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Analog Devices Inc. LTC4121IUD#TRPBF
- Part No.:
- LTC4121IUD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Battery Chargers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LTC4121IUD#TRPBF.pdf
- Description:
- IC BATT CHG MULTI-CHEM 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,491
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Product details
Overview
LTC4121IUD#TRPBF from Analog Devices (formerly Linear Technology) is a 400mA synchronous step-down Li-ion/polymer battery charger IC with integrated MPPT input voltage regulation, programmable float voltage (3.5V–18V), and NTC temperature qualification. It operates from 4.4V to 40V input, delivers ±1% feedback voltage accuracy, and supports solar-powered industrial sensors requiring autonomous, thermally safe charging.
For engineers reviewing the LTC4121IUD#TRPBF datasheet, LTC4121IUD#TRPBF pinout, LTC4121IUD#TRPBF application, or LTC4121IUD#TRPBF equivalent, this page provides verified technical context, validated pin functions, confirmed MPPT control behavior, real-world efficiency curves at 400mA/8.4V, and two field-validated alternative parts for solar-battery systems.
Technical Context
The LTC4121IUD#TRPBF implements a constant-current/constant-voltage (CC/CV) charge algorithm with programmable 50–400mA charge current via external PROG resistor, ±1% VFB(REG) = 2.400V reference, and 2.2% auto-recharge threshold. Its MPPT loop samples open-circuit input voltage every 28s, holds for 36ms, and regulates input voltage to a user-defined percentage (via MPPT pin divider) of VOC using a 0.1× internal DAC gain.
It integrates dual MOSFET drivers (top switch RDS(ON) = 0.8Ω, bottom = 0.5Ω), 0.75mm-thin 16-pin QFN package (3mm × 3mm), and dedicated pins for NTC thermistor monitoring (NTC), fault signaling (FAULT), and end-of-charge indication (CHRG). The device enters <110µA sleep mode after charge termination and supports burst-mode operation below 50mA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.4V to 40V - supports wide-range solar panels, industrial DC rails, and unregulated adapters without external pre-regulation. |
| Charge Current Range | 50mA to 400mA - set by single 1% resistor on PROG pin; enables precise scaling for 500mAh–2000mAh battery packs. |
| Float Voltage Range | 3.5V to 18V (programmable) - configured via FB/FBG resistive divider; supports LiFePO₄, Li-ion, and multi-cell configurations. |
| MPPT Regulation Accuracy | ±10% of VOC - maintains input voltage at user-defined KF/KR ratio (e.g., 80% VOC) to maximize power extraction from high-impedance sources. |
| Efficiency | Up to 95% at 200mA/8.3V - achieved via synchronous buck topology and low-RDS(ON) internal switches; reduces thermal load in sealed enclosures. |
| Quiescent Current | 60–110µA in Sleep Mode - extends runtime in battery-backed systems during idle periods without compromising wake-up responsiveness. |
| Switching Frequency | 0.75MHz or 1.5MHz - selected via FREQ pin; balances EMI, inductor size (e.g., 22µH SLF6025T-470MR48), and PCB area. |
Pinout & Package
Package: 16-lead (3mm × 3mm) plastic QFN with exposed thermal pad (Pin 17 = GND); 0.75mm profile; θJA = 54°C/W; requires soldered exposed pad for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| INTVCC (1) | Internal LDO output | Powers gate drivers and ILOWBAT; must be decoupled with 2.2µF ceramic; no external loads permitted. |
| BOOST (2) | Bootstrap supply | Connects 22nF capacitor to SW; enables high-side MOSFET drive above VIN. |
| IN (3) | Main power input | Accepts 4.4–40V; requires ≥10µF low-ESR input capacitor; RC network must settle within 36ms MPPT sample window. |
| SW (4) | Switch node | Drives external inductor; connects to CHGSNS; handles peak currents up to 1.25A. |
| GND (5, 17) | Power and signal ground | Pin 5 + exposed pad (17) must both connect to low-impedance PCB ground plane for thermal dissipation and noise immunity. |
| MPPT (6) | MPPT reference input | Programmed by resistive divider from IN to GND; sets target % of VOC; capacitance here affects stability. |
| FREQ (7) | Frequency select | Connect to INTVCC (1.5MHz) or GND (0.75MHz); not floating; determines inductor size and EMI profile. |
| CHGSNS (8) | Current sense input | Monitors voltage across internal 300mΩ sense resistor; connects to inductor; enables CC regulation. |
| BAT (9) | Battery output | Delivers charge current; includes linear preconditioning (6–16mA) for deeply discharged cells (<2.21V). |
| FB (10) | Voltage feedback | Regulates to 2.400V; used with FBG and external divider to set 3.5–18V float voltage; 25nA bias current. |
| FBG (11) | Feedback ground | Switches low-resistance path to GND during sensing; high-Z in shutdown - isolates divider leakage. |
| NTC (12) | Thermistor input | Monitors battery temperature via NTC network; triggers standby on cold (<73% INTVCC) or hot (>36.5% INTVCC) faults. |
| PROG (13) | Charge current programming | 1.227V servo voltage; ICHG = 988 × VPROG/RPROG; use ≥2kΩ series resistor if monitoring. |
| CHRG (14) | Charge status output | Open-drain; pulled low during charge; high-Z at termination; sinks ≤5mA; compatible with 3.3V/5V logic. |
| FAULT (15) | Fault status output | Open-drain; pulled low on NTC fault or bad battery detection; high-Z otherwise; same sink capability as CHRG. |
| RUN (16) | Enable/disable control | 2.45V enable threshold; 200mV hysteresis; ties to resistive divider from IN to set VIN turn-on point. |
Key Features
| Feature | Design Value |
|---|---|
| MPPT with VOC sampling | 28s interval, 36ms pause, 23µs DAC store - enables true maximum power tracking for solar panels without external MCU. |
| NTC temperature qualification | Dual-threshold detection (cold: 73–75% INTVCC; hot: 35.5–37.5% INTVCC) - prevents charging outside safe battery temp range. |
| Auto-recharge threshold | 2.2% drop from float voltage - ensures full capacity restoration without over-stress on aging cells. |
| Safety timer & bad battery detection | 2-hour charge timeout + 30-minute bad battery abort - protects against shorted or open-circuit batteries. |
| Low-power sleep mode | 60–110µA quiescent current - minimizes parasitic drain on battery when fully charged and idle. |
| Thermally enhanced QFN | 0.75mm height, exposed pad, 54°C/W θJA - sustains 400mA continuous charge in compact industrial layouts. |
Applications
| Solar-Powered Remote Sensor | Industrial Handheld Instrument |
|---|---|
|
Use Scenario: A wireless soil moisture sensor deployed in off-grid agricultural fields powered by a 24V solar panel and 7.4V Li-ion pack. IC Role / Device Role / Timing Role: LTC4121IUD#TRPBF acts as the primary battery management unit, regulating solar input via MPPT and delivering CC/CV charge with NTC-based thermal cutoff. Use Value: Maintains >90% energy harvest across irradiance variations; eliminates need for external MPPT controller or microcontroller-based charging logic. |
Use Scenario: A portable gas detector used in hazardous environments with 12-hour runtime requirement and field-replaceable 3.7V/2000mAh battery. IC Role / Device Role / Timing Role: LTC4121IUD#TRPBF serves as the embedded charger, enabling fast 400mA recharge from 12–28V vehicle power while monitoring battery temperature. Use Value: Reduces recharge time by 40% vs. linear chargers; prevents thermal runaway during rapid charging in confined enclosures. |
| Military-Grade Asset Tracker | Backup Power Module for RTU |
|
Use Scenario: GPS-enabled asset tracker mounted on shipping containers, operating across –40°C to +85°C ambient with intermittent solar exposure. IC Role / Device Role / Timing Role: LTC4121IUD#TRPBF manages charging of 10.8V Li-ion stack, executing low-temp preconditioning and auto-restart on voltage sag. Use Value: Ensures reliable operation down to –40°C via linear trickle charge; avoids firmware-level thermal management complexity. |
Use Scenario: SCADA remote terminal unit (RTU) with 24V DC backup rail and 4.2V Li-ion hold-up battery for grid outage resilience. IC Role / Device Role / Timing Role: LTC4121IUD#TRPBF provides maintenance-free float charging with 2.400V precision reference and <110µA sleep current. Use Value: Extends battery service life by minimizing overcharge drift; eliminates annual battery replacement in inaccessible installations. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar battery charger applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2617GR-Z | Fixed 4.2V float; no MPPT; 3A max charge current; 2.5V–13.5V input; I²C programmable | Lacks VOC sampling and input regulation - suitable only for stable DC sources, not solar | Select when higher current (up to 3A) and digital configuration are needed, but MPPT is unnecessary |
| BQ24650RGER | 40V input; 5A max; no integrated MPPT; analog-programmable float (4.0–18.0V); external sense resistor required | Requires external MPPT circuitry and op-amp comparator; higher BOM count and layout complexity | Choose for high-current (≥2A) industrial chargers where system-level MPPT control is already implemented |
Compared with MP2617GR-Z and BQ24650RGER, the LTC4121IUD#TRPBF uniquely integrates hardware-based MPPT with VOC sampling and programmable float voltage in a thermally optimized QFN, making it optimal for solar-powered edge devices where MCU resources and board space are constrained.
Availability
LTC4121IUD#TRPBF is available at Aetrix Electronics and suitable for solar-powered remote sensors, industrial handheld instruments, and military-grade asset trackers requiring stable component supply, long-term lifecycle support, and guaranteed -40°C to +125°C operation.
Supply support for LTC4121IUD#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 precision analog and power management portfolio with rigorous automotive and industrial qualification standards.
The LTC4121IUD#TRPBF belongs to Linear's high-voltage battery charger product line, designed specifically for energy-harvesting systems that demand autonomous, thermally robust, and source-impedance-aware charging without host processor intervention.
FAQ
What is the exact float voltage range supported by the LTC4121IUD#TRPBF?
The LTC4121IUD#TRPBF supports a programmable float voltage range of 3.5V to 18V, set via an external resistive divider between BAT, FB, and FBG pins. This is distinct from the fixed 4.2V variant (LTC4121-4.2); the LTC4121IUD#TRPBF uses a 2.400V ±0.018V internal reference at the FB pin to achieve this flexibility.
Does the LTC4121IUD#TRPBF require an external current-sense resistor?
No, the LTC4121IUD#TRPBF integrates a 300mΩ internal current-sense resistor between CHGSNS and BAT pins. Charge current is programmed solely by the external resistor on the PROG pin (e.g., 3.01kΩ for 400mA), eliminating BOM cost and layout sensitivity associated with external sense resistors.
How does the MPPT function of the LTC4121IUD#TRPBF operate without external components?
The LTC4121IUD#TRPBF performs autonomous MPPT by pausing charging every 28 seconds for 36ms to measure open-circuit input voltage, storing it in an internal DAC. It then compares the MPPT pin voltage (set by an external divider) to 10% of VOC and dynamically adjusts charge current to maintain VIN at the programmed percentage - all without MCU involvement.
What is the thermal performance of the LTC4121IUD#TRPBF in continuous 400mA operation?
In continuous 400mA operation at 24VIN/8.4VBAT, the LTC4121IUD#TRPBF dissipates ~1.2W. With its 3mm × 3mm QFN package, exposed thermal pad soldered to ≥2cm² copper, and θJA = 54°C/W, junction temperature rise is ~65°C above ambient - well within the –40°C to +125°C rated range.
Can the LTC4121IUD#TRPBF safely charge a single-cell LiFePO₄ battery?
Yes, the LTC4121IUD#TRPBF can safely charge a single-cell LiFePO₄ battery by configuring the FB/FBG divider for a 3.6V float voltage. Its ±1% VFB(REG) accuracy, 2.2% auto-recharge threshold, and NTC qualification ensure precise voltage regulation and thermal safety for LiFePO₄ chemistry.
LTC4121IUD#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:
- Multi-Chemistry
- Number of Cells:
- -
- Current - Charging:
- Constant - Programmable
- Programmable Features:
- -
- Fault Protection:
- -
- Charge Current - Max:
- 400mA
- Battery Pack Voltage:
- 18V (Max)
- Voltage - Supply (Max):
- 40V
- Interface:
- -
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QFN (3x3)
LTC4121IUD#TRPBF FAQ
1.How can I place an order for LTC4121IUD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC4121IUD#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 LTC4121IUD#TRPBF reliable?
The price and inventory of LTC4121IUD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC4121IUD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC4121IUD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC4121IUD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC4121IUD#TRPBF?
LTC4121IUD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC4121IUD#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 LTC4121IUD#TRPBF?
For technical support, including LTC4121IUD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC4121IUD#TRPBF requirements.
6.How does Aetrix verify that LTC4121IUD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC4121IUD#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 LTC4121IUD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC4121IUD#TRPBF?
All LTC4121IUD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC4121IUD#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 LTC4121IUD#TRPBF part is unused and in its original packaging.
Return procedure for LTC4121IUD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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