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Analog Devices Inc. LTC3256IMSE#PBF
- Part No.:
- LTC3256IMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Voltage Regulators - Linear + Switching
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3256IMSE#PBF.pdf
- Description:
- IC REG DL BUCK/LINEAR 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,884
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Product details
Overview
LTC3256IMSE#PBF from Analog Devices (formerly Linear Technology) is a wide-input switched-capacitor dual-output DC/DC converter with integrated watchdog timer and power-good monitoring. It delivers 5V @ 100mA and 3.3V LDO @ 250mA from 5.5V–38V input, uses automatic 2:1/1:1 charge pump mode switching, and features 1.1V buffered reference for system diagnostics in automotive ECU and industrial housekeeping applications.
For engineers reviewing the LTC3256IMSE#PBF datasheet, LTC3256IMSE#PBF pinout, LTC3256IMSE#PBF application, or LTC3256IMSE#PBF equivalent, key selection criteria include input transient tolerance (38V), independent enable control (EN3/EN5), dual power-good outputs (PG3/PG5), reset/watchdog timing configurability (RT/WT), and thermal performance in the 16-lead MSOP package with exposed pad.
Technical Context
The LTC3256IMSE#PBF implements a multimode step-down charge pump pre-regulator that automatically selects 2:1 mode (for VIN > ~10.1V) or 1:1 mode (for VIN < ~7.2V) to maximize efficiency across its 5.5V–38V input range. Its 5V output is sourced either from OUTCP via an overcurrent-protected PMOS switch or directly from VIN via a gated 1:1 regulator when OUTCP drops below 5V.
The device integrates safety-critical functions including independent power-good comparators per output, a buffered 1.1V reference (±32mV over temp), adjustable reset timeout (via RT capacitor), and watchdog timer with upper/lower boundaries (via WT capacitor). Overtemperature protection activates at 150°C junction temperature, and it tolerates indefinite short circuits on both outputs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5.5V to 38V - supports 12V automotive systems and withstands load-dump transients without external clamping. |
| 5V Output Capability | 4.85V to 5.19V regulation, 100mA max - stable for microcontroller I/O and CAN transceiver VCC rails. |
| 3.3V LDO Output | 3.17V to 3.37V regulation, 250mA max - powers low-noise analog circuitry and digital logic with <1% line/load regulation. |
| Quiescent Current | 20µA (both outputs regulating, no load) - enables always-on monitoring in safety-critical systems. |
| Watchdog Timing | Internal: 37.5ms–2s window; External: configurable via CWT - ensures deterministic fault recovery in ISO26262-compliant designs. |
| Reset Function | Adjustable timeout (150–260ms internal; 26–44ms external via CRT) with RSTI comparator threshold (1.1–1.26V) - provides flexible power-on and brownout reset control. |
| Reference Output | 1.068V–1.132V buffered bandgap (2kΩ output impedance) - enables self-test of ADC references and voltage monitors. |
Pinout & Package
The LTC3256IMSE#PBF is housed in a thermally enhanced 16-lead MSOP package with exposed GND pad (pin 17), requiring soldering to PCB ground plane for thermal performance (θJC = 10°C/W, θJA = 40°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| C– (1) | Flying capacitor negative terminal | Connects to negative side of 1µF ceramic flying capacitor; critical for charge pump energy transfer. |
| C+ (2) | Flying capacitor positive terminal | Connects to positive side of 1µF ceramic flying capacitor; forms charge transfer path with C–. |
| OUTCP (3) | Charge pump regulated output | Provides ~5.05V pre-regulated supply; powers 3.3V LDO and feeds 5V output switch; requires ≥10µF X7R bypass. |
| OUT5 (4) | 5V regulated output | Delivers up to 100mA; sourced from OUTCP (2:1 mode) or VIN (1:1 mode); includes overvoltage/undervoltage protection. |
| REFOUT (5) | Buffered 1.1V reference | Low-impedance diagnostic reference; must be bypassed with 0.1µF ceramic for PSRR optimization. |
| OUT3 (6) | 3.3V LDO output | Delivers up to 250mA; powered exclusively by OUTCP; includes independent PG3 monitoring. |
| PG3 (7) | 3.3V power-good open-drain | Signals OUT3 regulation status; requires external pull-up to OUT3/OUT5/OUTCP for system sequencing. |
| PG5 (8) | 5V power-good open-drain | Signals OUT5 regulation status; independent of PG3; enables staggered power-up control. |
| RST (9) | Reset open-drain output | Asserts low during reset timeout; high-impedance during watchdog period; requires external pull-up. |
| WT (10) | Watchdog timer capacitor pin | Configures watchdog upper boundary time; tie to OUTCP for ~1.6s default or to GND to disable. |
| RT (11) | Reset timeout capacitor pin | Configures reset timeout duration; leave open for minimum (~200ms) or connect CRT for extended delay. |
| RSTI (12) | Reset input comparator | Triggers reset when voltage falls below 1.1–1.26V threshold; used for external brownout detection. |
| WDI (13) | Watchdog input | Must be toggled within watchdog window (37.5ms–2s); floating or static states assert RST. |
| VIN (14) | Main power input | Supplies charge pump and internal circuitry; accepts 5.5V–38V; requires ≥10µF low-ESR ceramic bypass. |
| EN3 (15) | 3.3V LDO enable | Logic-high enables OUT3 and starts charge pump; 1µA internal pull-down; 38V tolerant. |
| EN5 (16) | 5V output enable | Logic-high enables OUT5 and starts charge pump; 1µA internal pull-down; 38V tolerant. |
| GND (17) | Exposed thermal pad | Must be soldered to PCB ground plane; serves as primary thermal path and electrical ground reference. |
Key Features
| Feature | Design Value |
|---|---|
| Automatic 2:1/1:1 charge pump mode switching | Maximizes efficiency across 5.5V–38V input range; reduces power dissipation by >2W vs dual-LDO at 12V/350mA. |
| Independent EN3/EN5 control | Enables flexible power sequencing-e.g., bring up 3.3V rail first for analog subsystems before enabling 5V digital loads. |
| Dual open-drain power-good outputs (PG3/PG5) | Allows independent monitoring of each output's regulation status for fault isolation and system-level health checks. |
| Buffered 1.1V reference (REFOUT) | Supports self-test of ADC references and voltage monitors in functional safety applications (ISO26262 diagnostic coverage). |
| Configurable reset and watchdog timers | RT and WT pins accept external capacitors for precise timeout tuning-critical for meeting ASIL-B timing requirements. |
| 38V input transient tolerance | Withstands automotive load-dump events without external TVS diodes, simplifying front-end protection design. |
Applications
| Automotive ECU Power Supply | Industrial Housekeeping Supply |
|---|---|
Use Scenario: Powers microcontroller core, CAN transceiver, and sensor interface in engine control unit under 12V battery with load-dump transients. IC Role / Device Role / Timing Role: Dual-output power management IC providing isolated 5V (CAN VCC) and 3.3V (MCU I/O) rails with independent enable and power-good signaling. Use Value: Eliminates need for two discrete LDOs and external transient protection, reducing BOM count and board area while meeting AEC-Q100 Grade 1 temp range (–40°C to 125°C). | Use Scenario: Supplies FPGA configuration, real-time clock, and communication peripherals in programmable logic controller with 24V DC input. IC Role / Device Role / Timing Role: Wide-input housekeeping regulator delivering stable 3.3V and 5V from unregulated 24V rail, with watchdog supervision for firmware integrity. Use Value: Reduces thermal stress in enclosed enclosures via 2:1 charge pump efficiency-dissipates <1.5W at full load vs >3.5W for dual-LDO alternatives. |
| Low-Power 12V-to-5V/3.3V Conversion | Safety-Critical Diagnostic Reference Source |
Use Scenario: Replaces inefficient linear regulators in battery-backed IoT gateway converting 12V PoE-derived supply to 5V/3.3V logic rails. IC Role / Device Role / Timing Role: Inductorless step-down converter minimizing EMI and enabling ultra-thin PCB designs where magnetics are prohibited. Use Value: Achieves >85% efficiency at 12V→5V/3.3V conversion with 20µA quiescent current-extending battery life in always-on monitoring nodes. | Use Scenario: Provides traceable reference voltage for self-test routines in medical infusion pump controller requiring ISO 13485 compliance. IC Role / Device Role / Timing Role: Buffered bandgap reference generator with known accuracy (±32mV) and low output impedance (2kΩ) for ADC calibration. Use Value: Enables in-system verification of voltage monitor thresholds without external instrumentation-reducing test time and field failure risk. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-output wide-input regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS65263-1RGER | Two synchronous buck converters (not charge pump); 4.5V–18V input; no integrated watchdog or REFOUT. | Requires external timing components for reset/watchdog; lacks diagnostic reference; better suited for high-current (>500mA) non-safety applications. | Select when higher output current and lower EMI from inductor-based regulation are prioritized over input voltage range and functional safety features. |
| MAX20404ATPA/VY+ | Single 3.3V/5V dual-output buck; 3V–36V input; includes watchdog but no buffered reference or independent PG outputs. | No REFOUT pin; single PG output shared between rails; less granular fault reporting than LTC3256IMSE#PBF's dual PG3/PG5. | Select when board space is constrained and 36V max input suffices, but avoid if system-level diagnostics require dedicated 1.1V reference or independent power-good signaling. |
Compared with TPS65263-1RGER and MAX20404ATPA/VY+, the LTC3256IMSE#PBF uniquely combines 38V input tolerance, dual independent power-good outputs, buffered 1.1V reference, and configurable watchdog/reset timing in a single MSOP package-making it optimal for ISO26262-compliant automotive and industrial safety systems where diagnostic coverage and transient robustness are mandatory.
Availability
LTC3256IMSE#PBF is available at Aetrix Electronics and suitable for automotive ECU power supplies, industrial PLC housekeeping rails, and low-power 12V-to-5V/3.3V conversion requiring stable component supply and long-term lifecycle support.
Supply support for LTC3256IMSE#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 acquired Linear Technology in 2017 and maintains its precision analog and power management portfolio. Linear Technology pioneered high-performance switching regulators and remains a leader in rugged, high-reliability power ICs.
The LTC3256IMSE#PBF belongs to Linear's automotive-grade power management family, designed specifically for safety-critical applications requiring wide-input operation, integrated diagnostics, and AEC-Q100-compliant reliability in harsh environments.
FAQ
What is the maximum input voltage rating for the LTC3256IMSE#PBF?
The LTC3256IMSE#PBF has an absolute maximum input voltage rating of 38V on the VIN pin, and it is engineered to tolerate automotive load-dump transients up to this level without external protection. Its operating input voltage range is specified from 5.5V to 38V, with guaranteed performance across the full –40°C to 125°C junction temperature range. This makes the LTC3256IMSE#PBF suitable for 24V industrial and 12V automotive systems where input surges are common.
How does the LTC3256IMSE#PBF manage power sequencing between its 5V and 3.3V outputs?
The LTC3256IMSE#PBF supports independent power sequencing via separate EN3 and EN5 enable inputs. Asserting EN3 high turns on the 3.3V LDO only after the charge pump output (OUTCP) reaches 97.5% of regulation; asserting EN5 high enables the 5V output similarly, but with additional soft-start to limit inrush. This allows designers to power up the 3.3V rail first for analog subsystems before enabling the 5V rail for digital loads-ensuring clean, controlled startup in complex systems using the LTC3256IMSE#PBF.
Can the LTC3256IMSE#PBF operate without external timing capacitors on RT and WT pins?
Yes, the LTC3256IMSE#PBF can operate without external capacitors on RT and WT. Leaving RT open configures an internal ~200ms reset timeout; tying WT to OUTCP sets a ~1.6s watchdog upper boundary. Both pins have internal current sources enabling default timing, eliminating mandatory external components. However, adding capacitors provides precise, temperature-stable adjustment-critical for meeting strict ISO26262 timing constraints in safety applications using the LTC3256IMSE#PBF.
What is the purpose of the REFOUT pin on the LTC3256IMSE#PBF, and how is it used?
The REFOUT pin on the LTC3256IMSE#PBF delivers a buffered 1.1V bandgap reference (1.068V–1.132V, ±32mV) with 2kΩ output impedance, intended for system-level diagnostics and self-test. It must be bypassed with a 0.1µF ceramic capacitor to maximize PSRR. In safety-critical designs, REFOUT enables verification of ADC reference accuracy, voltage monitor thresholds, and power supply integrity-directly supporting ISO26262 diagnostic coverage requirements for the LTC3256IMSE#PBF.
Does the LTC3256IMSE#PBF require external flying and input capacitors, and what are the minimum values?
Yes, the LTC3256IMSE#PBF requires external capacitors: a 1µF ceramic flying capacitor (CFLY) between C+ and C– pins, and ≥10µF low-ESR ceramic input capacitor on VIN. The flying capacitor must be X7R/X5R ceramic rated ≥6V; polarized types (tantalum, electrolytic) are prohibited. For VIN bypassing, 10µF is the recommended minimum-lower values may allow input noise to couple to outputs, degrading regulation and increasing ripple. These values are mandatory for achieving the rated 350mA total output current and thermal performance of the LTC3256IMSE#PBF.
LTC3256IMSE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tube
- 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#PBF FAQ
1.How can I place an order for LTC3256IMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3256IMSE#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 LTC3256IMSE#PBF reliable?
The price and inventory of LTC3256IMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3256IMSE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3256IMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3256IMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3256IMSE#PBF?
LTC3256IMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3256IMSE#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 LTC3256IMSE#PBF?
For technical support, including LTC3256IMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3256IMSE#PBF requirements.
6.How does Aetrix verify that LTC3256IMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3256IMSE#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 LTC3256IMSE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3256IMSE#PBF?
All LTC3256IMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3256IMSE#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 LTC3256IMSE#PBF part is unused and in its original packaging.
Return procedure for LTC3256IMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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