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Analog Devices Inc. LTC3256IMSE#TRPBF
- Part No.:
- LTC3256IMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Voltage Regulators - Linear + Switching
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3256IMSE#TRPBF.pdf
- Description:
- IC REG DL BUCK/LINEAR 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,865
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Product details
Overview
LTC3256IMSE#TRPBF from Analog Devices (formerly Linear Technology) is a wide-input-range switched-capacitor dual-output DC/DC converter with integrated watchdog timer and power-good monitoring. It delivers regulated 5V (100mA max) and 3.3V (250mA max) outputs from 5.5V–38V input, using multimode charge pump pre-regulation and LDO post-regulation. Designed for automotive ECU and industrial housekeeping supplies, it reduces power dissipation by >2W vs dual-LDO solutions at 12VIN/350mA load.
For engineers reviewing the LTC3256IMSE#TRPBF datasheet, LTC3256IMSE#TRPBF pinout, LTC3256IMSE#TRPBF application, or LTC3256IMSE#TRPBF equivalent, key selection criteria include its 2:1/1:1 automatic charge pump mode switching, independent enable control per output, buffered 1.1V reference for diagnostics, and ISO26262 diagnostic coverage support in safety-critical systems.
Technical Context
The LTC3256IMSE#TRPBF implements a two-stage regulation architecture: a multimode step-down charge pump (2:1 or 1:1) generates OUTCP (5.05V nominal), which powers both the 5V output switch and the 3.3V LDO. Mode selection is fully automatic based on VIN and load - 2:1 mode dominates above ~10.1V for peak efficiency, while 1:1 mode engages below ~7.2V to sustain regulation.
Its integrated safety subsystem includes independent power-good comparators (PG3/PG5), reset controller with adjustable timeout (via RT pin), watchdog timer with configurable upper/lower boundaries (via WT/WDI), overcurrent protection per output, and overtemperature shutdown (TJMAX = 150°C). The buffered 1.1V reference (REFOUT) enables system-level self-test without external components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5.5V to 38V - supports 12V/24V automotive and industrial rails with 38V transient tolerance. |
| 5V Output Capability | Fixed 5V ±2% (4.85–5.19V), 100mA max - powered via fault-protected PMOS switch from OUTCP or VIN-powered 1:1 regulator when VIN < 10V. |
| 3.3V Output Capability | Fixed 3.3V ±2.5% (3.17–3.37V), 250mA max - supplied by low-dropout LDO fed from OUTCP. |
| Quiescent Current | 20µA (both outputs regulating, no load); 0.5µA (shutdown) - enables always-on subsystems with minimal battery drain. |
| Charge Pump Modes | Automatic 2:1 (VIN/2) and 1:1 (VIN) switching - maximizes efficiency across full input range without external control. |
| Reference Output | 1.1V ±3% buffered bandgap (1.068–1.132V), 2kΩ output impedance - provides stable diagnostic voltage for safety-critical monitoring. |
| Thermal Rating | –40°C to 125°C operating junction temperature (I-grade), θJA = 40°C/W - validated for under-hood automotive environments. |
Pinout & Package
Package: 16-lead MSOP with exposed thermal pad (pin 17 = GND), thermally enhanced for high-power density operation in constrained layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| C– (1) | Flying capacitor negative terminal | Connects to negative side of ceramic flying capacitor (CFLY); critical for charge transfer timing and efficiency. |
| C+ (2) | Flying capacitor positive terminal | Connects to positive side of CFLY; forms charge pump switching node with C–. |
| OUTCP (3) | Charge pump regulated output | 5.05V nominal supply for OUT5 switch and OUT3 LDO; requires ≥10µF X7R ceramic bypass. |
| OUT5 (4) | 5V regulated output | Delivers up to 100mA; internally connected to OUTCP via PMOS switch when enabled and VIN > 10V. |
| REFOUT (5) | Buffered 1.1V reference | Stable diagnostic voltage source; must be bypassed with 0.1µF ceramic for optimal PSRR. |
| OUT3 (6) | 3.3V LDO output | Delivers up to 250mA; powered exclusively from OUTCP; soft-started on EN3 assertion. |
| PG3 (7) | 3.3V power-good open-drain | Asserts high-Z when OUT3 reaches 97.5% of regulation; requires external pull-up to OUT3/OUT5/OUTCP. |
| PG5 (8) | 5V power-good open-drain | Asserts high-Z when OUT5 reaches 97.5% of regulation; same pull-up requirement as PG3. |
| RST (9) | Reset open-drain output | Drives low during reset timeout; high-Z during watchdog period; requires external pull-up. |
| WT (10) | Watchdog timer control | External capacitor sets upper boundary timeout; tie to OUTCP for ~1.6s default; grounding disables watchdog. |
| RT (11) | Reset timeout control | External capacitor sets reset duration; tie to OUTCP for ~200ms default; open for minimum timeout. |
| RSTI (12) | Reset input comparator | Triggers reset when voltage falls below 1.16–1.26V threshold; used for external system fault signaling. |
| WDI (13) | Watchdog input | Must be toggled within tWDL–tWDU window (50–62.5ms internal, 200–340ms external); floating prohibited. |
| VIN (14) | Main power input | Supplies IC control circuitry and charge pump; accepts 5.5–38V with –0.3V to 38V absolute max rating. |
| EN3 (15) | 3.3V LDO enable | Logic-high enables OUT3 and triggers charge pump startup; 38V-tolerant with 1µA internal pulldown. |
| EN5 (16) | 5V output enable | Logic-high enables OUT5 and triggers charge pump startup; identical voltage tolerance and pulldown as EN3. |
| GND (17) | Exposed thermal pad | Must be soldered to PCB ground plane for thermal performance (θJC = 10°C/W) and electrical integrity. |
Key Features
| Feature | Design Value |
|---|---|
| Automated 2:1/1:1 charge pump mode switching | Eliminates manual mode selection and external control logic while maintaining >85% efficiency across 5.5–38V input range. |
| Independent output enable (EN3/EN5) | Enables flexible power sequencing - e.g., bring up 3.3V first for microcontroller core, then 5V for peripherals - reducing inrush and system startup time. |
| Integrated watchdog timer with adjustable bounds | Supports fail-safe system recovery via programmable tWDL/tWDU; eliminates need for external watchdog IC in ISO26262-compliant designs. |
| Buffered 1.1V reference (REFOUT) | Provides traceable, low-impedance diagnostic voltage for ADC-based system health checks without loading internal bandgap. |
| Overvoltage/undervoltage monitoring (PG3/PG5) | Each output has dedicated window comparator with defined trip thresholds - enables precise fault detection before downstream damage occurs. |
| 38V input transient tolerance | Withstands automotive load-dump events without external clamping, simplifying front-end protection design and improving BOM cost. |
Applications
| Automotive ECU Power Supply | Industrial Housekeeping Supply |
|---|---|
Use Scenario: Powering microcontroller core (3.3V), CAN transceiver (5V), and sensor interface circuitry in engine control units exposed to 12V/24V battery rails and load-dump transients. IC Role / Device Role / Timing Role: Dual-output primary power management IC providing isolated, monitored, and sequenced 3.3V/5V rails with built-in watchdog and reset supervision. Use Value: Replaces discrete LDO + supervisor + watchdog solution, cutting board space by 40% and eliminating 3 external ICs while meeting AEC-Q100 Grade 1 requirements. | Use Scenario: Generating bias voltages for PLC I/O modules, fieldbus interfaces, and analog signal conditioning circuits in factory automation equipment. IC Role / Device Role / Timing Role: Wide-input housekeeping regulator delivering stable 3.3V/5V from unregulated 12–36V DC distribution bus with fault reporting and diagnostics. Use Value: Enables single-rail input architecture across diverse industrial platforms, reducing need for multiple input converters and simplifying compliance testing for IEC 61000-4 immunity standards. |
| Low-Power 12V-to-Dual-Rail Conversion | Safety-Critical Diagnostic Subsystem |
Use Scenario: Converting 12V vehicle battery to 5V for USB peripherals and 3.3V for MCU in telematics gateways where thermal headroom is limited. IC Role / Device Role / Timing Role: High-efficiency switched-capacitor converter minimizing heat generation compared to linear regulators, especially at full 350mA combined load. Use Value: Reduces power dissipation by >2W versus dual-LDO solution at 12VIN, enabling fanless enclosure design and extending component lifetime in sealed enclosures. | Use Scenario: Providing reference voltage and supervised power for functional safety monitors in medical devices or rail signaling controllers requiring ASIL-B compliance. IC Role / Device Role / Timing Role: Integrated diagnostic resource delivering buffered 1.1V reference, independent power-good signals, and configurable reset/watchdog timing for safety mechanism validation. Use Value: Achieves >90% diagnostic coverage per ISO26262 Annex D without external redundancy, accelerating FMEDA analysis and reducing certification effort. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-output wide-input DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3265EMSE#TRPBF | Single 3.3V output only; no 5V rail; includes inverting charge pump for negative supply generation. | Not suitable for dual-rail 5V/3.3V systems; targets bipolar supply needs (±3.3V) in precision analog front-ends. | Select LTC3256IMSE#TRPBF when dual independent positive rails are required; choose LTC3265 for split-supply instrumentation. |
| TPS65263-1RGER | Inductor-based buck/buck converter; higher peak efficiency (>92%) but requires 2 inductors and more external components. | Better suited for high-current (>500mA) or noise-sensitive applications where EMI filtering is critical; lacks integrated watchdog or REFOUT. | Choose LTC3256IMSE#TRPBF for inductorless, compact, safety-feature-rich designs; select TPS65263-1RGER for maximum efficiency at >200mA per rail with lower ripple. |
Compared with LTC3265EMSE#TRPBF and TPS65263-1RGER, the LTC3256IMSE#TRPBF uniquely combines dual fixed outputs, automatic charge pump mode switching, integrated watchdog/reset, and buffered reference in a single 16-pin MSOP - making it optimal for space-constrained, safety-aware automotive and industrial housekeeping applications where inductor count and diagnostic capability are decisive factors.
Availability
LTC3256IMSE#TRPBF is available at Aetrix Electronics and suitable for automotive ECU power supplies, industrial housekeeping systems, and low-power 12V-to-dual-rail conversion requiring stable component supply, long-term lifecycle support, and AEC-Q100-aligned reliability.
Supply support for LTC3256IMSE#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 legacy high-performance power management portfolio with rigorous automotive and industrial qualification standards.
The LTC3256IMSE#TRPBF belongs to Linear's switched-capacitor DC/DC converter family, engineered specifically for inductorless, high-reliability power conversion in harsh environments - emphasizing fault resilience, diagnostic coverage, and wide-input operation for automotive and industrial control systems.
FAQ
What is the maximum total output current supported by the LTC3256IMSE#TRPBF?
The LTC3256IMSE#TRPBF supports up to 100mA on the 5V output (OUT5) and up to 250mA on the 3.3V LDO output (OUT3), for a total of 350mA combined. These limits are specified across the full input voltage range (5.5V–38V) and operating temperature (–40°C to 125°C), with derating applied if junction temperature exceeds 150°C due to ambient or power dissipation conditions.
How does the LTC3256IMSE#TRPBF handle input voltages below 10V?
When VIN drops below ~10.1V, the LTC3256IMSE#TRPBF automatically transitions the charge pump from 2:1 to 1:1 mode to maintain regulation. Below ~7.2V, the 5V output switches from OUTCP to a VIN-powered 1:1 regulator, while the 3.3V LDO remains fed from OUTCP. This ensures continuous regulation across the full 5.5V–38V range without external intervention.
Can the watchdog timer in the LTC3256IMSE#TRPBF be disabled?
Yes, the watchdog timer in the LTC3256IMSE#TRPBF can be disabled by tying both WT and WDI pins to GND. This configuration prevents RST assertion due to watchdog timeout, allowing use of the device's reset functionality independently. Note that floating WDI is prohibited and may cause unpredictable behavior.
What is the purpose of the REFOUT pin on the LTC3256IMSE#TRPBF?
The REFOUT pin on the LTC3256IMSE#TRPBF provides a buffered 1.1V ±3% bandgap reference voltage with 2kΩ output impedance. It enables system-level self-testing and diagnostic functions - such as ADC calibration or voltage margining - without loading the internal reference, supporting ISO26262 diagnostic coverage requirements in safety-critical applications.
Does the LTC3256IMSE#TRPBF require external flying capacitors, and what are the specifications?
Yes, the LTC3256IMSE#TRPBF requires an external ceramic flying capacitor (CFLY) between C+ and C– pins. It must be ≥0.4µF over temperature and voltage (X5R/X7R dielectric), rated for ≥6V, and placed close to the IC. Polarized types (tantalum, electrolytic) are prohibited. Typical value is 1µF, as shown in the standard application circuit.
LTC3256IMSE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Topology:
- Step-Down (Buck) (1), Linear (LDO) (1)
- Number of Outputs:
- 2
- Frequency - Switching:
- -
- Voltage/Current - Output 1:
- 5V, 100mA
- Voltage/Current - Output 2:
- 3.3V, 250mA
- Voltage/Current - Output 3:
- -
- w/LED Driver:
- No
- w/Supervisor:
- No
- w/Sequencer:
- Yes
- Voltage - Supply:
- 5.5V ~ 38V
- Operating Temperature:
- -40°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LTC3256IMSE#TRPBF FAQ
1.How can I place an order for LTC3256IMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3256IMSE#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 LTC3256IMSE#TRPBF reliable?
The price and inventory of LTC3256IMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3256IMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3256IMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3256IMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3256IMSE#TRPBF?
LTC3256IMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3256IMSE#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 LTC3256IMSE#TRPBF?
For technical support, including LTC3256IMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3256IMSE#TRPBF requirements.
6.How does Aetrix verify that LTC3256IMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3256IMSE#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 LTC3256IMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3256IMSE#TRPBF?
All LTC3256IMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3256IMSE#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 LTC3256IMSE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3256IMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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