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Analog Devices Inc. LTC3879EMSE#PBF
- Part No.:
- LTC3879EMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3879EMSE#PBF.pdf
- Description:
- IC REG CTRLR BUCK 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:406
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Product details
Overview
LTC3879EMSE#PBF from Analog Devices (formerly Linear Technology) is a synchronous step-down switching regulator controller optimized for high-frequency operation and fast transient response in distributed power systems. It features valley current mode control without external sense resistor, ±1% 0.6V reference, 43ns minimum on-time, and supports input range 4V–38V with output down to 0.6V. Used in embedded computing power rails requiring tight regulation under dynamic load steps.
For engineers reviewing the LTC3879EMSE#PBF datasheet, LTC3879EMSE#PBF pinout, LTC3879EMSE#PBF application, or LTC3879EMSE#PBF equivalent, key selection criteria include its No RSENSE™ architecture, programmable current limit with foldback, forced continuous/discontinuous mode control, and compatibility with low-ESR ceramic output capacitors in high step-down ratio designs.
Technical Context
The LTC3879EMSE#PBF implements constant-on-time valley current mode control, enabling wide VIN range operation (4V–38V) and stable regulation at very low duty cycles. Its architecture eliminates need for external current-sense resistor or slope compensation while supporting pre-biased output start-up and adjustable soft-start or tracking.
Switching frequency is set via external resistor on ION pin and compensated for VIN variation to maintain line stability. Dual N-channel MOSFET gate drivers provide 2.5Ω pull-up / 1.2Ω pull-down resistance on TG and 2.5Ω/0.7Ω on BG, with <20ns rise/fall times and 15ns synchronous switch timing delays.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports wide industrial and telecom input rails including 5V, 12V, 24V, and 28V systems. |
| Feedback Reference | ±1% 0.6V - enables precise output regulation from 0.6V up to 90% VIN with minimal drift over temperature. |
| Min On-Time | 43ns - allows high step-down ratios (e.g., 24V→1.2V at 400kHz) without pulse-skipping instability. |
| Current Sense Method | No RSENSE™ valley sensing - uses bottom MOSFET RDS(ON) for current measurement, eliminating sense resistor losses and layout complexity. |
| Package | 16-pin MSOP with exposed thermal pad - provides enhanced thermal performance (θJA = 40°C/W) in compact footprint. |
| Operating Temp | –40°C to +85°C - qualified for industrial ambient conditions without derating. |
| PGOOD Accuracy | ±10% window with 2% hysteresis - ensures reliable system-level power sequencing and fault detection. |
Pinout & Package
Package: 16-lead plastic MSOP with exposed SGND pad (Pin 17), thermally enhanced for high-current DC/DC applications.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| TRACK/SS (1) | Soft-start & tracking input | Internal 1μA pull-up; capacitor sets ramp time or resistor divider enables rail tracking during start-up. |
| PGOOD (2) | Open-drain power-good flag | Pulled low when VFB deviates >±10% from 0.6V; 12μs turn-on delay ensures stable regulation before assertion. |
| VRNG (3) | VDS sense range select | Sets max valley current threshold (22–98mV typical) by scaling bottom FET VDS sense voltage via 0.133×VRNG. |
| MODE (4) | Continuous/discontinuous mode control | Tie to SGND for forced CCM; tie to INTVCC for DCM at light loads to improve efficiency. |
| ITH (5) | Error amplifier output & current limit threshold | Voltage (0–2.4V) sets valley current comparator threshold; also serves as compensation node for loop stability. |
| SGND (6) | Signal ground reference | Reference for all small-signal pins; must connect to PGND at single point to avoid noise coupling. |
| ION (7) | On-time programming input | Resistor from VIN sets one-shot timer current; determines switching frequency with VIN compensation. |
| VFB (8) | Feedback input | Connects to resistive divider from VOUT; regulates output by comparing to 0.6V internal reference. |
| RUN (9) | Enable/shutdown control | 1.5V threshold: <0.7V = micropower shutdown (18μA); 0.7–1.5V = bias enabled, no switching; >1.5V = full operation. |
| VIN (10) | Main input supply | Accepts 4–38V; requires RC filter to PGND for noise immunity in noisy environments. |
| INTVCC (11) | Internal 5.3V regulator output | Powers gate drivers and control logic; requires ≥1μF X5R/X7R ceramic decoupling to PGND. |
| BG (12) | Bottom gate driver output | Drives gate of synchronous N-MOSFET between PGND and INTVCC; 0.7Ω pull-down resistance. |
| PGND (13) | Power ground return | Low-impedance return path for bottom FET source, CIN negative, and CINTVCC negative terminals. |
| SW (14) | Switch node | Connects to source of top FET and drain of bottom FET; swings from ~–0.3V to VIN; ties to bootstrap capacitor negative terminal. |
| TG (15) | Top gate driver output | Drives gate of high-side N-MOSFET between SW and BOOST; 2.5Ω pull-up / 1.2Ω pull-down resistance. |
| BOOST (16) | Bootstrap supply | Connects to positive terminal of bootstrap capacitor; floats with SW to enable high-side drive above VIN. |
| Exposed Pad (17) | Thermal & signal ground | Internally connected to SGND; must be soldered to PCB copper for thermal dissipation and noise control. |
Key Features
| Feature | Design Value |
|---|---|
| No RSENSE™ valley current sensing | Eliminates external sense resistor and associated power loss, board space, and layout sensitivity - uses bottom MOSFET RDS(ON) as current sensor. |
| Programmable current limit with foldback | Protects against short-circuits by reducing current limit setpoint when VOUT drops below 50% of regulation - prevents thermal runaway during faults. |
| Adjustable soft-start or tracking | Enables controlled power-up into pre-biased outputs or coordinated sequencing with other rails using external resistor divider on TRACK/SS pin. |
| Dual-mode operation (CCM/DCM) | Forced continuous mode (via MODE=SGND) ensures low-noise operation; discontinuous mode (MODE=INTVCC) improves light-load efficiency. |
| Stable with low-ESR ceramic capacitors | Supports modern high-frequency, low-profile ceramic output caps without requiring added ESR - reduces component count and improves transient response. |
Applications
| Server VR13 Core Power | Industrial PLC I/O Module |
|---|---|
Use Scenario: Providing tightly regulated 1.2V/15A core voltage to Intel Xeon processors in 1U rack servers with rapid load transients up to 10A/μs. IC Role / Device Role / Timing Role: Synchronous step-down controller managing dual N-MOSFET power stage with valley current mode for sub-100ns transient recovery. Use Value: 43ns minimum on-time enables stable 24V→1.2V conversion at 400kHz; No RSENSE™ architecture preserves >92% peak efficiency at full load. | Use Scenario: Generating isolated 3.3V/5A auxiliary rail from 24V field bus in programmable logic controller backplane with strict EMC requirements. IC Role / Device Role / Timing Role: High-efficiency buck controller operating in forced continuous mode (MODE=SGND) to suppress audible switching noise and meet CISPR-22 Class A limits. Use Value: Programmable switching frequency (via ION resistor) allows tuning to avoid sensitive frequency bands; PGOOD output enables safe FPGA configuration sequencing. |
| Telecom Base Station RF PA Bias | Automotive ADAS Camera Module |
Use Scenario: Delivering clean, low-noise 5V/3A bias supply to GaN RF power amplifiers in 5G macro base stations where ripple must stay <5mVpp. IC Role / Device Role / Timing Role: Precision buck controller using ceramic output capacitors and valley current sensing to minimize output impedance across 10Hz–1MHz. Use Value: ±1% 0.6V reference and <0.1% load regulation ensure stable PA gain; adjustable VRNG pin allows optimization for low-RDS(ON) MOSFETs to reduce thermal stress. | Use Scenario: Powering 1.8V image sensor and 3.3V ISP in automotive surround-view camera module with cold-crank (4.5V) and load-dump (38V) survivability. IC Role / Device Role / Timing Role: Wide-input buck controller supporting 4V–38V operation with integrated overvoltage protection and pre-biased start-up capability. Use Value: Input UVLO (3.3V–4.0V) and OVP protect downstream silicon; smooth start-up into pre-biased outputs prevents image corruption during ignition cycling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3891EMSE#PBF | Includes integrated 5V LDO for gate drive; wider VIN range (4.5V–60V); no VRNG pin; fixed 50ns min on-time. | Preferred for higher-input systems (>38V) or where dedicated gate-drive rail simplifies design; lacks VRNG-based current threshold flexibility. | Select when input exceeds 38V or integrated LDO reduces BOM count; not drop-in due to different pinout and control architecture. |
| MP2918GL-Z | Monolithic 30V/12A buck converter (not controller); no external MOSFET support; 0.6V reference; 105°C rating. | Used in space-constrained, lower-current applications where integration outweighs efficiency and thermal management needs. | Choose for simplified layout and lower component count in ≤12A designs; not suitable for high-current or thermally demanding applications requiring discrete FETs. |
Compared with LTC3891EMSE#PBF, the LTC3879EMSE#PBF offers finer current-sense threshold adjustment via VRNG and superior transient response due to shorter 43ns min on-time, while MP2918GL-Z trades external FET flexibility for integration and smaller footprint in mid-power applications.
Availability
LTC3879EMSE#PBF is available at Aetrix Electronics and suitable for server VRMs, industrial PLCs, telecom power supplies, and automotive ADAS modules requiring stable component supply with guaranteed long-term availability.
Supply support for LTC3879EMSE#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 full product support, documentation, and manufacturing continuity for all Linear ICs including the LTC series.
The LTC3879 belongs to Linear's high-performance power controller family designed specifically for high-efficiency, high-transient-response DC/DC conversion in space- and thermally-constrained embedded systems.
FAQ
What is the minimum on-time specification for the LTC3879EMSE#PBF and why does it matter?
The LTC3879EMSE#PBF has a guaranteed minimum on-time of 43ns. This parameter directly determines the lowest achievable output voltage at a given input voltage and switching frequency - for example, enabling stable 24V-to-1.2V conversion at 400kHz. Shorter min on-time prevents pulse-skipping and maintains regulation in high step-down ratio applications common in CPU/GPU core power supplies.
How does the VRNG pin affect current sensing in the LTC3879EMSE#PBF?
The VRNG pin on the LTC3879EMSE#PBF scales the maximum allowable valley current sense threshold as 0.133 × VRNG. With VRNG tied to SGND (0V), the threshold is ~30mV; with VRNG tied to INTVCC (5.3V), it rises to ~75mV. This allows designers to match the controller's current sensing range to the RDS(ON) of selected MOSFETs - critical for accurate current limiting and optimal efficiency across temperature and load.
Can the LTC3879EMSE#PBF start up into a pre-biased output, and how is this enabled?
Yes, the LTC3879EMSE#PBF supports smooth start-up into a pre-biased output. This is enabled by default - the controller monitors the TRACK/SS pin and only begins switching once the feedback voltage (VFB) rises above the internal 0.6V reference. During start-up, the top and bottom MOSFETs remain off until regulation is established, preventing reverse current flow and output voltage overshoot.
What is the purpose of the MODE pin on the LTC3879EMSE#PBF, and how does it affect efficiency?
The MODE pin on the LTC3879EMSE#PBF selects between forced continuous conduction mode (CCM) and discontinuous conduction mode (DCM). When tied to SGND, CCM is enforced - ideal for low-noise, high-current applications. When tied to INTVCC, DCM activates at light loads, reducing switching losses and improving light-load efficiency by allowing inductor current to fall to zero between cycles.
Does the LTC3879EMSE#PBF require an external sense resistor for current monitoring?
No, the LTC3879EMSE#PBF does not require an external sense resistor. It implements No RSENSE™ valley current mode control, using the voltage drop across the bottom N-channel MOSFET's RDS(ON) between SW and PGND pins to measure inductor valley current. This eliminates sense resistor power loss, board area, and layout sensitivity while maintaining accurate current limiting and cycle-by-cycle protection.
LTC3879EMSE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 4V ~ 38V
- Frequency - Switching:
- -
- Duty Cycle (Max):
- -
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LTC3879EMSE#PBF FAQ
1.How can I place an order for LTC3879EMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3879EMSE#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 LTC3879EMSE#PBF reliable?
The price and inventory of LTC3879EMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3879EMSE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3879EMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3879EMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3879EMSE#PBF?
LTC3879EMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3879EMSE#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 LTC3879EMSE#PBF?
For technical support, including LTC3879EMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3879EMSE#PBF requirements.
6.How does Aetrix verify that LTC3879EMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3879EMSE#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 LTC3879EMSE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3879EMSE#PBF?
All LTC3879EMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3879EMSE#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 LTC3879EMSE#PBF part is unused and in its original packaging.
Return procedure for LTC3879EMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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