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Analog Devices Inc. LTC4121EUD#TRPBF
- Part No.:
- LTC4121EUD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Battery Chargers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LTC4121EUD#TRPBF.pdf
- Description:
- IC BATT CHG MULTI-CHEM 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,600
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Product details
Overview
LTC4121EUD#TRPBF from Analog Devices (formerly Linear Technology) is a 400mA synchronous step-down Li-ion/polymer battery charger IC with integrated MPPT control, programmable float voltage (3.5V–18V), ±1% feedback voltage accuracy, and 4.4V–40V wide input range. It regulates input voltage to maintain maximum power transfer from high-impedance sources such as solar panels and supports NTC temperature-qualified charging in handheld instruments and industrial sensors.
For engineers reviewing the LTC4121EUD#TRPBF datasheet, LTC4121EUD#TRPBF pinout, LTC4121EUD#TRPBF application, or LTC4121EUD#TRPBF equivalent, key selection criteria include its 16-pin 3mm×3mm QFN package, 95% peak efficiency, 2.400V ±0.007V internal reference, 1.5MHz/0.75MHz selectable switching frequency, and support for both programmable and fixed-voltage variants within the same footprint.
Technical Context
The LTC4121EUD#TRPBF implements a synchronous buck topology with dual-loop control: a primary CC/CV battery regulation loop and an auxiliary MPPT loop that samples open-circuit input voltage every ~28 seconds and adjusts charge current to hold VIN at a user-defined percentage (e.g., 90%) of VOC. Its internal 2.400V reference feeds a precision error amplifier driving PWM logic with 120ns minimum on-time and 94% max duty cycle.
It integrates thermally enhanced protection including low-battery preconditioning (2.21V threshold), trickle-charge mode (1.68V FB rising), bad-battery fault detection (30-minute timeout), and NTC monitoring with cold/hot thresholds referenced to INTVCC (74% and 36.5% respectively). The RUN pin enables precise input-voltage-based startup via external resistor divider.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.4V to 40V - supports direct connection to unregulated solar panels, 24V industrial rails, and automotive systems without pre-regulation. |
| Charge Current | 50mA to 400mA programmable via PROG pin resistor - enables scalable design across battery capacities from 200mAh to 2000mAh. |
| Float Voltage | Programmable 3.5V–18V (LTC4121 variant) - allows single-chip compatibility with LiFePO₄ (3.6V), Li-ion (4.2V), and multi-cell configurations. |
| Feedback Accuracy | ±1% at VFB = 2.400V - ensures ±0.024V absolute voltage tolerance critical for cell longevity and safety compliance. |
| MPPT Regulation | Adjusts charge current to maintain VIN ≥ 90% of VOC - delivers up to 30% more energy harvest under partial shading or low-light conditions. |
| Switching Frequency | Selectable 0.75MHz or 1.5MHz via FREQ pin - balances inductor size (SLF6025T-470MR48 typical) against EMI and efficiency trade-offs. |
| Thermal Shutdown | 125°C junction limit with 54°C/W θJA - requires exposed pad soldering to PCB ground plane for reliable operation at full load. |
Pinout & Package
Package: 16-lead (3mm × 3mm) plastic QFN with exposed thermal pad (Pin 17 = GND). Requires soldering of exposed pad to PCB ground for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| INTVCC (1) | Internal LDO output | Powers gate drivers and low-battery linear charge circuit; must be decoupled with 2.2µF ceramic capacitor; no external loading permitted. |
| 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 4.4V–40V; requires ≥10µF low-ESR input capacitance to stabilize MPPT sampling during 36ms open-circuit measurement. |
| SW (4) | Switch node | Drives external inductor (e.g., SLF6025T-470MR48); connects to CHGSNS; carries pulsed current up to 1.25A peak. |
| GND (5,17) | Power and thermal ground | Pin 5 and exposed pad (17) must connect to common PCB ground plane; exposed pad essential for thermal dissipation. |
| MPPT (6) | MPPT reference input | Accepts resistive divider from IN to set % of VOC where regulation engages; parasitic capacitance must be minimized to avoid loop instability. |
| FREQ (7) | Frequency select | Logic-level input: tie to INTVCC for 1.5MHz (smaller inductors), GND for 0.75MHz (lower EMI and higher efficiency at light loads). |
| CHGSNS (8) | Current sense input | Monitors charge current via internal 300mΩ sense resistor between CHGSNS and BAT; sets ICHG accuracy and safety limits. |
| BAT (9) | Battery output | Delivers regulated charge current; requires 22µF low-ESR ceramic capacitor; supports linear precharge (6–16mA) below 2.21V. |
| FB (10) | Voltage feedback | Sets float voltage via resistive divider from BAT→FB→FBG; 25nA bias current compensated by 588kΩ Thevenin resistance. |
| FBG (11) | Feedback ground | Switches low-resistance path to GND during active regulation; high-impedance in shutdown to reduce battery leakage. |
| NTC (12) | Temperature monitor | Interfaces with NTC thermistor network (INTVCC→NTC→GND); triggers standby on cold (<74% INTVCC) or hot (>36.5% INTVCC) faults. |
| PROG (13) | Charge current programming | 1.227V servo voltage; ICHG = 988 × VPROG / RPROG - enables accurate current setting with standard 1% resistors (e.g., 3.01kΩ = 400mA). |
| CHRG (14) | Charge status output | Open-drain indicator: pulled low during active charge; high-impedance at end-of-charge (timer or C/10 termination). |
| FAULT (15) | Fault status output | Open-drain indicator: pulled low on NTC fault or bad-battery condition (VBAT < 2.15V after timeout); high-impedance otherwise. |
| RUN (16) | Enable control | 2.45V enable threshold with 200mV hysteresis; resistor divider from IN sets minimum input voltage for automatic startup. |
Key Features
| Feature | Design Value |
|---|---|
| MPPT with 28-second sampling interval | Maintains >90% of available source power under variable irradiance or partial shading without external microcontroller. |
| Programmable float voltage (3.5V–18V) | Enables single BOM for multiple battery chemistries (Li-ion, LiFePO₄, NiMH) and series configurations (1S–4S). |
| Integrated NTC temperature qualification | Eliminates need for external ADC or comparator; supports JEITA-compliant charging profiles with cold/hot thresholds. |
| Low-quiescent sleep mode (60–110µA) | Extends battery life in always-on sensor nodes by reducing system standby current when battery is fully charged. |
| Auto-recharge at 2.2% voltage drop | Prevents battery self-discharge degradation by initiating new CC/CV cycle when VBAT falls below float voltage × 0.978. |
| Bad battery fault detection (30-min timeout) | Protects system from damaged cells by terminating charge if battery fails to reach 2.15V within 30 minutes. |
Applications
| Solar-Powered Remote Sensors | Industrial Handheld Instruments |
|---|---|
|
Use Scenario: Battery-powered environmental sensor node deployed in off-grid locations with intermittent solar input. IC Role / Device Role / Timing Role: Primary battery charger managing energy harvesting from 12V solar panel while regulating Li-ion pack voltage and preventing overcharge. Use Value: MPPT algorithm increases daily energy harvest by 22% under cloudy conditions; 40V input rating eliminates need for input overvoltage clamping. |
Use Scenario: Portable multimeter with rechargeable Li-ion battery and USB/solar dual-input charging capability. IC Role / Device Role / Timing Role: Synchronous buck charger providing fast 400mA CC/CV charge with automatic reconditioning for infrequently used devices. Use Value: Programmable float voltage supports both 3.7V single-cell and 7.4V two-cell packs; NTC qualification prevents charging in extreme ambient temperatures. |
| Military-Grade Asset Trackers | Smart Agriculture Edge Nodes |
|
Use Scenario: GPS-enabled asset tracker operating in wide temperature ranges (-40°C to +85°C) with solar-assisted battery maintenance. IC Role / Device Role / Timing Role: Robust battery management IC delivering reliable charge control despite thermal cycling and vibration-induced connector wear. Use Value: –40°C to 125°C operating range and 125°C thermal shutdown ensure field reliability; low 110µA sleep current extends 5-year deployment life. |
Use Scenario: Soil moisture and temperature node powered by small solar panel in remote fields with seasonal light variation. IC Role / Device Role / Timing Role: Energy-harvesting charger adapting charge current dynamically to match available solar power while maintaining battery health. Use Value: 28-second MPPT sampling and 36ms open-circuit measurement enable stable operation even with rapidly changing irradiance; 4.4V min input allows start-up at dawn. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar battery charger applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX77751BEFG+T | Single-cell 4.2V fixed-output; integrates USB OTG boost; lacks MPPT and programmable float voltage. | Targeted at USB-centric portable electronics; not suitable for solar or multi-chemistry use cases. | Choose MAX77751BEFG+T only when USB host functionality and space-constrained single-cell charging are primary requirements. |
| BQ24650RGER | External MOSFET controller (not integrated switch); supports up to 14.4V float; no MPPT or NTC integration. | Requires additional FETs, gate drivers, and thermal sensing circuitry; suited for high-power (>2A) industrial chargers. | Choose BQ24650RGER when designing custom high-current chargers with discrete power stages and flexible thermal management. |
Compared with MAX77751BEFG+T and BQ24650RGER, the LTC4121EUD#TRPBF uniquely combines integrated MPPT, programmable float voltage, and NTC qualification in a 3mm×3mm QFN-enabling compact, solar-optimized battery charging without external controllers or compensation networks.
Availability
LTC4121EUD#TRPBF is available at Aetrix Electronics and suitable for solar-powered devices, industrial handheld instruments, and military-grade asset trackers requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC4121EUD#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 high-performance analog IC portfolio, emphasizing precision power management, signal conditioning, and robust industrial interfaces.
The LTC4121EUD#TRPBF belongs to Linear's battery charger product line, designed specifically for energy-harvesting applications where input source impedance varies significantly-such as solar, thermoelectric, or piezoelectric generators.
FAQ
What is the maximum input voltage supported by the LTC4121EUD#TRPBF?
The LTC4121EUD#TRPBF supports an absolute maximum input voltage of 43V on the IN pin, with continuous operation specified from 4.4V to 40V. This wide range allows direct interface with unregulated 24V industrial rails, 36V solar arrays, and automotive systems without external pre-regulation circuitry. Operation above 40V risks exceeding the device's safe operating area and is not recommended for sustained use.
How does the MPPT function work in the LTC4121EUD#TRPBF?
The LTC4121EUD#TRPBF implements hardware-based MPPT by pausing charging every ~28 seconds for 36ms to measure open-circuit input voltage (VOC), storing it in an internal DAC, then comparing the real-time MPPT pin voltage against 10% of VOC. If the MPPT voltage drops below this threshold, the charger reduces charge current to regulate VIN at the programmed VMP level-maximizing power extraction without software or external components.
Can the LTC4121EUD#TRPBF charge batteries other than Li-ion?
Yes-the LTC4121EUD#TRPBF supports multiple chemistries via its programmable float voltage (3.5V–18V). With appropriate external resistor dividers on FB/FBG pins, it can safely charge LiFePO₄ (3.6V), LiMn₂O₄ (4.0V), and multi-cell Li-ion (e.g., 8.4V for 2S). The fixed-voltage LTC4121-4.2 variant is limited to single-cell Li-ion/polymer only.
What is the purpose of the FBG pin on the LTC4121EUD#TRPBF?
The FBG (Feedback Ground) pin on the LTC4121EUD#TRPBF provides a low-impedance return path for the FB voltage divider during active regulation, improving accuracy by minimizing bias current error. In shutdown or disabled modes, FBG becomes high-impedance to eliminate unnecessary battery drain through the divider network-reducing quiescent current by up to 1µA compared to fixed-ground solutions.
Does the LTC4121EUD#TRPBF require external MOSFETs for operation?
No-the LTC4121EUD#TRPBF integrates both high-side and low-side synchronous MOSFETs within the IC. It drives an external inductor directly from the SW pin and uses internal 300mΩ sensing between CHGSNS and BAT to regulate charge current. No external power switches, gate drivers, or current-sense amplifiers are required for basic operation.
LTC4121EUD#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)
LTC4121EUD#TRPBF FAQ
1.How can I place an order for LTC4121EUD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC4121EUD#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#TRPBF reliable?
The price and inventory of LTC4121EUD#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#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC4121EUD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC4121EUD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC4121EUD#TRPBF?
LTC4121EUD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC4121EUD#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#TRPBF?
For technical support, including LTC4121EUD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC4121EUD#TRPBF requirements.
6.How does Aetrix verify that LTC4121EUD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC4121EUD#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#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC4121EUD#TRPBF?
All LTC4121EUD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC4121EUD#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#TRPBF part is unused and in its original packaging.
Return procedure for LTC4121EUD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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