Part Review and Datasheet Verification

flux

Completed the L9961TR part review and saved the detailed findings in l9961tr-part-review.
Key flags: the Datasheet URL was already set to ST’s official PDF, but the project properties show incorrect Part Type: Inductors and Package or Case Code: TO; official package is VFQFPN 5x5x1 32L P0.5. The main pinout mismatches are pin 13 and pin 27, which the ST-sourced pin table lists as GND while the symbol currently uses TM_ENTER and TM1.
Suggested next steps:
  • Correct the package and part-type properties.
  • Verify pins 13/27 directly in the PDF before editing the symbol.
  • Populate Pin Type and Pin Description properties from the datasheet.
  • Verify exact QFN exposed-pad and perimeter-pad geometry before fabrication.
adrian95

adrian95

Populate Pin Type and Pin Description properties from the datasheet.

flux

I’ll update each terminal’s Pin Type and Pin Description from the ST L9961 datasheet pin table, then re-read the schematic to verify the properties landed correctly.

flux

The first pass added the datasheet detail, but Flux warned that several Pin Type values were non-standard; I’m normalizing them to Flux’s supported Pin Type options while keeping the detailed electrical behavior in Pin Description.

flux

Populated Pin Type and Pin Description for all 33 terminals and verified the updates in the schematic.
I normalized Pin Type values to Flux-supported options while preserving datasheet-specific details like analog input, open-drain, active level, and pull-down behavior in Pin Description. Pins 13 and 27 are now treated as GND terminals based on the ST pin table.
Fix properties and review
Fix part properties
Verify symbol pinout
Check footprint geometry
Run ERC DRC

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L9961TR Part Review
Date: 2026-06-16
Reviewed project part metadata
  • Project/part: L9961TR
  • Manufacturer Part Number: L9961TR
  • Manufacturer: STMicroelectronics
  • Description: STMicroelectronics chip for consumer battery management applications up to 5 cells
  • Published part UID: 378a4c67-6a43-4c57-88e1-181569521462
  • Current Datasheet URL: https://www.st.com/resource/en/datasheet/l9961.pdf
  • Existing project properties found:
Official datasheet / web reference
The Datasheet URL was already set, so no Datasheet property update was required. Web lookup confirmed the official ST datasheet and ST product/eStore pages:
Web result identified datasheet DS14012 Rev 6, March 2025, order code L9961-TR.
Key datasheet specs found
  • Function: Battery management system solution
  • Application: Consumer battery management up to 5 cells
  • Package: VFQFPN 5 mm x 5 mm x 1 mm, 32 leads, 0.5 mm pitch
  • Order code / shipping: L9961-TR, tape and reel
  • Pin count: 32 perimeter pins plus exposed pad/thermal pad in the footprint context
  • Interfaces/signals include I2C SCL/SDA, ready/fault outputs, cell inputs C0-C5, current sense inputs, charge/discharge gate/source pins, charge pump pins, NTC input, fuse pre-driver, wake/ship inputs, VB, VREG, and GND pins.
Pinout cross-check

Table

PinDatasheet nameSymbol terminal in projectResult
1C0C0Match
2ISENSEPISENSEPMatch
3ISENSEMISENSEMMatch
4GNDGNDMatch
5SCLSCLMatch
6SDASDAMatch
7RDYRDYMatch
8VREGVREGMatch
9NTCNTCMatch
10ODODMatch
11FAULTN_SAFEFAULTN_SAFEMatch
12FAULTNFAULTNMatch
13GNDTM_ENTERMismatch: datasheet says GND; project has TM_ENTER
14WAKEUPWAKEUPMatch
15NSHIPNSHIPMatch
16FUSEFUSEMatch
17DCHGDCHGMatch
18VSDVSDMatch
19VSCVSCMatch
20CHGCHGMatch
21VCP1MVCP1MMatch
22VCP1PVCP1PMatch
23VCP2MVCP2MMatch
24VCP2PVCP2PMatch
25VCPVCPMatch
26VBVBMatch
27GNDTM1Mismatch: datasheet says GND; project has TM1
28C5C5Match
29C4C4Match
30C3C3Match
31C2C2Match
32C1C1Match
EPExposed pad / thermal padEP, pin number 33Present as a separate pad/terminal; verify against ST land pattern whether EP is required electrically/thermally and how it should be numbered in Flux.
Symbol review
  • Symbol has 33 terminals: 32 numbered terminals plus EP numbered 33.
  • Most pin names and numbers match the ST pinout.
  • Mismatches found:
    • Pin 13 should be GND per the web-extracted ST pin table, but the project symbol names it TM_ENTER.
    • Pin 27 should be GND per the web-extracted ST pin table, but the project symbol names it TM1.
  • All terminal Pin Type properties are currently Unspecified. These should be improved using datasheet signal types (Power input/output, Analog input/output, Digital input/open-drain, etc.).
Footprint review
  • Layout contains a 5 mm x 5 mm square outline/silkscreen and 33 pad nodes, consistent with a 32-lead QFN-style package plus exposed pad.
  • Package metadata mismatch: current Package or Case Code property is TO, but the official ST package is VFQFPN 5x5x1 32L P0.5.
  • The current layout output did not expose pad geometry dimensions/coordinates in the structured tree view, so exact land pattern dimensions were not fully verified against ST mechanical drawings.
Property mismatches / cleanup recommendations
  1. Change Part Type from Inductors to an IC/Battery Management IC classification.
  2. Change Package or Case Code from TO to VFQFPN 5x5x1 32L P0.5 or equivalent.
  3. Correct symbol pin 13 from TM_ENTER to GND, unless an alternate L9961 datasheet revision proves pin 13 is a test-mode pin.
  4. Correct symbol pin 27 from TM1 to GND, unless an alternate L9961 datasheet revision proves pin 27 is a test-mode pin.
  5. Populate terminal Pin Type and Pin Description properties from the datasheet.
  6. Verify exact exposed pad size and perimeter pad dimensions against the ST mechanical/land-pattern data before using the footprint for fabrication.
Notes on verification limitations
The built-in datasheet query did not return matching OCR results for the L9961 PDF, so the pin table was verified through web search results pointing to ST official sources. Critical pin changes should still be checked against the current official PDF manually before committing symbol edits.

  • Reviewed project part metadata

  • Official datasheet / web reference

  • Key datasheet specs found

  • Pinout cross-check

  • Symbol review

  • Footprint review

  • Property mismatches / cleanup recommendations

  • Notes on verification limitations

Documents

Assets

L9961TR-thumb.png

L9961TR-thumb.png

L9961TR-thumbThumbnail
L9961TR

L9961TR

L9961TR.stp3D Model
svg

L9961TR

L9961TR Symbol.svgDefault
kicad_mod

L9961TR

QFN50P500X500X100-33N-D.kicad_modFootprint

L9961TR

L9961TR thumbnail
Battery Multi-Function Controller IC Lithium Ion/Polymer 32-VFQFPN (5x5)
L9961 is part of a complete battery pack monitoring, balancing, and protecting system for Li-Ion and Li-Polymer cells in 3, 4 or 5 series configurations. The L9961 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 performing also 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 I2C peripheral. The IC also integrates a dual pre-driver programmable in both HS/LS configurations for driving pack relays. 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 pack controller and other external circuitry in both standby and normal operation modes. The IC protects the battery pack against over/under voltage conditions and monitors for over/ under temperature. 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 re-programming the device at each wake-up.
Features • 2 μA shipment - DEEP SLEEP mode current and 5 μA standby consumption (with VREG LDO active) standby consumption (with VREG LDO active) • Integrated 3.3 V VREG LDO for supplying MCU and LEDs • Measures cell voltage (3 to 5 cells), with over/undervoltage detection and balance undervoltage protection • 12-bit voltage measurement with maximum error of ±15 mV in the [1.5 – 4.5] V range, for -40 °C < TJ < 105 °C • Measures stack voltage, with over/under voltage detection and plausibility check vs. sum of cells • Measures pack temperature via NTC, with over/undertemperature detection • Ratiometric temperature measurement with ±0.8% max. gain error in the [0.2 – VREG] V range, for -40 °C < TJ < 105 °C • Measures battery current, with Coulomb counting, overcurrent (both directions) and short-circuit in discharge protection. • 16-bit signed current measurement with 0.1% full scale error at room temperature • I 2C peripheral for device programming and data transfers over I2C bus • Cell balancing supporting up to 70 mA per cell • Dual configurable HS/LS predriver for pack relay management • Pack fuse management • Embedded NVM for configuration parameters storage • High hotplug robustness Applications • Cordless power tools • Backup energy storage systems and UPS • Light electric vehicles (e-bikes, scooters, etc.) • Portable and semi-portable equipment • Medical equipment
#L9961TR #BatteryManagement #BMS #LiIonBattery #LiPoBattery #STMicroelectronics #BatteryProtection #CellBalancing #CoulombCounting #PowerManagement #EmbeddedSystems #EnergyStorage #EBike #PowerTools #ElectronicsDesign

Properties

L9961TR

STMicroelectronics

Integrated Circuit

st.com/resource/en/datasheet/l9961.pdf

IC

parametric-v1

VFQFPN 5x5x1 32L P0.5

creativecommons.org/licenses/by/4.0/

Pricing & Availability

DPN

Stock

Qty 1

1

0

$1.306

1

1.6K

$2.83

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