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Analog Devices Inc. LTC3879IUD#TRPBF
- Part No.:
- LTC3879IUD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LTC3879IUD#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,669
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Product details
Overview
LTC3879IUD#TRPBF 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 voltages from 4V to 38V with output down to 0.6V. It enables high step-down ratios in communications infrastructure and embedded computing applications.
For engineers reviewing the LTC3879IUD#TRPBF datasheet, LTC3879IUD#TRPBF pinout, LTC3879IUD#TRPBF application, or LTC3879IUD#TRPBF equivalent, key selection criteria include its No RSENSE™ architecture, programmable current limit with foldback, dual N-channel MOSFET drive capability, and support for pre-biased soft-start - all critical for high-efficiency, high-density DC/DC converter design.
Technical Context
The LTC3879IUD#TRPBF implements constant-on-time valley current mode control, eliminating need for slope compensation or external current-sense resistors. Its architecture enables stable operation with low-ESR ceramic output capacitors and supports both forced continuous and discontinuous conduction modes via the MODE pin.
It uses the bottom MOSFET's RDS(ON) for valley current sensing, with maximum VDS threshold programmable via VRNG pin (0.2V–2V), yielding typical valley sense thresholds of 30mV (VRNG = SGND) or 75mV (VRNG = INTVCC). The ITH pin serves as both error amplifier output and current limit threshold control point (0V–2.4V range).
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% at 0.6V - enables precise regulation of low-voltage outputs (e.g., 1.2V, 1.8V, 3.3V) with minimal drift over temperature. |
| Min On-Time | 43ns - allows high step-down ratios (e.g., 24V→1.2V at 400kHz) without pulse-skipping or instability. |
| Switching Frequency | Programmable via external RON - provides pseudo-fixed frequency operation compensated for VIN variation. |
| Current Limit | Programmable with foldback - protects against short-circuit faults by progressively reducing current setpoint when VOUT drops below 50% regulation. |
| Package | 16-pin 3mm × 3mm QFN - thermally enhanced layout with exposed pad (SGND) for improved power dissipation (θJA = 68°C/W). |
| Operating Temp | –40°C to +85°C - qualified for industrial and embedded computing environments. |
Pinout & Package
Package: 16-lead (3mm × 3mm) plastic QFN with exposed thermal pad (Pin 17 = SGND, must be soldered to PCB).
| 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 - supports pre-biased start-up. |
| PGOOD (2) | Open-drain power-good monitor | Asserts low when VFB deviates >±10% from 0.6V - provides system-level fault signaling with 12μs delay. |
| VRNG (3) | VDS sense range select | Sets max valley current sense threshold: 0.133×VRNG (e.g., 30mV at SGND, 75mV at INTVCC) - enables MOSFET RDS(ON) optimization. |
| MODE (4) | Conduction mode control | INTVCC = DCM (light-load efficiency); SGND = forced CCM (low-noise, predictable EMI) - selectable per system requirement. |
| ITH (5) | Error amp output / current limit threshold | 0V–2.4V range controls valley current trip point and loop compensation - direct interface to RC network for stability tuning. |
| SGND (6) | Signal ground reference | Reference for all analog circuitry; must connect to PGND at single point to avoid noise coupling into feedback path. |
| ION (7) | On-time current input | Resistor from VIN sets one-shot timer current - determines switching frequency and provides VIN compensation. |
| VFB (8) | Feedback input | Connects to resistor divider from VOUT; regulates to 0.6V reference - high-impedance (±50nA) input minimizes divider current error. |
| RUN (9) | Enable/shutdown control | 1.5V threshold: <0.7V = micropower shutdown (18μA), 0.7–1.5V = bias-on/no-switching, >1.5V = full operation - supports sequencing. |
| VIN (10) | Main input supply | 4V–38V input rail; requires local RC filter to PGND for noise immunity - powers internal circuits and gate drivers. |
| INTVCC (11) | 5.3V internal regulator output | Supplies TG/BG drivers and logic; requires ≥1μF X5R/X7R ceramic decoupling to PGND - dropout <200mV at 50mA load. |
| BG (12) | Bottom gate driver | Drives synchronous N-MOSFET source-to-PGND; 0.7Ω pull-down / 2.5Ω pull-up - optimized for fast turn-off to prevent shoot-through. |
| PGND (13) | Power ground return | High-current return path for bottom MOSFET, CIN, and CINTVCC - must be low-inductance connection near MOSFET source. |
| SW (14) | Switch node | Connects to inductor, bottom MOSFET drain, and bootstrap capacitor negative terminal - swings from –0.3V to VIN. |
| TG (15) | Top gate driver | Drives top N-MOSFET source-to-SW; 1.2Ω pull-down / 2.5Ω pull-up - supports bootstrap operation up to 38V input. |
| BOOST (16) | Bootstrap supply | Connects to bootstrap capacitor positive terminal - floats with SW to enable high-side N-MOSFET drive above VIN. |
Key Features
| Feature | Design Value |
|---|---|
| No RSENSE™ valley current sensing | Eliminates power loss and board space of external sense resistor; uses bottom MOSFET RDS(ON) - reduces BOM count and improves efficiency at high currents. |
| Adjustable output voltage soft-start or tracking | Capacitor on TRACK/SS sets monotonic ramp time; resistor divider enables precise rail sequencing (e.g., 1.2V tracking 1.8V) - prevents inrush and ensures safe power-up. |
| Programmable current limit with foldback | Current threshold set by ITH voltage; folds back under severe overload (VOUT <50% regulation) - protects MOSFETs and inductor during short-circuit events. |
| Dual N-channel MOSFET synchronous drive | Integrated 5.3V gate drivers with matched rise/fall times (<20ns) and dead-time control (15ns) - enables efficient, shoot-through-free operation up to 400kHz. |
| Stable with low-ESR ceramic output capacitors | Valley current mode eliminates need for ESR-based zero - supports compact, high-reliability ceramic COUT instead of electrolytic/tantalum - reduces size and extends lifetime. |
Applications
| Telecom Power Supply | Server VRM Core |
|---|---|
Use Scenario: 48V intermediate bus conversion to 12V/5V/3.3V rails in 1RU telecom chassis with strict EMI limits. IC Role / Device Role / Timing Role: Primary step-down controller managing high-current POL converters with forced CCM (MODE = SGND) for deterministic switching frequency. Use Value: 43ns min on-time enables 48V→3.3V conversion at 400kHz; programmable frequency avoids sensitive RF bands; PGOOD enables hot-swap controller interlock. | Use Scenario: CPU/GPU core voltage regulation in data center servers requiring sub-1V outputs with <10mV ripple and <10μs transient recovery. IC Role / Device Role / Timing Role: High-bandwidth valley current mode controller delivering fast load-step response (Figure G02/G03) and pre-biased start-up for multi-rail sequencing. Use Value: Extremely fast transient response (±10A steps in <5μs) maintains VDD within spec; TRACK/SS enables coordinated ramp with memory I/O rails. |
| Industrial PLC I/O Module | Networking Switch ASIC Supply |
Use Scenario: Field-powered 24V input conversion to isolated 5V/3.3V for digital I/O and sensor interfaces in harsh factory environments. IC Role / Device Role / Timing Role: Robust controller operating across –40°C to +85°C with wide VIN range and integrated OVP/UVLO - manages unregulated industrial input. Use Value: ±1% 0.6V reference ensures stable low-voltage rails; output overvoltage protection (OVP) safeguards downstream logic; QFN package withstands thermal cycling. | Use Scenario: Compact 12V→0.85V conversion for high-speed switch ASICs in 10G/25G Ethernet line cards with space-constrained PCB layouts. IC Role / Device Role / Timing Role: High-efficiency synchronous buck controller using ceramic output caps and low-RDS(ON) MOSFETs - delivers >90% efficiency at 15A load. Use Value: Stable with low-ESR ceramics reduces footprint vs. electrolytics; 3mm×3mm QFN saves board area; adjustable soft-start prevents ASIC latch-up during power-up. |
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#TRPBF | Wider VIN range (4.5V–60V); integrated LDO for bias; no VRNG pin - fixed 50mV valley sense threshold. | Preferred for 48V telecom or automotive applications where input exceeds 38V; lacks VRNG flexibility for MOSFET optimization. | Select LTC3891 when input >38V is required or integrated bias simplifies design; not drop-in due to different pinout and sense architecture. |
| MP2918GL-Z | Lower IQ (1.2mA vs 1.35mA typ); fixed 500kHz frequency; no TRACK/SS or VRNG pins - simplified feature set. | Suitable for cost-sensitive, fixed-frequency applications where soft-start tracking and MOSFET VDS optimization are unnecessary. | Choose MP2918 for basic POL needs with smaller footprint (QFN-12); lacks LTC3879IUD#TRPBF's precision reference, foldback current limit, and transient performance. |
Compared with LTC3891EMSE#TRPBF and MP2918GL-Z, the LTC3879IUD#TRPBF offers superior flexibility in valley current threshold programming (VRNG), faster transient response, and tighter reference accuracy - making it optimal for high-performance, thermally constrained, or multi-rail sequenced systems where design margin and reliability are critical.
Availability
LTC3879IUD#TRPBF is available at Aetrix Electronics and suitable for distributed power systems, embedded computing platforms, and communications infrastructure requiring stable component supply, extended temperature operation, and high-efficiency DC/DC conversion.
Supply support for LTC3879IUD#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 legacy of high-performance power management ICs with rigorous qualification and long-term product support.
The LTC3879IUD#TRPBF belongs to Linear's high-frequency synchronous buck controller family, designed specifically for fast-transient, high-step-down-ratio applications in space-constrained and thermally demanding environments.
FAQ
What is the minimum on-time specification for the LTC3879IUD#TRPBF and why does it matter?
The LTC3879IUD#TRPBF has a guaranteed minimum on-time of 43ns. This parameter directly enables high step-down ratio conversions - for example, generating 1.2V from a 24V input at 400kHz - without pulse-skipping or instability. Shorter on-times allow higher frequency operation while maintaining regulation, which is essential for compact, high-density power supplies in networking and computing equipment using the LTC3879IUD#TRPBF.
How does the VRNG pin affect current sensing in the LTC3879IUD#TRPBF?
The VRNG pin on the LTC3879IUD#TRPBF sets the maximum allowable valley current sense voltage as 0.133×VRNG. When tied to SGND (0V), the typical valley sense threshold is 30mV; when tied to INTVCC (~5.3V), it rises to ~75mV. This allows designers to match the controller's sensitivity to the RDS(ON) of their selected bottom MOSFET - optimizing signal-to-noise ratio and minimizing conduction losses across varying loads and temperatures in the LTC3879IUD#TRPBF application.
Can the LTC3879IUD#TRPBF start up into a pre-biased output, and how is this enabled?
Yes, the LTC3879IUD#TRPBF supports smooth start-up into a pre-biased output. This is enabled by the TRACK/SS pin: when held below 0.6V during startup, the controller regulates VFB to the TRACK/SS voltage rather than the internal 0.6V reference. As the TRACK/SS voltage ramps (e.g., via capacitor or external rail), the output follows - preventing reverse current flow and ensuring controlled ramp-up even when the output capacitor is already charged, a critical capability in redundant or hot-swap LTC3879IUD#TRPBF designs.
What is the purpose of the MODE pin on the LTC3879IUD#TRPBF, and how does it affect efficiency?
The MODE pin on the LTC3879IUD#TRPBF selects between discontinuous conduction mode (DCM) and forced continuous conduction mode (CCM). Tying MODE to INTVCC enables DCM at light loads - reducing switching losses and improving light-load efficiency. Tying MODE to SGND forces CCM - providing predictable EMI profile and lower output ripple but with reduced light-load efficiency. This dual-mode capability allows system designers to optimize the LTC3879IUD#TRPBF for either efficiency or noise requirements depending on operational load profile.
Does the LTC3879IUD#TRPBF include output overvoltage protection, and how does it function?
Yes, the LTC3879IUD#TRPBF includes dedicated output overvoltage protection (OVP). If the feedback voltage (VFB) rises above +10% of 0.6V (i.e., >0.66V), the controller immediately disables both top and bottom gate drivers (TG and BG) to halt switching and protect downstream components. Recovery requires cycling the RUN pin or removing the fault condition. This hardware-based OVP operates independently of the control loop and is active across the full operating temperature range - a critical safety feature in the LTC3879IUD#TRPBF for mission-critical power systems.
LTC3879IUD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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-QFN (3x3)
LTC3879IUD#TRPBF FAQ
1.How can I place an order for LTC3879IUD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3879IUD#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 LTC3879IUD#TRPBF reliable?
The price and inventory of LTC3879IUD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3879IUD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3879IUD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3879IUD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3879IUD#TRPBF?
LTC3879IUD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3879IUD#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 LTC3879IUD#TRPBF?
For technical support, including LTC3879IUD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3879IUD#TRPBF requirements.
6.How does Aetrix verify that LTC3879IUD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3879IUD#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 LTC3879IUD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3879IUD#TRPBF?
All LTC3879IUD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3879IUD#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 LTC3879IUD#TRPBF part is unused and in its original packaging.
Return procedure for LTC3879IUD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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