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Analog Devices Inc. LTC3875EUH#PBF
- Part No.:
- LTC3875EUH#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 40-WFQFN Exposed Pad
- Datasheet:
-
LTC3875EUH#PBF.pdf
- Description:
- IC REG CTRLR BUCK 40QFN
- Quantity:
- Payment:
- Shipping:
Inventory:160
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Product details
Overview
LTC3875EUH#PBF from Analog Devices (formerly Linear Technology) is a dual-output, 2-phase synchronous step-down DC/DC controller driving all-N-channel MOSFET stages. It enables high-efficiency, high-current regulation (e.g., 1.2V/60A) using low-DCR inductor sensing with ±0.5% 0.6V reference accuracy, 4.5V–38V input range, and programmable 250kHz–720kHz switching frequency - deployed in telecom power systems and server VRMs.
For engineers reviewing the LTC3875EUH#PBF datasheet, LTC3875EUH#PBF pinout, LTC3875EUH#PBF application, or LTC3875EUH#PBF equivalent, key selection criteria include dual-phase thermal balancing, DCR temperature compensation for precision current limiting, true remote differential sensing per channel, and phase-lockable clock output supporting up to 12-phase parallel operation.
Technical Context
The LTC3875EUH#PBF implements dual independent current-mode control loops with 180° inter-phase timing to reduce input ripple and EMI. Each channel features dedicated SNSA+/SNS– (AC) and SNSD+/SNS– (DC) sense inputs, enabling low-DCR inductor current measurement with 5× signal gain and programmable 10mV–30mV threshold via ILIM.
Its architecture integrates dual remote-sense differential amplifiers (VOSNS1+/VOSNS1–, VOSNS2+/VOSNS2–), per-channel thermal compensation (TCOMP1/TCOMP2), and a shared TAVG node for multi-IC thermal balancing. The device supports forced CCM, Burst Mode, or pulse-skipping via MODE/PLLIN and includes internal 5.5V INTVCC regulation with EXTVCC bypass capability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V - supports wide industrial and telecom bus voltages including 12V, 24V, and 48V intermediate rails. |
| Output Voltage Accuracy | ±0.5% at 0.6V reference - ensures tight regulation across 0.6V–3.5V range with low-DCR sensing, critical for CPU/GPU core supplies. |
| Switching Frequency | 250kHz to 720kHz (programmable via FREQ pin) - enables optimization of size vs. efficiency; supports synchronization across multiple phases. |
| Current Sense Threshold | 10mV to 30mV (5 levels, set by ILIM) - allows precise foldback current limiting with low-DCR inductors (e.g., 0.32mΩ), minimizing power loss. |
| Thermal Compensation | DCR temperature coefficient compensation via TCOMP1/TCOMP2 pins - maintains accurate current limit over –40°C to 125°C junction range. |
| Package | 40-lead 5mm × 5mm QFN (UH), 0.4mm pitch - compact footprint with exposed PGND pad for thermal management in high-power density designs. |
| Remote Sensing | Dual true differential amplifiers (VOSNS1±, VOSNS2±) - rejects PCB trace IR drop, enabling accurate load-point voltage regulation. |
Pinout & Package
Package: 40-lead (5mm × 5mm) plastic QFN (UH), 0.4mm pitch, exposed SGND/PGND pad (Pin 41) requiring PCB soldering for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| TK/SS1 (1), TK/SS2 (8) | Soft-start & tracking input | Internal 1.25µA current charges external capacitor to ramp output voltage; enables coordinated startup with other rails. |
| VOSNS1+ (2), VOSNS2+ (6) | Positive remote sense input | Connects to top of output divider; differential pair rejects common-mode noise and PCB resistance error. |
| VOSNS1– (3), VOSNS2– (7) | Negative remote sense input | Must connect to load-side ground point - not local IC ground - to enable true Kelvin sensing. |
| ITH1 (4), ITH2 (5) | Error amplifier output / current threshold | Voltage sets peak inductor current; used for loop compensation and current limit programming. |
| FREQ (15) | Oscillator programming | 10µA sink current - resistor to ground sets frequency from 250kHz to 720kHz; also accepts DC voltage input. |
| PGOOD (19) | Power-good open-drain output | Asserts low when either output deviates >±7.5% from target for >20µs - enables system sequencing and fault reporting. |
| TG1 (29), TG2 (21) | Top gate driver outputs | Floating drivers with INTVCC swing referenced to SW node - drive N-channel high-side MOSFET gates. |
| BG1 (27), BG2 (23) | Bottom gate driver outputs | Ground-referenced drivers - switch N-channel low-side MOSFETs with 1.5Ω RDS(ON) pull-down. |
| CLKOUT (31) | Phase-programmable clock output | Outputs synchronized clock with 60°/90°/120° phase shift (set by PHASMD) for multi-controller interleaving. |
| SGND/PGND (41) | Signal & power ground | Exposed pad - must be soldered to large PCB copper area for thermal dissipation and low-impedance return path. |
Key Features
| Feature | Design Value |
|---|---|
| Dual 180° phased controllers | Reduces RMS input capacitor current by ~30% and lowers conducted EMI vs. single-phase design. |
| Low-DCR current sensing with 5× gain | Enables use of sub-1mΩ inductors without external op-amps - improves efficiency and thermal performance at >40A loads. |
| Per-channel DCR temperature compensation | Compensates inductor DCR drift using external NTC thermistors on TCOMP1/TCOMP2 - maintains ±5% current limit accuracy over temperature. |
| Thermal balancing (ENTMPB enabled) | Adjusts per-phase current sharing across multiple LTC3875s or parallel phases - equalizes thermal stress and extends system lifetime. |
| Programmable fast transient response (IFAST) | Channel 2 only - reduces output voltage droop during sudden load steps by pre-emptively increasing duty cycle. |
| Three operating modes (MODE/PLLIN) | Select forced CCM (low noise), Burst Mode (light-load efficiency), or pulse-skipping (transient response) - no external components needed. |
Applications
| Telecom Base Station Power | Server CPU Core Supply |
|---|---|
Use Scenario: High-density 48V-to-1.2V conversion for ASIC/FPGA in 5G radio units with strict thermal limits and <100µs transient response requirements. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing two parallel 30A phases with interleaved timing and thermal balancing. Use Value: Achieves >92% efficiency at 60A with 0.32mΩ DCR inductors; DCR temperature compensation prevents current runaway at elevated ambient temperatures. |
Use Scenario: Precision 1.0V–1.8V core supply for x86 processors in rack-mounted servers, requiring ±0.5% regulation and coordinated power-up sequencing. IC Role / Device Role / Timing Role: Dual-output controller delivering independent, tracked voltages (e.g., VDD/VDDQ) with soft-start ramping and PGOOD monitoring. Use Value: Dual remote-sense differential amplifiers eliminate PCB IR drop errors; 0.6V reference tolerance ensures compliance with JEDEC DDR5 core voltage specs. |
| Industrial DC Power Distribution | High-Performance Test Equipment |
Use Scenario: Modular 24V-to-3.3V/5V power subsystem in programmable logic controllers (PLCs), operating continuously at –40°C to +85°C. IC Role / Device Role / Timing Role: Dual-output controller powering I/O and communication modules with independent RUN pin control and thermal shutdown. Use Value: Wide –40°C to 125°C operating range and guaranteed specifications over full temp range ensure reliability; UVLO hysteresis prevents brownout oscillation. |
Use Scenario: Low-noise, low-ripple analog supply for high-speed ADC/DAC signal chains in automated test equipment (ATE), where PSRR and stability are critical. IC Role / Device Role / Timing Role: Dual-phase controller operating in forced CCM mode with fixed 500kHz frequency and external clock sync for deterministic timing. Use Value: Very low output voltage ripple (<10mV p-p) achieved via precise current-mode control and optimized loop compensation - preserves SNR in 16-bit+ converters. |
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 |
|---|---|---|---|
| LTC3873EUH#PBF | Single-output, non-phase-lockable, no DCR temperature compensation or thermal balancing; same 40-pin UH package. | Suitable for simpler, lower-cost single-rail designs without multi-phase coordination or precision thermal management. | Select when only one regulated output is required and thermal derating margins are sufficient without active balancing. |
| ISL95812IRZ-T7A | Single-chip dual-phase controller with integrated MOSFET drivers but no DCR temperature compensation; supports Intel VR12.5/VR13 protocols. | Targeted at client CPU VRMs with SMBus interface and dynamic VID; lacks independent remote sensing per channel. | Choose for Intel-compatible notebook/desktop platforms requiring VID-based voltage scaling and integrated drivers - not for custom industrial telecom rails. |
Compared with LTC3875EUH#PBF, LTC3873EUH#PBF reduces feature count and cost for single-output needs, while ISL95812IRZ-T7A trades analog flexibility for digital protocol compliance - neither offers the same combination of dual independent remote sensing, DCR thermal compensation, and scalable multi-phase synchronization.
Availability
LTC3875EUH#PBF is available at Aetrix Electronics and suitable for telecom base station power, server CPU core supplies, and industrial DC distribution systems requiring stable component supply, long-term lifecycle support, and guaranteed parametric performance over –40°C to 125°C.
Supply support for LTC3875EUH#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 LTC3875EUH#PBF belongs to Linear's PolyPhase® synchronous controller family, designed specifically for high-current, multi-phase DC/DC conversion in space-constrained, thermally demanding infrastructure equipment.
FAQ
What is the maximum supported switching frequency for the LTC3875EUH#PBF?
The LTC3875EUH#PBF supports a programmable switching frequency range from 250kHz to 720kHz, set via a resistor on the FREQ pin (10µA sink current). At VFREQ = 2.4V or higher, the nominal frequency reaches 720kHz - verified across –40°C to 125°C. This enables optimization of magnetic size versus conduction losses in high-current applications like server VRMs.
Does the LTC3875EUH#PBF support true remote sensing on both outputs simultaneously?
Yes, the LTC3875EUH#PBF integrates two independent remote-sense differential amplifiers: VOSNS1+/VOSNS1– for Channel 1 and VOSNS2+/VOSNS2– for Channel 2. Each pair must be connected directly across the load (not at the converter output) to reject PCB trace resistance - enabling accurate regulation at the point-of-load for both outputs without shared sensing errors.
How does the thermal balancing function work in the LTC3875EUH#PBF?
When ENTMPB is grounded, the LTC3875EUH#PBF enables thermal balancing by mirroring currents from TCOMP1 and TCOMP2 onto the TAVG pin. External resistors on TRSET1/TRSET2 convert sensed temperature voltages into balancing currents. The summed current adjusts per-phase ITH thresholds to equalize thermal stress across parallel channels or multiple LTC3875EUH#PBF ICs - validated in multichip 12-phase configurations.
Can the LTC3875EUH#PBF operate with only one output enabled?
Yes, the LTC3875EUH#PBF supports independent channel control: pulling RUN1 below 1.14V disables Channel 1 while Channel 2 remains active, and vice versa. Both channels shut down only when both RUN pins fall below threshold. This allows flexible power sequencing, partial-system operation, and fault isolation - confirmed in the Absolute Maximum Ratings and Operation sections of the datasheet.
What is the purpose of the SNSA+ and SNSD+ pins on the LTC3875EUH#PBF?
SNSA+ (AC sense) and SNSD+ (DC sense) provide separate inputs for enhanced current measurement: SNSA+/SNS– detects AC ripple for fast transient response, while SNSD+/SNS– provides DC current for accurate average current limiting. When used together with proper RC network, they enable 5× gain for low-DCR inductors - a key differentiator of the LTC3875EUH#PBF versus standard current-mode controllers.
LTC3875EUH#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 40-WFQFN Exposed Pad
- Packaging:
- Tube
- 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 ~ 720kHz
- Duty Cycle (Max):
- -
- 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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 40-QFN (5x5)
LTC3875EUH#PBF FAQ
1.How can I place an order for LTC3875EUH#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3875EUH#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 LTC3875EUH#PBF reliable?
The price and inventory of LTC3875EUH#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3875EUH#PBF is usually 5 days.
3.What payment methods are accepted for LTC3875EUH#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3875EUH#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3875EUH#PBF?
LTC3875EUH#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3875EUH#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 LTC3875EUH#PBF?
For technical support, including LTC3875EUH#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3875EUH#PBF requirements.
6.How does Aetrix verify that LTC3875EUH#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3875EUH#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 LTC3875EUH#PBF meets industry standards.
7.What is the process for return or replacement of LTC3875EUH#PBF?
All LTC3875EUH#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3875EUH#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 LTC3875EUH#PBF part is unused and in its original packaging.
Return procedure for LTC3875EUH#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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