Power Controller Module v1.5

Version Details
v1 Original design
v1.5 Simplified power controller for time efficiency

This module will be a simple power regulator for the rest of the balloon modules. It will regulate the power from a common voltage battery pack out to several required voltages.

Key differences from original design:

  • No current measurement
  • No charge counting
  • No 12v regulator
  • Battery pack will not be 4.5v, it will be 12v

Team Members

  • Dan Bowen




BOM Google Spreadsheet

  • TMP101 Temp sensor
  • WSB 8-pin Connector
  • Pololu Step-Down Voltage Regulator D15V35F5S3 set to 3.3v
  • Pololu Step-Down Voltage Regulator D15V35F5S3 set to 5v
  • Heater on/off circuit (transistor)
  • Voltage measurement circuit


One 9-13.5v pack will be present to serve two commercial 3.3v and 5v regulator boards, and provide raw voltage for ~12v output as well. There will be several strings in parallel to provide for long duration operation.


Power output should be:

9-13.5v 2A+
5v 1A
3.3v 1A


Main Bus

This will connect to the main White Star Bus, providing power to all other modules connected to said bus. Please see the hardware specs for the White Star Bus 7-Pin connector. The connector must implement power as well as I2C communications.

The Temp sensor that extends into the battery pack should be logically on the main I2C bus, but the power controller microcontroller needs to identify it in device scans.

Battery Pack

Single String Cells: 10
Pack Starting Voltage: 15
Pack Depletion Voltage: 10
Capacity per string: 3000mAH @ 0C for 1A draw

Pin Purpose
2 Batt V+
3 Heater Vcc

_ []

_ –> Power Controller Board
[] –> 10 batteries (one string)

There will be five(5) strings of ten(10) batteries and one(1) string of four(4) batteries for the cut-down.
In column 1, from top to bottom: power controller, string of four, string of ten, string of ten.
In column 2, from top to bottom: string of ten, string of ten, string of ten.


  • Voltage Divider for Raw Pack voltage, connected to AD7992 I2C A/D converter.
    • On PCB
  • TI TMP101 - This tiny SMD temp sensor is also a settable thermostat that could control the heater automatically.
    • This should be in Comparator Mode, Alert Polarity inverted, to automatically control the heater. This will produce a 1 output when the temp drops below the LOW limit, and return to 0 output when the temp rises again above the HIGH limit. Set the Low and High limits pretty close to eachother, just a few degrees apart should be good.

PCB Jumper Settings

Bold indicates must be set for flight.

    1. Choose battery source for heater power, Main pack or separate Heater pack
    2. Options
      1. Pad near H in “HTRPWR”
        1. Separate Heater pack
      2. Pad near W in “HTRPWR”
        1. Main pack
    1. Set I2C address of temp sensor.
    2. Options
      1. Pad near T
        1. ?
      2. Pad near R
        1. ?
  3. VOLTSENS (Next to white star bus connector, these directions are when holding with WSB connector above the solder jumper)
    1. Sets the I2C Address pin of the AD7992
    2. Options
      1. Left
        1. GND
      2. No connections
        1. Float
      3. Right
        1. 3.3v

Power Regulation

3.3v @ ~1A

  • Pololu Step-Down Voltage Regulator D15V35F5S3 Dist center to center 0.093

5v @~1A

  • Pololu Step-Down Voltage Regulator D15V35F5S3

9-13.5v @ ~2A

  • No regulator


This module will need to dump heat from the voltage regulators into the actual battery pack. Arrange the regulators and make heat sinks so that the heat sinks extend into the battery pack.

hardware/powercontrol/v1.5.txt · Last modified: 2018/07/29 17:58 (external edit)
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