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Analog Devices Inc. LTC3876EFE#PBF
- Part No.:
- LTC3876EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Special Purpose Regulators
- Package:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3876EFE#PBF.pdf
- Description:
- IC REG CTRLR DDR 2OUT 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,782
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Product details
Overview
LTC3876EFE#PBF from Analog Devices (formerly Linear Technology) is a dual-channel synchronous DC/DC controller IC designed specifically for DDR memory power delivery, integrating VDDQ and VTT regulation with differential sensing and a precision ±50mA linear VTTR reference. It supports DDR1–DDR3 standards, operates from 4.5V to 38V input, delivers VDDQ from 1.0V to 2.5V (±0.67% accuracy), and provides VTT/VTTR from 0.5V to 1.25V with <20mV total DC error. It is used in high-density motherboard memory and server applications requiring tight voltage tracking and fast transient response.
For engineers reviewing the LTC3876EFE#PBF datasheet, LTC3876EFE#PBF pinout, LTC3876EFE#PBF application, or LTC3876EFE#PBF equivalent, key selection considerations include its dual-channel valley current mode control, programmable 200kHz–2MHz switching frequency, differential VDDQ sensing architecture, ±50mA VTTR load capability, and thermal performance in the 38-lead TSSOP package with exposed pad.
Technical Context
The LTC3876EFE#PBF implements two independent controlled-on-time, valley current mode controllers-one for VDDQ (Channel 1) and one for VTT (Channel 2)-with separate ITH compensation nodes, differential sense amplifiers, and programmable current-sense voltage ranges via VRNG pins. Its VDDQ regulation uses a differential feedback loop (VOUTSENSE1+ / VOUTSENSE1−) referenced to 0.6V, while VTTR is derived as 0.5 × (VDDQSNS − VOUTSENSE1−) with Kelvin-sensed output and ±1.2% regulation over temperature.
It features synchronized dual-phase operation via MODE/PLLIN and CLKOUT, configurable phase offset (0°/180°/240°), forced continuous or discontinuous mode per channel, and integrated protection including PGOOD monitoring, overvoltage lockout (±5% to ±10%), current limit foldback, and short-circuit recovery-enabling robust DDR termination in high-current, low-voltage systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V - supports wide-range industrial/server inputs including 5V, 12V, and 24V rails without pre-regulation. |
| VDDQ Output Range & Accuracy | 1.0V to 2.5V, ±0.67% - enables precise compliance with DDR1/2/3 VDDQ specs and future low-voltage DDRX standards. |
| VTT/VTTR Output Range & Error | 0.5V to 1.25V, <20mV total DC error - ensures accurate DDR termination voltage tracking under ±10A load and ±50mA VTTR sourcing/sinking. |
| Switching Frequency | 200kHz to 2MHz, programmable via RT resistor or external clock - allows optimization of size, efficiency, and EMI in space-constrained memory subsystems. |
| Min On/Off Time | tON(MIN) = 30ns, tOFF(MIN) = 90ns - supports high VIN-to-low VOUT conversion (e.g., 12V→1.5V) at high frequencies without pulse-skipping. |
| Package & Thermal | 38-lead TSSOP with exposed PGND pad, θJA = 28°C/W - enables >20A VDDQ and ±10A VTT delivery with manageable board-level thermal design. |
| Current Sensing | RSENSE or DCR sensing, VRNG-programmable range (30mV–120mV) - accommodates low-loss inductor DCR or precision shunt resistors for accurate valley-current control. |
Pinout & Package
Package: 38-lead plastic TSSOP (FE package), 11.9mm × 4.4mm × 1.1mm, exposed thermal pad (Pin 39) soldered to PGND for enhanced thermal performance and noise immunity.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| ITH1 (Pin 14) | Channel 1 error amplifier output & compensation node | Controls VDDQ valley current threshold; 0.8V = zero inductor current; 0–2.4V range enables full-load regulation and stability tuning. |
| VDDQSNS (Pin 6) | VDDQ sense reference for VTTR divider | Provides positive input to internal 210kΩ resistor divider; sets VTTR = 0.5 × (VDDQSNS − VOUTSENSE1−); tied to INTVCC disables VTTR. |
| VTTR (Pin 7) | Buffered VTT reference output | Kelvin-connected, ±50mA capable linear reference; directly drives DDR VREF pin with 1.2% accuracy over temperature and load. |
| MODE/PLLIN (Pin 9) | Mode selection / external clock sync input | SGND = discontinuous VDDQ + forced-continuous VTT; INTVCC = forced-continuous both channels; external clock enables system-wide synchronization. |
| TRACK/SS1 (Pin 15) | VDDQ soft-start and tracking input | Internal 1μA pull-up charges external capacitor; regulates VDDQ to track external supply or ramp smoothly to final setpoint. |
| SENSE1+/SENSE1− (Pins 18/19) | Differential current sense inputs (Channel 1) | Support Kelvin RSENSE or DCR sensing; SENSE− has 500kΩ internal resistor to SGND - critical for accurate valley detection and transient response. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent valley current mode controllers | Enables simultaneous, optimized regulation of VDDQ and VTT with separate compensation, current limits, and soft-start - no cross-coupling or shared instability risks. |
| Differential VDDQ sensing with remote ground (VOUTSENSE1−) | Eliminates PCB IR drop errors in high-current paths; maintains ±0.67% VDDQ accuracy even with 20A load and 10mΩ trace resistance. |
| Integrated ±50mA VTTR linear reference with Kelvin output | Delivers stable DDR VREF without external op-amps or discrete references; 1.2% regulation over –40°C to 125°C ensures JEDEC-compliant memory interface timing. |
| Programmable 200kHz–2MHz switching frequency | Allows trade-off between inductor size (higher fSW) and conduction loss (lower fSW); RT resistor or external clock support simplifies multi-rail synchronization. |
| Asymmetric current sense range (VRNG1/VRNG2) | Per-channel VRNG pins scale max sense voltage from 30mV to 120mV - supports low-RDS(on) MOSFETs or high-accuracy shunts without gain-switching complexity. |
Applications
| Server Memory Subsystem | High-Density Motherboard DDR3 |
|---|---|
|
Use Scenario: Dual-rank DDR3 RDIMM power on 1U/2U rack servers with 12V input and strict thermal envelope. IC Role / Device Role / Timing Role: Primary VDDQ/VTT controller delivering 1.5V/20A and 0.75V/±10A with differential sensing and VTTR tracking. Use Value: Enables single-chip DDR power with <20mV VTT tracking error and fast load-step response (<10μs settling), reducing BOM count and improving signal integrity. |
Use Scenario: Desktop/workstation motherboard supporting DDR3-1600 with 4GB–16GB modules and 5V/12V rail inputs. IC Role / Device Role / Timing Role: Integrated DDR termination controller managing VDDQ regulation and VTT sourcing/sinking during read/write bursts. Use Value: Eliminates need for discrete VTT LDO + VDDQ buck controller; differential sensing maintains VDDQ accuracy across PCB voltage drops up to 25mV. |
| Industrial Embedded Memory Module | Network Equipment DDR Interface |
|
Use Scenario: Fanless industrial PC with extended temperature operation (–40°C to 85°C ambient) and DDR3 SO-DIMM. IC Role / Device Role / Timing Role: DDR power controller providing VDDQ/VTT with guaranteed ±0.67% accuracy and VTTR load regulation over full temp range. Use Value: Ensures reliable memory initialization and sustained operation across temperature extremes without recalibration or margining. |
Use Scenario: 10G Ethernet line card with DDR3 buffer memory interfacing FPGA and PHY, powered from 3.3V/12V hybrid supply. IC Role / Device Role / Timing Role: High-precision DDR termination IC synchronizing VDDQ/VTT switching to system clock via MODE/PLLIN input. Use Value: Reduces jitter-sensitive timing violations by aligning VTT switching edges with data strobes using programmable CLKOUT phase (0°/180°/240°). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DDR power controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3876IUHF#PBF | Same silicon, 38-lead QFN (5mm × 7mm) package with θJA = 34°C/W; higher thermal resistance than TSSOP variant. | Better suited for compact layouts where QFN footprint is preferred; requires more aggressive PCB copper pour for equivalent 20A VDDQ performance. | Select when board area is constrained and thermal vias can be deployed under exposed pad; not drop-in due to different land pattern and solder profile. |
| ISL6522CRZ-T | Single-channel DDR controller (VDDQ only); no integrated VTTR reference or VTT controller; requires external VTT LDO and tracking circuitry. | Limited to simpler DDR1/DDR2 designs without stringent VTT sourcing/sinking requirements; lacks differential VDDQ sensing. | Choose only for cost-sensitive, low-current DDR1 applications where VTT is handled separately; not suitable for DDR3 0.75V/±10A or differential-sense requirements. |
Compared with LTC3876IUHF#PBF and ISL6522CRZ-T, the LTC3876EFE#PBF uniquely integrates dual-channel control, differential VDDQ sensing, and ±50mA VTTR in a thermally optimized TSSOP package - making it the only option that meets full JEDEC DDR3 termination specifications without supplemental components.
Availability
LTC3876EFE#PBF is available at Aetrix Electronics and suitable for server memory subsystems, high-density motherboard DDR3 implementations, and industrial embedded memory modules requiring stable component supply, long-term lifecycle support, and guaranteed parametric performance across –40°C to 125°C junction temperature.
Supply support for LTC3876EFE#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and computing markets.
The LTC3876EFE#PBF belongs to Linear's high-efficiency DC/DC controller product line, engineered specifically for demanding DDR memory power architectures requiring precision voltage tracking, fast transient response, and robust fault protection in servers and enterprise infrastructure.
FAQ
What is the primary function of the LTC3876EFE#PBF in DDR memory systems?
The LTC3876EFE#PBF serves as a complete dual-channel DDR power controller, regulating both VDDQ (1.0V–2.5V, up to 20A) and VTT (0.5V–1.25V, ±10A) while providing a precision ±50mA VTTR reference. Its differential VDDQ sensing and Kelvin-connected VTTR output ensure JEDEC-compliant voltage accuracy under dynamic load conditions - a core requirement for stable DDR1/2/3 operation. The LTC3876EFE#PBF eliminates the need for separate VDDQ buck controllers and VTT LDOs in high-performance memory subsystems.
Does the LTC3876EFE#PBF support DDR4 or LPDDR standards?
No, the LTC3876EFE#PBF is explicitly specified for DDR1, DDR2, and DDR3 compatibility in its datasheet and typical applications. It does not support DDR4's 1.2V VDDQ spec with tighter ±25mV tolerance, nor LPDDR's ultra-low voltage (1.1V/0.6V) or command/address termination requirements. Its VDDQ range (1.0V–2.5V) and VTTR tracking architecture are optimized for DDR3's 1.5V/0.75V and DDR2's 1.8V/0.9V operating points - not DDR4's 1.2V/0.6V or LPDDR4's 1.1V/0.6V rails.
How does the differential VDDQ sensing work on the LTC3876EFE#PBF?
The LTC3876EFE#PBF uses dedicated VOUTSENSE1+ and VOUTSENSE1− pins to measure the true differential voltage across the VDDQ output capacitors. VOUTSENSE1− connects to the negative terminal of the output capacitor bank and serves as the remote ground reference for both VDDQ regulation and the internal VTTR resistor divider. This architecture rejects PCB trace IR drop and noise, enabling ±0.67% VDDQ accuracy even with 20A load currents and milliohm-level board resistance - a capability confirmed in the Electrical Characteristics table under VDFB1(REG) and line/load regulation specs.
Can the LTC3876EFE#PBF operate in forced continuous conduction mode (FCCM) on both channels?
Yes, the LTC3876EFE#PBF supports forced continuous conduction mode on both channels by tying the MODE/PLLIN pin to INTVCC. In this configuration, Channel 1 (VDDQ) and Channel 2 (VTT) operate synchronously with fixed frequency and no diode emulation. The datasheet confirms this in the PIN FUNCTIONS section and Figure G10–G12, where PHASMD-controlled phase relationships and FCCM transient waveforms are demonstrated. Discontinuous mode is only enabled on Channel 1 when MODE/PLLIN is grounded - Channel 2 remains forced-continuous regardless of MODE/PLLIN state to maintain VTTR tracking integrity.
What is the purpose of the DTR1 pin on the LTC3876EFE#PBF?
The DTR1 (Detect Load Transient) pin on the LTC3876EFE#PBF reduces VDDQ overshoot during rapid load release (e.g., DDR burst read ending). When load current drops suddenly, the DTR1 voltage falls below half of INTVCC, triggering immediate bottom-gate (BG1) turn-off to accelerate inductor current decay. This feature is validated in Figure G09 (Load Release VTT) and G07 (Load Release VDDQ), showing sub-10μs recovery. To disable DTR1, tie the pin to INTVCC - a design choice confirmed in the PIN FUNCTIONS description on page 11 of the datasheet.
LTC3876EFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Controller, DDR
- Voltage - Input:
- 4.5V ~ 38V
- Number of Outputs:
- 2
- Voltage - Output:
- Adjustable
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-TSSOP-EP
LTC3876EFE#PBF FAQ
1.How can I place an order for LTC3876EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3876EFE#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 LTC3876EFE#PBF reliable?
The price and inventory of LTC3876EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3876EFE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3876EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3876EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3876EFE#PBF?
LTC3876EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3876EFE#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 LTC3876EFE#PBF?
For technical support, including LTC3876EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3876EFE#PBF requirements.
6.How does Aetrix verify that LTC3876EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3876EFE#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 LTC3876EFE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3876EFE#PBF?
All LTC3876EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3876EFE#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 LTC3876EFE#PBF part is unused and in its original packaging.
Return procedure for LTC3876EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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