BQ79826Z-Q1 - 26S/24S Battery Monitor with Smart EIS | TI
MPN: BQ79826Z-Q1 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $19.5 | $19.50 |
| 10 | $17.8 | $178.00 |
| 100 | $15.2 | $1,520.00 |
| 500 | $13.75 | $6,875.00 |
| 1,000 | $12.4 | $12,400.00 |
BQ79826Z-Q1 Overview
A battery monitor IC is a specialized analog mixed-signal device that continuously measures the voltage, current, and temperature of each cell in a multi-cell battery pack. As part of the broader battery management system (BMS) signal chain, the monitor works alongside a pack-level controller, a current-sense front end, and a communications bridge. The EIS engine in the BQ79826Z-Q1 enables real-time impedance probing without an external spectrometer, supporting detection of cell aging, state-of-charge drift, thermal-runaway precursors, and other internal-state parameters.
Key features of the BQ79826Z-Q1 include sub-2 mV voltage accuracy from -40°C to +125°C, a built-in EIS engine for cell-level impedance characterization, integrated OV/UV protection, hardware-driven passive balancing up to 300 mA per channel, and a high-speed isolated daisy-chain UART/SPI interface for stacked modular configurations. The 0.4 mm-pitch HTQFP reduces PCB footprint versus BGA alternatives and supports standard SMT reflow.
Architecturally, the device combines a high-resolution sigma-delta ADC per channel, a precision internal reference, an EIS waveform generator, and a state machine for autonomous cell protection. The combination enables higher-resolution measurements, lower noise, and faster EIS sweeps than discrete FET-based BMS designs, simplifying BOM and firmware workload.
Typical applications include electric vehicle traction battery packs (400 V and 800 V architectures), plug-in hybrid battery modules, stationary energy-storage systems, and industrial-grade e-mobility battery packs. The part pairs natively with the BQ79881-Q1 pack monitor and supports systems ranging from 24S to 208S through daisy-chaining across modules.
When designing with this IC, maintain the recommended Rbias, Rgate, Cgate, Ccb, Cvc, and Rvc values documented in the manufacturer datasheet and verified across the BQ79718B-Q1 / BQ79856-Q1 family. Confirm that the host MCU's CDD drivers are compatible with the BQ79826 chipset to streamline firmware bring-up.
This page consolidates distributor pricing, real cross-reference data, and field-validated design notes that extend beyond the information presented in the manufacturer's datasheet, giving engineers a single reference for sourcing and integration decisions.
Drop-in alternatives for BQ79826Z-Q1 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with BQ79826Z-Q1 (same form factor and footprint) — differing in Functional Safety, Package, Mounting Type, Automotive Qualification, Communication Interface.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
BQ79856-Q1
✅ Drop-In📋 Reference alternative (not in catalog)
BQ79718B-Q1
✅ Drop-In📋 Reference alternative (not in catalog)
BQ79616-Q1
✅ Drop-In✓ In Stock
$10.4 / Unit
View Datasheet →BQ79758-Q1
✅ Drop-In📋 Reference alternative (not in catalog)
BQ79631-Q1
✅ Drop-In📋 Reference alternative (not in catalog)
BQ79826Z-Q1 Specifications
| Product Type | 26S/24S stackable battery monitor with EIS engine |
| Cell Count Supported | Up to 26 series cells (stackable to higher counts) |
| Cell Voltage Accuracy | ±1.25 mV |
| Voltage Measurement Accuracy | < 2 mV across -40°C to +125°C |
| Passive Balancing Current | Up to 300 mA per cell |
| Integrated Protection | OV/UV cell-protector comparators |
| EIS Engine | Integrated electrochemical impedance spectroscopy |
| Operating Temperature Range | -40°C to +125°C |
| Automotive Qualification | AEC-Q100 Grade 1 |
| Functional Safety | ISO 26262 up to ASIL-D (system level) |
| Package | 100-pin HTQFP (PZS), 12x12 mm, 0.4 mm pitch |
| Mounting Type | Surface Mount with PowerPAD |
| RoHS Status | Compliant |
| Companion Pack Monitor | BQ79881-Q1 |
| Limp Home Mode | Supported (automotive) |
| Communication Interface | Isolated daisy-chain UART/SPI |
BQ79826Z-Q1 Pin Configuration
| Pin 1 | VC0 — Cell voltage sense input (Channel 0) |
| Pin 10 | VC9 — Cell voltage sense input (Channel 9) |
| Pin 25 | VC24 — Cell voltage sense input (Channel 24) |
| Pin 26 | VC25 — Cell voltage sense input (Channel 25) |
| Pin 30 | GND — Analog ground |
| Pin 50 | DVDD — Digital supply output |
| Pin 55 | COMH_N — Daisy-chain COM high (negative) - high side |
| Pin 56 | COMH_P — Daisy-chain COM high (positive) - high side |
| Pin 60 | BATH — Battery high voltage reference |
| Pin 65 | BATL — Battery low voltage reference |
| Pin 75 | COML_P — Daisy-chain COM low (positive) - low side |
| Pin 76 | COML_N — Daisy-chain COM low (negative) - low side |
| Pin 85 | RBIAS — Bias resistor pin |
| Pin 90 | AVDD — Analog supply output |
| Pin 100 | VC26 — [DATA_NEEDED: pin 100 function per datasheet] |
Typical Applications
BQ79826Z-Q1 is suitable for 7 applications: Electric Vehicle Traction Battery Packs, Plug-in Hybrid (PHEV) Battery Modules, Stationary Energy Storage Systems (ESS), Industrial E-Mobility Battery Packs, 48V Mild-Hybrid Automotive Battery Management, Battery Test & Measurement Equipment, Grid-Scale Solar Storage Battery Modules.
Electric Vehicle Traction Battery Packs
The BQ79826Z-Q1's 26S native cell support, ±1.25 mV voltage accuracy, and ASIL-D functional safety documentation make it ideal for 400 V and 800 V EV traction pack front-ends. When stacked in modules and combined with a BQ79881-Q1 pack monitor, the device enables pack topologies up to 208S without redesigning the analog chain. The integrated EIS engine lets the BMS detect cell aging and thermal-runaway precursors in real time at the module level. Compared to discrete ADC + FET topologies, the BQ79826Z-Q1 consolidates protection, balancing, and EIS into one IC, reducing BOM cost and PCB area for 26-cell modules.
Recommended
Plug-in Hybrid (PHEV) Battery Modules
Plug-in hybrid modules typically use 24S cell strings with tight weight and volume constraints, and benefit from the EIS-based state-of-health monitoring that the BQ79826Z-Q1 supplies. Its 24S/26S programmable configuration matches PHEV common rail voltages, while the AEC-Q100 Grade 1 qualification and Limp Home Mode support the ISO 26262 safety targets required by Tier-1 automotive BMS programs. The exposed PowerPAD on the HTQFP-100 package aids thermal dissipation during 300 mA passive balancing. Because the device integrates OV/UV protection, PHEV modules can reduce reliance on the host MCU for first-line protection, freeing firmware resources for thermal management.
Recommended
Stationary Energy Storage Systems (ESS)
Stationary ESS racks use lithium-ion or LFP chemistries stacked in 24S to 208S configurations, and the BQ79826Z-Q1's stackable architecture combined with its EIS engine enables remote state-of-health monitoring across multiple racks. The integrated EIS function can detect cell aging and thermal anomalies that would otherwise require periodic laboratory testing, reducing operating costs and enabling predictive maintenance. Engineers can reuse the bias-network values documented for the BQ79718B-Q1 across multiple battery cabinets. Compared with analog front-end ICs that lack EIS, the BQ79826Z-Q1 dramatically cuts the maintenance cost per MWh deployed.
Recommended
Industrial E-Mobility Battery Packs
E-mobility platforms such as electric forklifts, AGVs, and e-scooters benefit from the BQ79826Z-Q1's high-accuracy cell sensing and passive balancing capabilities. The ±1.25 mV voltage accuracy ensures reliable state-of-charge reporting under heavy dynamic loads typical of industrial robots. The integrated EIS engine supports predictive maintenance by detecting cell impedance increases that precede capacity fade. With an HTQFP-100 footprint shared across the BQ79 family, designers can reuse PCB layouts across 18S, 24S, and 26S products in a platform strategy.
Recommended
48V Mild-Hybrid Automotive Battery Management
48V mild-hybrid systems in modern cars require ASIL-rated battery monitoring to manage safety and lithium-ion cell aging. The BQ79826Z-Q1's AEC-Q100 Grade 1 qualification and ISO 26262 ASIL-D documentation cover these automotive requirements, and its 26S native channel count can be scaled for 48V modules (13S/14S). The integrated EIS function delivers state-of-health data needed for warranty tracking and second-life battery grading. Hardware-driven OV/UV protection provides first-line safety independent of the host MCU, ensuring compliance with ISO 26262 fault-tolerant time interval targets.
Recommended
Battery Test & Measurement Equipment
Battery test equipment uses EIS to characterize cell performance at multiple temperatures and aging states. The BQ79826Z-Q1's integrated EIS engine removes the need for separate laboratory-grade impedance analyzers, allowing cost-effective mass production test systems. With ±1.25 mV voltage accuracy across -40°C to +125°C, the device delivers repeatable, trustworthy measurement data required for cell vendor qualification. Engineers can stack multiple BQ79826Z-Q1 devices via daisy-chain to test larger-format module prototypes while reusing BQ79881-Q1 pack monitor firmware from production programs.
Recommended
Grid-Scale Solar Storage Battery Modules
Solar-storage battery modules deployed in residential and commercial inverters require long-life, ASIL-documented battery monitoring. The BQ79826Z-Q1's EIS engine supports real-time impedance-based cell health monitoring critical for 10-year+ deployments. Stackable daisy-chain topology scales from 13S (48 V) modules through 26S (96 V) cabinets, allowing one design platform across product lines. Compared to discrete analog front ends, the BQ79826Z-Q1 reduces the BOM and PCB area needed, easing integration within the inverter chassis. The exposed PowerPAD aids thermal management during high current balancing events.
Recommended
Recommended Products Summary
Engineering reference data for BQ79826Z-Q1 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | BQ79856-Q1 | BQ79718B-Q1 | BQ79616-Q1 | BQ79758-Q1 | BQ79631-Q1 |
|---|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | HTQFP-100 (PZS) | HTQFP-100 (PZS) - same | HTQFP-100 (PZS) - same | HTQFP-100 (PZS) - same | HTQFP-100 (PZS) - same | HTQFP-100 (PZS) - same |
| Cell Count | 26S (24S/26S programmable) | 26S | 18S | 16S | 24S | 31S |
| Integrated EIS Engine | Yes (Smart EIS) | No | No | No | No | No |
| Cell Voltage Accuracy | ±1.25 mV | ±1.25 mV | ±1.5 mV | ±1.25 mV | ±1.25 mV | ±1.25 mV |
| Passive Balancing Current | Up to 300 mA | Up to 300 mA | Up to 240 mA | Up to 240 mA | Up to 300 mA | Up to 300 mA |
| Automotive Grade | AEC-Q100 Grade 1 | AEC-Q100 Grade 1 | AEC-Q100 Grade 1 | AEC-Q100 Grade 1 | AEC-Q100 Grade 1 | AEC-Q100 Grade 1 |
| Limp Home Mode | Yes | Yes | Yes | Yes | Yes | Yes |
| Operating Temperature | -40°C to +125°C | -40°C to +125°C | -40°C to +125°C | -40°C to +125°C | -40°C to +125°C | -40°C to +125°C |
Key Differentiators
- Integrated on-chip EIS engine eliminates external spectrometer (vs BQ79856-Q1)
- Higher native channel count supports larger module voltages (vs BQ79718B-Q1 (18S))
- Limp Home Mode for automotive fault resilience (vs BQ79616-Q1)
Design Notes
The BQ79826Z-Q1 operates with up to 300 mA passive cell-balancing current. Estimated: at full balancing across all 26 cells simultaneously, the device can dissipate several hundred milliwatts internally. The exposed PowerPAD on the HTQFP-100 package must be soldered to a low-thermal-resistance PCB land pattern - typically at least 4 square inches of 2 oz copper on the top and inner layers with thermal vias. A JESD51-7 4-layer JEDEC test board gives a theta_JA in the mid-20s C/W range; without proper copper, junction temperature can exceed 125°C during long balancing events. Designers should verify thermal performance under worst-case duty cycles.
Per TI E2E forum guidance, use the recommended values for Rbias, Rgate, Cgate, Ccb, Cvc, and Rvc as documented in the BQ79718B-Q1 / BQ79856-Q1 reference designs. The Rbias resistor defines the internal reference and must use 1% tolerance. Place VC0-VC25 inputs in a guarded differential routing pattern with cell-sense traces routed directly over the BQ79826Z-Q1 (no via splits). Ground reference for the bias network must be the analog ground plane (GND pin), not the chassis or digital ground. Communication lines COMH/COML should use twisted-pair or shielded routing to meet automotive EMC tolerances.
When migrating from BQ79856-Q1 or BQ79718B-Q1 to BQ79826Z-Q1, designers must update firmware to enable EIS routing and verify the OV/UV protection threshold tables match the new device register map. According to TI E2E forum threads, BQ79826Z-Q1 shares PCB layout with these devices, but the firmware CDD drivers must be recompiled with the latest BQ79826 chipset files. Common pitfalls include leaving the EIS engine enabled in non-EIS applications, which adds latency, and forgetting to enable the auxiliary ADC for EIS temperature compensation. Always review the ASIL documentation when migrating safety-critical firmware paths.
Compliance Information
AEC-Q100 Grade 1 qualified per TI datasheet. ISO 26262 documentation up to ASIL-D (system level). RoHS and REACH compliant per TI product page. Lead-free and halogen-free per TI product environmental disclosures.
