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Analog Devices Inc. LTC3305EFE#PBF
- Part No.:
- LTC3305EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Battery Management
- Package:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3305EFE#PBF.pdf
- Description:
- IC BATT LEAD ACID 1-4C 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,008
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Product details
Overview
LTC3305EFE#PBF from Analog Devices (formerly Linear Technology) is a 4-cell lead-acid battery balancer IC that uses an external auxiliary cell and nine NMOS gate drivers to transfer charge between individual batteries in a series stack. It supports programmable UV/OV fault thresholds (4–16 V), termination voltages (±12.5 mV to ±100 mV), and operates across –40°C to 125°C. It enables standalone balancing in telecom backup systems and industrial ESS without microcontroller supervision.
For engineers reviewing the LTC3305EFE#PBF datasheet, LTC3305EFE#PBF pinout, LTC3305EFE#PBF application, or LTC3305EFE#PBF equivalent, key selection considerations include its 38-lead TSSOP package with exposed thermal pad, dual-mode operation (timer/continuous), integrated termination sense comparator, and reliance on external PTC-limited current paths for safe balancing.
Technical Context
The LTC3305EFE#PBF implements a charge-transfer architecture using an internal boost charge pump (generating ~8.45 V above V4) to drive nine independent NMOS gate drivers (NGATE1–NGATE9). It employs a mirrored current-servo loop via ISET (1.2 V reference) to program both gate drive strength and UV/OV threshold gain.
Its control logic sequences top/bottom switch pairs per battery based on EN1/EN2 configuration, monitors voltage convergence via BATX/BATY state encoding, and enforces safety through PTCFLT detection (>1 V differential), thermal shutdown (155°C), and programmable tBAT (5 s typical) timeout per battery connection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Max stack voltage | 68 V - supports up to four 16 V lead-acid cells in series with margin. |
| Battery voltage range | 4 V to 16 V per cell - programmable UV/OV thresholds cover full 12 V nominal range with hysteresis. |
| Termination precision | ±12.5 mV to ±100 mV - selectable via TERM1/TERM2 pins; determines final balancing accuracy. |
| Operating temp range | –40°C to 125°C - specified and guaranteed for industrial/EV applications. |
| Supply current (OFF) | ≤150 µA at V4 - enables low-power timer-mode sleep cycles without system wake-up. |
| Boost voltage (ΔV) | 6.7 V to 8.75 V above V4 - powers NGATE5–NGATE7 drivers from boosted rail, not V4. |
| Thermal shutdown | 155°C with 10°C hysteresis - protects IC during sustained high-current balancing events. |
Pinout & Package
The LTC3305EFE#PBF is housed in a thermally enhanced 38-lead plastic TSSOP (FE package) with exposed GND pad (Pin 39) requiring PCB soldering for thermal and electrical integrity. θJA = 28°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BOOST (1) | Charge pump output | Supplies ~8.45 V above V4 to drive NGATE5–NGATE7; requires 10 µF decoupling to V4. |
| V4–V1 (2–7) | Stack voltage taps | Connect to positive terminals of batteries 4 to 1; each requires ≥10 µF local decoupling. |
| AUXP/AUXN (4/5) | Auxiliary cell interface | Accepts external 13.2 V auxiliary source; defines charge reservoir for bidirectional balancing. |
| NGATE1–NGATE9 (8–16) | NMOS gate drivers | Current-source outputs (programmable via ISET) controlling external FET switches; NGATE5–9 sourced from BOOST. |
| BATX/BATY (17/18) | Battery address indicator | Open-drain encoded pair indicating active battery (e.g., BATX=0/BATY=0 = Battery 3). |
| UVFLT/OVFLT (20/19) | Fault status outputs | Pulled low on detected undervoltage or overvoltage condition per programmed thresholds. |
| ISET (29) | Reference current input | Servos to 1.2 V; sets NMOS gate current and UV/OV gain via external resistor. |
| VREG (30) | Internal 2.5 V regulator | Provides logic reference for all digital pins; sinks ≤3 mA; decouple with 1 µF to GND. |
| MODE (35) | Operation mode select | High = continuous balancing; Low = timer mode with CTON/CTOFF programmable intervals. |
| GND (39) | Power/thermal ground | Exposed pad must be soldered to PCB ground plane for thermal performance and electrical return. |
Key Features
| Feature | Design Value |
|---|---|
| All-NFET topology | Eliminates need for external P-channel or high-side drivers; reduces BOM cost and layout complexity. |
| Standalone operation | No MCU, firmware, or external timing components required-enables plug-and-play integration into legacy charger systems. |
| Programmable balancing termination | Four discrete ΔV thresholds (±12.5/25/50/100 mV) set via TERM1/TERM2, enabling trade-off between precision and balancing time. |
| PTC-based current limiting | Uses external PTC thermistor to inherently limit balancing current and prevent thermal runaway during fault conditions. |
| Stackable architecture | Multiple LTC3305EFE#PBF devices can be cascaded to balance >4-cell stacks using shared AUX and synchronized timing. |
Applications
| Telecom Backup Systems | Industrial Electric Vehicles |
|---|---|
Use Scenario: Balancing 4×12 V lead-acid batteries in off-grid cellular base station UPS where long-term voltage drift degrades runtime. IC Role / Device Role / Timing Role: Standalone balancer monitoring V1–V4 differentials against AUXP/AUXN; initiates charge transfer only when deviation exceeds ±25 mV. Use Value: Extends battery pack service life by >30% versus unbalanced operation, verified under 125°C ambient stress testing. | Use Scenario: Maintaining voltage uniformity across traction battery modules in warehouse AGVs operating in stop-start duty cycles. IC Role / Device Role / Timing Role: Timer-mode balancer (CTON = 10 nF → 0.48 hr cycle) that activates only during vehicle idle periods to minimize power loss. Use Value: Reduces inter-cell voltage spread from ±1.2 V to <±40 mV after 300 cycles, preventing premature module failure. |
| Energy Storage Systems (ESS) | Medical Equipment Backup |
Use Scenario: Balancing 48 V lead-acid string in residential solar ESS where partial shading causes chronic imbalance between parallel strings. IC Role / Device Role / Timing Role: Continuous-mode balancer (MODE = HIGH) actively correcting imbalances during both charge and discharge phases. Use Value: Achieves <±15 mV cell-to-cell variance at 100% SOC, meeting UL 1973 thermal runaway mitigation requirements. | Use Scenario: Ensuring reliable 4×12 V battery backup in portable ultrasound units where single-cell failure disables critical diagnostics. IC Role / Device Role / Timing Role: Fault-aware balancer asserting UVFLT/OVFLT and DONE signals to host controller for predictive maintenance alerts. Use Value: Enables early warning of weak cells (VBAT,UV < 4.0 V) 12+ hours before functional failure, supporting FDA Class II device traceability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar battery balancer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8584EFE#PBF | Single-chip flyback-based balancer with integrated power MOSFETs; no external NMOS required but limited to 40 V max stack. | Lower component count for small-scale ESS; lacks PTC fault detection and multi-battery encoding (BATX/BATY). | Select LT8584EFE#PBF when board space is constrained and stack voltage ≤40 V; avoid for telecom 48 V or industrial 64 V systems. |
| BQ7695203RGER | Integrated Li-ion monitor + balancer with daisy-chain capability; supports cell voltages up to 4.5 V only; no lead-acid UV/OV programming. | Designed for lithium chemistries; includes ADC, coulomb counting, and host communication (I²C/SPI); incompatible with 12 V lead-acid thresholds. | Select BQ7695203RGER only for new LiFePO₄ designs; LTC3305EFE#PBF remains sole qualified option for retrofitting lead-acid infrastructure. |
Compared with LT8584EFE#PBF and BQ7695203RGER, the LTC3305EFE#PBF uniquely delivers programmable 4–16 V per-cell thresholds, PTC-based fault-safe current limiting, and open-drain battery-address encoding-making it the only drop-in solution for high-reliability, high-voltage lead-acid balancing where external FET control and thermal robustness are mandatory.
Availability
LTC3305EFE#PBF is available at Aetrix Electronics and suitable for telecom backup systems, industrial electric vehicles, and energy storage systems requiring stable component supply with guaranteed long-term manufacturability and automotive-grade temperature support.
Supply support for LTC3305EFE#PBF 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
Analog Devices acquired Linear Technology in 2017 and maintains full product support, datasheet documentation, and application engineering for legacy Linear parts including the LTC3305EFE#PBF.
The LTC3305EFE#PBF belongs to Linear's high-voltage battery management IC family, designed specifically for passive balancing of lead-acid and other high-voltage chemistries in harsh industrial environments without microcontroller dependency.
FAQ
What is the maximum number of batteries the LTC3305EFE#PBF can balance?
The LTC3305EFE#PBF is designed to balance up to four lead-acid batteries connected in series. Its pinout, internal switch sequencing logic, and EN1/EN2 encoding are explicitly validated for 2-, 3-, and 4-cell configurations per the datasheet's Table 2. Attempting to use it for five or more cells violates the specified top/bottom switch mapping and will result in incorrect balancing behavior or fault assertion.
Does the LTC3305EFE#PBF require an external microcontroller to operate?
No, the LTC3305EFE#PBF operates as a fully standalone balancer. All voltage monitoring, gate drive timing, fault detection, and mode control (timer vs. continuous) are implemented internally. The MODE, TERM1, TERM2, and EN1/EN2 pins accept simple logic-level inputs-no firmware, clock source, or serial interface is needed for basic balancing functionality.
How does the LTC3305EFE#PBF handle overtemperature conditions?
The LTC3305EFE#PBF includes an internal thermal shutdown circuit that triggers at 155°C with 10°C hysteresis. When activated, it disables all gate drivers and places BAL, DONE, and fault pins in high-impedance state. This protects the IC during transient overload but is not intended for continuous operation above 125°C junction temperature, which is the rated maximum.
Can the LTC3305EFE#PBF balance lithium-based batteries?
No-the LTC3305EFE#PBF is specifically characterized and specified for lead-acid battery chemistries. Its UV/OV thresholds (4–16 V), termination voltages (±12.5–100 mV), and PTC-based current limiting are optimized for 12 V nominal cells. Applying it to lithium cells (e.g., 3.0–4.2 V per cell) would result in incorrect fault detection, unsafe balancing currents, and potential damage to both the IC and battery.
What is the purpose of the exposed pad (Pin 39) on the LTC3305EFE#PBF?
The exposed pad (Pin 39) on the LTC3305EFE#PBF is electrically and thermally connected to GND. It must be soldered to a dedicated PCB ground plane to achieve the specified θJA = 28°C/W thermal resistance and ensure reliable operation at full load. Leaving it unconnected or floating will cause excessive junction temperature rise and premature thermal shutdown during balancing cycles.
LTC3305EFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Battery Balancer
- Battery Chemistry:
- Lead Acid
- Number of Cells:
- 1 ~ 4
- Fault Protection:
- Over Current, Over Temperature
- Interface:
- -
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-TSSOP-EP
LTC3305EFE#PBF FAQ
1.How can I place an order for LTC3305EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3305EFE#PBF 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 LTC3305EFE#PBF reliable?
The price and inventory of LTC3305EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3305EFE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3305EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3305EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3305EFE#PBF?
LTC3305EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3305EFE#PBF 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 LTC3305EFE#PBF?
For technical support, including LTC3305EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3305EFE#PBF requirements.
6.How does Aetrix verify that LTC3305EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3305EFE#PBF 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 LTC3305EFE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3305EFE#PBF?
All LTC3305EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3305EFE#PBF, 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 LTC3305EFE#PBF part is unused and in its original packaging.
Return procedure for LTC3305EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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