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Analog Devices Inc. LTC3255EDD#PBF
- Part No.:
- LTC3255EDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LTC3255EDD#PBF.pdf
- Description:
- IC REG CHARG PUMP ADJ 50MA 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,862
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Product details
Overview
LTC3255EDD#PBF from Analog Devices (formerly Linear Technology) is a switched-capacitor step-down DC/DC converter designed for current-fed industrial power rails, specifically 4mA to 20mA current loops. It delivers up to 7.4mA output from a 4mA input, supports 4V–48V input and 2.4V–12.5V adjustable output, operates in automatic 2:1/1:1 charge-pump modes, and features integrated VIN shunt regulation and PGOOD monitoring.
For engineers reviewing the LTC3255EDD#PBF datasheet, LTC3255EDD#PBF pinout, LTC3255EDD#PBF application, or LTC3255EDD#PBF equivalent, key selection criteria include shunt-mode current multiplication capability, fault-protected operation across –52V to +60V input transients, thermal performance in the 3mm × 3mm DFN package, and compatibility with precision feedback resistor networks for programmable output voltage.
Technical Context
The LTC3255EDD#PBF implements a multimode switched-capacitor architecture with automatic 2:1 or 1:1 conversion ratio selection based on VIN, VOUT, and load conditions. Its internal shunt regulator-enabled by connecting SHUNT to BIAS-allows stable operation from high-impedance current sources while maintaining 2:1 mode exclusively.
Regulation is achieved via Burst Mode® control: fixed-charge packets are delivered until FB reaches 1.200V (±2.4mV), then the IC enters ultra-low-quiescent sleep (16µA). The PGOOD open-drain output asserts high-impedance when FB exceeds 94% of final regulation voltage, supporting system power sequencing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 48V - supports wide industrial supply rails and withstands reverse polarity down to –52V without damage. |
| Output Voltage Range | 2.4V to 12.5V adjustable - set via external resistor divider on FB pin; regulated to 1.200V ±2.4mV at feedback node. |
| Max Output Current | 7.4mA with shunt enabled (4mA input), 50mA with shunt disabled - enables current multiplication in 4–20mA loop-powered systems. |
| Quiescent Current | 16µA at no load in regulation - enables long-term operation in low-power housekeeping supplies. |
| Oscillator Frequency | 500kHz - determines charge-transfer timing and influences capacitor sizing for ripple and efficiency. |
| Thermal Limit | 150°C max junction temperature - requires exposed pad (Pin 11) soldered to PCB ground plane for θJA ≤ 43°C/W. |
| Protection Features | Overtemperature shutdown, output short-circuit limiting (120mA), and input fault tolerance - ensures robustness in harsh industrial environments. |
Pinout & Package
Package: 10-lead (3mm × 3mm) plastic DFN with exposed thermal pad (Pin 11 = GND). Requires soldering of exposed pad to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| C+ (Pin 1) | Flying capacitor positive terminal | Connects to one side of external flying capacitor; must not be driven externally. |
| VOUT (Pin 2) | Regulated output voltage node | Delivers final stepped-down voltage; bypassed with ≥1µF low-ESR ceramic capacitor. |
| FB (Pin 3) | Feedback reference input | Servo point for 1.200V regulation; connected to resistor divider between VOUT and GND. |
| SHUNT (Pin 4) | Shunt regulator enable/disable control | Connect to BIAS to enable VIN shunt (for current-loop use); connect to GND to disable. |
| PGOOD (Pin 5) | Open-drain power-good indicator | High-impedance when VOUT ≥94% of target; requires external pull-up for logic-level signaling. |
| EN (Pin 6) | Enable/disable logic input | Active-high; drives low to shut down IC and reduce VIN current to 3µA. |
| BIAS (Pin 7) | Internal bias supply decoupling | Must connect ≥0.1µF ceramic capacitor (≥10V rating) to GND for stable operation. |
| GND (Pins 8 & 11) | Ground reference and thermal path | Pin 8 = signal GND; Pin 11 = exposed thermal pad - both must connect to PCB ground plane. |
| C– (Pin 9) | Flying capacitor negative terminal | Connects to other side of flying capacitor; must not be driven externally. |
| VIN (Pin 10) | Main input supply connection | Accepts 4V–48V; requires ≥1µF low-ESR ceramic bypass capacitor to GND. |
Key Features
| Feature | Design Value |
|---|---|
| Current multiplication in 4–20mA loops | Converts 4mA input into continuous 7.4mA output at 3.3V - eliminates need for external boost stages in loop-powered sensors. |
| Automatic 2:1/1:1 mode switching | Maintains regulation across full VIN range without manual configuration - 2:1 mode engages when VIN > 2×VOUT, improving efficiency. |
| VIN shunt regulator with compliance control | Clamps VIN to ~2×VOUT + 3.5V (for VOUT ≤5.5V) - prevents violation of current-loop compliance voltage limits. |
| Burst Mode® regulation | Reduces no-load quiescent current to 16µA while preserving tight output regulation - critical for battery-backed or energy-harvested systems. |
| Fault protection suite | Withstands –52V to +60V input transients, survives indefinite output shorts, and includes overtemperature shutdown - meets industrial reliability requirements. |
Applications
| 4–20mA Current Loop Sensors | Industrial Housekeeping Supplies |
|---|---|
Use Scenario: Powering loop-powered pressure, temperature, or flow transmitters where VIN is derived from a 4–20mA current source with limited compliance voltage. IC Role / Device Role / Timing Role: LTC3255EDD#PBF acts as a current-multiplying, shunt-regulated step-down converter that maintains stable VOUT despite varying loop current and input impedance. Use Value: Enables 7.4mA load current from 4mA loop input - sufficient to power microcontrollers, ADCs, and analog front-ends without violating 24V loop compliance. | Use Scenario: Generating auxiliary bias rails (e.g., 3.3V or 5V) in PLCs, RTUs, or motor drives where main supply is 24VDC or higher. IC Role / Device Role / Timing Role: LTC3255EDD#PBF serves as an inductor-free, low-noise housekeeping supply replacing inefficient linear regulators or bulky buck converters. Use Value: Delivers up to 50mA output with 16µA quiescent current and no magnetic components - reduces board area and EMI in space-constrained control modules. |
| Factory Automation I/O Modules | SCADA Remote Terminal Units |
Use Scenario: Powering isolated digital I/O channel circuitry in DIN-rail mounted I/O blocks where input voltage varies widely (e.g., 12–48VDC). IC Role / Device Role / Timing Role: LTC3255EDD#PBF provides regulated output with automatic mode switching and fault protection - ensuring reliable operation during brownouts or surges. Use Value: Maintains regulation across 4V–48V input with built-in reverse-polarity and short-circuit immunity - eliminates need for external TVS or fuse protection in field-deployed hardware. | Use Scenario: Supplying microcontroller, radio, and sensor subsystems in solar-powered or battery-backed RTUs operating from unregulated 12–36V battery banks. IC Role / Device Role / Timing Role: LTC3255EDD#PBF functions as a highly efficient, low-quiescent step-down converter with PGOOD signaling for system power sequencing and watchdog reset coordination. Use Value: Achieves >80% efficiency at 50mA load and signals valid rail presence via PGOOD - enabling deterministic boot and low-power sleep states in remote telemetry systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switched-capacitor step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3265EDD#PBF | Includes dual low-noise LDOs and inverting charge pump; no VIN shunt regulator; 50mA max output; wider input (4.5–32V). | Targeted at precision analog signal chains requiring clean ±rails; lacks current-loop shunt functionality. | Select when bipolar supplies or ultra-low-noise biasing are required - not suitable for 4–20mA current multiplication. |
| MAX17521ATP+T | Inductor-based synchronous buck; 4.5–60V input; 3.3V/500mA fixed output; 15µA quiescent current; no shunt mode. | Higher output current and efficiency at medium loads; requires inductor; no current-loop support. | Choose for higher-power housekeeping rails where inductors are acceptable and shunt regulation is unnecessary. |
Compared with LTC3255EDD#PBF, LTC3265EDD#PBF adds precision analog support but removes current-loop shunt capability, while MAX17521ATP+T offers higher current and efficiency using magnetics - making LTC3255EDD#PBF uniquely suited for inductor-free, current-fed industrial power conversion.
Availability
LTC3255EDD#PBF is available at Aetrix Electronics and suitable for industrial control, factory automation, sensor conditioning, and SCADA systems requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for LTC3255EDD#PBF 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) acquired Linear Technology in 2017 and maintains its portfolio of high-performance power management ICs for industrial, automotive, and communications markets.
The LTC3255 product line was designed specifically for ruggedized, inductor-free power conversion in current-loop and wide-input industrial applications - emphasizing fault resilience, current multiplication, and thermal robustness in compact DFN and MSOP packages.
FAQ
What is the maximum output current capability of the LTC3255EDD#PBF in shunt-enabled mode?
The LTC3255EDD#PBF delivers up to 7.4mA DC output current when the SHUNT pin is connected to BIAS and supplied with a 4mA input current at 3.3V output. This current multiplication is enabled by the integrated VIN shunt regulator and locked 2:1 charge-pump operation - a core feature distinguishing LTC3255EDD#PBF from standard step-down converters.
How does the LTC3255EDD#PBF achieve regulation without an inductor?
The LTC3255EDD#PBF uses a switched-capacitor (charge-pump) topology with internal C+ and C– terminals for an external flying capacitor. It transfers discrete charge packets between VIN and VOUT in 2:1 or 1:1 ratios, controlled by a 500kHz oscillator and Burst Mode® feedback loop - eliminating magnetic components while maintaining regulation across 4V–48V input and 2.4V–12.5V output ranges.
Can the LTC3255EDD#PBF operate safely with reverse-polarity input voltage?
Yes. The LTC3255EDD#PBF withstands input voltages from –52V to +60V without damage. When VIN goes below ground, internal protection diodes limit VOUT to within one diode drop of GND, safeguarding downstream circuitry - a critical capability for field-wiring scenarios in industrial environments where polarity errors may occur.
What is the role of the SHUNT pin on the LTC3255EDD#PBF, and how should it be configured?
The SHUNT pin on the LTC3255EDD#PBF selects shunt regulator operation: connect to BIAS to enable VIN clamping for 4–20mA current-loop use, or connect to GND to disable shunt mode for standard voltage-fed applications. Floating the pin is prohibited - incorrect configuration causes undefined behavior or failure to regulate.
Does the LTC3255EDD#PBF require external compensation components for stability?
No. The LTC3255EDD#PBF employs a fixed-frequency, current-mode charge-pump architecture with internal compensation. Stability is ensured by proper selection of external capacitors - specifically ≥0.4µF ceramic flying capacitor, ≥1µF low-ESR input capacitor, and ≥10µF low-ESR output capacitor - per the layout guidelines in the official datasheet for LTC3255EDD#PBF.
LTC3255EDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Charge Pump
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 48V
- Voltage - Output (Min/Fixed):
- 2.4V
- Voltage - Output (Max):
- 12.5V
- Current - Output:
- 50mA
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LTC3255EDD#PBF FAQ
1.How can I place an order for LTC3255EDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3255EDD#PBF 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 LTC3255EDD#PBF reliable?
The price and inventory of LTC3255EDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3255EDD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3255EDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3255EDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3255EDD#PBF?
LTC3255EDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3255EDD#PBF 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 LTC3255EDD#PBF?
For technical support, including LTC3255EDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3255EDD#PBF requirements.
6.How does Aetrix verify that LTC3255EDD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3255EDD#PBF 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 LTC3255EDD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3255EDD#PBF?
All LTC3255EDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3255EDD#PBF, 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 LTC3255EDD#PBF part is unused and in its original packaging.
Return procedure for LTC3255EDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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