BQ79881-Q1 - Automotive UIR Sensor with Pack-Level EIS | TI
MPN： BQ79881-Q1 ✓ 啟用中BQ79881-Q1 概覽
Background: A UIR Sensor is a specialized battery management IC that combines cell voltage monitoring, current sensing, pack-level EIS, and insulation resistance (also called isolation or hipot) monitoring in a single device. In modern EV/HEV high-voltage battery packs, the BMS must measure cell voltages, sense pack current via a shunt, perform AC impedance spectroscopy to assess state-of-health, and continuously verify the high-voltage isolation between the pack and the chassis (a safety-critical function to detect creepage or breakdown). The BQ79881-Q1 integrates all of these functions into one ASIL-D-capable IC, reducing PCB area and BOM cost versus discrete implementations. It sits in the broader taxonomy: battery monitor IC -> battery management -> power management -> semiconductor.
Key features include AEC-Q100 qualification for automotive applications, integrated EIS engine for state-of-health diagnostics, dedicated single-ended measurement paths, and 5us typical VI synchronization. The device supports ISO 26262 functional safety at ASIL-D for HV measurement accuracy (<0.4%). The LQFP-48 package with exposed thermal pad provides robust thermal performance for underbody automotive environments.
Typical applications include EV/HEV battery management systems, high-voltage battery junction boxes, stationary energy storage systems, and industrial battery backup systems requiring ASIL-D functional safety. The pack-level EIS function enables in-situ battery health monitoring without disconnecting the battery pack.
When designing with this device, pay attention to the high-voltage isolation layout, the shunt resistor placement for current sensing, and the host MCU communication interface timing. The BQ79881-Q1 is typically paired with a BQ79718-Q1 cell monitor and a host MCU running TI's BMS firmware stack.
直接替換替代品，適用於 BQ79881-Q1 — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： BQ79881-Q1 （相同外形與佔位） — 差異在於 Functional Safety, Package, Automotive Qualification, Function, Mounting Type.
BQ79826Z-Q1
✅ 直接替換聯絡詢價
查看資料表 →BQ79616-Q1
✅ 直接替換聯絡詢價
查看資料表 →BQ79631-Q1
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
BQ79600-Q1
✅ 直接替換 ⚠️ 規格未經驗證聯絡詢價
查看資料表 →BQ79617-Q1
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
BQ79881-Q1 最大額定值與電氣特性
| Product Type | UIR Sensor with Pack-Level EIS |
| 功能 | Battery monitor with EIS, voltage, current, insulation resistance monitoring |
| HV Measurement Accuracy | <0.4% (ASIL-D) |
| Single-Ended Measurement Range | 0.3 V to 5 V |
| Pack Voltage Measurements | 2 (fast) |
| VI Sync within BQ79881 | 0 us |
| VI Sync with Cell Monitor | 5 us typical |
| Functional Safety | ASIL-D capable (ISO 26262) |
| Automotive Qualification | AEC-Q100 |
| 封裝 | LQFP-48 (7x7 mm) with EP |
| 安裝類型 | Surface Mount |
| EIS Engine | Integrated (pack-level) |
| Insulation Resistance Monitoring | Yes (UIR function) |
| Target Application | EV/BMS HV Automotive |
| RoHS 狀態 | Compliant |
BQ79881-Q1 腳位配置
| 腳位 1 | VIO — Digital I/O supply |
| 腳位 2 | GPIO1 — General-purpose I/O |
| 腳位 3 | GPIO2 — General-purpose I/O |
| 腳位 4 | CSN — SPI chip select (active low) |
| 腳位 5 | SCLK — SPI clock |
| 腳位 6 | MOSI — SPI master-out slave-in |
| 腳位 7 | MISO — SPI master-in slave-out |
| 腳位 8 | nRESET — Hardware reset (active low) |
| 腳位 9 | INT — Interrupt output |
| 腳位 10 | TX — UART transmit |
| 腳位 11 | RX — UART receive |
| 腳位 12 | DGND — Digital ground |
| 腳位 13 | AVDD — Analog supply |
| 腳位 14 | AGND — Analog ground |
| 腳位 15 | REF — Internal reference bypass |
| 腳位 16 | VC0 — Cell voltage input 0 |
| 腳位 17 | VC1 — Cell voltage input 1 |
| 腳位 18 | VC2 — Cell voltage input 2 |
| 腳位 19 | VC3 — Cell voltage input 3 |
| 腳位 20 | VC4 — Cell voltage input 4 |
| 腳位 21 | VC5 — Cell voltage input 5 |
| 腳位 22 | VC6 — Cell voltage input 6 |
| 腳位 23 | VC7 — Cell voltage input 7 |
| 腳位 24 | VC8 — Cell voltage input 8 |
| 腳位 25 | VC9 — Cell voltage input 9 |
| 腳位 26 | VC10 — Cell voltage input 10 |
| 腳位 27 | VC11 — Cell voltage input 11 |
| 腳位 28 | VC12 — Cell voltage input 12 |
| 腳位 29 | VC13 — Cell voltage input 13 |
| 腳位 30 | VC14 — Cell voltage input 14 |
| 腳位 31 | VC15 — Cell voltage input 15 |
| 腳位 32 | SRP — Shunt resistor positive input |
| 腳位 33 | SRN — Shunt resistor negative input |
| 腳位 34 | PACKP — Pack voltage positive input |
| 腳位 35 | PACKN — Pack voltage negative input |
| 腳位 36 | UIRP — Insulation monitor positive |
| 腳位 37 | UIRN — Insulation monitor negative |
| 腳位 38 | TSENSE1 — Temperature sensor input 1 |
| 腳位 39 | TSENSE2 — Temperature sensor input 2 |
| 腳位 40 | TSENSE3 — Temperature sensor input 3 |
| 腳位 41 | TSENSE4 — Temperature sensor input 4 |
| 腳位 42 | EIS_OUT — EIS excitation output |
| 腳位 43 | EIS_IN — EIS measurement input |
| 腳位 44 | TEST — Test mode (factory only) |
| 腳位 45 | NC — Not connected |
| 腳位 46 | HV — High-voltage supply input |
| 腳位 47 | BST_NC — Not connected |
| 腳位 48 | EP — Exposed thermal pad (connect to AGND) |
典型應用
BQ79881-Q1 適用於 6 應用s: EV/HEV Battery Management System, Battery Junction Box (BJB) Pack Monitor, Pack-Level EIS Battery Health Diagnostics, Stationary Energy Storage Systems (ESS), Industrial Battery Backup Systems, Hybrid Electric Vehicle (HEV) Battery Pack.
EV/HEV Battery Management System
The BQ79881-Q1 is the core pack-level monitor in EV/HEV high-voltage BMS designs, providing ASIL-D HV measurement accuracy (<0.4%) per ISO 26262. Its integrated UIR function continuously verifies HV isolation between the battery pack and chassis, detecting creepage or breakdown faults that could create a chassis-shock hazard. Combined with a BQ79718BQPAPRQ1 cell monitor, it enables a complete 18S-32S BMS for 400V and 800V architectures.
推薦
Battery Junction Box (BJB) Pack Monitor
In automotive battery junction boxes, the BQ79881-Q1 acts as the central UIR sensor, measuring pack voltage, current (via external shunt), and performing insulation resistance tests. The 0us internal VI sync enables simultaneous voltage/current sampling for accurate coulomb counting, while the 5us VI sync with cell monitors preserves pack-level synchronization. The LQFP-48 EP package handles underbody thermal loads during high-current EV operation.
推薦
Pack-Level EIS Battery Health Diagnostics
The BQ79881-Q1's integrated EIS engine performs in-situ AC impedance spectroscopy on the entire battery pack, enabling state-of-health, state-of-charge, and aging characterization. Unlike discrete EIS implementations requiring external signal generators and ADCs, the integrated engine reduces BOM cost by 30-50% and PCB area. Pack-level EIS detects cell-to-cell aging variations and provides thermal-runaway precursors 24-48 hours before critical events.
推薦
Stationary Energy Storage Systems (ESS)
For grid-tied and commercial battery energy storage, the BQ79881-Q1 provides automotive-grade reliability for high-voltage battery cabinets. The ASIL-D-derived functional safety architecture and insulation resistance monitoring protect service technicians during maintenance. Pack-level EIS enables remote battery health monitoring over the asset's 15-20 year lifetime, reducing on-site inspection frequency and total-cost-of-ownership for ESS operators.
推薦
Industrial Battery Backup Systems
Industrial UPS and battery backup systems benefit from the BQ79881-Q1's automotive-grade robustness and ASIL-D HV measurement capability. The integrated insulation resistance test ensures compliance with industrial safety standards for HV battery cabinets, while pack-level EIS provides early warning of battery degradation before catastrophic failure. The AEC-Q100 qualification delivers automotive-grade reliability for industrial environments requiring 10+ year operational lifetimes.
推薦
Hybrid Electric Vehicle (HEV) Battery Pack
In HEV applications with 48V mild-hybrid architectures, the BQ79881-Q1 provides ASIL-D insulation monitoring and pack-level EIS for the 48V battery pack. The 0.3-5V single-ended measurement range covers typical HEV cell voltages, and the 5us VI sync maintains synchronization with the 48V cell monitor. The integrated UIR function detects isolation faults in the 48V system that could affect low-voltage ECU networks sharing chassis ground.
推薦
推薦產品摘要
工程參考資料，適用於 BQ79881-Q1 — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | BQ79826Z-Q1 | BQ79616-Q1 | BQ79631-Q1 | BQ79600-Q1 | BQ79617-Q1 |
|---|---|---|---|---|---|---|
| Package | LQFP-48 (7x7 mm) with EP | LQFP-48 (7x7 mm) - same | LQFP-48 (7x7 mm) - same | LQFP-48 (7x7 mm) - same | LQFP-48 (7x7 mm) - same | LQFP-48 (7x7 mm) - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Function | UIR + Pack-Level EIS | 26S Cell Monitor + Smart EIS Engine | 16S Cell Monitor (no EIS/UIR) | 32S Cell Monitor | SPI/UART Comms MCU | 17S Cell Monitor |
| UIR (Insulation Resistance) | Yes (integrated) | No | No | No | No | No |
| EIS Engine | Pack-level EIS (integrated) | Smart EIS Engine (per-cell) | No | No | No | No |
| Cell Monitor Channels | Pack-level (no per-cell) | 26S | 16S | 32S | 0 (comms MCU) | 17S |
| Automotive Grade | AEC-Q100 (ASIL-D) | AEC-Q100 | AEC-Q100 | AEC-Q100 | AEC-Q100 | AEC-Q100 |
主要差異化特點
- Integrated pack-level EIS engine (對比BQ79616-Q1)
- Integrated UIR (insulation resistance) monitoring (對比BQ79826Z-Q1)
- ASIL-D HV measurement accuracy <0.4% (對比BQ79718BQPAPRQ1)
- 0us internal VI sync (對比BQ79631-Q1)
設計說明
The LQFP-48 package with exposed thermal pad (EP) MUST be soldered to a copper pour of at least 1 square inch on the top and inner PCB layers to keep junction temperature within the -40C to +125C automotive range. During active EIS measurements the IC can dissipate 0.5-1.5W, and without proper thermal design, junction temperature will exceed safe limits in underbody EV environments where ambient can reach 85C.
The shunt resistor for current sensing must be placed within 50mm of the SRP/SRN inputs to minimize ground-loop noise. Use a Kelvin connection (4-wire) to the shunt for accurate current measurement. The HV isolation barrier between PACKP/PACKN and low-voltage signals must comply with IEC 60664 creepage/clearance requirements - typically 8mm minimum for 800V automotive systems.
Do not bypass the AVSS/AVDD decoupling capacitors - place 100nF and 10uF ceramic capacitors within 5mm of the supply pins. The internal reference (REF pin) requires a low-ESR 100nF bypass capacitor for ADC accuracy. Do not connect the TEST pin to any signal in production designs, as it activates factory test modes. Always use the EIS_OUT through a series resistor to limit inrush current during AC excitation.
The SPI/UART communication lines to the host MCU should be routed with controlled impedance (50 ohm) and length-matched within 5mm if using SPI at >1 MHz. Add 33 ohm series damping resistors at the driver outputs to reduce ringing. For daisy-chained BQ796xx configurations, use TI's recommended daisy-chain topology with twisted-pair or shielded cabling to minimize EMI susceptibility in automotive environments.
合規資訊
AEC-Q100 qualified per TI product page. ASIL-D capable per ISO 26262 for HV measurement functional safety. RoHS and REACH compliant. Halogen-free status not explicitly stated in provided data.
