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Analog Devices Inc. LT3651EUHE-4.1#PBF
- Part No.:
- LT3651EUHE-4.1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Battery Chargers
- Package:
- 36-WFQFN Exposed Pad
- Datasheet:
-
LT3651EUHE-4.1#PBF.pdf
- Description:
- IC BATT CHG LI-ION 1CELL 36QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,512
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Product details
Overview
LT3651EUHE-4.1#PBF from Analog Devices (formerly Linear Technology) is a monolithic 4A synchronous step-down Li-ion battery charger IC for single-cell applications, supporting 6.5V–32V input and delivering 4.1V float voltage with 0.5% accuracy, ±7.5% charge current accuracy, and NTC-based temperature monitoring. It enables high-efficiency charging in automotive cradles and industrial handheld instruments.
For engineers reviewing the LT3651EUHE-4.1#PBF datasheet, LT3651EUHE-4.1#PBF pinout, LT3651EUHE-4.1#PBF application, or LT3651EUHE-4.1#PBF equivalent, key selection criteria include its 4A programmable charge current, C/10 or timer-based termination, dynamic input current limiting via ILIM, thermal foldback protection, and 36-pin QFN package with exposed SW and GND pads.
Technical Context
The LT3651EUHE-4.1#PBF implements average current mode control using dual error amplifiers (V-EA and C-EA) to regulate constant-current/constant-voltage charging. Its synchronous switcher uses bootstrapped high-side drive (BOOST pin) and an integrated low-side MOSFET, with oscillator frequency set by RT (54.9kΩ = 1MHz).
It integrates preconditioning below 2.85V BAT, auto-recharge at 97.5% of 4.1V float, bad battery detection after 22.5 minutes of preconditioning, and thermal foldback triggered above 125°C junction temperature - all managed by internal logic without external microcontroller intervention.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6.5V to 32V (40V absolute max); supports 12V/24V automotive and industrial supplies without external regulators. |
| Float Voltage | 4.1V ±0.5%; precisely regulated reference for Li-ion cell termination and maintenance. |
| Max Charge Current | 4A programmable via SENSE–BAT resistor; 95mV sense threshold enables accurate current setting. |
| Charge Termination | Selectable C/10 detection (8.6mV sense threshold) or user-programmable timer (0.68µF = 3 hours). |
| NTC Monitoring | 1.25V–0.29V input range with 10% hysteresis; supports standard 10kΩ B3380 thermistors for 0°C–40°C safe charging. |
| Package | 36-pin QFN (5mm × 6mm, 0.75mm height); exposes SW (Pin 38) and GND (Pin 37) for thermal management. |
| Standby Current | 85µA typical; minimizes parasitic drain when battery is fully charged and system idle. |
Pinout & Package
LT3651EUHE-4.1#PBF is housed in a 36-pin plastic QFN package (5mm × 6mm, 0.75mm profile) with two exposed thermal pads: Pin 37 (GND) and Pin 38 (SW), both requiring PCB soldering for electrical integrity and thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| NTC (1) | Battery temperature monitor input | Sources 50µA into external 10kΩ NTC; voltage readback enables 0°C–40°C charging window enforcement. |
| ACPR (2) | Open-collector AC present status | Sinks up to 10mA when VIN valid; signals power availability to host system without level-shifting. |
| BAT (3) | Kelvin battery voltage sense | High-impedance input (<0.1µA bias post-charge); enables precise float regulation and auto-recharge at 4.0V. |
| SENSE (4) | Charge current sense return | Measures voltage drop across RSENSE; sets average charge current with 95mV full-scale for 4A operation. |
| BOOST (5) | High-side gate drive bootstrap rail | Requires ≥1µF capacitor to SW; sustains >4V gate drive for low RDS(on) during switching. |
| GND (6,23,31,37) | Power and signal ground | Pins 37 (exposed pad) must be soldered to PCB plane; provides primary thermal path and reference for all analog blocks. |
| SW (7,11–18,22,38) | Synchronous switch node | Multiple pins reduce inductance; Pin 38 (exposed pad) must be soldered for thermal conduction and low-loss switching. |
| TIMER (24) | Charge cycle timeout programming | 0.68µF to GND sets 3-hour full-charge timer; grounding disables timer, enabling C/10-only termination. |
| FAULT (25) | Open-collector fault indicator | Pulled low on NTC out-of-range, bad battery, or thermal shutdown; compatible with VIN-level pull-ups. |
| CHRG (26) | Open-collector charge status | Pulled low during active charging; high-impedance when terminated or in standby - direct LED interface. |
| SHDN (27) | Enable/disable control with UVLO | 1.20V threshold with 95mV hysteresis; reduces VIN supply to 17µA in shutdown mode. |
| ILIM (28) | Input current limit programming | Voltage sets max CLP–CLN sense voltage (1V = 95mV); enables dynamic input current limiting and soft-start. |
| CLP/CLN (29/30) | System input current sense inputs | Differential pair monitors input current via external resistor; allows charge current reduction to hold total system load constant. |
| VIN (32–34) | Main power input | Three parallel pins handle high-current input path; accepts up to 32V DC with 40V absolute max rating. |
| RNG/SS (35) | Charge current range and soft-start | Voltage sets max SENSE–BAT sense voltage (1V = 95mV); capacitor to GND enables controlled current ramp-up. |
| RT (36) | Oscillator frequency set | 54.9kΩ to GND programs 1MHz switching; adjusts frequency from 250kHz to 1.1MHz for EMI or efficiency trade-offs. |
Key Features
| Feature | Design Value |
|---|---|
| Dynamic Input Current Limiting | Regulates battery charge current in real time to maintain constant total system input current, preventing upstream supply overload. |
| Auto-Recharge at 97.5% Float | Triggers new CC/CV cycle when BAT drops to 4.0V (97.5% of 4.1V), extending runtime without manual intervention. |
| Bad Battery Detection | Halts charging and asserts FAULT if battery fails to reach 2.85V within 22.5 minutes - prevents unsafe charging of damaged cells. |
| Thermal Foldback Protection | Reduces charge current progressively above 125°C junction temperature, avoiding thermal runaway while maintaining partial functionality. |
| Preconditioning Below 2.85V | Automatically limits charge current to 15% of programmed value until battery recovers to safe voltage, protecting deeply discharged Li-ion cells. |
Applications
| Industrial Handheld Instruments | 12V to 24V Automotive Systems |
|---|---|
Use Scenario: Portable test equipment powered by removable Li-ion packs, operating in variable ambient temperatures and requiring long field runtime. IC Role / Device Role / Timing Role: Primary battery charger managing CC/CV profile, NTC-based thermal safety, and auto-recharge between usage cycles. Use Value: Enables reliable multi-year field operation with no user service intervention, leveraging 0.5% float voltage accuracy and 4A fast recharge capability. | Use Scenario: In-vehicle diagnostic tools or telematics modules powered from 12V/24V vehicle batteries with wide input transients. IC Role / Device Role / Timing Role: High-input-voltage battery charger that withstands load-dump spikes up to 40V and maintains stable 4.1V cell regulation. Use Value: Eliminates need for external TVS or pre-regulator stages due to 32V operating range and 40V absolute max rating. |
| Desktop Cradle Chargers | Notebook Computers |
Use Scenario: Docking station providing simultaneous charging and system power to handheld devices with hot-swap battery access. IC Role / Device Role / Timing Role: Dual-role power manager handling input current limiting (via CLP/CLN) and precise battery termination (via SENSE/BAT). Use Value: Ensures cradle remains within USB-C PD or proprietary adapter limits while delivering full 4A to battery without overheating. | Use Scenario: Embedded battery charging subsystem in compact notebooks where space and thermal density are constrained. IC Role / Device Role / Timing Role: Monolithic charger integrating synchronous FETs, thermal sensing, and status signaling in a low-profile QFN. Use Value: Reduces BOM count by eliminating discrete MOSFETs and external current sense amps, saving >15mm² PCB area. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Li-ion battery charger applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BQ24610RGER | 4A max charge current, 4.1V float, but lacks integrated NTC monitoring and requires external thermistor bias circuitry. | Supports same 6V–32V input and 1-cell Li-ion, but needs additional components for temperature safety compliance. | Choose BQ24610RGER only if external thermistor conditioning is already implemented and board space permits added passives. |
| MP2617GQ-Z | 4A capable, 4.1V float, includes NTC monitoring, but maximum input is 28V (vs. 32V) and no programmable input current limiting via CLP/CLN. | Suitable for 12V/19V systems but not 24V automotive where transient tolerance is critical; no system-level input current control. | Select MP2617GQ-Z when operating strictly below 28V and when system-level input current coordination is unnecessary. |
Compared with BQ24610RGER and MP2617GQ-Z, the LT3651EUHE-4.1#PBF uniquely combines 32V input tolerance, integrated NTC bias and monitoring, and dual-loop current control (battery + system input), making it optimal for ruggedized portable and automotive applications demanding full safety autonomy.
Availability
LT3651EUHE-4.1#PBF is available at Aetrix Electronics and suitable for industrial handheld instruments, 12V to 24V automotive systems, and desktop cradle chargers requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT3651EUHE-4.1#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 its high-performance analog IC portfolio, emphasizing precision power management, signal conditioning, and robust industrial-grade reliability.
The LT3651EUHE-4.1#PBF belongs to Linear's monolithic Li-ion charger product line, designed specifically for wide-input, high-current battery charging in harsh environments including automotive, industrial, and portable instrumentation.
FAQ
What is the exact float voltage accuracy of the LT3651EUHE-4.1#PBF?
The LT3651EUHE-4.1#PBF delivers 4.1V nominal float voltage with ±0.5% accuracy over –40°C to 125°C junction temperature. This specification is guaranteed by design and confirmed in the Electrical Characteristics table (Page 3), where min/typ/max values are 4.08V/4.10V/4.12V at full temperature range.
Does the LT3651EUHE-4.1#PBF support automatic recharge, and at what threshold?
Yes, the LT3651EUHE-4.1#PBF automatically initiates a new charge cycle when the BAT pin voltage falls to 97.5% of its 4.1V float voltage - i.e., 4.0V. This behavior is explicitly defined in the Electrical Characteristics table under "Battery Recharge Voltage Hysteresis" (–105mV) and confirmed in the OPERATION section (Page 10).
How is input current limiting implemented on the LT3651EUHE-4.1#PBF?
The LT3651EUHE-4.1#PBF implements input current limiting using differential inputs CLP and CLN, with regulation controlled by the ILIM pin voltage. A 1V signal on ILIM corresponds to 95mV across the CLP–CLN sense resistor, enabling precise system-level current capping independent of battery charge state.
What thermal protection mechanisms does the LT3651EUHE-4.1#PBF include?
The LT3651EUHE-4.1#PBF features three thermal protections: (1) junction temperature foldback above 125°C (reducing charge current), (2) NTC-based battery temperature monitoring (0°C–40°C window), and (3) thermal shutdown with automatic recovery. These are detailed in the FEATURES list and OPERATION section (Pages 1–11).
Can the LT3651EUHE-4.1#PBF be used without an NTC thermistor?
Yes - the NTC pin (Pin 1) may be left unconnected if temperature monitoring is not required. The datasheet states: "If this function is not desired, leave the NTC pin unconnected." All other charging functions remain fully operational, though battery thermal safety is disabled.
LT3651EUHE-4.1#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 36-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Battery Chemistry:
- Lithium Ion/Polymer
- Number of Cells:
- 1
- Current - Charging:
- Constant - Programmable
- Programmable Features:
- Current, Timer
- Fault Protection:
- Over Temperature
- Charge Current - Max:
- 4A
- Battery Pack Voltage:
- 4.1V
- Voltage - Supply (Max):
- 32V
- Interface:
- -
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 36-QFN (5x6)
LT3651EUHE-4.1#PBF FAQ
1.How can I place an order for LT3651EUHE-4.1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3651EUHE-4.1#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 LT3651EUHE-4.1#PBF reliable?
The price and inventory of LT3651EUHE-4.1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3651EUHE-4.1#PBF is usually 5 days.
3.What payment methods are accepted for LT3651EUHE-4.1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3651EUHE-4.1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3651EUHE-4.1#PBF?
LT3651EUHE-4.1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3651EUHE-4.1#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 LT3651EUHE-4.1#PBF?
For technical support, including LT3651EUHE-4.1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3651EUHE-4.1#PBF requirements.
6.How does Aetrix verify that LT3651EUHE-4.1#PBF is sourced from the original manufacturer or authorized distributors?
All LT3651EUHE-4.1#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 LT3651EUHE-4.1#PBF meets industry standards.
7.What is the process for return or replacement of LT3651EUHE-4.1#PBF?
All LT3651EUHE-4.1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3651EUHE-4.1#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 LT3651EUHE-4.1#PBF part is unused and in its original packaging.
Return procedure for LT3651EUHE-4.1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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