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UM0612
User manual
STEVAL-ISQ008V1, fuel gauge implementation
based on the STM32F103x
Introduction
This user manual describes the functions of a single cell Li-Ion battery fuel gauge
technology using an MCU within the STM32 (ARM Cortex™-M3 core) family. The fuel gauge
demonstration board is used to show the capability of an STM32 microcontroller to be used
for battery fuel capacity monitoring. The fuel gauge implementation is based on the STM32
microcontroller; the MCU is used for monitoring the capacity of a single cell Li-Ion battery.
An on-chip 12-bit ADC from the STM32 family is used for battery capacity calculation.
The fuel gauge technology is a smart system which monitors battery capacity, predicts
remaining capacity, and displays its status. The basic ideology used for battery capacity
measurements is Coulomb counting, in which the current flowing through the battery is
continuously monitored and integrated to calculate the capacity. Current measurement is
done when the battery is both discharging and charging. Therefore both the IN and OUT
current are taken into account to calculate the remaining capacity of the battery. Battery
capacity is measured in mAh.
Figure 1.
STEVAL-ISQ008V1, fuel gauge demonstration board
September 2010
Doc ID 15176 Rev 1
1/28
www.st.com
www.BDTIC.com/ST
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Summary of Contents for ST STEVAL-ISQ008V1
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Page 1: Figure 1. Steval-Isq008V1, Fuel Gauge Demonstration Board
Therefore both the IN and OUT current are taken into account to calculate the remaining capacity of the battery. Battery capacity is measured in mAh. Figure 1. STEVAL-ISQ008V1, fuel gauge demonstration board September 2010 Doc ID 15176 Rev 1 1/28 www.st.com... -
Page 2: Table Of Contents
Bill of material ..........22 2/28 Doc ID 15176 Rev 1 www.BDTIC.com/ST... - Page 3 Revision history ......... . . 27 Doc ID 15176 Rev 1 3/28 www.BDTIC.com/ST...
- Page 4 Document revision history ..........27 4/28 Doc ID 15176 Rev 1 www.BDTIC.com/ST...
- Page 5 List of figures Figure 1. STEVAL-ISQ008V1, fuel gauge demonstration board ......1 Figure 2.
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Page 6: Getting Started
Voltage drop across the 100 mΩ sense resistor is used to evaluate the capacity of the battery.This voltage drop is measured by ADC of the STM32 MCU and from this measured voltage, the battery current is calculated. 6/28 Doc ID 15176 Rev 1 www.BDTIC.com/ST... -
Page 7: External Supplied Block
The USB Connector is used for external power supply source only. Table 1. Power selection jumper positions Switch jumper SW2 Action PIN 1 and 2 shorted USB power supply selected PIN 2 and 3 shorted External DC power source selected Doc ID 15176 Rev 1 7/28 www.BDTIC.com/ST... -
Page 8: Figure 3. External Supply Selection
Getting started UM0612 Figure 3. External supply selection 8/28 Doc ID 15176 Rev 1 www.BDTIC.com/ST... -
Page 9: Fuel Gauge Application
Table Table 2. Jumper J4 connections Jumper J4 Action PIN 1 and 2 shorted Battery connected to battery charger PIN 2 and 3 shorted Battery connected to load at jumper J8 Doc ID 15176 Rev 1 9/28 www.BDTIC.com/ST... -
Page 10: Lcd Display Section
900 mAh. 10/28 Doc ID 15176 Rev 1 www.BDTIC.com/ST... -
Page 11: Battery State Of Health Not Known
25 (+/-3) mA. This is the consumption of the microcontroller, op amp, and voltage regulator When capacity learning is ongoing, allow the battery to charge fully first and then discharge fully, don't interrupt the charging and discharging cycles in this phase Doc ID 15176 Rev 1 11/28 www.BDTIC.com/ST... -
Page 12: Battery State Of Health Is Known
“Battery Low” message flashes on the LCD. When battery voltage goes below 3.0 V, then the discharging path through the external resistor is automatically disabled using a P-Channel MOSFET and system consumption falls to ~25 mA. 12/28 Doc ID 15176 Rev 1 www.BDTIC.com/ST... -
Page 13: Lcd Messages
Table 3. Battery capacity variation due to temperature Temperature % Variation in capacity < -20 °C -20 °C to -10 °C -10 °C to 0 °C 0 °C to 10 °C Doc ID 15176 Rev 1 13/28 www.BDTIC.com/ST... -
Page 14: Self-Discharge Compensation
½ % per day 20<=temp<30 1 % per day 30<=temp<40 2 % per day 40<=temp<50 4 % per day 50<=temp<60 8 % per day 60<=temp<70 16 % per day 70<=temp 32 % per day 14/28 Doc ID 15176 Rev 1 www.BDTIC.com/ST... -
Page 15: Flow Chart For Fuel Gauge Demonstration Board
UM0612 Flow chart for fuel gauge demonstration board Flow chart for fuel gauge demonstration board Figure 6. Flow chart Doc ID 15176 Rev 1 15/28 www.BDTIC.com/ST... - Page 16 The D1 LED shows the running status of the fuel gauge system. When the fuel gauge application is running, D1 blinks onboard, and when the fuel gauge is not working, this LED is off. 16/28 Doc ID 15176 Rev 1 www.BDTIC.com/ST...
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Page 17: The Stm32 As Fuel Gauge
During startup of the application for the first time, the system performs the self calibration for the offset of the operational amplifier and the LCD shows the message “Self Calib ON” for the period this calibration is done. Doc ID 15176 Rev 1 17/28 www.BDTIC.com/ST... -
Page 18: Demonstration Board Schematics
Demonstration board schematics Figure 7. Microcontroller section www.BDTIC.com/ST... -
Page 19: Figure 8. Power Section
UM0612 Demonstration board schematics Figure 8. Power section Doc ID 15176 Rev 1 19/28 www.BDTIC.com/ST... -
Page 20: Figure 9. Op-Amp-Section
Demonstration board schematics UM0612 Figure 9. OP-AMP-section Figure 10. USB section 20/28 Doc ID 15176 Rev 1 www.BDTIC.com/ST... -
Page 21: Figure 11. Lcd Section
UM0612 Demonstration board schematics Figure 11. LCD section Figure 12. JTAG-CONN section Doc ID 15176 Rev 1 21/28 www.BDTIC.com/ST... -
Page 22: Bill Of Material
Oriole or 16 x 1 Bergstrip ODM16216-9SL3/AX Oriole alphanumeric LCD equivalent 3M electronic J2,J5 Jtag connector 10 x 2 header 30320-6002HB Mouser 517-30320-6002 solutions division 2-pin Bergstrip 2 pin Samtec TSW-102-23-G-S J4,J9,SW2 3-pin Bergstrip 3 x1-pin Bergstrip Samtec TSW-103-23-G-S www.BDTIC.com/ST... - Page 23 SMD0805 Farnell 1301711 08051A102J4T2A C16,C17,C21, 1 µF SMD0805 Vishay/Sprague 298D105X0050P2T Digi-Key 718-1720-1-ND Panasonic - ECG 10 nF SMD0805 ECJ-2VB1H103K PCC103BNTR-ND or equivalent R1,R2,R3,R10, R12,R14,R15, R17,R18,R19, Panasonic - ECG 10 kΩ SMD0805 ERJ-6GEYJ103V Digi-Key P10KACT-ND R20,R22,R23, or equivalent R30,R35, R38,R39,R61 www.BDTIC.com/ST...
- Page 24 ERJ-6GEYJ102V Digi-Key P1.0KATR-ND or equivalent Panasonic - ECG 470 Ω R51,R52,R53 SMD0805 ERJ-6GEYJ471V Digi-Key P470ATR-ND or equivalent Panasonic - ECG 56 kΩ SMD0805 ERJ-6GEYJ563V Digi-Key P56KACT-ND or equivalent Panasonic - ECG 3.6 kΩ SMD0805 ERJ-6GEYJ362V Digi-Key P3.6KACT-ND or equivalent www.BDTIC.com/ST...
- Page 25 1435952 R59,R62(OPTI Panasonic - ECG SMD0805 ERJ-6GEY0R00V Digi-Key P0.0ATR-ND OAL) or equivalent Panasonic - ECG 100 kΩ SMD0805 ERJ-6GEYJ104V Digi-Key P100KACT-ND or equivalent RMCF 1/10 2M 1% 2 MΩ SMD0805 RMCF 1/10 2 M 1 % R Digi-Key RMCF1/102MFRCT-ND www.BDTIC.com/ST...
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Page 26: Table 6
Abbreviations UM0612 Abbreviations Table 6. Abbreviations Word Abbreviation Liquid crystal display Universal serial bus Real time clock 26/28 Doc ID 15176 Rev 1 www.BDTIC.com/ST... -
Page 27: Table 7
UM0612 Revision history Revision history Table 7. Document revision history Date Revision Changes 06-Sep-2010 Initial release Doc ID 15176 Rev 1 27/28 www.BDTIC.com/ST... - Page 28 No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such third party products or services or any intellectual property contained therein.
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