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.
| 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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| 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 | ||
| Application brief | Supercap last gasp failsafe power for RF comunications in E-Meters | Jan. 27, 2019 |
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