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Analog Devices Inc. LTC3879EUD#TRPBF
- Part No.:
- LTC3879EUD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LTC3879EUD#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,915
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Product details
Overview
LTC3879EUD#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 no-RSENSE valley current mode control, 4V–38V input range, ±1% 0.6V reference, 43ns minimum on-time, and dual N-channel MOSFET drive - enabling high-efficiency 1.2V/15A conversion in communications infrastructure.
For engineers reviewing the LTC3879EUD#TRPBF datasheet, LTC3879EUD#TRPBF pinout, LTC3879EUD#TRPBF application, or LTC3879EUD#TRPBF equivalent, key selection criteria include its valley current sensing architecture, VRNG-programmable current threshold, forced continuous/discontinuous mode control, and compatibility with low-ESR ceramic output capacitors in compact QFN layouts.
Technical Context
The LTC3879EUD#TRPBF implements constant-on-time valley current mode control without external sense resistors or slope compensation. Its ION pin sets switching frequency via resistor programming, with VIN-compensated timing to maintain line stability across 4V–38V input.
It supports pre-biased soft-start, adjustable output voltage tracking, and programmable current limit with foldback. The MODE pin selects between forced continuous mode (for low-noise applications) and discontinuous mode (for light-load efficiency), while VRNG configures peak VDS sense voltage from 26.6mV to 266mV.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports wide-input industrial and telecom supplies without external regulators. |
| Feedback Reference | 0.6V ±1% - enables precise regulation of low-voltage outputs like 1.2V CPU cores. |
| Min On-Time | 43ns - allows high step-down ratios (e.g., 28V→1.2V at 400kHz) without pulse-skipping instability. |
| Switching Frequency | User-programmable via ION resistor - delivers pseudo-fixed frequency with VIN compensation for stable line regulation. |
| Current Sense Method | No RSENSE valley current mode - uses bottom MOSFET RDS(ON) for lossless sensing; VRNG pin scales threshold from 22mV to 98mV. |
| Protection Features | Programmable current limit with foldback, output overvoltage protection, and PGOOD monitoring - ensures safe operation during shorts or rail faults. |
| Package | 16-pin 3mm × 3mm QFN with exposed SGND pad - provides low thermal resistance (θJC = 4.2°C/W) for high-current designs. |
Pinout & Package
Package: 16-lead (3mm × 3mm) plastic QFN with exposed thermal pad (Pin 17 = SGND). Requires soldering of exposed pad to PCB for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| TRACK/SS (1) | Soft-start & tracking input | Controls output ramp rate via capacitor or tracks external supply; internal 1μA pull-up enables simple RC start-up. |
| PGOOD (2) | Power-good open-drain output | Asserts low when VOUT deviates >±10% from regulation - used for system sequencing and fault signaling. |
| VRNG (3) | VDS sense range select | Sets max valley current threshold as 0.133×VRNG; ties to SGND (30mV) or INTVCC (75mV) for default operation. |
| MODE (4) | Continuous/discontinuous mode control | Ground = forced CCM (low EMI); INTVCC = DCM enabled (high light-load efficiency). |
| ITH (5) | Error amplifier output & current threshold | 0.8V = zero-sense threshold; EA adjusts ITH to match load current - serves as loop compensation node. |
| SGND (6) | Signal ground reference | Reference for all analog circuitry; must connect to PGND at single point to avoid noise coupling. |
| ION (7) | On-time current input | Resistor from VIN sets one-shot timer current - determines switching frequency with VIN compensation. |
| VFB (8) | Feedback input | Compares output divider voltage to 0.6V reference; ±50nA input bias enables high-impedance dividers. |
| RUN (9) | Enable/shutdown control | <0.7V = micropower shutdown (18μA); 0.7–1.5V = bias on, drivers off; >1.5V = full operation. |
| VIN (10) | Main input supply | 4V–38V input rail; requires RC filter to PGND for noise immunity in noisy environments. |
| INTVCC (11) | Internal 5.3V regulator output | Powers gate drivers and logic; requires ≥1μF X5R/X7R ceramic decoupling to PGND. |
| BG (12) | Bottom gate driver | Drives synchronous MOSFET source-to-PGND; 0.7Ω pull-down resistance enables fast turn-off. |
| PGND (13) | Power ground return | Low-impedance return for high di/dt currents; must tie directly to bottom MOSFET source and CIN/COUT negatives. |
| SW (14) | Switch node | Connects to bootstrap capacitor negative terminal; swings from ~–0.4V to VIN - critical for layout integrity. |
| TG (15) | Top gate driver | Drives top MOSFET gate referenced to SW; 2.5Ω pull-up/pull-down supports fast edge rates (20ns). |
| BOOST (16) | Bootstrap supply | Connects to bootstrap capacitor positive terminal; floats up to VIN + (INTVCC – 0.4V) for high-side drive. |
Key Features
| Feature | Design Value |
|---|---|
| No RSENSE valley current sensing | Eliminates power loss and board space of external sense resistor; leverages MOSFET RDS(ON) with VRNG-scaling for accuracy. |
| Adjustable soft-start/tracking | Capacitor on TRACK/SS sets monotonic output ramp; resistor divider enables rail tracking for multi-voltage sequencing. |
| Pre-biased output start-up | Supports hot-plug and partial-power scenarios where output is already energized before controller enable. |
| Programmable current limit with foldback | Protects against short circuits by reducing current setpoint when VOUT drops below 50% - prevents thermal runaway. |
| Stable with low-ESR ceramic capacitors | Enables use of compact, high-frequency MLCCs instead of bulky electrolytics - reduces solution size and improves reliability. |
Applications
| Telecom Base Station Power | Server CPU Core Supply |
|---|---|
Use Scenario: 48V intermediate bus converted to 1.2V/15A for FPGA or ASIC core logic in 5G radio units. IC Role / Device Role / Timing Role: Primary step-down controller managing high-current, fast-transient loads with <50μs recovery from 0A→10A steps. Use Value: 43ns min on-time and valley current mode ensure stable regulation at 28:1 step-down ratio without subharmonic oscillation. | Use Scenario: Point-of-load converter supplying 1.2V to multi-core x86 processors with dynamic DVFS voltage scaling. IC Role / Device Role / Timing Role: Synchronous buck controller delivering tightly regulated output with PGOOD sequencing and VRNG-adjusted current sensing. Use Value: Adjustable VRNG (0.2V–2V) enables optimal current threshold selection across MOSFET RDS(ON) variation and temperature drift. |
| Industrial PLC I/O Module | Networking Switch ASIC Supply |
Use Scenario: 24V field bus powering isolated 3.3V/5A digital I/O banks with strict EMI limits. IC Role / Device Role / Timing Role: Controller operating in forced continuous mode (MODE = GND) to suppress audible noise and RF emissions. Use Value: MODE pin direct control eliminates need for external logic; TG/BG drivers with 20ns rise/fall times minimize switching losses. | Use Scenario: High-density 1U switch chassis requiring multiple 0.85V/20A rails from 12V mid-rail with minimal footprint. IC Role / Device Role / Timing Role: Compact QFN-packaged controller enabling dense layout with integrated boost capacitor routing. Use Value: 3mm × 3mm QFN package with exposed SGND pad achieves θJC = 4.2°C/W - sustains 15A output without heatsink. |
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 |
|---|---|---|---|
| LTC3891EUD#TRPBF | Includes integrated 5V/150mA LDO for gate drive; wider 4.5V–60V input range; no VRNG pin - fixed 30mV current sense threshold. | Better suited for systems needing auxiliary bias rail; less flexible for MOSFET RDS(ON) optimization. | Select LTC3891EUD#TRPBF when integrated LDO simplifies BOM and input exceeds 38V. |
| MP2918GL-Z | Fixed 600kHz frequency; no VRNG or MODE pins; lower 2.5V–18V input range; lacks pre-biased start-up support. | Targeted at cost-sensitive consumer applications with narrow input and simpler feature set. | Select MP2918GL-Z only for low-complexity 12V-input systems where valley current scaling and DCM/CCM control are unnecessary. |
Compared with LTC3879EUD#TRPBF, LTC3891EUD#TRPBF adds integrated bias but sacrifices VRNG flexibility, while MP2918GL-Z reduces feature count and input range - making LTC3879EUD#TRPBF optimal for high-flexibility, wide-input industrial and telecom POL designs.
Availability
LTC3879EUD#TRPBF is available at Aetrix Electronics and suitable for distributed power systems, embedded computing, and communications infrastructure requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LTC3879EUD#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC3879 belongs to ADI's Power by Linear™ high-efficiency DC/DC controller family, designed specifically for high-frequency, fast-transient, no-RSENSE synchronous buck regulation in space-constrained and thermally demanding applications.
FAQ
What is the minimum on-time specification for LTC3879EUD#TRPBF and why does it matter?
The LTC3879EUD#TRPBF has a guaranteed minimum on-time of 43ns. This parameter is critical for high step-down ratio applications - for example, converting 28V to 1.2V at 400kHz requires a ~17% duty cycle, which corresponds to ~425ns on-time; the 43ns spec ensures reliable pulse generation even at extreme ratios without skipping cycles or losing regulation. The LTC3879EUD#TRPBF achieves this via precision one-shot timing controlled by the ION pin current.
How does the VRNG pin affect current sensing in LTC3879EUD#TRPBF?
The VRNG pin on the LTC3879EUD#TRPBF sets the maximum allowable valley current sense voltage as 0.133×VRNG, scaling the effective current limit threshold from 22mV to 98mV depending on VRNG voltage (0.2V–2V). When VRNG = SGND, threshold is ~30mV; when VRNG = INTVCC (~5.3V), it is ~75mV. This allows designers to optimize sensing accuracy and noise immunity for specific MOSFET RDS(ON) values and temperature ranges - a capability not found in fixed-threshold controllers. The LTC3879EUD#TRPBF uses this to maintain precision across process and thermal variation.
Can LTC3879EUD#TRPBF start up into a pre-biased output, and how is it configured?
Yes, the LTC3879EUD#TRPBF supports smooth start-up into a pre-biased output - essential for hot-swap and redundant power systems. This behavior is enabled by default and requires no external configuration; the controller monitors VFB during start-up and avoids reverse current by controlling gate drive timing based on sensed output voltage. The RUN pin must be brought above 1.5V to initiate operation, and the TRACK/SS pin remains inactive until regulation begins. This functionality is verified in the LTC3879EUD#TRPBF datasheet Figure G06 and is intrinsic to its valley current mode architecture.
What package type and thermal characteristics apply to LTC3879EUD#TRPBF?
The LTC3879EUD#TRPBF uses a 16-lead 3mm × 3mm plastic QFN package with exposed thermal pad (Pin 17 = SGND). Its thermal performance is characterized by θJA = 68°C/W and θJC = 4.2°C/W - significantly better than the MSOP variant - enabling high-current operation (e.g., 15A) without external heatsinking when the exposed pad is properly soldered to a thermal plane. The small footprint supports dense POL layouts in telecom and server applications where board area is constrained. This package is standard for the LTC3879EUD#TRPBF across all temperature grades.
Does LTC3879EUD#TRPBF require an external sense resistor for current limiting?
No, the LTC3879EUD#TRPBF does not require an external sense resistor. It implements No RSENSE™ valley current mode control by measuring the voltage drop across the bottom N-channel MOSFET's RDS(ON) between SW and PGND pins. The VRNG pin allows scaling of the current sense threshold from 22mV to 98mV, eliminating power loss, board space, and tolerance errors associated with discrete resistors. This architecture is confirmed in the LTC3879EUD#TRPBF datasheet Features list and Functional Diagram - and is a defining characteristic of the LTC3879EUD#TRPBF.
LTC3879EUD#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)
LTC3879EUD#TRPBF FAQ
1.How can I place an order for LTC3879EUD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3879EUD#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 LTC3879EUD#TRPBF reliable?
The price and inventory of LTC3879EUD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3879EUD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3879EUD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3879EUD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3879EUD#TRPBF?
LTC3879EUD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3879EUD#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 LTC3879EUD#TRPBF?
For technical support, including LTC3879EUD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3879EUD#TRPBF requirements.
6.How does Aetrix verify that LTC3879EUD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3879EUD#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 LTC3879EUD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3879EUD#TRPBF?
All LTC3879EUD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3879EUD#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 LTC3879EUD#TRPBF part is unused and in its original packaging.
Return procedure for LTC3879EUD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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