My Inquiry
My Account
Analog Devices Inc. LTC3855EUJ#TRPBF
- Part No.:
- LTC3855EUJ#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 40-WFQFN Exposed Pad
- Datasheet:
-
LTC3855EUJ#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 40QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,761
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LTC3855EUJ#TRPBF from Analog Devices (formerly Linear Technology) is a dual, 180° out-of-phase, current-mode synchronous step-down DC/DC controller driving all-N-channel MOSFET stages. It features differential remote sensing, programmable current sense thresholds (30/50/75 mV), 0.6 V ±0.75% reference accuracy, and supports up to 12-phase operation via CLKOUT/PHASMD. Used in high-efficiency 1.8 V/1.2 V CPU core supplies for telecom base stations.
For engineers reviewing the LTC3855EUJ#TRPBF datasheet, LTC3855EUJ#TRPBF pinout, LTC3855EUJ#TRPBF application, or LTC3855EUJ#TRPBF equivalent, key selection criteria include input voltage range (4.5 V–38 V), output voltage capability (0.6 V–12.5 V), phase-lockable frequency (250 kHz–770 kHz), DCR temperature compensation, and dual PGOOD outputs for rail monitoring.
Technical Context
The LTC3855EUJ#TRPBF implements two independent PolyPhase® current-mode control loops with shared oscillator synchronization and configurable phase relationships (0°/180°/240°). Each channel integrates a transconductance error amplifier (gm = 2 mmho), programmable current limit via ILIM pins, and dedicated ITH pins for loop compensation and peak-current threshold control.
Its differential remote sense amplifier (gain = 0.998–1.002 V/V, PSRR = 100 dB, GBW = 3 MHz) enables precise load regulation at 0.6 V–3.3 V outputs, while the internal 5 V INTVCC regulator (4.8 V–5.2 V, ±2% load regulation) powers gate drivers and logic. The device supports Burst Mode®, pulse-skipping, and forced continuous conduction modes across –40°C to +85°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5 V to 38 V - supports 5 V, 12 V, 24 V, and 36 V intermediate bus systems without external pre-regulation. |
| Output Voltage Range | 0.6 V to 12.5 V - covers DDR memory, FPGA core, ASIC, and DSP supply rails; 0.6 V to 3.3 V with differential remote sense enabled. |
| Reference Accuracy | ±0.75% at 0.6 V - ensures tight output regulation under line/load/temperature variation for sensitive digital loads. |
| Switching Frequency | 250 kHz to 770 kHz (programmable via FREQ pin) - allows optimization of size vs. efficiency; phase-locked to external clock via MODE/PLLIN. |
| Current Sense Threshold | 30 mV / 50 mV / 75 mV (set by ILIM pin state) - enables low-loss DCR sensing or precision RSENSE with minimal power loss. |
| Package | 40-pin (6 mm × 6 mm) QFN with exposed SGND pad - provides low thermal resistance (θJA = 33°C/W) and robust high-frequency layout grounding. |
| Operating Temperature | –40°C to +85°C - qualified for commercial and industrial ambient environments including telecom equipment and embedded computing. |
Pinout & Package
40-pin (6 mm × 6 mm) plastic QFN package with exposed signal ground (SGND) pad (Pin 41), rated for –40°C to +85°C operation. Exposed pad must be soldered to PCB for thermal and signal integrity.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| TG1/TG2 | Top Gate Driver Outputs | Drive gates of high-side N-MOSFETs with 2.6 Ω pull-up / 1.5 Ω pull-down RDS(ON); require bootstrap capacitors tied to BOOST1/BOOST2. |
| BG1/BG2 | Bottom Gate Driver Outputs | Drive gates of low-side N-MOSFETs with 2.4 Ω pull-up / 1.1 Ω pull-down RDS(ON); referenced to PGND1/PGND2. |
| SENSE1+/SENSE2+, SENSE1–/SENSE2– | Current Sense Comparator Inputs | Differential inputs for DCR or RSENSE networks; bias current ±1 µA enables high-impedance sensing. |
| VFB1/VFB2 | Error Amplifier Feedback Inputs | Accept remote-sensed feedback from resistor dividers; regulate output to 0.6 V reference with ±0.75% accuracy. |
| DIFFP/DIFFN/DIFFOUT | Differential Remote Sense Amplifier | True Kelvin sense interface: DIFFP connects to load point, DIFFN to output capacitor ground, DIFFOUT feeds VFB1/VFB2 via divider. |
| ILIM1/ILIM2 | Current Limit Threshold Select | Set max sense voltage to 30 mV (GND), 50 mV (float), or 75 mV (INTVCC) - configures trade-off between sensing loss and noise immunity. |
| CLKOUT/PHASMD | Multiphase Clock Interface | CLKOUT provides synchronized clock output; PHASMD selects relative phase (0°/180°/240°) for multi-controller stacking up to 12 phases. |
| PGOOD1/PGOOD2 | Power Good Indicators | Open-drain outputs asserting low when VOUT deviates >±10% from target after 20 µs mask timer - enable system sequencing and fault reporting. |
Key Features
| Feature | Design Value |
|---|---|
| Dual 180° phased controllers | Reduces input ripple current by ~70%, enabling smaller bulk capacitance and lower EMI in high-current 12 V input systems. |
| Programmable DCR temperature compensation | Uses ITEMP1/ITEMP2 pins with external NTC thermistors to dynamically adjust sense gain and maintain accurate current limiting over temperature. |
| True remote sensing differential amplifier | 0.998–1.002 V/V gain, 2 mV offset, and 100 dB PSRR eliminate IR drop errors in long PCB traces or connectors for sub-1% load regulation. |
| Three light-load operating modes | Burst Mode® (highest efficiency), pulse-skipping (low ripple/audio noise), or forced continuous (lowest output ripple) - selected via MODE/PLLIN pin state. |
| Adjustable soft-start and tracking | TK/SS1/TK/SS2 pins accept external capacitors (soft-start) or resistor dividers (voltage tracking) to coordinate startup sequencing across multiple rails. |
Applications
| Telecom Base Station Power | Industrial PLC CPU Core Supply |
|---|---|
Use Scenario: Dual-output 1.8 V @ 15 A and 1.2 V @ 15 A supply for multicore baseband processors in 4G/LTE macrocell radios. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller providing tightly regulated, low-noise, high-efficiency core power with coordinated soft-start and PGOOD sequencing. Use Value: 95% peak efficiency at full load minimizes thermal design burden; differential remote sense maintains ±1% regulation despite 50 mΩ board trace resistance. | Use Scenario: High-reliability 3.3 V and 1.2 V dual-rail supply for ARM-based PLC controllers operating in harsh factory environments. IC Role / Device Role / Timing Role: Dual-channel controller with independent RUN/PGOOD and wide VIN (4.5 V–38 V) tolerates brownouts and battery-backed operation. Use Value: –40°C to +85°C rating and DCR temperature compensation ensure stable current limiting across ambient extremes without sense resistor drift. |
| Medical Imaging FPGA Power | Data Center SSD Controller Supply |
Use Scenario: Low-noise, fast-transient 1.0 V @ 20 A supply for Xilinx Kintex FPGAs in portable ultrasound scanners. IC Role / Device Role / Timing Role: Dual-phase controller configured in 12-phase stack (via CLKOUT) delivering ultra-low ripple and <10 µs load-step response. Use Value: Pulse-skipping mode suppresses audible noise during idle; foldback current limiting protects against short-circuit faults on dense BGA packages. | Use Scenario: Compact 1.8 V @ 12 A supply for NVMe SSD controllers requiring high efficiency and strict transient response in 1U servers. IC Role / Device Role / Timing Role: Dual-channel controller with differential remote sense compensating for VRM-to-SSD connector losses and PCB plane resistance. Use Value: 30 mV current sense threshold enables use of low-value DCR inductor (<0.5 mΩ), reducing conduction loss and thermal footprint. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-phase synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3857EUFD#TRPBF | Higher integration: includes integrated MOSFET drivers with enhanced shoot-through protection and improved current sense accuracy (±0.5%); supports wider frequency range (100 kHz–1 MHz). | Targeted at higher-density, lower-component-count designs where driver losses dominate efficiency; requires different layout due to integrated drivers. | Select LTC3857EUFD#TRPBF when minimizing external components and achieving <1% current sense error is critical; not pin-compatible with LTC3855EUJ#TRPBF. |
| MP2918GL-Z | Single-chip dual-phase controller with integrated MOSFET drivers and PMBus interface; lacks differential remote sense amplifier and DCR temperature compensation. | Suitable for digitally managed power systems requiring telemetry and dynamic margining; limited to 0.6 V–5.5 V outputs and no true Kelvin sensing. | Choose MP2918GL-Z for PMBus-enabled systems needing telemetry and programmable margins; requires redesign for remote sense and thermal compensation functions. |
Compared with LTC3857EUFD#TRPBF and MP2918GL-Z, the LTC3855EUJ#TRPBF delivers unmatched analog precision in differential remote sensing and DCR thermal compensation-critical for analog-sensitive medical and test equipment-while maintaining flexibility in discrete MOSFET selection and layout optimization.
Availability
LTC3855EUJ#TRPBF is available at Aetrix Electronics and suitable for telecom infrastructure, industrial automation, and medical imaging applications requiring stable component supply, extended temperature support, and long-term production continuity.
Supply support for LTC3855EUJ#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 leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets.
The LTC3855EUJ#TRPBF belongs to ADI's Power by Linear™ family of high-efficiency, high-reliability DC/DC controllers designed specifically for demanding multiphase core and I/O power delivery in telecom, computing, and instrumentation systems.
FAQ
What is the maximum output voltage supported by the LTC3855EUJ#TRPBF?
The LTC3855EUJ#TRPBF supports an output voltage range of 0.6 V to 12.5 V when the differential remote sense amplifier is disabled. When DIFFP/DIFFN are used, the regulated output is limited to 0.6 V to 3.3 V to maintain amplifier linearity and stability. This constraint is specified in the Electrical Characteristics table under "VOUT Range" and confirmed in the Applications Information section.
How does the ILIM pin configure the current sense threshold on the LTC3855EUJ#TRPBF?
The ILIM1 and ILIM2 pins on the LTC3855EUJ#TRPBF set the maximum current sense voltage per channel: tying to SGND selects 30 mV, leaving floating selects 50 mV, and connecting to INTVCC selects 75 mV. These states directly program internal current comparator reference levels, enabling optimization between sensing resistor power loss and noise immunity - values are verified in the Electrical Characteristics table (VSENSE(MAX) rows).
Can the LTC3855EUJ#TRPBF operate in single-phase mode?
Yes, the LTC3855EUJ#TRPBF can operate in single-phase mode by configuring only one channel (e.g., disabling RUN2) while using the second channel's CLKOUT or PHASMD pins for synchronization if needed. Its architecture inherently supports independent channel enable/disable, and the datasheet confirms this in the Shutdown and Start-Up section - no hardware modification is required beyond RUN pin control.
What is the purpose of the DIFFOUT pin on the LTC3855EUJ#TRPBF?
The DIFFOUT pin on the LTC3855EUJ#TRPBF is the output of the integrated differential remote sense amplifier. It delivers a buffered, high-PSRR version of the sensed load voltage, which is typically fed into VFB1 or VFB2 through an external resistive divider to close the regulation loop with true Kelvin feedback - ensuring accurate output voltage at the load point regardless of PCB trace resistance.
Does the LTC3855EUJ#TRPBF support external frequency synchronization?
Yes, the LTC3855EUJ#TRPBF supports external frequency synchronization via the MODE/PLLIN pin. Applying an external clock signal to this pin engages the internal PLL, locking both channels to the incoming frequency while forcing forced continuous conduction mode. This behavior is explicitly documented in the Pin Functions and Operation sections, and the PLL compensation network is fully integrated on-die.
LTC3855EUJ#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 40-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 2
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 4.5V ~ 38V
- Frequency - Switching:
- 250kHz ~ 770kHz
- Duty Cycle (Max):
- 95%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Phase Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 40-QFN (6x6)
LTC3855EUJ#TRPBF FAQ
1.How can I place an order for LTC3855EUJ#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3855EUJ#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 LTC3855EUJ#TRPBF reliable?
The price and inventory of LTC3855EUJ#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3855EUJ#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3855EUJ#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3855EUJ#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3855EUJ#TRPBF?
LTC3855EUJ#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3855EUJ#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 LTC3855EUJ#TRPBF?
For technical support, including LTC3855EUJ#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3855EUJ#TRPBF requirements.
6.How does Aetrix verify that LTC3855EUJ#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3855EUJ#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 LTC3855EUJ#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3855EUJ#TRPBF?
All LTC3855EUJ#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3855EUJ#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 LTC3855EUJ#TRPBF part is unused and in its original packaging.
Return procedure for LTC3855EUJ#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LTC3855EUJ#TRPBF Tags
-
UCC28C45DR
Texas Instruments
-
UCC28C40DR
Texas Instruments
-
UCC28C43DR
Texas Instruments
-
ZXSC410E6TA
Diodes Incorporated
-
LM3524DMX/NOPB
Texas Instruments
-
LM3489MMX/NOPB
Texas Instruments
-
MIC2102YML-TR
Microchip Technology
-
LM5148RGYR
Texas Instruments
-
TL598CDR
Texas Instruments
-
LM5155DSSR
Texas Instruments
-
LM25085MYX/NOPB
Texas Instruments
-
UCC2813DTR-0
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
