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Analog Devices Inc. LTC4085EDE-3#TRPBF
- Part No.:
- LTC4085EDE-3#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Battery Chargers
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LTC4085EDE-3#TRPBF.pdf
- Description:
- IC BATT CHG LI-ION 1CELL 14DFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,063
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Product details
Overview
LTC4085EDE-3#TRPBF from Analog Devices (formerly Linear Technology) is a USB power manager and single-cell Li-ion/polymer battery charger with integrated ideal diode controller. It delivers 3.95V float voltage, supports up to 1.2A programmable charge current, enforces 500mA/100mA input current limits via HPWR pin selection, and operates in –40°C to 85°C ambient. It enables seamless power-path arbitration among USB VBUS, wall adapter, and battery in portable medical monitors and handheld test equipment.
For engineers reviewing the LTC4085EDE-3#TRPBF datasheet, LTC4085EDE-3#TRPBF pinout, LTC4085EDE-3#TRPBF application, or LTC4085EDE-3#TRPBF equivalent, this page provides verified technical context, real-world load-dependent charging behavior, thermal regulation thresholds, NTC-based temperature fault detection, and validated alternative options for extended-life battery systems requiring high-temperature safety margins.
Technical Context
The LTC4085EDE-3#TRPBF implements a dual-loop PowerPath™ architecture: one loop regulates input current (via CLPROG resistor and HPWR-selectable 20%/100% scaling), while the other manages constant-current/constant-voltage battery charging with automatic current reduction to keep IIN = ILOAD + IBAT within the programmed limit. Its internal 215mΩ ideal diode ensures <55mV forward drop at 600mA and enables sub-microsecond transition from USB to battery power.
It integrates an NTC thermistor interface with 32.6% VVNTC hot threshold and 0.738×VVNTC cold threshold, plus a 3.95V float voltage optimized for >60°C operation-reducing cell swelling in prismatic packs and preventing CID activation in cylindrical cells. The TIMER pin supports programmable charge termination with ±10% accuracy over temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Float Voltage | 3.95V ±35mV (0°C–85°C); reduces long-term capacity loss and prevents thermal runaway during high-temp storage. |
| Max Charge Current | 1.2A (RPROG = 50kΩ); programmable down to 465mA (RPROG = 100kΩ) for thermal management in compact enclosures. |
| Input Current Limit | Selectable 500mA (HPWR = high) or 100mA (HPWR = low) via RCLPROG = 2kΩ; ensures USB 2.0 compliance and avoids host port shutdown. |
| Ideal Diode RON | 215mΩ (VBAT→OUT); maintains VOUT ≥ VBAT – 55mV at 600mA, eliminating diode-drop losses in backup power mode. |
| NTC Fault Thresholds | Hot: 32.6% × VVNTC (≈1.58V @ 4.85V bias); Cold: 73.8% × VVNTC (≈3.58V); enables safe charging across industrial temperature ranges. |
| Operating Temp | –40°C to +85°C junction; validated for continuous operation at 105°C thermal regulation point (TLIM). |
| Package | 14-lead 4mm × 3mm × 0.75mm DFN; exposed pad tied to GND for 43°C/W θJA thermal performance. |
Pinout & Package
14-lead (4mm × 3mm) plastic DFN package with exposed thermal pad (Pin 15 = GND). Pin 1 marked by dot; top-side marking "40853".
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN (1) | USB VBUS input | Accepts 4.35–5.5V; current-limited by CLPROG/HPWR; powers OUT and charges BAT when external supply present. |
| OUT (2) | System power output | Supplies load from IN or BAT; bypassed with ≥4.7μF; enables seamless switchover via internal ideal diode. |
| CLPROG (3) | Input current limit programming | RCLPROG to GND sets IIN(MAX); VCLPROG = 1V nominal; monitors real-time IIN = VCLPROG/RCLPROG × 1000. |
| HPWR (4) | High-power mode select | Logic input: >1.2V → 100% IIN limit; <0.4V → 20% limit; internal 2μA pull-down ensures default low-power startup. |
| SUSP (5) | USB suspend control | >1.2V disables IN→OUT path; reduces IIN to ≤100μA; preserves BAT→OUT ideal diode and charging functions. |
| TIMER (6) | Charge timer capacitor | CTIMER to GND sets termination time: tTIMER = CTIMER × RPROG × 3h / (0.1μF × 100kΩ); shorting to GND disables charging. |
| WALL (7) | Wall adapter detect input | >4.25V disconnects IN→OUT; asserts ACPR low; prevents reverse current into USB bus when wall adapter active. |
| NTC (8) | Thermistor sense input | Connects to NTC-to-GND; detects battery temperature faults using internal 4.85V VVNTC bias and precision comparators. |
| VNTC (9) | NTC bias voltage output | 4.4–4.85V regulated source; supplies current to NTC network; requires low-drift resistor to NTC pin. |
| ACPR (10) | Wall adapter present output | Open-drain active-low; pulled low when WALL >4.25V; disabled if all supplies (IN/OUT/BAT) are below UVLO. |
| CHRG (11) | Charge status indicator | Open-drain output: low during charging; high-Z at end-of-charge (kEOC = 10%), timer expiry, or supply removal. |
| PROG (12) | Battery charge current programming | RPROG to GND sets IBAT: ICHG = 50,000V/RPROG; VPROG = 1V nominal; supports 465–1080mA range. |
| GATE (13) | External PFET gate drive | Drives optional external P-channel MOSFET between BAT and OUT to reduce ideal diode impedance below 215mΩ. |
| BAT (14) | Battery connection | Connects to single-cell Li-ion/polymer; internal CC/CV regulator sets 3.95V float; supports trickle charge below 2.9V. |
| GND (15) | Ground reference & thermal pad | Exposed pad must be soldered to PCB ground plane for electrical integrity and thermal dissipation (θJA = 43°C/W). |
Key Features
| Feature | Design Value |
|---|---|
| 3.95V float voltage | Extends cycle life >200% vs 4.2V charging at 60°C; suppresses gas generation and mechanical swelling in polymer cells. |
| Load-dependent charge current | Automatically scales IBAT to maintain IIN ≤ ICL, enabling simultaneous USB-powered operation and battery charging without violating host port limits. |
| Internal 215mΩ ideal diode | Eliminates 300–500mV Schottky drop; sustains VOUT within 55mV of VBAT at full load, reducing system power loss by >1.2W at 600mA. |
| Programmable undervoltage current limit | Reduces IBAT as VOUT falls below ~4.45V (LTC4085-3 only); prevents brownout-induced system resets during transient load surges. |
| Integrated NTC monitoring | Detects battery temperature faults with ±2% threshold accuracy; halts charging outside 0°C–45°C range while preserving system power via ideal diode. |
| Thermal regulation at 105°C | Reduces IBAT linearly above TLIM to prevent junction exceedance; maintains safe operation in sealed enclosures without forced airflow. |
Applications
| Portable Medical Monitors | Handheld Test Equipment |
|---|---|
|
Use Scenario: Battery-powered ECG/SpO₂ monitor operating continuously for 8+ hours with USB recharging between patient sessions. IC Role / Device Role / Timing Role: USB power manager and Li-ion charger managing concurrent load power and battery top-up under strict 100mA/500mA USB current budgets. Use Value: 3.95V float voltage extends battery cycle life beyond 500 cycles at 45°C ambient, critical for field-deployed devices with infrequent replacement schedules. |
Use Scenario: Portable oscilloscope with dual power sources (USB bus and internal Li-ion) requiring glitch-free switchover during cable disconnect. IC Role / Device Role / Timing Role: PowerPath™ controller providing sub-5μs ideal diode transition from USB to battery, maintaining 5V rail stability during hot-plug events. Use Value: Internal 215mΩ ideal diode eliminates need for external Schottky, saving 3.2mm² PCB area and reducing BOM cost by $0.18/unit. |
| Industrial Data Loggers | Wearable Health Trackers |
|
Use Scenario: Remote environmental sensor logging temperature/humidity every 10 seconds in unventilated enclosures reaching 70°C. IC Role / Device Role / Timing Role: Temperature-aware charger enforcing NTC-based thermal cutoff and reduced float voltage to prevent electrolyte decomposition. Use Value: Hot-threshold detection at 32.6% × VVNTC ensures charging halts before cell reaches 45°C, avoiding permanent capacity loss in high-ambient deployments. |
Use Scenario: Fitness band with 120mAh Li-polymer battery, charged daily via micro-USB, requiring minimal standby current during sleep mode. IC Role / Device Role / Timing Role: Ultra-low-quiescent-power USB manager drawing only 22μA in suspend mode while retaining battery monitoring and ideal diode readiness. Use Value: 22μA battery drain in SUSP=5V mode extends shelf life to >18 months, meeting OEM requirements for pre-shipped consumer devices. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar USB power management and Li-ion charging applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC4085EDE-4#TRPBF | Same 3.95V float and NTC thresholds, but lacks automatic output undervoltage current limit (no VOUT-sense feedback for IBAT reduction). | Suitable for fixed-load systems where VOUT droop is not expected; unsuitable for dynamic loads prone to brownout. | Select LTC4085EDE-4#TRPBF only when load regulation is stable and undervoltage protection is handled externally. |
| BQ24075RGTR | 4.2V float, no ideal diode, no NTC interface, 1.5A max charge current; uses different PROG resistor scaling (1000V/RPROG). | Targeted at cost-sensitive consumer electronics; lacks thermal safety features and seamless PowerPath™ arbitration. | Choose BQ24075RGTR for non-temperature-critical applications with simpler power architectures and lower BOM cost targets. |
Compared with LTC4085EDE-4#TRPBF, the LTC4085EDE-3#TRPBF adds critical undervoltage current limiting to prevent system reset during transient load spikes, while BQ24075RGTR trades off safety and power-path intelligence for higher peak charge current and lower unit cost-making it viable only in thermally benign, statically loaded environments.
Availability
LTC4085EDE-3#TRPBF is available at Aetrix Electronics and suitable for portable medical monitors, handheld test equipment, and industrial data loggers requiring stable component supply, long-term lifecycle support, and guaranteed performance across –40°C to 85°C.
Supply support for LTC4085EDE-3#TRPBF 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 legacy of high-performance analog ICs for precision power, signal conditioning, and timing applications.
The LTC4085 product line was designed specifically for USB-powered portable systems needing intelligent power-path arbitration, battery longevity optimization, and robust thermal management-addressing design challenges in medical, industrial, and ruggedized consumer electronics.
FAQ
What is the primary function of the LTC4085EDE-3#TRPBF in a USB-powered system?
The LTC4085EDE-3#TRPBF serves as a USB power manager and Li-ion charger that arbitrates between USB VBUS, wall adapter, and battery sources while enforcing strict input current limits. It ensures compliant USB operation (≤100mA/500mA), delivers regulated 3.95V float charging, and enables seamless power switchover via its internal ideal diode-making the LTC4085EDE-3#TRPBF essential for portable devices requiring both runtime extension and safe, long-life battery management.
How does the LTC4085EDE-3#TRPBF handle thermal regulation during charging?
The LTC4085EDE-3#TRPBF incorporates a dedicated thermal regulation circuit that activates at 105°C junction temperature (TLIM), linearly reducing charge current to prevent overheating. This feature operates independently of ambient temperature sensors and maintains safe operation even in sealed enclosures. The LTC4085EDE-3#TRPBF also uses its 3.95V float voltage to minimize heat-generating side reactions during constant-voltage phase-ensuring reliable performance without external thermal management components.
Can the LTC4085EDE-3#TRPBF be used without an NTC thermistor?
Yes-the LTC4085EDE-3#TRPBF can operate without an NTC thermistor by grounding the NTC pin, which disables temperature monitoring and allows charging across the full voltage range. However, this removes critical overtemperature protection for the battery. For applications requiring safety certification (e.g., IEC 62368-1), the NTC interface must be implemented using a precision thermistor network referenced to the VNTC pin. The LTC4085EDE-3#TRPBF's NTC circuit is integral to its thermal safety architecture.
What distinguishes the LTC4085EDE-3#TRPBF from the LTC4085EDE-4#TRPBF?
The LTC4085EDE-3#TRPBF includes automatic output undervoltage current limiting, which reduces battery charge current when VOUT falls below ~4.45V to prevent system brownout. The LTC4085EDE-4#TRPBF omits this feature while sharing identical 3.95V float voltage, NTC thresholds, and PowerPath™ functionality. Therefore, the LTC4085EDE-3#TRPBF is required for dynamically loaded systems, whereas the LTC4085EDE-4#TRPBF suits fixed-load applications where VOUT remains stable.
What is the recommended layout practice for the exposed thermal pad on the LTC4085EDE-3#TRPBF DFN package?
The exposed thermal pad (Pin 15) of the LTC4085EDE-3#TRPBF must be soldered directly to a solid copper GND plane using ≥4 thermal vias (0.3mm diameter) spaced evenly beneath the pad. This achieves the specified 43°C/W θJA and prevents junction temperature exceedance during 1.2A charging. Floating or undersized pads cause thermal throttling and premature timer expiration. The LTC4085EDE-3#TRPBF's performance and reliability depend critically on proper thermal pad implementation per Linear Technology AN133 guidelines.
LTC4085EDE-3#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PowerPath™
- Package/Case:
- 14-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Battery Chemistry:
- Lithium Ion/Polymer
- Number of Cells:
- 1
- Current - Charging:
- Constant - Programmable
- Programmable Features:
- -
- Fault Protection:
- -
- Charge Current - Max:
- 1.5A
- Battery Pack Voltage:
- 3.95V
- Voltage - Supply (Max):
- 5.5V
- Interface:
- USB
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-DFN (4x3)
LTC4085EDE-3#TRPBF FAQ
1.How can I place an order for LTC4085EDE-3#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC4085EDE-3#TRPBF 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 LTC4085EDE-3#TRPBF reliable?
The price and inventory of LTC4085EDE-3#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC4085EDE-3#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC4085EDE-3#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC4085EDE-3#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC4085EDE-3#TRPBF?
LTC4085EDE-3#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC4085EDE-3#TRPBF 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 LTC4085EDE-3#TRPBF?
For technical support, including LTC4085EDE-3#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC4085EDE-3#TRPBF requirements.
6.How does Aetrix verify that LTC4085EDE-3#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC4085EDE-3#TRPBF 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 LTC4085EDE-3#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC4085EDE-3#TRPBF?
All LTC4085EDE-3#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC4085EDE-3#TRPBF, 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 LTC4085EDE-3#TRPBF part is unused and in its original packaging.
Return procedure for LTC4085EDE-3#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LTC4085EDE-3#TRPBF Tags
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