My Inquiry
My Account
Analog Devices Inc. LTC3855EFE#TRPBF
- Part No.:
- LTC3855EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3855EFE#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,882
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LTC3855EFE#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 4.5 V to 38 V input with 0.6 V to 12.5 V output - used in high-efficiency dual-rail power supplies for telecom baseband processors.
For engineers reviewing the LTC3855EFE#TRPBF datasheet, LTC3855EFE#TRPBF pinout, LTC3855EFE#TRPBF application, or LTC3855EFE#TRPBF equivalent, key selection criteria include phase-lockable 250–770 kHz operation, DCR temperature compensation, dual PGOOD outputs, and FE-package thermal performance in space-constrained intermediate-bus systems.
Technical Context
The LTC3855EFE#TRPBF implements two independent PolyPhase® current-mode control loops with synchronized but anti-phase switching to reduce input ripple and EMI. Each channel uses a transconductance error amplifier (gm = 2 mmho) and a precision 0.6 V reference with ±0.75% accuracy over temperature, enabling tight regulation of dual output rails like 1.8 V/1.2 V for FPGA core/I/O domains.
Its integrated differential remote sense amplifier (gain = 1.00 V/V, PSRR = 100 dB, GBW = 3 MHz) enables accurate load-point regulation despite PCB IR drop, while programmable ILIM pins select 30/50/75 mV current sense thresholds to support either DCR or discrete RSENSE sensing - critical for thermally stable current limiting in high-current industrial power modules.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5 V to 38 V - supports 5 V, 12 V, and 24 V intermediate bus architectures without external pre-regulation. |
| Output Voltage Range | 0.6 V to 12.5 V - covers DDR memory, CPU cores, ASICs, and analog subsystems with single-controller flexibility. |
| Reference Accuracy | ±0.75% at 0.6 V - ensures <±9 mV absolute output tolerance at 1.2 V rail, meeting tight FPGA core voltage specs. |
| Switching Frequency | 250 kHz to 770 kHz (programmable via FREQ pin) - allows optimization of size vs. efficiency; 500 kHz typical balances inductor size and conduction loss. |
| Current Sense Threshold | 30 / 50 / 75 mV (selectable per channel via ILIM pins) - enables use of low-value DCR or RSENSE to minimize power loss and thermal rise. |
| Differential Sense Gain | 0.998–1.002 V/V - maintains <±0.2% gain error across temperature, preserving remote-sense accuracy under thermal stress. |
| Operating Temperature | –40°C to +85°C (E-grade) - qualified for commercial/industrial environments including telecom line cards and medical imaging power supplies. |
Pinout & Package
Package: 38-lead plastic TSSOP (FE package), 11.9 mm × 4.4 mm × 1.0 mm, exposed pad (Pin 39 = SGND), RoHS-compliant, moisture sensitivity level 3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SENSE1+, SENSE1− SENSE2+, SENSE2− | Current sense comparator inputs | Accept differential voltage across DCR network or sense resistor; bias current ±1 µA minimizes error in low-RSENSE designs. |
| VFB1, VFB2 | Error amplifier feedback inputs | Receive scaled output voltage; ±50 nA input current enables high-impedance dividers without loading error. |
| DIFFP, DIFFN, DIFFOUT | Differential remote sense amplifier I/O | Enable Kelvin connection to load; DIFFOUT drives VFB via divider to correct for trace resistance up to 3.3 V max output. |
| TG1, TG2 BG1, BG2 | Top/bottom gate drivers | Drive N-MOSFET gates with 2.6 Ω pull-up / 1.5 Ω pull-down RDS(ON); 25 ns transition times support fast switching with minimal shoot-through risk. |
| ILIM1, ILIM2 | Current limit threshold select | Ground = 30 mV, float = 50 mV, INTVCC = 75 mV - configures sense threshold without external resistors or firmware. |
| PGOOD1, PGOOD2 | Open-drain power-good indicators | Assert low when output deviates >±10% from setpoint after 20 µs debounce - enables sequenced startup in multi-rail systems. |
Key Features
| Feature | Design Value |
|---|---|
| Dual 180° phased controllers | Reduces input capacitor RMS current by ~30% and lowers conducted EMI vs. single-phase, easing compliance with EN55032 Class B. |
| Programmable DCR temperature compensation | ITEMP1/ITEMP2 pins accept NTC thermistors near inductors to dynamically adjust sense gain, maintaining current limit accuracy across –40°C to +85°C ambient. |
| Three light-load operating modes | Burst Mode® (floating MODE/PLLIN), pulse-skipping (INTVCC), or forced continuous (GND) - selectable per system noise/efficiency trade-off without changing hardware. |
| True remote sensing amplifier | Integrated differential amp with 2 mV offset and 100 dB PSRR rejects supply noise and enables <±5 mV regulation at point-of-load under dynamic load steps. |
| 12-phase expandability | CLKOUT and PHASMD pins allow synchronization of up to six LTC3855 devices (12 phases total) for >100 A single-output supplies with interleaved ripple cancellation. |
Applications
| Telecom Baseband Power | Industrial PLC CPU Core |
|---|---|
Use Scenario: Dual-rail 1.8 V @ 15 A and 1.2 V @ 15 A supply for LTE/5G baseband processors with tight transient response requirements. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller providing coordinated, out-of-phase switching and differential remote sensing at processor VRM. Use Value: Achieves >94% peak efficiency at full load and <10 mV load-step deviation using DCR current sensing and programmable soft-start. | Use Scenario: High-reliability 3.3 V and 1.2 V power for ARM-based PLC CPUs operating continuously in 60°C cabinet environments. IC Role / Device Role / Timing Role: Dual-channel controller with DCR temperature compensation and dual PGOOD signals for fault-tolerant power sequencing. Use Value: Maintains ±0.75% output accuracy across temperature via 0.6 V reference and compensates for inductor heating-induced DCR drift. |
| Medical Imaging Subsystem | Data Center SSD Controller |
Use Scenario: Low-noise, low-ripple dual 2.5 V and 1.1 V rails powering ADC front-ends and FPGA logic in portable ultrasound units. IC Role / Device Role / Timing Role: Dual-phase controller configured in forced continuous mode to suppress audible noise and ensure sub-100 µVpp output ripple. Use Value: Uses internal slope compensation and anti-shoot-through logic to eliminate gate drive overlap, reducing EMI that could corrupt sensitive analog acquisition. | Use Scenario: Compact 1.8 V @ 12 A and 3.3 V @ 8 A power for NVMe SSD controllers requiring rapid load-step response and high efficiency at partial load. IC Role / Device Role / Timing Role: Dual-channel controller with Burst Mode® operation and adjustable soft-start for cold-boot sequencing and standby power optimization. Use Value: Delivers <25 µA shutdown current and >88% efficiency at 10% load via adaptive light-load mode selection and low-IQ design. |
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 |
|---|---|---|---|
| ISL95812IRZ-T | Single-chip dual-phase controller with integrated MOSFET drivers only; no differential remote sense amplifier or DCR tempco. | Suitable for cost-sensitive, lower-precision applications where board space is constrained but remote sensing is not required. | Select ISL95812IRZ-T when integrated drivers suffice and remote sense accuracy is secondary to BOM count reduction. |
| MP8765GL-Z | Monolithic dual-phase buck with 30 V max VIN, fixed 0.6 V ref (±1%), no CLKOUT/PHASMD for multiphase expansion. | Targeted at consumer SSDs and embedded displays where 12-phase scalability and ultra-precise remote sensing are unnecessary. | Choose MP8765GL-Z for simplified layout and lower component count in non-critical, volume-sensitive designs. |
Compared with ISL95812IRZ-T and MP8765GL-Z, the LTC3855EFE#TRPBF uniquely combines differential remote sensing, programmable DCR temperature compensation, and 12-phase expandability - making it the only option among the three qualified for high-accuracy, thermally stable, multi-kW telecom and medical power systems.
Availability
LTC3855EFE#TRPBF is available at Aetrix Electronics and suitable for telecom infrastructure, industrial automation, and medical imaging power supplies requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LTC3855EFE#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 high-performance power management portfolio with rigorous automotive- and industrial-grade qualification.
The LTC3855EFE#TRPBF belongs to Linear's PolyPhase® controller family, designed specifically for high-current, multi-phase DC/DC conversion in space- and thermally-constrained systems where efficiency, accuracy, and reliability are non-negotiable.
FAQ
What is the maximum input voltage rating for the LTC3855EFE#TRPBF?
The LTC3855EFE#TRPBF has an absolute maximum input supply voltage (VIN) rating of 40 V, with recommended operating range from 4.5 V to 38 V. Exceeding 40 V risks permanent damage per Absolute Maximum Ratings. The device is commonly deployed in 12 V and 24 V intermediate bus systems, and its wide range accommodates battery-backed industrial rails and telecom -48 V derived supplies.
How does the LTC3855EFE#TRPBF implement differential remote sensing?
The LTC3855EFE#TRPBF integrates a dedicated differential amplifier with pins DIFFP, DIFFN, and DIFFOUT. DIFFP connects directly to the remote load positive node, DIFFN to the local output capacitor ground, and DIFFOUT feeds into VFB1 or VFB2 via a resistor divider. With 0.998–1.002 V/V gain, <2 mV offset, and 100 dB PSRR, it actively corrects for PCB trace resistance - enabling ±5 mV regulation accuracy at the load even with 50 mΩ path resistance.
Can the LTC3855EFE#TRPBF operate in single-phase mode?
Yes, the LTC3855EFE#TRPBF can be configured for single-phase operation by disabling one channel via its RUN pin (pull below 1.2 V) and routing both TK/SS and VFB signals to the active channel. However, its architecture is optimized for dual-phase interleaving - using only one phase forfeits benefits like reduced input ripple, lower EMI, and shared thermal load across MOSFETs and inductors.
What are the supported light-load operating modes of the LTC3855EFE#TRPBF?
The LTC3855EFE#TRPBF supports three configurable light-load modes via the MODE/PLLIN pin: Burst Mode® (pin floating), pulse-skipping PWM (pin tied to INTVCC), and forced continuous conduction (pin tied to SGND). Each mode trades off efficiency, output ripple, and acoustic noise - Burst Mode® achieves <25 µA quiescent current but introduces low-frequency ripple, while forced continuous eliminates ripple at the cost of ~3× higher light-load losses.
Does the LTC3855EFE#TRPBF require external components for DCR temperature compensation?
No - the LTC3855EFE#TRPBF implements DCR temperature compensation internally using ITEMP1 and ITEMP2 pins. Connect NTC thermistors near each inductor to these pins; the IC sources 10 µA (typ) to generate a voltage proportional to temperature, which adjusts the current sense gain in real time. No external op-amps, DACs, or calibration firmware are needed - compensation is fully analog and self-contained within the LTC3855EFE#TRPBF.
LTC3855EFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 38-TFSOP (0.173", 4.40mm Width) 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:
- 38-TSSOP-EP
LTC3855EFE#TRPBF FAQ
1.How can I place an order for LTC3855EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3855EFE#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 LTC3855EFE#TRPBF reliable?
The price and inventory of LTC3855EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3855EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3855EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3855EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3855EFE#TRPBF?
LTC3855EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3855EFE#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 LTC3855EFE#TRPBF?
For technical support, including LTC3855EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3855EFE#TRPBF requirements.
6.How does Aetrix verify that LTC3855EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3855EFE#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 LTC3855EFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3855EFE#TRPBF?
All LTC3855EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3855EFE#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 LTC3855EFE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3855EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LTC3855EFE#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…
