SLVAF41A March   2021  – November 2021 TPS61094


  1.   Trademarks
  2. 1Introduction of the Smart Meter
  3. 2The Traditional Power Solution of the Smart Meter
    1. 2.1 Connecting the Battery Directly
    2. 2.2 The Pure Boost TPS61094 or TPS610995 Solution
  4. 3The TPS61094 with Supercap Solution
    1. 3.1 TPS61094 Description
    2. 3.2 System Operation Description
  5. 4Solution Comparison
  6. 5Supercap Behavior and Design
    1. 5.1 Supercap Life Time
    2. 5.2 Supercap Leakage Currrent
    3. 5.3 Supercap Parameter Design in TPS61094 Solution
  7. 6Test Report Based on TPS61094 Solution
    1. 6.1 Test Waveform
      1. 6.1.1 NB-IoT Data Transmission
      2. 6.1.2 Supercap Charging
    2. 6.2 Efficiency
  8. 7References
  9. 8Revision History

Connecting the Battery Directly

The traditional solution is the direct battery connection solution, like Figure 2-1. The communication model such as NB-IoT is connected with the LiSOCl2 and HLC package directly. The voltage of the LiSOCl2 and HLC package is about 3.6 V at room temperature. When the smart meter does the transmission, the HLC supports the high pulse current for the NB-IoT. During sleep mode, the LiSOCl2 charges the HLC and supports the whole system consumption.

GUID-20210201-CA0I-MVPN-4G4P-C8TVTDS2NFLC-low.png Figure 2-1 Direct Battery Connection Solution

The disadvantage of the direct battery connection solution is customers must choose HLC1550 instead of HLC1520. Because the LiSOCl2 and HLC package has the poor performance at cold temperature (-25 degC or -40 degC) , like in Figure 2-2 and Figure 2-3. Figure 2-2 is the performance of ER26500 and HLC1520 at high pulse current (250 mA / 250 ms). In the waveform, the voltage of the battery package is down to 3.4 V at high pulse current. It is too little margin to power the whole system. Figure 2-3 is the performance of ER26500 and HLC1550, because HLC1550 has a bigger size and higher current capability, the voltage is down to 3.6 V, and it can support the whole system and do the transmission. But HLC1550 has bigger size and higher cost.

Another disadvantage of this solution is the discharge current of LiSOCl2 is uncontrolled. In the Figure 2-2 and Figure 2-3, the discharge current of LiSOCl2 is up to 15 mA and 5 mA, respectively. The LiSOCl2 cannot achieve the maximum capacity, referring Figure 1-2.

GUID-20210207-CA0I-VQPN-KZXX-QB3VC3P4L3QP-low.gif Figure 2-2 The Performance of ER26500 and HLC1520 at -25 degC
GUID-20210207-CA0I-LBHW-1FMF-S6K2M5TZ3H9D-low.gif Figure 2-3 The Performance of ER26500 and HLC1550 at -25 degC