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Analog Devices Inc. LTC3877IUK#PBF
- Part No.:
- LTC3877IUK#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Special Purpose Regulators
- Package:
- 44-WFQFN Exposed Pad
- Datasheet:
-
LTC3877IUK#PBF.pdf
- Description:
- IC REG CTRL 6 BIT VID 2OUT 44QFN
- Quantity:
- Payment:
- Shipping:
Inventory:117
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Product details
Overview
LTC3877IUK#PBF from Analog Devices (formerly Linear Technology) is a dual-phase, constant-frequency, current-mode synchronous step-down controller with VID voltage programming and ultra-low-value DCR current sensing. It delivers precise 0.6V–1.23V output (6-bit parallel VID), supports up to 60A per phase, achieves 40ns minimum on-time, and operates across 4.5V–38V input for high-efficiency FPGA and processor core power supplies.
For engineers reviewing the LTC3877IUK#PBF datasheet, LTC3877IUK#PBF pinout, LTC3877IUK#PBF application, or LTC3877IUK#PBF equivalent, key selection considerations include dual-phase current sharing accuracy (≤5% mismatch), ±0.5% reference voltage tolerance, DCR temperature compensation via ITEMP pin, remote differential sensing on both channels, and phase-lockable 250kHz–1MHz operation with programmable channel phasing.
Technical Context
The LTC3877IUK#PBF implements a proprietary current-sense architecture that amplifies low-amplitude DCR signals by 5× using SNSD+/SNSA+ inputs, enabling accurate sensing with inductors as low as 0.32mΩ. Its dual error amplifiers (EA1/EA2) drive ITH1/ITH2 pins to control peak current, while integrated differential amplifiers (DIFFAMP1/DIFFAMP2) provide remote VOUT sensing with ±1% total regulation over temperature.
It features independent channel configuration via CHL_SEL pin: when asserted, it operates as a dual-phase single-output regulator with VID-programmable output; when grounded, channels operate independently with Channel 1 VID-enabled and Channel 2 resistor-set. The MODE/PLLIN pin selects Burst Mode, Pulse-Skip, or Forced Continuous Mode and accepts external synchronization clocks.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V - supports wide-input industrial and server rails without pre-regulation. |
| Output Voltage Range (VID) | 0.6V to 1.23V in 10mV steps - enables precise core voltage scaling for modern FPGAs and CPUs. |
| Min On-Time | 40ns - permits high-frequency operation (up to 1MHz) even at high step-down ratios (e.g., 12V→0.9V). |
| Current Sharing Accuracy | ≤5% max mismatch between phases - ensures balanced load distribution in multi-phase designs. |
| Reference Voltage Accuracy | ±0.5% over –40°C to 125°C - guarantees tight output regulation across full industrial temperature range. |
| DCR Temp Compensation | Programmable via ITEMP pin with 29–31μA current - actively corrects for inductor resistance drift over temperature. |
| Phase-Lockable Frequency | 250kHz to 1MHz - allows synchronization to system clock or other controllers to reduce EMI. |
Pinout & Package
Package: 44-lead (7mm × 7mm) plastic QFN with exposed thermal pad (Pin 45 = SGND/PGND), rated for –40°C to 125°C junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SNSA1+, SNSA2+ | AC current sense comparator (+) input | Accepts amplified ripple voltage from DCR network; enables low-noise sensing with ultra-low-DCR inductors. |
| SNSD1+, SNSD2+ | DC current sense comparator (+) input | Configures current limit scaling (5× increase when grounded); sets five programmable threshold levels via ILIM pin. |
| VOSNS1+, VOSNS1– | Channel 1 remote sense differential amplifier inputs | Connect directly to load point to eliminate PCB IR drop; enables true point-of-load regulation. |
| VFB2+, VFB2– | Channel 2 remote sense differential amplifier inputs | Provides independent high-accuracy feedback path for second phase or independent output. |
| CHL_SEL | Channel configuration control | High = dual-phase single-output mode with VID control; low = independent dual-output mode. |
| VID0–VID5, VID_EN | 6-bit parallel voltage identification interface | Enables dynamic core voltage adjustment during operation; VID_EN activates VID programming post-startup. |
| MODE/PLLIN | Operating mode select & sync input | Configures Burst/Pulse-Skip/Forced CCM; accepts external clock for deterministic phase alignment. |
| PHASMD | Phase offset programming | SGND = 180°, float = 180°, INTVCC = 240° phase shift between channels - optimizes ripple cancellation. |
Key Features
| Feature | Design Value |
|---|---|
| Dual differential remote sensing amplifiers | Enables <1% output voltage error at load point despite PCB trace resistance, critical for sub-1V core rails. |
| Ultra-low DCR current sensing (5× gain) | Supports inductor DCR as low as 0.32mΩ - maximizes efficiency in high-current (>60A) applications. |
| Programmable current limit with temperature compensation | Five ILIM-selectable thresholds + ITEMP-based DCR drift correction - maintains consistent OCP across –40°C to 125°C. |
| Adjustable soft-start and tracking | TK/SS1/TK/SS2 pins support independent ramp control or master-slave voltage sequencing - prevents inrush and ensures safe power-up of multi-rail systems. |
| Multi-IC PolyPhase operation (up to 12 phases) | CLKOUT and PHASMD pins enable precise inter-device phasing - reduces input/output capacitor requirements in high-power systems. |
Applications
| FPGA Core Power Supply | Server CPU VRM |
|---|---|
Use Scenario: Delivering dynamically scaled 0.6V–1.2V core voltage to Xilinx UltraScale+ or Intel Stratix 10 FPGAs under rapid load transients up to 40A/µs. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller providing tightly regulated, low-noise, fast-transient core power with VID-based voltage margining. Use Value: 40ns min on-time and 5% current mismatch ensure stable 1MHz operation at 12V→0.9V conversion with <1% output deviation during 0–60A load steps. |
Use Scenario: High-density 2-phase or 4-phase (via multiple LTC3877IUK#PBF) VRM powering AMD EPYC or Intel Xeon Scalable processors in 1U rack servers. IC Role / Device Role / Timing Role: Phase-configurable controller supporting interleaved operation, remote sensing, and system-level clock synchronization via MODE/PLLIN. Use Value: Integrated DCR temperature compensation and ±0.5% reference accuracy maintain ±1% total output regulation across –40°C to 125°C ambient, meeting VR14/IMVP9 spec limits. |
| Industrial PLC Power Module | AI Accelerator Board Power |
Use Scenario: Providing robust 3.3V or 5V auxiliary rail with independent channel operation (CHL_SEL = low) for I/O and communication subsystems in harsh industrial environments. IC Role / Device Role / Timing Role: Dual-channel controller operating in independent mode, leveraging PGOOD1/PGOOD2 for fault isolation and redundant monitoring. Use Value: Dual power-good outputs with 50µs delay and 235µs blanking during VID transitions ensure reliable system-level power sequencing and fault reporting. |
Use Scenario: Generating tightly tracked 0.8V GPU core and 1.2V memory rails on NVIDIA A100 or AMD MI250X accelerator cards requiring coincident voltage ramping. IC Role / Device Role / Timing Role: Master-slave tracking controller using TK/SS1/TK/SS2 pins to synchronize voltage ramps across multiple output domains. Use Value: Adjustable soft-start current (1.25µA) and external RC networks enable precise <1% tracking accuracy between rails during power-up and VID transitions. |
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 |
|---|---|---|---|
| MP2960GQ-Z | Fixed 600kHz frequency; no VID interface; requires external DAC for programmable output; lacks DCR temperature compensation. | Best suited for cost-sensitive, fixed-voltage applications where dynamic voltage scaling is unnecessary. | Select MP2960GQ-Z only when VID control, DCR temp compensation, and sub-1V accuracy are not required. |
| ISL95852IRZ-T | Supports 3-phase operation natively; includes integrated MOSFET drivers with higher gate drive strength; no CLKOUT or PHASMD for multi-chip synchronization. | Ideal for compact 3-phase VRMs in space-constrained client platforms, but less flexible for scalable PolyPhase expansion. | Choose ISL95852IRZ-T for 3-phase-only designs needing higher integration; retain LTC3877IUK#PBF for expandable 2–12 phase systems with precise phasing control. |
Compared with MP2960GQ-Z and ISL95852IRZ-T, the LTC3877IUK#PBF uniquely combines VID programmability, DCR temperature compensation, and configurable 2–12 phase PolyPhase capability - making it the only option supporting dynamic core voltage scaling with guaranteed ±1% regulation across full industrial temperature range in multi-controller systems.
Availability
LTC3877IUK#PBF is available at Aetrix Electronics and suitable for FPGA core power, server CPU VRMs, and industrial PLC power modules requiring stable component supply, long-term lifecycle support, and guaranteed –40°C to 125°C operation.
Supply support for LTC3877IUK#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 high-performance power management portfolio with rigorous automotive- and industrial-grade qualification.
The LTC3877IUK#PBF belongs to Linear's PolyPhase® synchronous controller family, engineered specifically for high-current, low-voltage DC/DC conversion in computing, data center, and AI acceleration platforms where efficiency, transient response, and thermal stability are critical.
FAQ
What is the operating temperature range for the LTC3877IUK#PBF?
The LTC3877IUK#PBF is specified for –40°C to 125°C junction temperature and is tested and guaranteed across this full range. Its internal 5.5V LDO (INTVCC), DCR temperature compensation circuitry, and ±0.5% reference voltage accuracy are all validated over –40°C to 125°C, making it suitable for demanding industrial and computing environments where thermal derating is critical. The "I" grade suffix confirms industrial temperature qualification.
How does the LTC3877IUK#PBF achieve accurate current sensing with very low DCR inductors?
The LTC3877IUK#PBF uses a proprietary dual-path current sensing architecture: SNSD+ inputs provide DC gain scaling (up to 5×) while SNSA+ inputs handle AC ripple amplification. This allows reliable sensing with inductors as low as 0.32mΩ, minimizing conduction losses. The ITEMP pin further compensates for DCR drift over temperature, ensuring consistent current limit accuracy across –40°C to 125°C without external thermistors.
Can the LTC3877IUK#PBF be used in single-phase configurations?
Yes, the LTC3877IUK#PBF supports single-phase operation via CHL_SEL pin configuration. When CHL_SEL is grounded, Channel 1 and Channel 2 operate independently - either can be disabled by tying its RUN pin low or configuring its feedback network appropriately. Channel 1 retains full VID functionality, while Channel 2 uses resistor-based feedback, enabling flexible single- or dual-output designs without hardware changes.
What is the purpose of the PHASMD pin on the LTC3877IUK#PBF?
The PHASMD pin on the LTC3877IUK#PBF sets the relative phase offset between Channel 1 and Channel 2: tied to SGND or left floating yields 180° phasing (optimal ripple cancellation), while tied to INTVCC yields 240° phasing. It also controls CLKOUT signal phasing, enabling deterministic synchronization when cascading multiple LTC3877IUK#PBF devices in PolyPhase systems up to 12 phases - reducing input/output capacitor stress and EMI.
Does the LTC3877IUK#PBF support output voltage tracking during startup?
Yes, the LTC3877IUK#PBF supports precise voltage tracking via TK/SS1 and TK/SS2 pins. When configured as master-slave, the master channel's TK/SS pin sets the ramp rate using an external capacitor, while the slave channel's TK/SS pin receives a scaled version of the master's feedback voltage through a resistor divider. Internal 1.25µA soft-start currents ensure monotonic, coordinated ramping with <1% tracking error - essential for powering multi-rail ASICs and FPGAs.
LTC3877IUK#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 44-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Controller, 6-bit VID
- Voltage - Input:
- 4.5V ~ 38V
- Number of Outputs:
- 2
- Voltage - Output:
- 0.6V ~ 3.5V, 0.6V ~ 5V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 44-QFN (7x7)
LTC3877IUK#PBF FAQ
1.How can I place an order for LTC3877IUK#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3877IUK#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 LTC3877IUK#PBF reliable?
The price and inventory of LTC3877IUK#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3877IUK#PBF is usually 5 days.
3.What payment methods are accepted for LTC3877IUK#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3877IUK#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3877IUK#PBF?
LTC3877IUK#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3877IUK#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 LTC3877IUK#PBF?
For technical support, including LTC3877IUK#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3877IUK#PBF requirements.
6.How does Aetrix verify that LTC3877IUK#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3877IUK#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 LTC3877IUK#PBF meets industry standards.
7.What is the process for return or replacement of LTC3877IUK#PBF?
All LTC3877IUK#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3877IUK#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 LTC3877IUK#PBF part is unused and in its original packaging.
Return procedure for LTC3877IUK#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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