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Analog Devices Inc. LTC4121EUD-4.2#TRPBF
- Part No.:
- LTC4121EUD-4.2#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Battery Chargers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LTC4121EUD-4.2#TRPBF.pdf
- Description:
- IC BATT CHG LI-ION 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,860
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Product details
Overview
LTC4121EUD-4.2#TRPBF from Analog Devices (formerly Linear Technology) is a 400mA synchronous step-down Li-Ion/Polymer battery charger IC with fixed 4.2V float voltage, MPPT input regulation, and NTC temperature qualification. It operates from 4.4V to 40V input, delivers up to 95% efficiency, and integrates safety timer termination, auto-recharge, and bad battery fault detection for solar-powered and industrial sensor applications.
For engineers reviewing the LTC4121EUD-4.2#TRPBF datasheet, LTC4121EUD-4.2#TRPBF pinout, LTC4121EUD-4.2#TRPBF application, or LTC4121EUD-4.2#TRPBF equivalent, key selection criteria include its fixed 4.2V float voltage accuracy (±1%), programmable 50–400mA charge current via PROG resistor, integrated MPPT algorithm for solar panel optimization, and thermally enhanced 3mm × 3mm QFN package with exposed thermal pad.
Technical Context
The LTC4121EUD-4.2#TRPBF implements a constant-current/constant-voltage charging profile with precise 4.200V ±0.012V float regulation and ±1% feedback accuracy. Its MPPT function samples open-circuit input voltage every 28 seconds, compares it against a user-programmed fraction (via MPPT pin resistive divider), and dynamically reduces charge current to maintain input voltage at the peak power point - critical for high-impedance sources like solar panels.
It features dual-stage low-battery preconditioning: linear trickle charge (6–16mA) below 2.21V battery threshold, followed by switch-mode trickle charge until reaching 2.91V, then full CC/CV charging. Fault handling includes dedicated FAULT pin assertion for NTC over/under-temperature and bad battery conditions, plus CHRG pin end-of-charge signaling and 2-hour safety timer.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Float Voltage | Fixed 4.200V ±0.012V - ensures safe, accurate full-charge termination for single-cell Li-Ion batteries without external feedback resistors. |
| Charge Current Range | 50mA to 400mA - set by single PROG resistor (3.01kΩ = 400mA); enables flexible battery capacity matching and thermal management. |
| Input Voltage Range | 4.4V to 40V - supports wide-range energy harvesting sources including 12V/24V industrial rails and solar panels with VOC up to 40V. |
| MPPT Sampling Interval | 28s pause period with 36ms sampling window - allows reliable open-circuit voltage capture without disrupting battery charging continuity. |
| Efficiency | Up to 95% at 200mA - achieved via synchronous buck topology with 0.8Ω top/0.5Ω bottom MOSFETs, minimizing conduction losses in portable systems. |
| Operating Temp Range | –40°C to +125°C junction - validated for harsh environments including automotive under-hood and industrial outdoor sensor nodes. |
| Package | 16-lead 3mm × 3mm QFN with exposed thermal pad - provides low θJA (54°C/W) for sustained high-current operation without external heatsinking. |
Pinout & Package
16-lead (3mm × 3mm) plastic QFN package with exposed thermal pad (Pin 17) soldered to PCB ground for optimal thermal and electrical performance. Pin pitch: 0.5mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| INTVCC (1) | Internal LDO output | Supplies gate drivers and ILOWBAT; requires 2.2µF decoupling; must not drive external loads beyond NTC bias network. |
| BOOST (2) | Bootstrap supply | Connects 22nF capacitor to SW to enable high-side MOSFET drive; critical for efficient synchronous rectification. |
| IN (3) | Main power input | Accepts 4.4–40V; requires ≥10µF low-ESR input capacitor; forms RC network with MPPT divider for stable open-circuit sampling. |
| SW (4) | Switch node | Drives external inductor; connects to CHGSNS; body diode conducts IN-to-BAT path when no input present. |
| GND (5,17) | Power and signal ground | Exposed pad (Pin 17) must be soldered to PCB GND plane for thermal dissipation and low-noise reference. |
| MPPT (6) | MPPT control input | Programs input voltage regulation point via resistive divider; sampled every 28s to track solar panel VOC drift. |
| FREQ (7) | Switching frequency select | Ground = 750kHz (lower EMI), INTVCC = 1.5MHz (smaller inductor size); not floating. |
| CHGSNS (8) | Current sense input | Monitors charge current via internal 300mΩ sense resistor between CHGSNS and BAT; enables accurate CC regulation. |
| BAT (9) | Battery output | Delivers charge current; requires 22µF low-ESR ceramic capacitor; sources 6–16mA linear precharge below 2.21V. |
| BATSNS (10) | Battery voltage sense | Direct connection to battery anode required; enables precise 4.2V regulation independent of trace resistance. |
| PROG (13) | Charge current programming | 1.227V servo voltage; ICHG = 988 × VPROG / RPROG - enables accurate current setting with standard 1% resistors. |
| CHRG (14) | Charge status indicator | Open-drain output pulled low during charging; high-impedance at end-of-charge (timer or C/10 threshold). |
| FAULT (15) | Fault status indicator | Open-drain output pulled low on NTC fault (hot/cold) or bad battery detection; remains high-impedance otherwise. |
| RUN (16) | Enable/shutdown control | 2.45V enable threshold with 200mV hysteresis; ties to VIN divider to set input UVLO activation point. |
Key Features
| Feature | Design Value |
|---|---|
| MPPT Input Regulation | Maintains input voltage at user-defined % of open-circuit voltage (e.g., 80% VOC) to maximize power extraction from solar panels without external controllers. |
| NTC Temperature Qualification | Monitors battery temperature via thermistor; pauses charging outside 0°C–45°C range and asserts FAULT pin - eliminates need for external thermal management logic. |
| Auto-Recharge Threshold | Triggers new charge cycle when battery voltage drops 2.2% below float voltage (≈93.8mV for 4.2V), preventing deep discharge in intermittently powered systems. |
| Bad Battery Detection | Terminates charging after 30-minute timeout if battery fails to reach 2.91V during preconditioning - protects against shorted or degraded cells. |
| Safety Timer Termination | Hard cutoff after 1.3–2.8 hours of continuous charging - prevents overcharge in case of failed voltage regulation or sensor fault. |
Applications
| Solar-Powered Remote Sensors | Industrial Handheld Instruments |
|---|---|
Use Scenario: Wireless environmental sensors deployed in off-grid locations powered by small solar panels with variable irradiance. IC Role / Device Role / Timing Role: LTC4121EUD-4.2#TRPBF acts as the sole power management IC, performing MPPT-regulated charging of a 3.7V Li-Ion cell while maintaining system uptime during cloud cover. Use Value: Delivers up to 95% conversion efficiency and extends battery runtime by 30–40% compared to non-MPPT chargers under partial shading conditions. | Use Scenario: Ruggedized handheld test equipment used in factory floors with intermittent AC power and backup battery operation. IC Role / Device Role / Timing Role: LTC4121EUD-4.2#TRPBF manages fast recharging from 12–24V DC inputs while enforcing strict 4.2V termination and thermal safety limits. Use Value: Enables <2-hour recharge time for 2000mAh batteries with built-in NTC qualification, eliminating risk of field failures due to battery overheating. |
| Medical Wearables | Military Portable Radios |
Use Scenario: Compact wearable health monitors requiring long battery life and reliable charging from USB or proprietary adapters. IC Role / Device Role / Timing Role: LTC4121EUD-4.2#TRPBF provides precise 4.2V Li-Ion charging with ultra-low sleep current (60–110µA) to minimize standby drain. Use Value: Achieves ≤1% float voltage error and <1000nA shutdown current, extending shelf life and reducing annual battery self-discharge by >50%. | Use Scenario: Tactical radios operating in extreme temperatures (-40°C to +70°C ambient) with solar or vehicle battery charging. IC Role / Device Role / Timing Role: LTC4121EUD-4.2#TRPBF executes cold-temperature preconditioning (linear charge down to -20°C) and hot-fault shutdown above +45°C. Use Value: Guarantees safe charging across full military temperature range without external thermal compensation circuitry. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Li-Ion battery charging applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BQ24610RTWR | Adjustable float voltage (4.0–14.4V), no integrated MPPT, requires external sense resistor for current programming. | Lacks autonomous solar optimization; suited for fixed-input industrial chargers where MPPT is unnecessary. | Select BQ24610RTWR when float voltage flexibility and cost sensitivity outweigh MPPT requirement. |
| MAX17599ATP+T | Wide-input buck controller (4.5–60V), no integrated battery management; requires external CC/CV loop and NTC interface. | Demands full custom design for charging functionality; lacks FAULT/CHRG status pins and safety timers. | Select MAX17599ATP+T only for high-voltage (>40V) or multi-cell applications where monolithic integration is secondary to input range. |
Compared with BQ24610RTWR and MAX17599ATP+T, the LTC4121EUD-4.2#TRPBF offers unique integration of MPPT, fixed-precision 4.2V regulation, and complete thermal/fault protection in a single 3mm × 3mm package - reducing BOM count by 7+ components and eliminating firmware dependency for solar charging.
Availability
LTC4121EUD-4.2#TRPBF is available at Aetrix Electronics and suitable for solar-powered devices, industrial handheld instruments, and medical wearables requiring stable component supply, long-term lifecycle support, and guaranteed parametric compliance.
Supply support for LTC4121EUD-4.2#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision instrumentation, industrial automation, and aerospace markets.
The LTC4121 product line was designed specifically for energy-constrained, wide-input battery charging applications - emphasizing MPPT efficiency, robust fault handling, and minimal external component count in compact QFN packages.
FAQ
What is the exact float voltage tolerance of the LTC4121EUD-4.2#TRPBF?
The LTC4121EUD-4.2#TRPBF has a guaranteed float voltage of 4.200V ±0.012V (±0.286%) over temperature, measured as VFLOAT = 4.188V (min) to 4.212V (max) at TJ = –40°C to +125°C. This tight tolerance ensures consistent Li-Ion cell termination without external calibration, directly supporting JEITA-compliant charging profiles.
How does the MPPT function operate in the LTC4121EUD-4.2#TRPBF?
The LTC4121EUD-4.2#TRPBF performs MPPT by pausing charging every 28 seconds for 36ms to measure open-circuit input voltage, storing it on an internal DAC. During normal operation, it compares the MPPT pin voltage (set by external resistor divider) against 10% of the stored VOC. If MPPT voltage falls below that level, charge current is reduced to regulate input voltage - optimizing power harvest from solar panels and other high-impedance sources.
Can the LTC4121EUD-4.2#TRPBF charge batteries below 0°C?
Yes - the LTC4121EUD-4.2#TRPBF supports cold-temperature charging via NTC qualification. When battery temperature drops below 0°C (detected by thermistor on NTC pin), it enters STANDBY mode and applies linear preconditioning current (6–16mA) until voltage reaches 2.91V, then resumes full charging. This prevents lithium plating and ensures safe low-temperature operation without external thermal management.
What is the minimum input voltage required for the LTC4121EUD-4.2#TRPBF to initiate charging?
The LTC4121EUD-4.2#TRPBF requires VIN ≥ 4.4V or VIN ≥ (VBAT + 160mV), whichever is greater, to enable charging. For a fully discharged 3.0V battery, minimum VIN is 3.16V - but the absolute minimum specified operating input is 4.4V. Below this, the device remains in undervoltage lockout regardless of RUN pin state.
Does the LTC4121EUD-4.2#TRPBF require external components for basic operation?
Yes - the LTC4121EUD-4.2#TRPBF requires seven essential external components: input capacitor (≥10µF), output capacitor (22µF), boost capacitor (22nF), inductor (e.g., 47µH), PROG resistor (e.g., 3.01kΩ), MPPT divider (two resistors), and NTC thermistor network. No external sense resistor is needed as current sensing is integrated between CHGSNS and BAT pins.
LTC4121EUD-4.2#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Battery Chemistry:
- Lithium Ion/Polymer
- Number of Cells:
- -
- Current - Charging:
- Constant - Programmable
- Programmable Features:
- -
- Fault Protection:
- -
- Charge Current - Max:
- 400mA
- Battery Pack Voltage:
- 4.2V
- Voltage - Supply (Max):
- 40V
- Interface:
- -
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QFN (3x3)
LTC4121EUD-4.2#TRPBF FAQ
1.How can I place an order for LTC4121EUD-4.2#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC4121EUD-4.2#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 LTC4121EUD-4.2#TRPBF reliable?
The price and inventory of LTC4121EUD-4.2#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC4121EUD-4.2#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC4121EUD-4.2#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC4121EUD-4.2#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC4121EUD-4.2#TRPBF?
LTC4121EUD-4.2#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC4121EUD-4.2#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 LTC4121EUD-4.2#TRPBF?
For technical support, including LTC4121EUD-4.2#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC4121EUD-4.2#TRPBF requirements.
6.How does Aetrix verify that LTC4121EUD-4.2#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC4121EUD-4.2#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 LTC4121EUD-4.2#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC4121EUD-4.2#TRPBF?
All LTC4121EUD-4.2#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC4121EUD-4.2#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 LTC4121EUD-4.2#TRPBF part is unused and in its original packaging.
Return procedure for LTC4121EUD-4.2#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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