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Analog Devices Inc. LTC3128IFE#TRPBF
- Part No.:
- LTC3128IFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3128IFE#TRPBF.pdf
- Description:
- IC REG BUCK BOOST ADJ 3A 24TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,095
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Product details
Overview
LTC3128IFE#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic buck-boost supercapacitor charger IC with accurate programmable average input current limit (0.5A–3A), active charge balancing, and programmable per-capacitor voltage limit (1.8V–3.0V). It operates from 1.73V to 5.5V input and regulates output from 1.8V to 5.5V, enabling safe, efficient charging of stacked supercapacitors in backup power systems for servers, RAID, and industrial controllers.
For engineers reviewing the LTC3128IFE#TRPBF datasheet, LTC3128IFE#TRPBF pinout, LTC3128IFE#TRPBF application, or LTC3128IFE#TRPBF equivalent, key selection criteria include its 24-lead TSSOP package, ±2% input current accuracy, 1.2MHz fixed switching frequency, thermal regulation at 135°C, and dual-loop control architecture supporting seamless buck/boost mode transitions without discontinuity in inductor current or loop stability.
Technical Context
The LTC3128IFE#TRPBF implements a proprietary four-switch buck-boost topology with synchronous rectification and dual control loops: a hysteretic voltage loop managing sleep mode entry/exit and proportional gain near regulation, and an internally compensated average input current loop enforcing precise 0.5A–3A limits via PROG pin resistor programming. Its zero-current comparator prevents reverse inductor current, improving light-load efficiency.
It integrates dedicated circuitry for active charge balancing-enabled when |VOUT/2 − VMID| exceeds 60mV-with peak/valley current thresholds of ±400mA/±50mA, and independent maximum capacitor voltage monitoring (programmed via MAXV pin resistor) that halts charging and initiates balancing if either capacitor exceeds the set threshold. Thermal regulation reduces current limit progressively above 135°C to avoid shutdown.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 1.73V to 5.5V - supports single-cell Li-ion, USB, or wide-input industrial supplies without external LDO pre-regulation. |
| VOUT Range | 1.8V to 5.5V - configurable via FB resistor divider; enables direct charging of 2.5V, 3.3V, or 5V supercapacitor stacks. |
| Avg Input Current Limit | 0.5A to 3.0A (±2%) - set by single RPROG resistor; ensures predictable source loading and thermal management during bulk charging. |
| Switching Frequency | 1.2MHz (typical) - enables compact 3.3µH inductor and low-profile ceramic output capacitors (e.g., 10µF ×2). |
| FB Reference Voltage | 0.580V (±1.3%) - high-accuracy internal reference enabling <±1% output voltage regulation over temperature and load. |
| Quiescent Current (Sleep) | <2µA from VOUT - extends battery/supercapacitor hold-up time in standby; critical for memory backup applications. |
| Thermal Regulation Threshold | 135°C (typical) - dynamically scales down input current limit to prevent thermal shutdown during high-power charging cycles. |
Pinout & Package
Package: 24-Lead Plastic TSSOP (FE), 4mm × 8.65mm × 1.1mm, exposed pad (Pin 25) soldered to PCB ground for thermal and electrical integrity (θJA = 38°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW1 (Pins 1, 4) | Switch Node A/B Connection | Connects internal P-channel (A) and N-channel (B) MOSFETs; ties to one end of power inductor. |
| RSENP (Pin 5) | Sense Resistor Power Output | High-current return path for input supply and system loads; requires local ≥10µF ceramic decoupling to GND. |
| RSENS (Pin 6) | Sense Resistor Signal Input | Low-impedance feedback node for input current sensing; must be short/wide trace to RSENP to minimize noise and offset. |
| RUN (Pin 7) | Logic-Controlled Enable | Active-high enable: ≥1.2V = normal operation; ≤0.3V = shutdown with <1µA IQ; tolerant of voltages >VIN/VOUT. |
| PROG (Pin 8) | Average Input Current Set | Programs 0.5A–3A limit via resistor to GND; gain = 52.7µA/A; requires CPROG for loop stability. |
| VIN (Pin 11) | Main Input Supply | Primary power input and internal VCC rail; requires ≥10µF ceramic decoupling close to pin and GND. |
| PFO (Pin 13) | Open-Drain Power Fail Output | Sinks current when monitored supply (via PFI) falls below programmed threshold; used for system-level brownout signaling. |
| PFI (Pin 14) | Power Fail Input | Resistive divider tap for supply monitoring; internal 0.58V reference + 0.2µA hysteresis current enables precise threshold setting. |
| MAXV (Pin 15) | Max Capacitor Voltage Set | Programs per-capacitor overvoltage limit (1.8V–3.0V) via resistor to GND; disables balancer if tied to GND. |
| FB (Pin 16) | Output Voltage Feedback | Connects to resistor divider mid-point; 0.580V reference enables 1.8V–5.5V output programming with <±1% accuracy. |
| PGOOD (Pin 17) | Open-Drain Power-Good Output | Pulls low when VOUT drops below 96.75% of programmed value; provides system reset or sequencing signal. |
| MID (Pin 18) | Stack Midpoint Sense | Connects to junction of two series supercapacitors; enables active balancing when |VOUT/2 − VMID| >60mV. |
| VOUTS (Pin 19) | Output Voltage Sense | Remote sense input for output voltage regulation; must be short trace to VOUT capacitor to reject PCB IR drop. |
| VOUTP (Pins 20, 21) | Synchronous Rectifier Output | High-current output node; connects directly to output filter capacitor bank (e.g., parallel 10µF ceramics). |
| SW2 (Pins 23, 24) | Switch Node C/D Connection | Connects internal N-channel (C) and P-channel (D) MOSFETs; ties to other end of power inductor. |
| GND (Pins 2, 3, 12, 25) | Power & Signal Ground | Common reference for all circuits; exposed pad (Pin 25) must be soldered to PCB ground plane for thermal performance. |
Key Features
| Feature | Design Value |
|---|---|
| Accurate Average Input Current Limit | ±2% tolerance over –40°C to 125°C, programmable 0.5A–3A range via single resistor - eliminates need for external current-sense amplifiers in backup power designs. |
| Active Charge Balancing | Efficient inductor-based charge transfer between stacked capacitors with 60mV enable threshold and ±400mA/±50mA peak/valley current control - replaces lossy passive balancing resistors. |
| Programmable Per-Capacitor Overvoltage Protection | Independent voltage limit (1.8V–3.0V) per capacitor in stack, set by single MAXV resistor - prevents individual capacitor failure in 2× supercapacitor configurations. |
| Thermal Regulation | Gradual reduction of input current limit starting at 135°C die temperature - maintains continuous operation under sustained high-power charging without thermal shutdown. |
| Burst Mode® Operation | <2µA quiescent current from VOUT in sleep state - maximizes hold-up time for memory backup and low-power IoT edge devices. |
Applications
| Memory Backup | RAID Controller Hold-Up |
|---|---|
Use Scenario: Maintaining SRAM or NVSRAM state during brief AC mains interruption in enterprise storage systems. IC Role / Device Role / Timing Role: Buck-boost supercapacitor charger providing regulated 2.5V/3.3V output with precise input current limiting and automatic charge balancing across dual 2.7V supercaps. Use Value: Ensures >72-hour data retention at 85°C with <1% output voltage drift and no external balancing components required. | Use Scenario: Sustaining write-cache power in enterprise RAID controllers during unexpected power loss events. IC Role / Device Role / Timing Role: High-efficiency (≥92% at 2A) charger managing 2× 10F supercapacitors in series, with active balancing and thermal regulation during rapid 3A bulk charge cycles. Use Value: Enables full cache flush within 20ms after power fail detection, meeting JEDEC JESD22-B111 reliability standards. |
| Industrial PLC Power Buffer | RF Transceiver Energy Storage |
Use Scenario: Providing uninterrupted 5V power to programmable logic controllers during factory line voltage sags or micro-interruptions. IC Role / Device Role / Timing Role: Wide-input (1.73V–5.5V) buck-boost charger regulating 5V output from 24V DC bus via intermediate 3.3V supercapacitor stack with PFI/PFO fault signaling. Use Value: Delivers 500ms hold-up time at 1.5A load with automatic brownout detection and graceful shutdown sequencing. | Use Scenario: Storing energy for burst transmission in 5G small-cell base stations requiring millisecond-scale power delivery. IC Role / Device Role / Timing Role: Fast-charging (3A limit) supercapacitor manager for 2.7V/100F stack, using MID-sensed active balancing to maintain <50mV inter-capacitor imbalance during repeated 10A RF bursts. Use Value: Achieves <100µs response time from charge-complete to full-power RF transmit, eliminating voltage droop-induced EVM degradation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar supercapacitor charger applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3129IFE#TRPBF | Higher 4A max input current limit; integrated 50mΩ sense resistor; identical 24-lead TSSOP package and pinout. | Supports faster charging of larger supercapacitor banks (>20F); same thermal design and layout compatibility. | Select when >3A charging current is required without external sense resistor redesign. |
| MAX17222ETA+T | Boost-only topology; 1.2A max input current; 12-lead TDFN package; no active balancing or per-capacitor OV protection. | Limited to single-capacitor charging; lacks MID-based balancing and MAXV monitoring; lower integration. | Choose only for cost-sensitive, low-current (≤1.2A), single-supercapacitor applications where balancing is handled externally. |
Compared with LTC3128IFE#TRPBF, LTC3129IFE#TRPBF offers higher current capability in identical packaging, while MAX17222ETA+T provides a lower-cost boost-only alternative lacking balancing and per-capacitor voltage monitoring-making LTC3128IFE#TRPBF uniquely suited for reliable, high-accuracy dual-supercapacitor backup systems.
Availability
LTC3128IFE#TRPBF is available at Aetrix Electronics and suitable for server backup power, industrial PLC hold-up, and RAID controller energy storage requiring stable component supply, long-term lifecycle support, and guaranteed -40°C to 125°C operation.
Supply support for LTC3128IFE#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 leader in high-performance analog, mixed-signal, and digital signal processing technologies, formed through the acquisition of Linear Technology in 2017.
The LTC3128IFE#TRPBF belongs to ADI's Power Management portfolio of high-efficiency DC/DC converters designed specifically for energy storage and backup power applications requiring precision current control, thermal resilience, and active cell balancing.
FAQ
What is the maximum input current limit achievable with LTC3128IFE#TRPBF?
The LTC3128IFE#TRPBF supports a programmable average input current limit up to 3.0A with ±2% accuracy over temperature. This is set by connecting a 3.57kΩ resistor from the PROG pin to GND. The device also includes fixed linear (5.0A typical) and peak (6.5A typical) inductor current limits that operate independently of the PROG setting. These secondary limits provide robust overcurrent protection during transient conditions without affecting the primary input current regulation of LTC3128IFE#TRPBF.
How does LTC3128IFE#TRPBF handle thermal management during high-current charging?
LTC3128IFE#TRPBF incorporates a thermal regulator that begins reducing the programmed input current limit when the die temperature exceeds 135°C (typical), preventing thermal shutdown. As temperature rises toward 165°C (thermal shutdown threshold), the current limit scales down to ~30% of its nominal value. Once the die cools below 135°C, the full programmed current limit is restored. This behavior-combined with the 24-lead TSSOP package's 38°C/W θJA-ensures continuous, controlled charging even under sustained 3A loads on properly designed PCBs with exposed-pad grounding.
Can LTC3128IFE#TRPBF charge a single supercapacitor, or is it limited to stacked configurations?
LTC3128IFE#TRPBF can safely charge both single and stacked supercapacitors. For a single capacitor, tie the MAXV pin to GND to disable per-capacitor overvoltage monitoring and the active charge balancer, and regulate output voltage solely via the FB pin (1.8V–5.5V range). For stacked configurations (e.g., two 2.7V caps), connect MAXV to a resistor for per-capacitor voltage limiting (1.8V–3.0V) and route MID to the capacitor junction to enable active balancing. The LTC3128IFE#TRPBF's dual-mode flexibility eliminates the need for separate part numbers.
What is the function of the MID pin in LTC3128IFE#TRPBF, and how must it be connected?
The MID pin in LTC3128IFE#TRPBF senses the midpoint voltage between two series-connected supercapacitors and enables the active charge balancer when |VOUT/2 − VMID| exceeds 60mV. For stacked capacitor operation, MID must be connected directly to the physical junction of the two capacitors using a short, low-impedance trace. If charging only one capacitor, MID must be tied to GND to disable balancing. Leaving MID floating is not permitted and will cause undefined balancer behavior. The LTC3128IFE#TRPBF uses MID-sensed voltage error to drive internal switches (C, D, F) and the shared inductor to transfer charge between capacitors with ±400mA peak current.
Does LTC3128IFE#TRPBF support power-fail detection and signaling, and how is it implemented?
Yes, LTC3128IFE#TRPBF integrates dedicated power-fail detection via the PFI (Power Fail Input) and PFO (Power Fail Output) pins. An external resistor divider from the monitored supply to GND sets the falling threshold at VPFI = 0.58V × (1 + R4/R3). When PFI voltage drops below this threshold, the open-drain PFO pin pulls low, signaling system-level brownout. Hysteresis (~0.2µA sink into PFI) prevents chatter. PFO is forced high-Z during LTC3128IFE#TRPBF shutdown. This self-contained detection requires no external comparators or pull-ups, simplifying backup power sequencing in servers and industrial controllers.
LTC3128IFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck-Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1.73V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 1.8V
- Voltage - Output (Max):
- 5.5V
- Current - Output:
- 3A
- Frequency - Switching:
- 1.2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-TSSOP
LTC3128IFE#TRPBF FAQ
1.How can I place an order for LTC3128IFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3128IFE#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 LTC3128IFE#TRPBF reliable?
The price and inventory of LTC3128IFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3128IFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3128IFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3128IFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3128IFE#TRPBF?
LTC3128IFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3128IFE#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 LTC3128IFE#TRPBF?
For technical support, including LTC3128IFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3128IFE#TRPBF requirements.
6.How does Aetrix verify that LTC3128IFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3128IFE#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 LTC3128IFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3128IFE#TRPBF?
All LTC3128IFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3128IFE#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 LTC3128IFE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3128IFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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