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Analog Devices Inc. LTC4425EDD#TRPBF
- Part No.:
- LTC4425EDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Management - Specialized
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LTC4425EDD#TRPBF.pdf
- Description:
- IC SUPERCAP CHRGR DIO/MON 12DFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,274
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Product details
Overview
LTC4425EDD#TRPBF from Analog Devices (formerly Linear Technology) is a linear supercapacitor charger with integrated ideal diode, active cell balancing, and V/I monitoring. It charges 2-cell series supercapacitor stacks from 2.7V–5.5V sources (Li-Ion, USB), delivers up to 2A peak charge current, maintains ≤50mΩ ideal diode on-resistance, and supports programmable 2.45V/2.7V per-cell voltage clamping for energy storage backup in portable instrumentation.
For engineers reviewing the LTC4425EDD#TRPBF datasheet, LTC4425EDD#TRPBF pinout, LTC4425EDD#TRPBF application, or LTC4425EDD#TRPBF equivalent, key selection criteria include its dual-mode charging (LDO vs. smart current-profile), real-time PROG-pin current monitoring, internal leakage balancing without external resistors, and thermal regulation at 105°C - all in a compact 3mm × 3mm DFN package.
Technical Context
The LTC4425EDD#TRPBF implements a constant-current/constant-voltage/constant-temperature charging architecture with two distinct operational modes: LDO mode (FB grounded) for fixed-output-voltage charging, and normal mode (FB tied to VIN) for VIN-tracking with adaptive current limiting based on VIN–VOUT differential. Its ideal diode controller maintains 15mV forward drop and shuts off instantly during reverse voltage conditions.
Internal circuitry includes a precision 1.2V bandgap reference, 1000× current-sense ratio between PROG and VOUT paths, dual shunt transistors for per-cell overvoltage protection, and an active VMID balancer that forces midpoint voltage to exactly VOUT/2 with ±1mA sourcing/sinking capability - eliminating need for external balancing networks.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 2.7V to 5.5V - supports direct connection to single-cell Li-Ion or USB 2.0/3.0 ports without input regulation. |
| Max Charge Current | 2A - programmable via PROG-to-GND resistor; enables rapid supercap stack pre-charge before high-power load engagement. |
| Ideal Diode RON | 50mΩ - minimizes conduction loss in high-peak/low-duty-cycle power delivery paths like PDA wake-up bursts. |
| Quiescent Current | 20µA - allows multi-year battery-backed operation in always-on monitoring equipment with supercap backup. |
| Cell Clamp Voltages | 2.45V or 2.7V - selectable via SEL pin; prevents electrolyte decomposition in 2.7V-rated supercaps while enabling higher energy density in 2.45V variants. |
| Thermal Regulation | 105°C - reduces charge current proactively to prevent PCB hotspots and ensure reliability in sealed industrial enclosures. |
| VMID Balancing Accuracy | ±20mV of VOUT/2 - corrects capacitor leakage mismatch without external components, extending stack lifetime beyond 100k cycles. |
Pinout & Package
Package: 12-lead 3mm × 3mm × 0.75mm plastic DFN (exposed pad = GND, must be soldered to PCB ground plane).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT (1,2) | Charger output / top of supercap stack | Delivers regulated charge current to stacked supercap anodes; connects directly to load or backup rail. |
| PROG (3) | Charge current programming & monitoring | Sets ICHG via RPROG; outputs 1V (LDO) or 0.1–1V (normal mode) proportional to actual charge current ×1000. |
| SEL (4) | Cell clamp voltage select | Logic low = 2.45V clamp; logic high = 2.7V clamp - configures maximum per-cell voltage before shunt activation. |
| FB (5) | Feedback for LDO mode / mode control | Grounded → LDO mode (programmable VOUT); tied to VIN → normal mode (VIN-tracking with inrush limiting). |
| EN (6) | Enable/disable control | High = active (20µA IQ); low = shutdown (<3µA) - enables system-level power sequencing and battery conservation. |
| PFI_RET (7) | Power-fail divider return | Internally grounded when EN = high; opens in shutdown to eliminate divider current drain from battery. |
| PFO (8) | Open-drain power-good/fail indicator | Pulled low if VIN < PFI threshold, VOUT not within 7.5% of target (LDO), or VOUT > VIN + 250mV (normal mode). |
| PFI (9) | Input voltage monitor input | Accepts resistor divider from VIN to PFI_RET; triggers PFO low when input drops below programmed undervoltage threshold. |
| VMID (10) | Supercap stack midpoint | Internally driven to VOUT/2; provides balancing reference and enables per-cell voltage monitoring for clamp control. |
| VIN (11,12) | Main input power supply | Accepts 2.7–5.5V sources; bypassed with ceramic capacitor; powers all internal circuitry including balancer and comparators. |
| GND (13) | Ground reference / thermal pad | Exposed pad must be soldered to PCB ground plane with multiple vias for θJA = 43°C/W thermal performance. |
Key Features
| Feature | Design Value |
|---|---|
| Smart charge current profile | Linearly scales from 10% to 100% of programmed current as VIN–VOUT drops from 750mV to 250mV - limits inrush without external soft-start circuitry. |
| Integrated cell balancing | Active VMID servo maintains exact VOUT/2 with ±1mA drive strength - eliminates 100kΩ+ external balancing resistors and associated leakage errors. |
| Real-time current monitoring | PROG pin voltage directly represents charge current (ICHRG = 1000 × VPROG/RPROG) - enables closed-loop battery management without sense resistors. |
| Dual overvoltage protection | Independent PMOS/NMOS shunts clamp top/bottom supercap voltages to 2.45V or 2.7V - prevents cell reversal and extends cycle life beyond 500k cycles. |
| Thermal foldback regulation | Reduces charge current continuously above 105°C junction temperature - sustains operation under sustained high ambient without thermal shutdown interruption. |
Applications
| Portable Instrumentation Power Backup | Industrial PDA Energy Storage |
|---|---|
Use Scenario: Maintaining real-time clock and sensor memory during main power interruption in handheld gas analyzers. IC Role / Device Role / Timing Role: Supercap charger and ideal diode providing seamless switchover from Li-Ion to 1F backup stack with <15mV dropout. Use Value: Enables >72-hour hold-up time with zero software intervention and no battery replacement maintenance. | Use Scenario: Supporting instant-on functionality and data logging continuity in warehouse inventory scanners after battery removal. IC Role / Device Role / Timing Role: Dual-mode charger managing 2-cell supercap stack recharge from USB host while acting as low-loss power path during operation. Use Value: Eliminates 5-second boot delay by sustaining 3.3V rail at 200mA for 15 seconds post-battery extraction. |
| Power Meter Supercap Backup | USB Modem Peak Load Support |
Use Scenario: Preserving meter calibration data and time-of-use logs during grid outages in smart electricity meters. IC Role / Device Role / Timing Role: Precision voltage-clamped charger ensuring each supercap remains within 2.45V limit to guarantee 10-year calendar life. Use Value: Achieves >100,000 write cycles to FRAM without voltage derating, meeting ANSI C12.1 compliance. | Use Scenario: Supplying burst current for LTE transmission in embedded USB modems powered solely by host port. IC Role / Device Role / Timing Role: Ideal diode + current-limited charger delivering 2A peaks to modem PA while limiting USB port stress to 500mA average. Use Value: Enables Class 10 LTE throughput without violating USB 2.0 suspend current limits or triggering host port overcurrent protection. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar supercapacitor charging applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC4425EMSE#TRPBF | Same die, 12-lead MSOP package (5.0mm × 4.0mm); θJA = 35°C/W; exposed pad soldering required. | Better thermal performance but larger footprint; preferred for high-ambient industrial designs with forced airflow. | Select when board layout allows larger package and thermal margin is critical over size constraints. |
| MAX5078ATA+ | Single-cell supercap charger only; no VMID balancing; 100mΩ ideal diode RON; no programmable clamp voltage. | Limited to 2.7V single-supercap systems; requires external balancing resistors; lacks per-cell overvoltage protection. | Choose only for cost-sensitive, single-cell applications where cell matching is guaranteed and thermal headroom exceeds 25°C. |
Compared with LTC4425EDD#TRPBF, the LTC4425EMSE#TRPBF offers superior thermal dissipation in space-tolerant layouts, while the MAX5078ATA+ sacrifices dual-cell support, balancing, and precision clamping for lower unit cost - making LTC4425EDD#TRPBF the only option supporting reliable 2-cell stack longevity in compact, thermally constrained designs.
Availability
LTC4425EDD#TRPBF is available at Aetrix Electronics and suitable for portable instrumentation, industrial PDAs, power meter backup circuits, and USB-powered modem designs requiring stable component supply across extended production lifecycles.
Supply support for LTC4425EDD#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, Inc. (ADI) is a global semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and power management.
The LTC4425EDD#TRPBF belongs to ADI's Linear Technology supercapacitor charger product line, engineered specifically for high-reliability energy storage backup in battery-constrained portable and industrial equipment where long-term voltage stability and cell balancing are critical.
FAQ
What is the primary function of the LTC4425EDD#TRPBF in a supercapacitor-based backup system?
The LTC4425EDD#TRPBF serves as a dual-function IC: it charges a 2-cell series supercapacitor stack using constant-current/constant-voltage/constant-temperature regulation, and simultaneously acts as a 50mΩ ideal diode to provide seamless power path control between source and load. Its integrated cell balancing, programmable voltage clamping, and PROG-pin current monitoring enable robust, maintenance-free backup power in portable instrumentation and industrial devices - all within the LTC4425EDD#TRPBF's compact DFN package.
How does the LTC4425EDD#TRPBF implement cell balancing without external resistors?
The LTC4425EDD#TRPBF incorporates an internal leakage balancing amplifier (LBA) that actively drives the VMID pin to precisely VOUT/2, compensating for inherent capacitance and leakage mismatches between the two series supercapacitors. This circuit sources or sinks up to ±1mA to maintain balance, eliminating the need for power-wasting external 100kΩ balancing resistors. The LTC4425EDD#TRPBF's LBA operates only when VIN is present, ensuring zero quiescent current penalty during backup-only operation.
Can the LTC4425EDD#TRPBF be used with a single supercapacitor instead of a 2-cell stack?
No - the LTC4425EDD#TRPBF is specifically designed for 2-cell series supercapacitor stacks. Its VMID pin, internal shunt transistors, and voltage clamp circuitry all assume a midpoint node between two equal cells. Using it with a single supercap would leave VMID unconnected (causing undefined behavior), disable cell balancing, and render the 2.45V/2.7V per-cell clamping ineffective. For single-cell applications, consider alternatives like the LTC3225 or MAX5078 - but the LTC4425EDD#TRPBF requires a true 2-cell configuration to function as specified.
What happens to the LTC4425EDD#TRPBF when the input voltage (VIN) drops below the output voltage (VOUT)?
When VIN falls below VOUT, the LTC4425EDD#TRPBF's ideal diode controller immediately turns off the internal PMOS pass device to prevent reverse current flow from the supercap stack back to the failing source. During this condition, the part draws only 20µA from VOUT to sustain internal comparators and the VMID balancer (if VIN was previously present). The PFO pin asserts low to signal power fail, and the LTC4425EDD#TRPBF continues regulating VOUT until the supercap voltage decays below the load's minimum operating threshold - ensuring uninterrupted operation during brief input interruptions.
How is the charge current programmed and monitored on the LTC4425EDD#TRPBF?
Charge current is programmed by connecting a resistor (RPROG) between the PROG pin and GND, where ICHG = 1000 × (1V / RPROG). Monitoring is achieved by measuring the PROG pin voltage: ICHG = 1000 × (VPROG / RPROG). In LDO mode, VPROG is held at 1.00V; in normal mode, it varies from 0.1V to 1.00V depending on VIN–VOUT differential - providing real-time current telemetry without external sense resistors. This dual functionality is intrinsic to the LTC4425EDD#TRPBF's architecture.
LTC4425EDD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 12-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Applications:
- Supercapacitor Charger
- Current - Supply:
- 20µA
- Voltage - Supply:
- 2.7V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 12-DFN (3x3)
LTC4425EDD#TRPBF FAQ
1.How can I place an order for LTC4425EDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC4425EDD#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 LTC4425EDD#TRPBF reliable?
The price and inventory of LTC4425EDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC4425EDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC4425EDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC4425EDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC4425EDD#TRPBF?
LTC4425EDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC4425EDD#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 LTC4425EDD#TRPBF?
For technical support, including LTC4425EDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC4425EDD#TRPBF requirements.
6.How does Aetrix verify that LTC4425EDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC4425EDD#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 LTC4425EDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC4425EDD#TRPBF?
All LTC4425EDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC4425EDD#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 LTC4425EDD#TRPBF part is unused and in its original packaging.
Return procedure for LTC4425EDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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