ST STEVAL-L99615C User manual

Introduction
The STEVAL-L99615C is an evaluation kit composed of an expansion board containing the L9961 IC for battery pack monitoring
solutions, and the NUCLEO-G071RB STM32 Nucleo-64 development board, aiming to demonstrate the performance and the
ease of integration with STMicroelectronics technology for BMS applications.
The kit exploits the characteristics of the L9961, able to monitor up to five Li-Ion battery cells in series configuration,
communicating with the STM32G071RB microcontroller, through the I²C interface.
The expansion board has been specifically developed to be stacked on the NUCLEO-G071RB development board through the
ST morpho connectors, and embeds a power connector able to connect it to a 5-cell battery pack, or alternatively to an external
power supply to emulate the battery pack.
A software package containing a dedicated firmware program for the STM32G071RB microcontroller and a GUI for the PC, has
been released to permit users to benefit from the demonstration, looking at the major significant characteristics described by
BMS application: cell voltage and stack voltage monitoring, stack current monitoring, temperature conversion via external NTC,
OV, and UV thresholds management, etc..
Figure 1. STEVAL-L99615C evaluation kit
Getting started with the STEVAL-L99615C evaluation kit based on the L9961
device for battery management system
UM3151
User manual
UM3151 - Rev 1 - April 2023
For further information contact your local STMicroelectronics sales office. www.st.com

1Getting started
1.1 Overview
The STEVAL-L99615C features:
• measurement of cell voltages (3 to 5 cells), with over/undervoltage detection
• measurement of stack voltage, with over/undervoltage detection and plausibility check vs. sum of cells
• measurement of battery pack temperature through an external NTC (emulated by an on-board trimmer)
with over/undertemperature detection
• measurement of battery current, with Coulomb counting, overcurrent, and short-circuit in discharge
protection
• battery cell balancing supporting up to 70 mA per cell
• dual configurable HS/LS pre-driver for pack relay management
• pack fuse management
• high hot plug robustness
1.2 System architecture
The STEVAL-L99615C evaluation kit consists of two subsystems:
• the NUCLEO-G071RB STM32 Nucleo-64 development board embedding the STM32G071RBT6
• the expansion board embedding the L9961 that monitors the battery pack and physically protects the
battery-packed application, contributing also to maintain the expected voltages
Figure 2. NUCLEO-G071RB - L9961 expansion board
1.2.1 NUCLEO-G071RB development board
The NUCLEO-G071RB STM32 Nucleo-64 development board is based on the high-performance Arm Cortex®-
M0+ 32-bit RISC core operating at up to 64 MHz frequency, with 128 KB flash memory and 16 KB SRAM.
The ST morpho headers allow expanding the functionality of the STM32 Nucleo open development platform with
a wide choice of specific shields.
The STM32 Nucleo-64 boards do not require any separate probe as they integrate the ST-LINK/V2-1 debugger/
programmer. They embed comprehensive, free STM32 software libraries and examples available with the
STM32CubeG0 MCU package.
Related links
Refer to the related ST web page NUCLEO-G071RB bill of materials and schematic diagrams
UM3151
Getting started
UM3151 - Rev 1 page 2/30

1.2.2 Expansion board
The expansion board hosts the L9961 BMS device, a complete battery pack monitoring, balancing, and protection
system for Li-Ion and Li-Polymer cells in 3, 4, or 5 series configurations. The device uses a high precision
ADC to provide cell voltage, stack voltage, and temperature conversion via external NTC. Voltage monitoring
functions are cyclically performed with a programmable loop time. Stack current is also monitored via a high
accuracy CSA, continuously running and also performing Coulomb counting. Cell balancing is available and can
be simultaneously activated on all cells. IC configuration and information exchange for SOC/SOH estimation are
performed via the I²C peripheral.
The IC also integrates a dual pre-driver programmable in both HS/LS configurations for driving pack relays. The
L9961 also implements battery pack fuse protection to prevent fire and explosion hazards. A 3.3 V regulator with
a high current capability is available for supplying a pack controller and other external circuitry in both standby
and normal operation modes. The IC protects the battery pack against over/undervoltage conditions and monitors
for over/undertemperature. It also features protection against overcurrent (both directions) and short-circuit in
discharge events. Safety relevant configurations can be stored in the internal NVM to avoid reprogramming the
device at each wake-up.
Figure 3. STEVAL-L99615C expansion board - top and bottom
UM3151
System architecture
UM3151 - Rev 1 page 3/30

1.2.3 Power supply section
In case a real battery is not available, it is possible to use the battery simulator embedded on the L9961 demo
board by installing a J5 jumper and by feeding the L9961 demo board through the CN2 connector (B+ and B-).
Figure 4. Power supply connector and battery simulator
1K
R23
1K
R24
1K
R25
1K
R26
1K
R27
470nF
C18
470nF
C19
470nF
C20
470nF
C21
470nF
C22
BATT_PACK
12
34
56
78
910
1112
1314
1516
J5
NT3
NT4
i
Battery Simulator
C2
C1
C0
B-
ISENSEN
ISENSEP
C4
C3
C5
B+
BATT_PACK
UM3151
System architecture
UM3151 - Rev 1 page 4/30

1.2.4 Pack relays stage
The L9961 uses a dual pre-driver stage to manage the external Charge (CHG) and Discharge (DCHG)
switches. The pre-driver stage can be configured as high-side or low-side by programming the CHG_HS_LS
and DCHG_HS_LS field.
To set the DCHG MOSFET to high-side operation, remove the J13 and J14 jumpers and install a jumper in J15
and J16 position 1-2 or for low-side operation, remove the J19 and J20 jumpers and install a jumper in position
2-3. To set the CHG MOSFET to high-side operation, install a jumper in J17 and J18 position 1-2 or for low-side
operation, install a jumper in position 2-3.
Figure 5. Pack relays schematic
J19
J14J13
CH+
CH-
Charge
Charge
J20
2M
R29
2M
R31
2M
R30
2M
R28
VSD
DCHG
CHG
VSC
CHG_DCHG
213
J17
213
J18
213
J16
213
J15
CHG_DCHG
TDCHG
TVSD
TVSC
TCHG
1
2
3
4
5 6 7 8
M3
STL210N4F7
1
2
3
4
5 6 7 8
M2
STL210N4F7
1 2 3 4
5 6 7 8
M4
STL210N4F7
1 2 3 4
5 6 7 8
M5
STL210N4F7
1 3
2
ITV4030L2015NR
2.2K
R1
GND
12
D1
MMSZ4701T1G
GND
FUSE
1
2
3 4
5 6
D
S
M1
STL7N6F7
Note: See L9961 datasheet for further details.
UM3151
System architecture
UM3151 - Rev 1 page 5/30

1.2.5 Fuse stage
Under certain conditions classified as permanent failures, the L9961 can be programmed to activate the FUSE
pre-driver. An external NMOS can be driven to blow up a fuse connected in series to the battery pack positive
terminal.
Figure 6. Fuse stage schematic
1 3
2
ITV4030L2015NR
2.2K
R1
GND
12
D1
MMSZ4701T1G
GND
FUSE
1
2
3 4
5 6
D
S
M1
STL7N6F7
B+
Note: See L9961 datasheet for further details.
UM3151
System architecture
UM3151 - Rev 1 page 6/30

1.2.6 L9961 demo board connectors
The CN1 is a 10-pin IDC style connector used to route sense signals from the remote 5-cell battery board to the
L9961 demo board. The connector contains the Kelvin connections for C0 through C5, the current sense resistors
differential voltage, and the NTC voltage, which can be used to route an external NTC and shunt resistor.
If the external Rshunt is used, R11 should be uninstalled and replaced with the new one.
If the external NTC is used, R12 should be removed. Once it has been removed, the user can connect the
external resistor between the NTC and OD pins. It is important to polarize the NTC with an external pull-up
resistor biased to VREG. For further details regarding the application circuit, please refer to the "Application
Information" section in the L9961 datasheet.
Figure 7. CN1 connector
C2
C1
C0
B-
ISENSEN
ISENSEP
C4
C3
C5
B+
C2
C1
C0
B-
ISENSEN
ISENSEP
C4
C3
C5
B+
1 2
3 4
5 6
7 8
9 10
CN1
10-Pin Male
OD
NTC
NTC
NTC
This is a 10-pin IDC style connector, which allows to either connect an Aardvark I2C/SPI Host Adapter or a Beagle
I2C/SPI Protocol Analyzer to the L9961 demo board.
Figure 8. CN3 connector
SCL
1GND 2
SDA
3NC/+5V 4
MISO
5NC/+5V 6
SCLK/MDC
7MOSI/MDIO 8
SS
9GND 10
CN3
AARDVARK 10-Pin Male
SDA
SCL
WAKEUP
RDY
FAULTN
FAULTN_SAFE
NSHIP
GND
UM3151
System architecture
UM3151 - Rev 1 page 7/30

2Jumpers and connectors
2.1 L9961 demo board jumpers and connectors
Table 1. L9961 demo board jumpers and connectors description
Name Description Configuration Type
CN1 Remote sense: used to route sense signals from
the 5-cell battery board to the L9961 demo board -10-pin IDC style
CN2 Battery pack: used to route the power signals from
the 5-cell battery board to the L9961 demo board -
4-pin
Phoenix
header
CN3 Total phase: used to connect an Aardvark I2C/SPI
Host Adapter or a Beagle I2C/SPI Protocol Analyzer -10-pin IDC
style
CN7,
CN10
ST morpho connector: used to place L9961 demo
board on top of the NUCLEO-G071RB micro board - -
J1 Used to measure current flowing into VB pin - -
J2 VIO voltage selector 1-2: 3.3 V from micro
2-3: 3.3 V from L9961 (VREG) -
J4 Used to select micro power source
OPEN: micro is fed from the NUCLEO-
G071RB micro board USB
CLOSE: micro is fed from VREG.
Note: If μC is fed from VREG,
JP3 jumper must be open on
the NUCLEO-G071RB micro
board
-
J5 Battery simulator: used to simulate battery pack
OPEN: battery simulator circuit is
disconnected.
Note: This configuration is used
when the 5-cell battery board
is connected
CLOSED: battery simulator circuit is
connected
Multiple
position
jumper
J6A Used to connect NSHIP pin to B+ - -
J6B Used to drive NSHIP pin from micro - -
J6C Used to drive WAKEUP pin from SW1 push button - -
J13, J14 Used to bypass the HS relay MOSFETs OPEN: when HS relay MOSFETs is used
CLOSED: when LS relay MOSFETs is used
Soldered
jumper
J19, J20 Used to bypass the LS relay MOSFETs OPEN: when LS relay MOSFETs is used
CLOSED: when HS relay MOSFETs is used
Soldered
jumper
J15,
J16,
J17, J18
Used to configure the relay MOSFETs to either high
or low-side usage
1-2: HS configuration is selected
2-3: LS configuration is used -
SW1
Push button: used to take the device out of
SHIPMENT state
Note: If J6C jumper is closed, the SW1
is also used to take the device out
of STADNBY state.
- -
UM3151
Jumpers and connectors
UM3151 - Rev 1 page 8/30

2.2 NUCLEO-G071RB micro board jumpers and connectors
Table 2. NUCLEO-G071RB micro board jumpers and connectors description
Name Description Configuration Type
CN2 STLINK USB connector - USB micro-B
CN7, CN10 ST morpho connector: used to pace L9961 demo
board on top of the NUCLEO-G071RB micro board - -
JP2 5 V jumper selection(1)
OPEN: no 5 V power
1-2 CLOSED: 5 V from STLINK
3-4 CLOSED: 5 V from VIN 7 V to 12 V
5-6 CLOSED: 5 V from E5V
7-8 CLOSED: 5 V from USB_CHG
-
JP3 STM32 VDD current measurement Opened when micro is powered from VREG -
1. See UM2324 for further details.
2.3 5-cell battery board connectors
Table 3. 5-cell battery board connectors description
Name Description Configuration Type
CN1 Remote sense: used to route sense signals from the 5-cell battery board to the
L9961 demo board - 10-pin IDC style
CN2 Battery pack: used to route the power signals from the 5-cell battery board to
the L9961 demo board - 4-pin Phoenix header
CN3 Charge/Discharge: used to connect a load or charger to the battery pack - 2-pin Phoenix header
UM3151
NUCLEO-G071RB micro board jumpers and connectors
UM3151 - Rev 1 page 9/30

3Application setup
3.1 System requirements
To set up the demo and run the application with the evaluation kit, the following items are required:
Figure 9. Demo setup: STEVAL-L9961 kit, power supply and USB Type-A to Micro-B cable
• STEVAL-L99615C kit
• USB Type-A to Micro-B cable
• a portable power supply (up to 20 V, 1 A) to feed the STEVAL-L99615C kit (in case a real battery
is not available), possibly equipped with a two or four position plug 7.62MM connector as the Wurth
691351400002 or 691351400004, like the one shown in Figure 9.
• the evaluation GUI contained in the STSW-L99615C
• a laptop to install the evaluation GUI contained in the STSW-L99615C
UM3151
Application setup
UM3151 - Rev 1 page 10/30