% and that it offers the lowest IQ in the industry.
Low power design is a key interest for many design engineers today. Technologies like the IoT and wearables require low power consumption largely due to their small form factors, which require small, lower-capacity batteries to power the system.
On top of this, IoT devices are often deployed as standalone devices. To mitigate the need to find and replace the batteries in these deployed devices, low power design is crucial.
DC-DC Converters and Low Power Design
One way designers try to implement low power design is by leveraging a DC-DC converter. Generally, a battery provides an unregulated and relatively high DC voltage to the system. This voltage varies based on the battery type and chemistry. For example, almost all lithium polymer batteries are either 3.7 V or 4.2 V.
Example of a DC-DC converter in a system. Image source Md Umar Hashmi et. al.
The problem is a lot of devices, especially those operating at low power, require much smaller operating voltages than those provided directly from a battery. The voltage from a battery may also be unstable, fluctuating based on things such as switching noise. To alleviate these issues, engineers use DC-DC converters, allowing them to work with desirable voltages that are well regulated (i.e. they don’t fluctuate in value).
A New DC-DC Converter By TI
Understanding the importance of DC-DC converters makes the newest release by Texas Instruments all the more exciting. Just this week, the company announced the TPS63900 buck-boost converter.
Simplified TPS63900 schematic. Image used courtesy of Texas Instruments
The release is particularly noteworthy because it claims that this new device can help improve battery life in devices by 50% thanks to a few stand-out features, including low quiescent current.
Power Saving Features
The TPS63900 incorporates a few features that support TI's claim of immense power savings.
First, it offers a dynamic voltage scaling function. What this means is that the output voltage of the device can be set to two different values and changed as needed. When the SEL pin changes state, the output voltage changes from one selected voltage to the other in 100-mV steps. In this way, a designer can intelligently lower the output voltage of the DC-DC converter when in standby mode, saving power by not providing the full operating voltage when it isn’t needed.
Second, the device offers an adjustable input current limit. The device can limit the current drawn from its supply so it can be used with batteries that do not support high peak currents. The input current limit is active during normal operation and at start-up to avoid high inrush current. This saves the user power because it doesn't overconsume current, affording the battery a longer lifespan.
Device quiescent current vs. VIN at varying temperatures. Image used courtesy of Texas Instruments
Finally, this device boasts an extremely low quiescent current of 75 nA at room temperature. Quiescent current or the current consumed when the device is not operating is an extremely important consideration in IoT applications.
If you consider a sensor that makes some sort of measurement and transmission once daily and is in sleep mode for the rest of the day, the majority of the device's life will be spent consuming quiescent current. As such, a low quiescent current is extremely valuable.
A Step Closer to Low Power
While it seems that Texas Instrument's claim of 50% battery life extension may be an ambitious statement, it's undeniable that its new DC-DC converter offers many power-saving features.
TI says TPS63900 is particularly well-suited for smart gas and water metering. Image (modified) used courtesy of Texas Instruments
With a growing need for low power design, this release by TI is a great step in the right direction and should benefit many designers who choose to use it in their system designs.