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Analog Devices Inc. LTC3128EFE#TRPBF
- Part No.:
- LTC3128EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3128EFE#TRPBF.pdf
- Description:
- IC REG BUCK BOOST ADJ 3A 24TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,130
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Product details
Overview
LTC3128EFE#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic buck-boost supercapacitor charger IC with accurate average input current limiting, active charge balancing, and programmable maximum capacitor voltage. It operates from 1.73V to 5.5V input, delivers up to 3A input current, regulates output from 1.8V to 5.5V, and supports stacked supercapacitor backup power systems in industrial servers and RAID storage.
For engineers reviewing the LTC3128EFE#TRPBF datasheet, LTC3128EFE#TRPBF pinout, LTC3128EFE#TRPBF application, or LTC3128EFE#TRPBF equivalent, key selection criteria include its ±2% input current limit accuracy, 1.2MHz fixed-frequency operation, thermal regulation down to 30% of programmed current, <2µA VOUT quiescent current in Burst Mode®, and support for active balancing of unmatched supercapacitors without external resistors.
Technical Context
The LTC3128EFE#TRPBF implements a proprietary continuous-mode 4-switch buck-boost topology that seamlessly transitions between buck, boost, and buck-boost modes without inductor current discontinuity or loop instability. Its dual-loop control includes a hysteretic voltage loop for sleep-state entry at regulation and an internally compensated average input current loop referenced to a 50mΩ internal sense resistor.
It integrates dedicated circuitry for active charge balancing via MID pin feedback, using SW1/SW2 and internal switches C/D/F to shuttle charge between stacked capacitors at frequencies determined by output voltage and inductor value. Thermal regulation activates at 135°C (typ), reducing input current limit progressively until thermal shutdown at 165°C (typ).
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 rails without pre-regulation |
| VOUT Range | 1.8V to 5.5V - programmable via FB divider; enables direct charging of 2.5V/3.3V/5V supercapacitor stacks |
| Avg Input Current Limit | 0.5A to 3.0A (±2% accuracy) - set by single PROG resistor; critical for battery-fed or current-limited sources |
| Max Cap Voltage | 1.8V to 3.0V per capacitor - set by single MAXV resistor; prevents overvoltage failure in series-stacked configurations |
| Switching Frequency | 1.2MHz (typ) - enables compact 3.3µH inductor and low-profile ceramic output capacitors |
| Quiescent Current (VOUT) | <2µA in Burst Mode® - preserves stored energy during long backup standby periods |
| Active Balancer Peak Current | 400mA - provides fast, efficient redistribution of charge between mismatched supercapacitors |
Pinout & Package
Package: 24-Lead Plastic TSSOP (FE package), 0.95mm nominal height, exposed thermal pad (Pin 25) requiring PCB solder connection for θJA = 38°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW1 (Pins 1, 4) | Switch node A/B connection | Connects to one end of power inductor; carries full switching current in buck/boost modes |
| RSENP (Pin 5) | Power output of internal sense resistor | Supplies system loads downstream of sense resistor; requires local 10µF ceramic bypass |
| RSENS (Pin 6) | Sense resistor signal input | Low-impedance return path for accurate input current measurement; must be short/wide trace to RSENP |
| RUN (Pin 7) | Logic-controlled enable/shutdown | High ≥1.2V enables operation; low ≤0.3V forces shutdown with <1µA IQ |
| PROG (Pin 8) | Average input current limit programming | Resistor-to-GND sets IIN limit (RPROG = 11 kΩ/A); capacitor adds noise filtering |
| VIN (Pin 11) | Main input supply and VCC source | High-current input pin; powers internal circuitry and feeds sense resistor; requires local 10µF ceramic |
| PFO (Pin 13) | Open-drain power-fail output | Sinks current when monitored supply falls below PFI threshold; signals host controller of impending brownout |
| PFI (Pin 14) | Power-fail monitor input | Accepts resistor divider from backup source; comparator triggers PFO at 0.58V reference |
| MAXV (Pin 15) | Maximum capacitor voltage programming | Resistor-to-GND sets per-capacitor overvoltage limit (RMAXV = 50 kΩ/V); disables balancer if grounded |
| FB (Pin 16) | Output voltage feedback | Resistor divider tap; 0.58V reference enables 1.8–5.5V VOUT programming with ±1.5% tolerance |
| PGOOD (Pin 17) | Open-drain power-good indicator | Pulls low when VOUT drops below 96.75% of programmed value; used for system sequencing |
| MID (Pin 18) | Active balancer midpoint sense | Connected to junction of stacked capacitors; enables balancing only when |VMID − (VOUT−VMID)| ≥60mV |
| VOUTS (Pin 19) | Output voltage sense input | High-impedance remote sense point; minimizes regulation error from PCB trace resistance |
| VOUTP (Pins 20, 21) | Synchronous rectifier output | High-current output node; connects directly to cathode of output filter capacitor |
| SW2 (Pins 23, 24) | Switch node C/D connection | Connects to other end of power inductor; complements SW1 in 4-switch topology |
| GND (Pins 2, 3, 12, 25) | Signal and power ground | Multiple GND pins + exposed thermal pad (Pin 25) must be soldered to PCB ground plane for thermal integrity |
Key Features
| Feature | Design Value |
|---|---|
| Accurate average input current limit | ±2% tolerance over –40°C to 125°C; enables precise power budgeting from weak or shared sources |
| Active charge balancing | 400mA peak current, 60mV activation threshold; eliminates need for lossy passive balancing resistors |
| Programmable per-capacitor overvoltage protection | 1.8V–3.0V range set by single resistor; prevents premature degradation of series-stacked supercaps |
| Thermal regulation | Reduces input current limit starting at 135°C die temp; avoids thermal shutdown during high-power charging |
| Burst Mode® operation | <2µA VOUT quiescent current; extends hold-up time in battery-backed or energy-harvesting applications |
| Integrated power-good and power-fail indicators | Open-drain outputs with defined thresholds and hysteresis; simplifies system-level power monitoring and sequencing |
Applications
| Server Backup Power | RAID Controller Hold-Up |
|---|---|
Use Scenario: Maintaining volatile cache and configuration data during AC mains interruption in 1U/2U rack servers. IC Role / Device Role / Timing Role: Buck-boost supercapacitor charger providing regulated 4.2V to parallel 2×940mF stack; actively balances capacitors during charge/discharge cycles. Use Value: Enables >10-second clean shutdown without battery replacement; thermal regulation prevents derating at 70°C ambient. | Use Scenario: Preserving write-cache integrity in enterprise RAID controllers during unexpected power loss. IC Role / Device Role / Timing Role: Charges 2.5V supercapacitor stack from 3.3V system rail; uses PFI/PFO to detect brownout and trigger immediate cache flush. Use Value: Guarantees data persistence with <1ms response to input collapse; ±2% current limit ensures predictable charge time across temperature. |
| Industrial PLC Memory Backup | RF Transceiver Energy Buffer |
Use Scenario: Retaining real-time clock and process state in programmable logic controllers operating in unregulated factory environments. IC Role / Device Role / Timing Role: Regulates 3.3V output from 12V DC input via buck mode; employs MID-based balancing to compensate for capacitor aging mismatch. Use Value: Extends memory retention beyond 72 hours at –40°C; <1µA shutdown IQ prevents battery drain during extended downtime. | Use Scenario: Supplying burst power for LTE/5G RF front-end amplifiers during transmission peaks in remote base stations. IC Role / Device Role / Timing Role: Boosts 2.4V battery rail to 4.8V for capacitor stack; uses 1.2MHz switching to minimize EMI near sensitive RF sections. Use Value: Delivers 3A peak charge current with <50mV output ripple; active balancing maintains voltage symmetry under asymmetric load transients. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar supercapacitor charger applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3129EFE#TRPBF | Higher 4A max input current; integrated 100mΩ sense resistor; no RSENS/RSENP separation | Optimized for higher-power backup where board space permits larger inductor; lacks separate RSENP for system load sharing | Select LTC3129EFE#TRPBF when >3A charging is required and system load integration is not needed |
| TPS61288EVM-679 | Boost-only topology; 2.5A max output current; no active balancing or MAXV programming | Requires pre-charged supercapacitor stack; suitable only for single-capacitor or externally balanced systems | Select TPS61288EVM-679 for cost-sensitive, lower-complexity boost-charger designs without balancing needs |
Compared with LTC3128EFE#TRPBF, LTC3129EFE#TRPBF offers higher current but less flexible system integration, while TPS61288EVM-679 reduces cost and complexity at the expense of balancing capability and input voltage range flexibility.
Availability
LTC3128EFE#TRPBF is available at Aetrix Electronics and suitable for server backup power, RAID controller hold-up, and industrial PLC memory backup requiring stable component supply and long-term lifecycle support.
Supply support for LTC3128EFE#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 power management ICs for precision, reliability, and efficiency-critical applications.
The LTC3128 belongs to ADI's Power by Linear™ supercapacitor charger product line, designed specifically for robust, high-accuracy backup power systems in industrial, computing, and communications infrastructure where capacitor aging, thermal stress, and long-term data integrity are paramount.
FAQ
What is the operating temperature range for the LTC3128EFE#TRPBF?
The LTC3128EFE#TRPBF is specified for operation from –40°C to +125°C junction temperature. This grade (E-grade) is guaranteed over 0°C to 85°C junction temperature and assured by design over the full –40°C to 125°C range, making it suitable for demanding industrial and computing environments where thermal margins are critical. The FE package's θJA of 38°C/W requires proper PCB thermal design to maintain reliability at maximum load.
How does the LTC3128EFE#TRPBF implement active charge balancing?
The LTC3128EFE#TRPBF implements active charge balancing by monitoring the voltage at the MID pin-the junction between two stacked supercapacitors-and using internal switches C, D, and F to shuttle charge between them via the main power inductor. Balancing activates when |VMID − (VOUT − VMID)| exceeds 60mV, with 400mA peak and 50mA valley current control. This eliminates reliance on inefficient passive resistors and ensures long-term capacitor reliability in LTC3128EFE#TRPBF-based systems.
Can the LTC3128EFE#TRPBF charge a single supercapacitor?
Yes, the LTC3128EFE#TRPBF can charge a single supercapacitor. In this configuration, the MAXV pin must be tied to GND to disable both the per-capacitor overvoltage comparator and the active charge balancer, and the MID pin must also be grounded. Output voltage is then regulated solely via the FB pin using a resistor divider, with the 0.58V internal reference enabling 1.8V–5.5V programming. The LTC3128EFE#TRPBF retains all core charging functions-including accurate input current limiting and power-good signaling-in single-capacitor mode.
What is the purpose of the RSENP and RSENS pins on the LTC3128EFE#TRPBF?
The RSENP (Pin 5) and RSENS (Pin 6) pins on the LTC3128EFE#TRPBF form a Kelvin-connected current sense interface. RSENP serves as the power output of the internal 50mΩ sense resistor and supplies external system loads downstream of the sense point. RSENS is the low-impedance signal return, requiring a short, wide PCB trace to RSENP to reject noise and ensure ±2% input current limit accuracy. This architecture allows the LTC3128EFE#TRPBF to regulate its own charging current while permitting independent loading of the same input rail-critical for shared-power backup systems.
Does the LTC3128EFE#TRPBF support input voltages below the output voltage?
Yes, the LTC3128EFE#TRPBF fully supports input voltages below the output voltage through its proprietary 4-switch buck-boost topology. When VIN < VOUT, it operates in boost mode using switches C and D to step up the input, maintaining regulation across the full 1.8V–5.5V output range even from as low as 1.73V input. This capability enables direct charging of 3.3V or 4.2V supercapacitor stacks from single-cell batteries or low-voltage industrial rails-without requiring external pre-regulators-making the LTC3128EFE#TRPBF uniquely suited for wide-input backup power applications.
LTC3128EFE#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
LTC3128EFE#TRPBF FAQ
1.How can I place an order for LTC3128EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3128EFE#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 LTC3128EFE#TRPBF reliable?
The price and inventory of LTC3128EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3128EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3128EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3128EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3128EFE#TRPBF?
LTC3128EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3128EFE#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 LTC3128EFE#TRPBF?
For technical support, including LTC3128EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3128EFE#TRPBF requirements.
6.How does Aetrix verify that LTC3128EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3128EFE#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 LTC3128EFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3128EFE#TRPBF?
All LTC3128EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3128EFE#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 LTC3128EFE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3128EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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