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UM3424
User manual
Getting started with the battery management system module based on
L99BM114 and L99BM1T
Introduction
The
STEVAL-L99BM114TX
is a battery management system (BMS) evaluation board that manages from 4 to 14 battery cells.
The main advantage of this evaluation board is ensuring isolated connection to an external MCU, thanks to the embedded
transceiver.
The board is based on the
L99BM114
Li-ion battery monitoring and protection chip for high-reliability applications and the
L99BM1T
general purpose SPI to isolated SPI bidirectional transceiver.
The main activity of the L99BM114 is monitoring the cells and battery node status through stack voltage measurement, cell
voltage measurement, temperature measurement, and coulomb counting.
Measurement and diagnostic tasks can be executed either on demand or at set intervals.
Measurement data are available for an external microcontroller to perform charge balancing and to compute the state of charge
(SOC) and the state of health (SOH).
The L99BM1T general purpose SPI to isolated SPI bidirectional transceiver can transfer communication data incoming from a
traditional 4-wire based SPI interface to a 2-wire isolated interface (and vice versa). In our board, the transceiver is configured
as a slave.
Figure 1.
STEVAL-BMS114TX evaluation board
Notice:
For dedicated assistance, submit a request through our online support portal at www.st.com/support.
UM3424 - Rev 1 - January 2025
www.st.com
For further information, contact your local STMicroelectronics sales office.
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Table of Contents
Related Manuals for ST STEVAL-L99BM114TX
Summary of Contents for ST STEVAL-L99BM114TX
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Page 1: Figure 1. Steval-Bms114Tx Evaluation Board
4-wire based SPI interface to a 2-wire isolated interface (and vice versa). In our board, the transceiver is configured as a slave. Figure 1. STEVAL-BMS114TX evaluation board Notice: For dedicated assistance, submit a request through our online support portal at www.st.com/support. UM3424 - Rev 1 - January 2025 www.st.com For further information, contact your local STMicroelectronics sales office. -
Page 2: Bms Evaluation Board Overview
6. Balancing resistors 7. Connector for the battery pack 8. Hot plug protection 9. GPIOs for external NTC connection handled by L99BM114 10. L99BM114 multicell battery monitoring and balancing IC Figure 2. STEVAL-L99BM114TX main components UM3424 - Rev 1 page 2/24... -
Page 3: Table 1. Steval-L99Bm114Tx Connector Details
UM3424 BMS evaluation board overview Table 1. STEVAL-L99BM114TX connector details Name Description Type Isolated serial communication port: 1. VBUS ISOH 2. ISOHm USB Type A connector 3. ISOHp 4. FaultH Battery connector: 1. VBAT_CELL 2. Cell 14 3. Cell 13 4. -
Page 4: Embedded Devices
UM3424 BMS evaluation board overview Name Description Type L99BM1T Transceiver configuration signal 1 – FAULT line 2 - DIS Multi pin connector 3 – ISOFreq 4 – BNE 5 – TXEN 6 – TXAmp 1 – GND 2 – VIO Multi pin connector 3 –... -
Page 5: Voltage Operating Range
UM3424 BMS evaluation board overview SPI peripheral can work up to 10 MHz when configured as Slave. SPI clock frequency can be programmed among (250 kHz; 1 MHz; 4 MHz; 8 MHz) when configured as Master. Isolated SPI peripheral features two different operating modes: slow @333 kbps and fast @2.66 Mbps. The asynchronicity between the two sides is internally managed, allowing all possible configuration frequencies on both peripherals to be used in application. -
Page 6: Bms Topologies
UM3424 BMS topologies BMS topologies The BMS boards can work in two different daisy chain topologies: single access and dual access ring. Single access configuration In a single access daisy chain configuration, a series of BMS is connected to an MCU board through a single transceiver connected to the STEVAL-BMS114 isolated ISOL port. -
Page 7: Dual Access Ring Configuration
UM3424 BMS topologies Dual access ring configuration A dual access ring configuration is implemented by adding another transceiver that makes the communication bidirectional. The secondary transceiver is used as a backup in case the primary transceiver fails. Data moves in opposite directions around the rings, and each ring remains independent of the other unless the primary ring fails. -
Page 8: Cell Current Measurement
UM3424 Cell current measurement Cell current measurement The current flowing into the external shunt resistance RSENSE is measured through a differential amplifier stage (connected between ISENSEP/ISENSEM pins) feeding a 18-bit ADC. The current conversion chain can be enabled through the CoulombCounter_en bit and runs in background to perform the Coulomb Counting Routine. -
Page 9: Fault Condition In Daisy Chains
UM3424 Fault condition in daisy chains Fault condition in daisy chains Figure 5. Fault LED on the STEVAL-BMS1T The fault LED on the STEVAL-BMS1T is related to the state of all the BMS nodes in the daisy chain. If an undervoltage, overvoltage, overcurrent, or overtemperature occurs on any cell of a BMS, a fault condition is detected. -
Page 10: Cell Balancing
UM3424 Cell balancing Cell balancing In the L99BM114, the Sx and Bx_x-1 pins are used to balance the charge of the cells by discharging the ones with a higher SOC. Balancing can be performed either with external resistors or internal MOSFETs. Cell balance drivers are powered by VBAT stack voltage. -
Page 11: Steval-Bms114Tx Schematic Diagrams
STEVAL-BMS114TX schematic diagrams Figure 7. STEVAL-BMS114TX circuit schematic (1 of 2) VBATT VBAT_UP STL8N10LF3 VBAT_BMS VBAT_BMS MPZ2012S102ATD25 RMREG 47nF N.M. 4.7uF VBAT_BMS 2.2uF 100nF 100pF 100nF 100K GND_EXT GND_BMS GND_BMS 100nF GND_BMS N.M. GND_BMS L99BM114 N.M. VREG GND_BMS VBAT VREG VREG CELL14 VCOM... -
Page 12: Figure 8. Steval-Bms114Tx Circuit Schematic (2 Of 2)
Figure 8. STEVAL-BMS114TX circuit schematic (2 of 2) mode 22pF N.M. ISOL 47nF ISOLp ISOLp 100nF 100nF ISOLp_L99BM114 I/O1 I/O1 60.4 ISOP VBUS ISOM R42 10nF ISOLm I/O2 I/O2 60.4 ISOLm ISOLm_L99BM114 ISOL USBLC6-2SC6Y N.M. NSLAVE 47nF 22pF TXEN TXEN/CPHA ISOFreq ISOFREQ SPICLKFREQ... -
Page 13: Steval-Bms114Tx Bill Of Materials
UM3424 STEVAL-BMS114TX bill of materials STEVAL-BMS114TX bill of materials Table 2. STEVAL-BMS114TX bill of materials Item Q.ty Ref. Part/value Description Manufacturer Order code C1, C8, C15, C19, C21, C29, C31, C33, C40, 0603 - 50V - 47nF 885012206093 C42, C45, C48, X7R Class II C50, C57, C59, C71, C75, C76... - Page 14 UM3424 STEVAL-BMS114TX bill of materials Item Q.ty Ref. Part/value Description Manufacturer Order code 2.54mm - 1 row 61900611121 - KK254 - Male Automotive 600 SMA6T68AY, D1, D4 W, 68V TVS in SMA6T68AY 0805 - Led D2, D9 Green 150080GS75000 Green - 3.2V 4.7V Zener SZMM3Z4V7T1 Voltage...
- Page 15 UM3424 STEVAL-BMS114TX bill of materials Item Q.ty Ref. Part/value Description Manufacturer Order code N-channel 100 V, 6.8 mΩ typ., 80 A STripFET F7 Power MOSFETs in D2PAK, DPAK, STD100N10F7, TO-220FP, STD100N10F7 DPAK I2PAK and TO-220 packages STripFET™ F7 Power MOSFET in a DPAK package N-Channel...
- Page 16 UM3424 STEVAL-BMS114TX bill of materials Item Q.ty Ref. Part/value Description Manufacturer Order code R53, R54, R55, 2010 - ±1% - 1.5K TE Connectivity 35021K5FT R57, R58 N.M. N.A. N.A. N.A. 0603 - ±1% - Panasonic ERJ3GEY0R00V 0.1W 0603 - ±0.5% - R68, R79, R89 0.25W, 0603 - Panasonic...
- Page 17 UM3424 STEVAL-BMS114TX bill of materials Item Q.ty Ref. Part/value Description Manufacturer Order code WR-WTB 2.00 mm Female for blister 62400113722 62400113722 Dual Row Crimp Contact WR-WTB 2.54 mm Female for blister 61900411621 61900411621 Terminal Housing WR-WTB 2.54 mm Female for blister 61900611621 61900611621 Terminal...
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Page 18: Board Versions
UM3424 Board versions Board versions Table 3. STEVAL-BMS114TX versions Finished good Schematic diagrams Bill of materials STV$BMS114TXA STV$BMS114TXA schematic diagrams STV$BMS114TXA bill of materials 1. This code identifies the STEVAL-BMS114TX evaluation board first version. UM3424 - Rev 1 page 18/24... -
Page 19: Regulatory Compliance Information
UM3424 Regulatory compliance information Regulatory compliance information Notice for US Federal Communication Commission (FCC) For evaluation only; not FCC approved for resale FCC NOTICE - This kit is designed to allow: (1) Product developers to evaluate electronic components, circuitry, or software associated with the kit to determine whether to incorporate such items in a finished product and (2) Software developers to write software applications for use with the end product. -
Page 20: Revision History
UM3424 Revision history Table 4. Document revision history Date Version Changes 10-Jan-2025 Initial release. UM3424 - Rev 1 page 20/24... -
Page 21: Table Of Contents
UM3424 Contents Contents BMS evaluation board overview........... . 2 Features . -
Page 22: List Of Figures
STEVAL-L99BM114TX main components ........ -
Page 23: List Of Tables
STEVAL-L99BM114TX connector details ........ - Page 24 ST’s terms and conditions of sale in place at the time of order acknowledgment. Purchasers are solely responsible for the choice, selection, and use of ST products and ST assumes no liability for application assistance or the design of purchasers’...
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