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Texas Instruments BQ78412DDWT
- Part No.:
- BQ78412DDWT
- Manufacturer:
- Texas Instruments
- Category:
- Battery Management
- Package:
- 44-PowerTSSOP (0.244", 6.20mm Width)
- Datasheet:
-
BQ78412DDWT.pdf
- Description:
- IC BATT GAS GAUGE DISP 44HTSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,627
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Product details
Overview
BQ78412DDWT from Texas Instruments is a stand-alone Pb-acid battery state-of-charge (SoC) and run-time-to-empty (RTTE) indicator IC for 12-V consumer UPS systems. It integrates voltage, current (±320 A peak), temperature, and time measurement; delivers ±15-min RTTE accuracy; drives a 10-LED bar graph; and stores cumulative warranty data internally.
For engineers reviewing the BQ78412DDWT datasheet, BQ78412DDWT pinout, BQ78412DDWT application, or BQ78412DDWT equivalent, this page details its gas-gauging architecture, UART/I²C interface configuration, LED display timing control, Pb-acid cell model programmability, and SoH-based REPLACE/WARN status reporting - all critical for UPS battery pack integration and field-warranty analytics.
Technical Context
The BQ78412DDWT implements rate- and temperature-compensated coulomb counting using a 1-mΩ sense resistor in the negative power path, with full-scale differential input of ±160 mV and 12-bit ADC resolution. Its on-chip temperature sensor and internal/external 8-MHz oscillator support runtime estimation across –40°C to +85°C.
It operates in three states - Active (display on, gas gauging active), Idle (display frozen, no coulomb counting), and Sleep (display off, minimal current draw) - triggered by configurable thresholds (TransToActive, IdleThresh, SleepTime). All states retain UART accessibility and periodic warranty logging.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Battery Voltage Range | 4 V to 26 V - supports 12-V nominal Pb-acid with overvoltage tolerance up to 30 V on VBAT+ |
| Current Measurement Range | ±320 A peak - enables high-power UPS monitoring using low-value external shunt |
| RTTE Accuracy | ±15 minutes - validated after capacity learning, critical for reliable UPS runtime prediction |
| Temperature Sensing | On-die sensor, ±1°C accuracy - used for SoC derating without external thermistor |
| Display Interface | SDAT/SCLK serial output - directly drives SN74HC164 shift registers for 10-LED bar graph |
| UART Data Rate | 9600 or 1200 baud - selectable via DevConfig1[11], compatible with RS-232 or IrDA transceivers |
| Supply Regulation | REG33 output: 3.3 V @ 100 µA–100 mA - powers AVDD/DVDD and external logic with 0.3% load regulation |
Pinout & Package
Package: DDW - 44-pin TSSOP with exposed thermal pad (bottom side); RoHS-compliant, lead-free.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RS+, RS– | Current sense differential input | Accepts ±160 mV full-scale shunt voltage; enables coulomb counting with 0.1-A step resolution |
| VS, AVSS | Battery voltage sensing reference | Measures 12-V battery potential relative to analog ground; supports 4–26 V operation |
| SDAT, SCLK | Serial display output | Drives external shift register (e.g., SN74HC164) to update 10-LED bar graph synchronously |
| RXD, TXD | UART communication I/O | Supports multi-drop addressing (default 0xFF); enables real-time SoC/SoH readback and parameter reprogramming |
| BUZZER | Digital alarm output | Active-high signal triggers audible warning for low-capacity, overvoltage, or undervoltage events |
| DISPEN | Display enable control | Blanks LED display during firmware updates; avoids visual flicker during status transitions |
| REG33 | On-chip 3.3-V regulator output | Powers internal analog/digital circuitry and external peripherals; eliminates need for external LDO |
| XIN, XOUT | Crystal oscillator interface | Optional 8-MHz crystal connection; improves timing accuracy vs. internal RC oscillator (±2.5% → ±0.5%) |
Key Features
| Feature | Design Value |
|---|---|
| Programmable Pb-acid cell models | 64-byte characterization table adjusts RTTE/SoC per discharge rate & temperature - enables accurate gauging across AGM, flooded, and gel variants |
| Two-stage SoH detection | Triggers WARN/REPLACE LEDs based on either FCC degradation (EOLCap) or cycle count (LifeCycles) - supports predictive battery replacement in deployed UPS units |
| Internal warranty data logging | Permanently stores cumulative usage metrics (charge cycles, deep discharges, temperature exposure) - retrievable only via manufacturer-secured UART sequence for audit compliance |
| Configurable LED bar graph | DevConfig1[5:2] sets display size (5–10 segments); DsplyConf1–5 define per-LED runtime allocation (e.g., 30 min/LED = 5-hr max display) |
| Multi-drop UART addressing | Supports daisy-chained battery packs via MultiDropAdr parameter - allows centralized monitoring of multiple 12-V modules using single host UART port |
Applications
| Consumer UPS Systems | 12-V Pb-Acid Battery Monitors |
|---|---|
Use Scenario: Stand-alone uninterruptible power supply for desktop PCs or network equipment, requiring runtime estimation and visual charge status during AC outage. IC Role / Device Role / Timing Role: Primary gas-gauge IC performing real-time coulomb counting, voltage/temperature compensation, and LED bar graph control - no host MCU required. Use Value: Delivers ±15-min RTTE accuracy and %SoC display without firmware development, reducing BOM cost and time-to-market for OEM UPS designs. |
Use Scenario: Embedded battery management module in telecom backup systems or security panels, where long-term reliability and field-replaceability are critical. IC Role / Device Role / Timing Role: Autonomous battery health monitor tracking FCC decay and cycle count; generates REPLACE/WARN status flags for maintenance alerts. Use Value: Enables predictive maintenance via internal SoH algorithms and tamper-resistant warranty logging - reduces service costs and warranty fraud risk. |
| Battery Warranty Analytics Tools | Industrial Backup Power Units |
Use Scenario: Factory test station or depot repair tool that retrieves historical battery usage data (deep discharge count, thermal stress hours) for warranty claim validation. IC Role / Device Role / Timing Role: Secure data logger storing cumulative metrics in nonvolatile memory; accessed via UART with manufacturer-specific command sequence. Use Value: Provides auditable, time-stamped battery lifecycle records - satisfies ISO 9001 traceability requirements and prevents unjustified warranty claims. |
Use Scenario: Ruggedized backup power for industrial controllers or SCADA systems operating in wide-temperature environments (–40°C to +85°C). IC Role / Device Role / Timing Role: Robust SoC estimator compensating for temperature-induced capacity drift using on-die sensor and firmware derating tables. Use Value: Maintains ±15-min RTTE accuracy across full industrial temperature range - ensures consistent runtime prediction despite ambient extremes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Pb-acid battery gauging applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BQ78350-R1 | Integrated fuel gauge + protector with integrated MOSFET drivers; supports Li-ion/Pb-acid; requires external MCU for display control | Targets smart battery packs needing protection + gauging; lacks built-in LED driver or buzzer output | Select when system requires overcurrent/overtemperature shutdown capability alongside gauging - not drop-in for BQ78412DDWT's standalone display function |
| MAX17205 | Li-ion-focused ModelGauge m5 algorithm; no native Pb-acid model; requires external shunt and MCU for display rendering | Designed for portable electronics; lacks Pb-acid-specific parameters (ChgEff, DsplyConf), SoH cycle tracking, or REG33 output | Choose only if migrating to Li-ion chemistry and adding host processor - unsuitable for direct 12-V UPS replacement due to missing Pb-acid firmware and display interface |
Compared with BQ78412DDWT, BQ78350-R1 adds protection but removes autonomous LED/buzzer functionality, while MAX17205 omits Pb-acid modeling entirely - making BQ78412DDWT uniquely suited for cost-sensitive, MCU-less 12-V UPS applications requiring field-serviceable runtime and health indicators.
Availability
BQ78412DDWT is available at Aetrix Electronics and suitable for consumer UPS systems, 12-V battery monitors, and warranty analytics tools requiring stable component supply, long-lifecycle support, and Pb-acid-specific gas-gauging accuracy.
Supply support for BQ78412DDWT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in battery management ICs.
The BQ78412DDWT belongs to TI's dedicated battery fuel gauge product line, engineered specifically for cost-effective, self-contained monitoring of lead-acid batteries in consumer and industrial backup power applications.
FAQ
What is the maximum battery capacity supported by the BQ78412DDWT?
The BQ78412DDWT supports Pb-acid batteries up to 327 Ah when measured at the 20-hour rate. This capacity limit is enforced by internal firmware scaling and coulomb-counting resolution; exceeding it may reduce RTTE accuracy. The BQ78412DDWT achieves this using a 1-mΩ sense resistor and 12-bit ADC, enabling precise current integration even at high Ah ratings.
Does the BQ78412DDWT require an external microcontroller to operate?
No, the BQ78412DDWT is a fully stand-alone gas-gauge IC. It performs all core functions - voltage/current/temperature measurement, coulomb counting, SoC/RTTE calculation, LED bar graph control, and buzzer signaling - without host MCU intervention. The BQ78412DDWT only requires external passive components (shunt, crystal optional) and LED drivers (e.g., SN74HC164) for full operation.
How does the BQ78412DDWT handle battery aging and capacity fade?
The BQ78412DDWT implements two independent capacity update methods: Learned Capacity (qualifies full discharge events to update FCC) and Age-Based Capacity (decrements FCC daily using CapDerateL/CapDerateH parameters). Both are configurable via UART and operate concurrently - ensuring accurate SoC tracking as the battery degrades over years of field use. The BQ78412DDWT stores all learned values in nonvolatile memory.
Can the BQ78412DDWT drive LEDs directly, or does it require external drivers?
The BQ78412DDWT does not drive LEDs directly. It outputs serialized display data via SDAT and clock pulses via SCLK to external shift registers like the SN74HC164, which then source/sink current to the LEDs. This architecture isolates the BQ78412DDWT from LED power demands and enables flexible display sizing (5–10 segments) without changing the IC's pinout or firmware.
What communication interfaces does the BQ78412DDWT support for configuration and data readback?
The BQ78412DDWT supports UART (NRZ or IrDA encoding) for full bidirectional communication - including parameter programming, real-time SoC/SoH readback, and warranty data retrieval. It also provides I²C pins (SCL/SDA) for internal use only (not user-accessible); these connect to on-die peripherals and cannot be used for external host communication. The BQ78412DDWT uses multi-drop addressing (default 0xFF) for multi-battery systems.
BQ78412DDWT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 44-PowerTSSOP (0.244", 6.20mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Battery Monitor
- Battery Chemistry:
- Lead Acid
- Number of Cells:
- 1
- Fault Protection:
- Over Voltage
- Interface:
- UART
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 44-HTSSOP
BQ78412DDWT FAQ
1.How can I place an order for BQ78412DDWT through Aetrix?
Please submit a Request for Quotation (RFQ) for BQ78412DDWT on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for BQ78412DDWT reliable?
The price and inventory of BQ78412DDWT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BQ78412DDWT is usually 5 days.
3.What payment methods are accepted for BQ78412DDWT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BQ78412DDWT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BQ78412DDWT?
BQ78412DDWT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BQ78412DDWT order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for BQ78412DDWT?
For technical support, including BQ78412DDWT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BQ78412DDWT requirements.
6.How does Aetrix verify that BQ78412DDWT is sourced from the original manufacturer or authorized distributors?
All BQ78412DDWT products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BQ78412DDWT meets industry standards.
7.What is the process for return or replacement of BQ78412DDWT?
All BQ78412DDWT units undergo pre-shipment inspection (PSI). If there is an issue with BQ78412DDWT, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The BQ78412DDWT part is unused and in its original packaging.
Return procedure for BQ78412DDWT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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