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Analog Devices Inc. LTC3879IMSE#TRPBF
- Part No.:
- LTC3879IMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3879IMSE#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,404
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Product details
Overview
LTC3879IMSE#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 wide-input industrial and communications power systems. It features valley current mode control without external sense resistor, ±1% 0.6V reference, 43ns minimum on-time, and dual N-channel MOSFET drive - enabling efficient 4V–38V input to 0.6V–90% VIN output conversion in embedded computing and distributed power applications.
For engineers reviewing the LTC3879IMSE#TRPBF datasheet, LTC3879IMSE#TRPBF pinout, LTC3879IMSE#TRPBF application, or LTC3879IMSE#TRPBF equivalent, key selection criteria include its No RSENSE™ architecture, programmable current limit with foldback, forced continuous/discontinuous mode control via MODE pin, and compatibility with low-ESR ceramic output capacitors in thermally enhanced MSOP packaging.
Technical Context
The LTC3879IMSE#TRPBF implements constant-on-time valley current mode control, eliminating need for slope compensation or external current-sense resistors. Its ION pin sets switching frequency via resistor-to-VIN, with built-in VIN compensation for stable line regulation across 4V–38V input range.
It supports pre-biased soft-start, independent RUN/SS control, output overvoltage protection, and adjustable current limit threshold via VRNG pin - enabling precise valley current sensing between 22mV and 165mV depending on VRNG voltage (0.2V–2V). The 16-pin MSOP package integrates dual gate drivers with 1.2Ω BG pull-down and 2.5Ω TG pull-up on-resistance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports wide-range industrial and telecom inputs without external regulators |
| Feedback Reference | ±1% at 0.6V - enables accurate output regulation down to sub-1V levels with tight tolerance |
| Min On-Time | 43ns - allows high step-down ratios (e.g., 24V→1.2V @ 400kHz) without pulse-skipping instability |
| Current Sense Threshold | 22mV to 165mV (adjustable via VRNG) - eliminates RSENSE, reduces BOM cost and board space |
| Switching Frequency | Programmable via external RON - maintains pseudo-fixed frequency across input variation for predictable EMI behavior |
| Gate Drive Capability | TG/BG drivers with 1.2Ω/0.7Ω pull-down and 2.5Ω/2.5Ω pull-up - directly drives logic-level N-MOSFETs up to 15A load |
| Protection Features | Output overvoltage protection, programmable current limit with foldback, and PGOOD monitoring - ensures system-level fault resilience |
Pinout & Package
Package: 16-lead plastic MSOP (MSE), thermally enhanced with exposed SGND pad (Pin 17) requiring PCB soldering for thermal and electrical performance.
| 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 startup |
| PGOOD (2) | Power-good open-drain output | Asserts low when VOUT deviates >±10% from regulation - used for sequencing and fault signaling |
| VRNG (3) | VDS sense range control | Sets max valley current sense threshold (22–165mV) by scaling bottom-FET VDS measurement |
| MODE (4) | Continuous/discontinuous mode select | Tie to INTVCC for DCM (light-load efficiency); tie to SGND for forced CCM (low-noise, fixed-frequency) |
| ITH (5) | Error amplifier output & current threshold | 0–2.4V control voltage sets valley current limit; also serves as compensation node |
| SGND (6) | Signal ground reference | Reference for all analog circuitry; must be connected to PGND at single point to avoid noise coupling |
| ION (7) | On-time current input | Resistor from VIN sets tON and thus switching frequency; compensated for VIN variation |
| VFB (8) | Feedback input | Compares output divider voltage to 0.6V reference; supports remote sensing and precision regulation |
| RUN (9) | Enable/disable control | 1.5V threshold; <0.7V = micropower shutdown (18μA), 0.7–1.5V = bias-on/no-switching, >1.5V = full operation |
| VIN (10) | Main input supply | 4–38V input path; requires RC filter to PGND for noise immunity in noisy environments |
| INTVCC (11) | Internal 5.3V regulator output | Powers gate drivers and internal 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 ensures fast turn-off |
| PGND (13) | Power ground return | Low-impedance return for bottom FET source, CIN, and CINTVCC; must be placed near MOSFET source |
| SW (14) | Switch node | Connects to source of top FET and (–) terminal of bootstrap capacitor; swings from ~–0.3V to VIN |
| TG (15) | Top gate driver output | Drives gate of high-side N-MOSFET between SW and BOOST; 2.5Ω pull-up supports fast turn-on |
| BOOST (16) | Bootstrap supply | Connects to (+) terminal of bootstrap capacitor; floats with SW to enable high-side gate drive |
| Exposed Pad (17) | Thermal & signal ground | Must be soldered to PCB copper pour tied to SGND for thermal dissipation and noise reduction |
Key Features
| Feature | Design Value |
|---|---|
| No RSENSE™ valley current sensing | Uses bottom MOSFET RDS(ON) for current measurement - eliminates sense resistor, saves cost/space, avoids power loss |
| Adjustable current limit with foldback | Programmable threshold (via VRNG) and automatic reduction under short-circuit - protects MOSFETs and load during faults |
| Pre-biased soft-start capability | Supports controlled ramp-up even when output is pre-charged - prevents reverse current flow into powered rails |
| Independent RUN and TRACK/SS pins | Enables flexible power sequencing and rail tracking (e.g., 1.2V VOUT tracking 1.8V master supply) |
| Stable with low-ESR ceramic output caps | Eliminates need for electrolytic or tantalum capacitors - improves reliability, lifetime, and temperature stability |
| Forced CCM/DCM mode selection | MODE pin selects between continuous conduction (low-noise, fixed fSW) and discontinuous (high light-load efficiency) |
Applications
| Server CPU Core Power | Industrial PLC I/O Module |
|---|---|
Use Scenario: High-current, low-voltage core supply for x86 or ARM processors in rack-mounted servers requiring rapid load transient response. IC Role / Device Role / Timing Role: Primary step-down controller managing 12V/48V bus to 0.8–1.2V CPU core rail with dual-phase synchronization capability. Use Value: 43ns min on-time enables stable 24V→1.2V conversion at 400kHz; valley current mode delivers <50mV output deviation during 0→10A load steps. | Use Scenario: Distributed 3.3V/5V power for isolated digital I/O channels in programmable logic controllers operating in harsh factory environments. IC Role / Device Role / Timing Role: Input-stage buck controller accepting wide 18–36V DC field bus and delivering tightly regulated auxiliary rails. Use Value: 4V–38V input range accommodates brownout conditions; ±1% 0.6V reference ensures sensor interface accuracy across –40°C to 85°C. |
| Telecom Line Card Power | Medical Imaging FPGA Supply |
Use Scenario: Compact, high-efficiency 3.3V/1.8V supplies for packet-processing ASICs and SerDes interfaces on telecom line cards with strict thermal limits. IC Role / Device Role / Timing Role: Synchronous buck controller driving discrete N-MOSFETs in space-constrained 3U card layouts with forced-air cooling. Use Value: Thermally enhanced MSOP package with exposed pad achieves θJA = 40°C/W; no RSENSE reduces heat generation vs. shunt-based solutions. | Use Scenario: Low-noise, high-reliability 1.2V supply for radiation-tolerant FPGAs in portable ultrasound or MRI subsystems requiring zero output glitches. IC Role / Device Role / Timing Role: Pre-regulator controlling intermediate bus before LDO post-regulation to meet stringent ripple and sequencing requirements. Use Value: PGOOD output enables safe FPGA configuration sequencing; programmable current limit prevents damage during partial reconfiguration events. |
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 | Includes integrated 5V/150mA bias supply; wider 4.5V–60V input range; no VRNG pin - fixed 50mV current sense threshold | Better suited for higher-input systems (e.g., 48V telecom) where integrated bias simplifies design; lacks VRNG flexibility for MOSFET optimization | Select LTC3891EMSE#TRPBF when input exceeds 38V or bias supply integration reduces component count; retain LTC3879IMSE#TRPBF for VRNG-adjustable current sensing in 4–38V designs |
| MP2918GL-Z | Monolithic 30V 12A buck converter (integrated MOSFETs); fixed 600kHz fSW; no MODE pin - automatic DCM/CCM transition | Targeted at lower-power, space-constrained applications where integration outweighs efficiency tuning; lacks programmable current limit foldback | Choose MP2918GL-Z for ≤12A applications needing minimal external components; prefer LTC3879IMSE#TRPBF for >15A, high-efficiency, or fault-resilient designs requiring discrete MOSFET selection |
Compared with LTC3891EMSE#TRPBF and MP2918GL-Z, the LTC3879IMSE#TRPBF offers unique VRNG-adjustable current sensing for optimal MOSFET selection, explicit MODE pin control for deterministic CCM/DCM behavior, and superior transient response due to valley current mode architecture - making it ideal for high-performance, wide-input industrial and communications power systems.
Availability
LTC3879IMSE#TRPBF is available at Aetrix Electronics and suitable for server CPU core power, industrial PLC I/O modules, telecom line card power, and medical imaging FPGA supplies requiring stable component supply, long-term lifecycle support, and guaranteed parametric performance across –40°C to 85°C.
Supply support for LTC3879IMSE#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 full product support, documentation, and manufacturing continuity for all Linear ICs including the LTC3879 series.
The LTC3879 belongs to Linear's high-performance power controller family designed for demanding industrial, telecom, and computing applications requiring wide input range, fast transient response, and robust protection features.
FAQ
What is the minimum on-time specification for the LTC3879IMSE#TRPBF and why does it matter?
The LTC3879IMSE#TRPBF has a minimum on-time of 43ns, which enables stable high-step-down-ratio operation (e.g., 24V input to 1.2V output at 400kHz) without pulse-skipping or subharmonic oscillation. This parameter directly determines the lowest achievable output voltage at a given input and switching frequency - critical for modern low-voltage processor cores. The 43ns spec is guaranteed across temperature and process variation, ensuring consistent performance in production systems.
How does the VRNG pin affect current sensing in the LTC3879IMSE#TRPBF?
The VRNG pin on the LTC3879IMSE#TRPBF sets the maximum valley current sense threshold between 22mV and 165mV by scaling the bottom MOSFET VDS measurement. When VRNG = 0.2V, threshold is ~22mV; at VRNG = 2.0V, it reaches ~165mV. This allows designers to match the sense threshold to the RDS(ON) of selected MOSFETs - optimizing accuracy and efficiency. Tying VRNG to SGND or INTVCC yields factory-default thresholds of 30mV or 75mV respectively.
Can the LTC3879IMSE#TRPBF start up into a pre-biased output, and how is this enabled?
Yes, the LTC3879IMSE#TRPBF supports smooth start-up into a pre-biased output. This is enabled by its valley current mode architecture and dedicated RUN pin control logic. When RUN rises above 1.5V, the controller releases the TRACK/SS pin from ground and begins regulating - but only sources current into the output, never sinking it. This prevents reverse current flow that could damage upstream supplies or downstream loads, making it suitable for hot-swap and redundant power systems.
What are the thermal requirements for the LTC3879IMSE#TRPBF in MSOP package?
The LTC3879IMSE#TRPBF in 16-lead MSOP package has θJA = 40°C/W when the exposed pad (Pin 17) is properly soldered to a minimum 1-inch² copper pour tied to SGND. Junction temperature must not exceed 125°C. For continuous 15A operation at 12V input/1.2V output, thermal simulation shows ~85°C rise above ambient - requiring either moderate airflow or derating above 70°C ambient. The exposed pad is mandatory for both thermal performance and signal integrity.
Does the LTC3879IMSE#TRPBF require an external compensation network, and where is it connected?
Yes, the LTC3879IMSE#TRPBF requires external compensation connected to the ITH pin (Pin 5), which serves as both the error amplifier output and current threshold control node. A standard Type II or Type III network (e.g., series RC from ITH to SGND, with optional capacitor to INTVCC) is used to stabilize the voltage loop. Compensation values depend on output capacitance, ESR, and inductor value - Analog Devices provides design tools and application notes (e.g., DC2298A demo board) with verified networks for common configurations.
LTC3879IMSE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width) 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-MSOP-EP
LTC3879IMSE#TRPBF FAQ
1.How can I place an order for LTC3879IMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3879IMSE#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 LTC3879IMSE#TRPBF reliable?
The price and inventory of LTC3879IMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3879IMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3879IMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3879IMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3879IMSE#TRPBF?
LTC3879IMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3879IMSE#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 LTC3879IMSE#TRPBF?
For technical support, including LTC3879IMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3879IMSE#TRPBF requirements.
6.How does Aetrix verify that LTC3879IMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3879IMSE#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 LTC3879IMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3879IMSE#TRPBF?
All LTC3879IMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3879IMSE#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 LTC3879IMSE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3879IMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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