Supercapacitor backup power supply for E-Meters reference design


Design files


This reference design automatically provides back-up voltages to an E-Meter during a power interruption. While the input voltage is between 10 V to 12 V, two buck controllers (TPS62147, TPS62173) generate 3.9 V at 2 A and 5 V at 150 mA. An optional synchronous boost generates 3.3 V at 50 mA. A discrete charge circuit charges a supercapacitor with a constant current up to an adjustable voltage of 2.7 V. When the input voltage fails, a synchronous boost takes over and boosts the supercap voltage to 3.9 V. The supercap capacitance and voltage defines the energy, which is available for the backup. The design enables a stable backup output of 3.9 V at 200 mA for about 70 s until the output voltage drops.

  • Seamless transition between mains power and back-up operation
  • Designed to support high output power RF communications such as LTE, NB-IOT, or wireless MBUS or 6LoWPAN
  • Single supercapacitor design to minimize system cost
  • Discrete constant current supercapacitor charger
  • Complete tested design with available design files and test report
Output voltage options PMP30528.1 PMP30528.2 PMP30528.3 PMP30528.4
Vin (Min) (V) 10 10 10 10
Vin (Max) (V) 12 12 12 12
Vout (Nom) (V) 5 3.3 3.9 3.9
Iout (Max) (A) .15 .05 2 2
Output Power (W) .75 .165 7.8 7.8
Isolated/Non-Isolated Non-Isolated Non-Isolated Non-Isolated Non-Isolated
Input Type DC DC DC DC
Topology Buck- Synchronous Buck- Synchronous Buck- Synchronous Buck- Synchronous
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A fully assembled board has been developed for testing and performance validation only, and is not available for sale.

Design files & products

Design files

Download ready-to-use system files to speed your design process.

TIDT093.PDF (1795 K)

Test results for the reference design, including efficiency graphs, test prerequisites and more

TIDRZ79.PDF (199 K)

Detailed schematic diagram for design layout and components

TIDRZ80.PDF (31 K)

Complete listing of design components, reference designators, and manufacturers/part numbers

TIDRZ81.PDF (224 K)

Detailed overview of design layout for component placement

TIDRZ83.ZIP (659 K)

Files used for 3D models or 2D drawings of IC components


Design file that contains information on physical board layer of design PCB

TIDRZ82.PDF (251 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Boost converters (integrated switch)

TPS610228-A boost converter with 0.5-V ultra-low input voltage

Data sheet: PDF | HTML
Boost converters (integrated switch)

TPS610981Low input voltage, 3.3-V output voltage, synchronous boost converter with integrated LDO

Data sheet: PDF | HTML
Buck converters (integrated switch)

TPS621473-17V 2.0A Step-Down Converter with 1% accuracy and PFM/Forced-PWM in 2x3QFN

Data sheet: PDF | HTML
Buck converters (integrated switch)

TPS621733–17V 0.5A Step-Down Converter in 2x2 QFN package

Data sheet: PDF | HTML
N-channel MOSFETs

CSD15571Q220-V, N channel NexFET™ power MOSFET, single SON 2 mm x 2 mm, 19.2 mOhm

Data sheet: PDF
P-channel MOSFETs

CSD25402Q3A-20-V, P channel NexFET™ power MOSFET, single SON 3 mm x 3 mm, 8.9 mOhm

Data sheet: PDF | HTML
Shunt voltage references

TL431Adjustable precision shunt regulator

Data sheet: PDF | HTML

Technical documentation

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Type Title Date
* Test report Supercapacitor backup power supply for E-Meters reference design Mar. 06, 2019
More literature A supercapacitor and battery backup power-supply design PPT Dec. 02, 2021
More literature Supercap last gasp failsafe power for RF comunications in E-Meters Jan. 27, 2019

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