BMS — key device selection
Engineering problem
Cell voltage and pack current must be measured accurately across the full temperature range, stored safely across power loss, and communicated over an isolated link — with a fault path that opens the contactor rather than relying on software alone.
System block diagram
Block list (text version)
- Input protection TVS / ESD protection
- Control Automotive MCU
- Power stage MOSFET (balancing / contactor drive)
- Data storage EEPROM / non-volatile memory
- Sensing Current-sense amplifier / op-amp
Input protection
Why this device： Sense harnesses and communication lines are exposed during service and assembly.
How to choose： Low-capacitance arrays on communication lines; TVS on the pack-side supply with adequate pulse energy.
| Part number | Brand | Category | Package | Qualification | Operating temperature | Key parameters | Docs | Actions |
|---|---|---|---|---|---|---|---|---|
| 1SMB30CAT3G In stock | onsemi | TVS Diodes | SMB | AEC-Q101 qualified | -55 °C ~ +150 °C | vrwm: 30 V · ppp: 600 W · direction: Uni-directional | Datasheet ↗ | |
| 1.5KE24CA-TP | MCC | Transient Voltage Suppressor | — | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| 1.5KE250A-TP In stock | MCC | TVS Diodes | DO-201AE | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| 1.5KE480A | WAYON | Transient Voltage Suppressor | — | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| 1.5SMC33CA | LITTLEFUSE | Transient Voltage Suppressor | — | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| 1.5SMC6.8CA In stock | Littelfuse | TVS Diodes | SMC | Qualification to be verified | To be confirmed | To be confirmed | To be confirmed |
Control
Why this device： Runs state-of-charge estimation, balancing strategy, diagnostics and CAN FD communication with the vehicle.
How to choose： Functional-safety level, ADC accuracy and the availability of a safety manual usually decide the shortlist.
| Part number | Brand | Category | Package | Qualification | Operating temperature | Key parameters | Docs | Actions |
|---|---|---|---|---|---|---|---|---|
| MKE04Z8VWJ4 In stock | NXP | Microcontrollers (MCU) | SOIC-20 | AEC-Q100 Grade 1 qualified | -40 °C ~ +125 °C | core: Arm Cortex-M0+ · freq: 48 MHz · flash: 8 KB | Datasheet ↗ | |
| ATMEGA32A-AU In stock | Microchip | Microcontrollers (MCU) | TQFP-44 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| ATSAM4S2AA-MU In stock | Microchip | Microcontrollers (MCU) | QFN-48 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| BS83A01C In stock | Holtek | Microcontrollers (MCU) | SOT-23-6 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| HT66F002/MSOP10 In stock | Holtek | Microcontrollers (MCU) | MSOP-10 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| MM32F0010A1N In stock | MindMotion | MCU (Value Line) | QFN-20 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ |
Sensing
Why this device： Pack current is the basis of SOC, SOH and over-current protection.
How to choose： Offset drift over temperature dominates SOC error at low current; check the drift specification, not just the initial offset.
| Part number | Brand | Category | Package | Qualification | Operating temperature | Key parameters | Docs | Actions |
|---|---|---|---|---|---|---|---|---|
| INA199B2QDCKRQ1 In stock | TI | Amplifiers & Linear | SOT-SC70-6 | AEC-Q100 Grade 1 qualified | -40 °C ~ +125 °C | supply: 2.7 ~ 26 V · channel: 1 · bw: 105 kHz | Datasheet ↗ | |
| LM2901MX/NOPB In stock | TI | Amplifiers & Linear | SOIC-14 | AEC-Q100 Grade 1 qualified | -40 °C ~ +125 °C | channel: 4 · bw: 1.3 MHz · vos: ±2 mV | Datasheet ↗ | |
| ACE358MTR-E1 In stock | ACE | Operational Amplifiers | SOP-8 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| AD822ARZ-REEL7 In stock | ADI | Operational Amplifiers | SOIC-8 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| LM258DR2G In stock | onsemi | Operational Amplifiers (Op-Amp) | SOIC-8 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| LM2903XK In stock | Runic | Comparators | SOT-23-5 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ |
Data storage
Why this device： SOC, SOH, fault logs and pack history must survive power loss.
How to choose： Check endurance at rated temperature and retention across the temperature profile, not the 25 °C figure.
| Part number | Brand | Category | Package | Qualification | Operating temperature | Key parameters | Docs | Actions |
|---|---|---|---|---|---|---|---|---|
| AT24C64D-SSHM-T In stock | Microchip | Memory (EEPROM/Flash) | SOIC-8 | AEC-Q100 Grade 1 qualified | -40 °C ~ +125 °C | density: 64 Kbit · iface: I²C · vcc: 1.7 ~ 5.5 V | Datasheet ↗ | |
| 24LC256-I/SM In stock | Microchip | Memory (EEPROM/Flash) | DFN | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| AT24C02C-SSHM-T In stock | Microchip | Memory (EEPROM/Flash) | SOT23 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| AT24CM01-SSHD-T In stock | Microchip | Memory (EEPROM/Flash) | SOIC-8 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| AT93C46DN-SH-T In stock | Microchip | Memory (EEPROM/Flash) | SOIC-8 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| DS1624S+ In stock | ADI | Digital Temperature Sensors (with EEPROM) | SOIC-8 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ |
Power stage
Why this device： Passive balancing resistors and contactor coils are switched by low-side MOSFETs.
How to choose： Low duty but must tolerate short-circuit energy; check SOA and thermal resistance rather than only RDS(on).
| Part number | Brand | Category | Package | Qualification | Operating temperature | Key parameters | Docs | Actions |
|---|---|---|---|---|---|---|---|---|
| BSC026N02KSGAUMA1 In stock | Infineon | OptiMOS Low-Voltage MOSFETs | SC026 | AEC-Q101 qualified | -55 °C ~ +150 °C | channel: N · vds: 25 V · id: 100 A | Datasheet ↗ | |
| 2N7002-TP In stock | MCC | Small-Signal MOSFETs | SOT-23 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| 2N7002DW-TP In stock | MCC | Small-Signal MOSFETs | SOT-363 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| 2N7002E-7-F In stock | Diodes | Small-Signal N-Channel MOSFETs | SOT-23 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| 2N7002K-TP In stock | MCC | Small-Signal MOSFETs | SOT-23 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ | |
| 2N7002KDQ-TP In stock | MCC | Small-Signal MOSFETs | SOT-23 | Qualification to be verified | To be confirmed | To be confirmed | Datasheet ↗ |
Key selection parameters
| Pack voltage | 48 V / 400 V / 800 V platforms |
| Cell count | Determines AFE channel count |
| Current range | Continuous and peak discharge / regen |
| Measurement accuracy | Typically ±1 mV cell, ±0.5% current |
| Functional safety | ASIL-B to ASIL-D depending on item |
FAQ
Do you supply AFE / cell monitor ICs?
We can source them; availability varies by brand and export status. Send the cell count and accuracy target and we will report what is realistically obtainable.
Is an EEPROM really needed if the MCU has internal flash?
Often yes — internal flash has lower endurance and writing it can stall code execution; external EEPROM isolates frequent logging from the program memory.
Related
Project inquiry
Fields follow the application, and the source application is recorded with the request.
Received. Your reference number —
We normally reply within one business day; urgent requests are escalated the same day.
To add documents, reply by email: richard@fastspeed-ic.com