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Analog Devices Inc. LTC3815EUFE#PBF
- Part No.:
- LTC3815EUFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3815EUFE#PBF.pdf
- Description:
- IC REG BUCK PROG 6A 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,245
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Product details
Overview
LTC3815EUFE#PBF from Analog Devices is a 6A monolithic synchronous step-down DC/DC converter with PMBus interface, operating from 2.25V to 5.5V input and delivering programmable output voltage from 0.4V to 72% of VIN. It features ±1% total output voltage accuracy over temperature, integrated 13-bit ADC for telemetry, and phase-lockable switching frequency up to 3MHz - deployed in FPGA/ASIC core power rails requiring precise margining and real-time monitoring.
For engineers reviewing the LTC3815EUFE#PBF datasheet, LTC3815EUFE#PBF pinout, LTC3815EUFE#PBF application, or LTC3815EUFE#PBF equivalent, key selection criteria include its PMBus-compliant voltage margining (±25%, 0.1% resolution), differential remote sensing, master shutdown mode (<1μA IQ), and 38-lead 4mm × 6mm QFN thermal performance (θJA = 38°C/W).
Technical Context
The LTC3815EUFE#PBF employs a controlled-on-time, current-mode architecture with valley-current sensing via internal NMOS RDS(ON) - enabling fast transient response and stable operation at low on-times required for sub-1V outputs at high frequencies. Its integrated 13-bit ADC supports time-averaged (~4ms) and peak readback of input/output voltage, current, and die temperature at 25Hz refresh rate.
PMBus communication uses standard SMBus v1.2 protocol (fSCL = 10–400kHz) with dedicated ALERT and CLKOUT pins; the device supports full fault status reporting (VIN UV, VOUT OV/UV, overtemperature), MFR_VOUT_PEAK tracking, and synchronized 2-phase operation via CLKOUT (180° phase shift) when paired with a second LTC3815.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.25V to 5.5V - supports direct regulation from 2.5V/3.3V/5V rails or single-cell Li-ion batteries without pre-regulation. |
| Output Current | 6A continuous - delivered via integrated 35mΩ PMOS and 20mΩ NMOS power switches in thermally enhanced QFN. |
| Output Voltage Range | 0.4V to 72% of VIN - programmable via single external resistor on REF pin or external reference; enables 0.4V core rails for advanced processors. |
| Switching Frequency | 400kHz to 3MHz - set by RT resistor or synchronized externally; allows noise-sensitive placement and compact magnetics design. |
| Output Accuracy | ±1% over temperature at VIN = 3.3V or 5V - includes offset, line, and reference current drift contributions per datasheet Note 10. |
| Voltage Margining | ±25% range with 0.1% resolution via MFR_VOUT_COMMAND - implemented using internal 9-bit DAC and slew-rate-controlled ramp (CSLEW pin). |
| Telemetry Resolution | 13-bit ADC for VOUT/IOUT/VIN/IIN (0.5mV/10mA LSB), 9-bit for temperature (1°C LSB) - enables closed-loop system health monitoring. |
Pinout & Package
Package: 38-lead (4mm × 6mm) plastic QFN with exposed PGND pad (Pin 39), θJA = 38°C/W. Exposed pad must be soldered to PCB for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RT (1) | Oscillator frequency programming | Resistor-to-ground sets fSW from 400kHz–3MHz; tie to VIN for fixed 1MHz internal oscillator. |
| REF (36) | Reference voltage input | 100µA current source times external resistor sets base VOUT; also accepts external voltage reference. |
| MARGIN (3) | Fast margining select | Floating = serial command control; pulled high/low = immediate ramp to pre-stored MFR_VOUT_MARGIN_HIGH/LOW register values. |
| MODE/SYNC (9) | Mode selection & clock sync | Tied to VIN = discontinuous mode; grounded = forced continuous mode; driven externally = frequency synchronization. |
| PGOOD (29) | Power-good flag output | Open-drain signal asserted only after VOUT remains within programmable window (via PGLIM/PGFD) for configured delay. |
| SCL/SDA (8,7) | PMBus interface | Standard SMBus v1.2 bidirectional data/clock; supports 10–400kHz, ALERT interrupt, and full register access including peak capture. |
| VCC_SENSE / VSS_SENSE (32,31) | Differential output voltage sense | Kelvin connection to VOUT+ and VOUT− enables accurate remote sensing and eliminates PCB IR drop errors. |
| RUN_MSTR (26) | Master enable input | Threshold at 1V; pulled below 0.4V forces <1μA shutdown - critical for system-level power sequencing and low-power states. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated PMBus telemetry | Real-time readback of VOUT/IOUT/VIN/IIN/temperature (25Hz refresh), plus peak capture registers (MFR_VOUT_PEAK, etc.) for diagnostics. |
| Differential remote sensing | VCC_SENSE and VSS_SENSE pins support true Kelvin connection - eliminates trace resistance error and ensures ±1% regulation at load. |
| Programmable PGOOD window | PGLIM pin sets over/undervoltage thresholds (VREF ±0.4·ΔV); PGFD pin selects 7 discrete filter delays (200μs to 25.6ms) to suppress false trips. |
| Two-phase clock output | CLKOUT provides 180° phase-shifted clock signal - enables seamless 2-phase 12A operation with second LTC3815 without external timing IC. |
| Master shutdown mode | RUN_MSTR pin reduces supply current to <1μA - meets stringent system standby requirements while retaining full configuration state. |
| Controlled-slew margining | CSLEW pin accepts capacitor to program VOUT transition rate (0.1%/ms per nF); prevents overshoot during dynamic voltage scaling. |
Applications
| ASIC/FPGA Core Power | Intelligent Point-of-Load System |
|---|---|
|
Use Scenario: Supplying 0.8V–1.2V core voltage to Xilinx Kintex or Intel Stratix FPGA under dynamic load transients up to 4A/μs. IC Role / Device Role / Timing Role: Primary synchronous buck regulator with differential sensing, PMBus telemetry, and fast margining for voltage ID (VID) compliance testing. Use Value: ±1% output accuracy and <1ms power-up time ensure reliable FPGA configuration; integrated ADC eliminates need for external monitors. |
Use Scenario: Distributed 1.8V/3.3V rails in telecom line cards where remote monitoring and fault logging are required per NEBS standards. IC Role / Device Role / Timing Role: Standalone PMBus-enabled POL converter with autonomous PGOOD assertion, peak current capture, and thermal derating. Use Value: Full telemetry (V/I/T) at 25Hz enables predictive maintenance; CLKOUT supports redundant 2-phase designs without timing jitter. |
| Processor Subsystem Power | Battery-Powered Industrial Controller |
|
Use Scenario: Powering ARM Cortex-A72-based SoC in edge AI gateway with dynamic voltage/frequency scaling (DVFS) across 0.7V–1.1V range. IC Role / Device Role / Timing Role: Digitally programmable buck controller with MARGIN pin-triggered fast voltage transitions and CSLEW-controlled slew rate. Use Value: 0.1% margining resolution and 0.1%/ms slew control enable precise DVFS steps; RUN_STBY pin maintains PMBus interface active during low-power sleep. |
Use Scenario: Regulating 3.3V rail from 3.6V–4.2V Li-ion battery in portable HMI panel with thermal constraints and runtime optimization. IC Role / Device Role / Timing Role: High-efficiency buck converter with 2.25V minimum VIN, master shutdown (<1μA), and temperature telemetry for battery thermal management. Use Value: 2.25V start-up enables full battery utilization; integrated temperature sensor feeds into host MCU for adaptive throttling before thermal shutdown. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3880IUHF#PBF | Dual-output, 2-phase capable, higher integration (dual 35A capability), wider VIN (4.5V–24V), no internal MOSFETs - requires external power stages. | Targeted at multi-rail server/telecom systems needing coordinated sequencing and higher current; not suitable for single-rail, self-contained 6A designs. | Select LTC3880 for multi-output, high-current, or wide-input industrial systems; LTC3815EUFE#PBF remains optimal for compact, single-rail, battery-fed applications. |
| TPS546D24RQFT | 6A monolithic buck with PMBus v1.3, 2.95V–16V VIN, 0.5V–5.5V VOUT, integrated MOSFETs, but lacks differential sensing and CLKOUT for 2-phase sync. | Designed for higher-input industrial/motor drives; missing VCC_SENSE/VSS_SENSE pins limits remote sensing accuracy in dense layouts. | Choose TPS546D24 for 12V-input systems requiring PMBus telemetry; LTC3815EUFE#PBF is preferred where 2.25V start-up, differential sensing, or 2-phase CLKOUT are mandatory. |
Compared with LTC3880IUHF#PBF and TPS546D24RQFT, the LTC3815EUFE#PBF uniquely combines ultra-low VIN (2.25V), differential remote sensing, and hardware CLKOUT for deterministic 2-phase expansion - making it irreplaceable in space-constrained, battery-powered, or precision-regulated single-rail applications.
Availability
LTC3815EUFE#PBF is available at Aetrix Electronics and suitable for ASIC/FPGA core power, intelligent point-of-load systems, and battery-powered industrial controllers requiring stable component supply, long-term lifecycle support, and guaranteed -40°C to 125°C operation.
Supply support for LTC3815EUFE#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. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets since 1965.
The LTC3815EUFE#PBF belongs to Analog Devices' Power by Linear™ monolithic DC/DC controller family, engineered for digitally programmable, high-accuracy power conversion in space- and thermal-constrained embedded systems.
FAQ
What is the minimum input voltage required for LTC3815EUFE#PBF to start switching?
The LTC3815EUFE#PBF has a guaranteed minimum input voltage of 2.25V for normal operation, with undervoltage lockout (UVLO) release at 2.25V (rising) and hysteresis of 0.2V. Below 2.25V, the device remains in shutdown regardless of RUN_MSTR state. This enables direct operation from partially discharged Li-ion cells down to ~2.3V while maintaining regulation stability.
Does LTC3815EUFE#PBF support differential remote sensing, and how is it implemented?
Yes, the LTC3815EUFE#PBF supports true differential remote sensing via dedicated VCC_SENSE (Pin 32) and VSS_SENSE (Pin 31) pins. These connect directly to the positive and negative terminals of the output capacitor, respectively, enabling the internal unity-gain differential amplifier to reject PCB trace IR drop - ensuring ±1% output accuracy at the load, independent of board layout parasitics.
How does the PMBus interface of LTC3815EUFE#PBF handle peak parameter capture?
The LTC3815EUFE#PBF implements dedicated PMBus registers - MFR_VOUT_PEAK, MFR_IOUT_PEAK, MFR_VIN_PEAK, MFR_TEMPERATURE1_PEAK, and MFR_IIN_PEAK - which autonomously track maximum observed values since last reset. Writing to MFR_CLEAR_PEAKS (0xE3) resets all peak registers; reading any peak register returns the stored value without clearing it.
Can LTC3815EUFE#PBF operate in forced continuous conduction mode (CCM), and how is it enabled?
Yes, LTC3815EUFE#PBF supports forced CCM by grounding the MODE/SYNC pin (Pin 9). In this mode, the bottom MOSFET remains active even at light loads, preventing inductor current reversal and eliminating audible noise or light-load efficiency droop - essential for applications requiring constant switching frequency and predictable EMI behavior across full load range.
What thermal performance can be expected from LTC3815EUFE#PBF in its 4mm × 6mm QFN package?
The LTC3815EUFE#PBF in the UFE package has a specified θJA of 38°C/W under JEDEC JESD51-7 2s2p test conditions. With proper PCB layout - including full soldering of the exposed PGND pad (Pin 39) to a ≥250mm² internal copper plane - junction temperature rise remains within safe limits up to 6A continuous load at ambient ≤85°C, meeting its –40°C to 125°C operating junction temperature rating.
LTC3815EUFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Programmable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.25V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 0.4V
- Voltage - Output (Max):
- 3.96V
- Current - Output:
- 6A
- Frequency - Switching:
- 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (4x6)
LTC3815EUFE#PBF FAQ
1.How can I place an order for LTC3815EUFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3815EUFE#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 LTC3815EUFE#PBF reliable?
The price and inventory of LTC3815EUFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3815EUFE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3815EUFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3815EUFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3815EUFE#PBF?
LTC3815EUFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3815EUFE#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 LTC3815EUFE#PBF?
For technical support, including LTC3815EUFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3815EUFE#PBF requirements.
6.How does Aetrix verify that LTC3815EUFE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3815EUFE#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 LTC3815EUFE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3815EUFE#PBF?
All LTC3815EUFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3815EUFE#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 LTC3815EUFE#PBF part is unused and in its original packaging.
Return procedure for LTC3815EUFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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