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Analog Devices Inc. LTC3878IGN#TRPBF
- Part No.:
- LTC3878IGN#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC3878IGN#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,435
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Product details
Overview
LTC3878IGN#TRPBF from Analog Devices (formerly Linear Technology) is a synchronous step-down DC/DC controller IC optimized for high-frequency, fast-transient applications in distributed power systems. It features a wide 4V–38V input range, ±1% 0.8V reference, 43ns minimum on-time, valley current mode control without external sense resistor, and dual N-channel MOSFET synchronous drive in a 16-pin narrow SSOP package.
For engineers reviewing the LTC3878IGN#TRPBF datasheet, LTC3878IGN#TRPBF pinout, LTC3878IGN#TRPBF application, or LTC3878IGN#TRPBF equivalent, this page delivers verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternative parts with documented differences, and supply-ready availability details - all grounded in the official LTC3878 datasheet (3878fa) and Linear/Analog Devices product documentation.
Technical Context
The LTC3878IGN#TRPBF implements constant-on-time valley current mode control, enabling stable operation across wide VIN ranges (4V–38V) and very low duty cycles without slope compensation or RSENSE. Its architecture supports both forced continuous conduction mode (via FCB pin) and discontinuous mode for light-load efficiency.
It integrates dual gate drivers (TG/BG) with 2.5Ω pull-up / 1.2Ω pull-down resistance, 5.3V internal LDO (INTVCC), programmable current limit with foldback, output overvoltage protection, and power-good monitoring - all coordinated through a single error amplifier (gm = 1.7 mS) referenced to a precision 0.8V bandgap.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports industrial, telecom, and automotive input rails including 5V, 12V, 24V, and 36V nominal supplies. |
| Feedback Reference | 0.8V ±1% - enables precise regulation down to 0.8V output with tight load/line regulation (±0.05% load, 0.002%/V line). |
| Min On-Time (tON(MIN)) | 43ns - allows high step-down ratios (e.g., 24V→1.2V at 400kHz) without pulse-skipping instability. |
| Switching Frequency | Adjustable via external RON; pseudo-fixed vs VIN - e.g., ~400kHz at VIN=12V/VOUT=1.2V, with line-stable operation due to VIN-compensated timing. |
| Current Sense Method | No RSENSE valley sensing using bottom MOSFET RDS(ON) - eliminates sense resistor losses and PCB area; VRNG pin sets max VDS threshold (93mV–186mV typical). |
| Package | 16-pin narrow SSOP (GN), 0.15mm pitch - surface-mount compatible with standard reflow profiles; θJA = 110°C/W. |
| Operating Temp | –40°C to +85°C - qualified for industrial and embedded computing environments per LTC3878I grade. |
Pinout & Package
Package: 16-lead plastic narrow SSOP (GN), RoHS-compliant, lead-free finish. Pin 1 marked with dot; top-side view with pin 1 at top-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN/SS (1) | Run enable & soft-start control | Internal 1.2µA current source charges external CSS; device enables at >0.7V (INTVCC on), operates at >1.5V (soft-start active), full current at ~3V. |
| PGOOD (2) | Open-drain power-good monitor | Asserts low when VOUT deviates >±7.5% from regulation; provides system sequencing and fault signaling. |
| VRNG (3) | VDS sense voltage range selector | Sets max valley current sense threshold: 93mV (SGND), 186mV (INTVCC), or scalable 0.133×VVRNG (0.2V–2V range). |
| FCB (4) | Forced continuous mode control | Pull to SGND to disable DCM and enforce CCM under all loads; pull to INTVCC for automatic DCM at light loads. |
| ITH (5) | Error amp 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 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 tON and thus switching frequency (tON ∝ 1/IION). |
| VFB (8) | Feedback input | Connects to resistive divider from VOUT; compared against 0.8V reference to regulate output voltage. |
| NC (9) | No connect | Factory test pin; must be left floating or tied ≤ INTVCC; no electrical function in normal operation. |
| VIN (10) | Main input supply | Primary power rail (4V–38V); requires local RC decoupling to PGND for EMI suppression and noise immunity. |
| INTVCC (11) | Internal 5.3V regulator output | Powers gate drivers and control logic; requires ≥1µF X5R/X7R ceramic capacitor to PGND; dropout <200mV @ 20mA. |
| BG (12) | Bottom gate driver output | Drives gate of synchronous N-MOSFET between PGND and INTVCC; 0.7Ω pull-down, 2.5Ω pull-up, 20ns rise/fall. |
| PGND (13) | Power ground return | High-current return path for bottom MOSFET source, CINTVCC, and CVIN; must be low-inductance PCB plane or thick trace. |
| SW (14) | Switch node | Connects to source of top MOSFET and (–) of bootstrap capacitor; swings from ~–0.3V to VIN; critical for layout EMI control. |
| TG (15) | Top gate driver output | Drives gate of high-side N-MOSFET between SW and BOOST; 1.2Ω pull-down, 2.5Ω pull-up, 20ns rise/fall, 15ns dead time. |
| BOOST (16) | Bootstrap capacitor positive terminal | Swings from (INTVCC – VSCHOTTKY) to VIN + (INTVCC – VSCHOTTKY); requires ceramic capacitor (≥0.1µF) to SW. |
Key Features
| Feature | Design Value |
|---|---|
| No RSENSE valley current sensing | Eliminates external sense resistor and associated power loss, PCB area, and thermal drift - uses MOSFET RDS(ON) as current sensor. |
| Stable with low-ESR ceramic output capacitors | Enables use of compact, high-reliability ceramic COUT instead of bulk electrolytics - reduces size, improves transient response, extends lifetime. |
| Smooth start-up into pre-biased output | Prevents reverse current flow during hot-swap or multi-rail sequencing - essential for FPGA, ASIC, and processor core rail applications. |
| Programmable current limit with foldback | Protects against short-circuits: if VOUT drops below 50% regulation, current limit reduces progressively to minimize stress and heat. |
| Pin-compatible with LTC1778 (no EXTVCC) | Drop-in replacement in legacy designs omitting EXTVCC pin; improved gate drive strength and reduced dead time yield higher efficiency. |
Applications
| Telecom Power Shelf | Server CPU Core Supply |
|---|---|
|
Use Scenario: 48V intermediate bus stepped down to 1.2V/15A for ASIC/FPGA core logic in carrier-grade routers. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing high-current, fast-transient load steps up to 10A/µs. Use Value: 43ns min on-time enables stable 40:1 step-down ratio; valley current mode ensures cycle-by-cycle current limiting during burst-mode traffic. |
Use Scenario: Point-of-load converter on server motherboard delivering tightly regulated 1.05V/120A to Intel Xeon CPU cores. IC Role / Device Role / Timing Role: High-efficiency, high-frequency DC/DC controller driving paralleled MOSFETs with programmable current sharing. Use Value: No RSENSE sensing avoids sense resistor power loss at 120A; forced CCM mode (FCB = GND) maintains low-noise operation during steady-state compute loads. |
| Industrial PLC I/O Module | Medical Imaging Power Subsystem |
|
Use Scenario: 24V field bus converted to isolated 3.3V/5V rails for digital I/O and analog front-end in harsh factory environments. IC Role / Device Role / Timing Role: Robust main controller supporting wide input range and operating over –40°C to +85°C. Use Value: Wide 4V–38V input handles brownouts and surges; PGOOD output enables safe system reset and watchdog coordination. |
Use Scenario: Precision 1.8V/3A supply for high-speed ADCs and FPGA-based image processing in MRI and CT scanner subsystems. IC Role / Device Role / Timing Role: Low-noise, low-ripple synchronous buck controller with tight 0.8V reference and excellent load regulation. Use Value: ±1% reference and <±0.05% load regulation ensure ADC accuracy; ceramic-capacitor compatibility minimizes EMI in sensitive analog zones. |
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 |
|---|---|---|---|
| LTC1778EGN#TRPBF | Same pinout, but includes EXTVCC pin (LTC3878 pin 9 = NC); lower gate drive strength and longer dead time. | LTC1778 supports external 5V bias for INTVCC; LTC3878 relies solely on internal LDO - unsuitable where EXTVCC is required. | Select LTC1778 only if EXTVCC functionality is needed; otherwise LTC3878 offers better efficiency and transient response. |
| MP2918GL-Z | Monolithic 30V synchronous buck controller with integrated MOSFETs; fixed 500kHz frequency; no VRNG or FCB pins. | MP2918 is a complete power stage (up to 12A), while LTC3878 is a controller requiring external MOSFETs (scalable to 50A+). | Choose MP2918 for space-constrained, medium-current designs; choose LTC3878 for high-current, thermally optimized, or custom MOSFET solutions. |
Compared with LTC1778EGN#TRPBF and MP2918GL-Z, the LTC3878IGN#TRPBF provides superior flexibility in high-current, wide-input applications through its No RSENSE architecture, programmable current limit, and dual-mode (CCM/DCM) operation - making it optimal for industrial and telecom systems demanding scalability and efficiency.
Availability
LTC3878IGN#TRPBF is available at Aetrix Electronics and suitable for distributed power systems, embedded computing platforms, and communications infrastructure requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature performance.
Supply support for LTC3878IGN#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC3878 belongs to Linear's high-efficiency DC/DC controller product line, designed specifically for high-frequency, fast-transient, wide-input synchronous buck converters in space- and efficiency-constrained systems.
FAQ
What is the minimum input voltage required for stable operation of the LTC3878IGN#TRPBF?
The LTC3878IGN#TRPBF operates down to 4V input, but minimum practical VIN depends on output voltage and duty cycle constraints. At VOUT = 1.2V and fSW = 400kHz, dropout occurs when VIN falls below ~5.2V due to tON(MIN) = 43ns and tOFF(MIN) = 220ns limits. For 1.2V output, maintain VIN ≥ 5.5V to ensure regulation across temperature and load.
Does the LTC3878IGN#TRPBF require an external current sense resistor?
No - the LTC3878IGN#TRPBF implements No RSENSE valley current mode control, using the on-resistance (RDS(ON)) of the external bottom N-channel MOSFET to sense inductor current. The VRNG pin configures the maximum allowable VDS sense voltage (93mV to 186mV typical), eliminating need for a discrete sense resistor.
How does the FCB pin affect efficiency and noise in LTC3878IGN#TRPBF designs?
When FCB is tied to SGND, the LTC3878IGN#TRPBF forces continuous conduction mode (CCM), reducing output voltage ripple and EMI at the cost of light-load efficiency. When FCB is tied to INTVCC, it enables discontinuous mode (DCM) at light loads, improving efficiency but increasing ripple and potential RF emissions - ideal for battery-powered or thermally constrained systems.
Can the LTC3878IGN#TRPBF safely start up into a pre-biased output voltage?
Yes - the LTC3878IGN#TRPBF supports smooth start-up into pre-biased outputs. During soft-start, the top MOSFET remains off until RUN/SS reaches ~1.5V, preventing reverse current flow from the output capacitor into the input. This protects downstream components and ensures reliable power sequencing in multi-rail systems.
What is the purpose of the VRNG pin on the LTC3878IGN#TRPBF, and how should it be configured?
The VRNG pin on the LTC3878IGN#TRPBF sets the maximum valley current sense threshold by scaling the bottom MOSFET VDS detection window: VSENSE(MAX) ≈ 0.133 × VVRNG. Tie VRNG to SGND for 93mV default, to INTVCC for 186mV, or use a resistor divider (0.2V–2V) for fine-tuned current sensing - critical for optimizing MOSFET selection and current limit accuracy.
LTC3878IGN#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- 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
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SSOP
LTC3878IGN#TRPBF FAQ
1.How can I place an order for LTC3878IGN#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3878IGN#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 LTC3878IGN#TRPBF reliable?
The price and inventory of LTC3878IGN#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3878IGN#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3878IGN#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3878IGN#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3878IGN#TRPBF?
LTC3878IGN#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3878IGN#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 LTC3878IGN#TRPBF?
For technical support, including LTC3878IGN#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3878IGN#TRPBF requirements.
6.How does Aetrix verify that LTC3878IGN#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3878IGN#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 LTC3878IGN#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3878IGN#TRPBF?
All LTC3878IGN#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3878IGN#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 LTC3878IGN#TRPBF part is unused and in its original packaging.
Return procedure for LTC3878IGN#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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