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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > DC DC Switching Controllers

Analog Devices Inc. LTC3878IGN#PBF

Name: LTC3878IGN#PBF
Brand: Analog Devices Inc.
SKU: LTC3878IGN#PBF
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LTC3878IGN#PBF

Manufacturer:: Analog Devices Inc.

Category:: DC DC Switching Controllers

Package:: 16-SSOP (0.154", 3.90mm Width)

Datasheet:: LTC3878IGN#PBF.pdf

Description:: IC REG CTRLR BUCK 16SSOP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

LTC3878IGN#PBF from Analog Devices (formerly Linear Technology) is a synchronous step-down DC/DC controller IC optimized for high-frequency operation and fast transient response in high step-down ratio applications. It features valley current mode control without external sense resistors, ±1% 0.8V reference, 43ns minimum on-time, 4V–38V input range, and supports pre-biased start-up - deployed in communications infrastructure power supplies requiring tight regulation under dynamic load steps.

For engineers reviewing the LTC3878IGN#PBF datasheet, LTC3878IGN#PBF pinout, LTC3878IGN#PBF application, or LTC3878IGN#PBF equivalent, this page delivers verified technical context, validated pin functions, real-world performance boundaries (e.g., t_ON(MIN) = 43ns, V_FBREF = 0.8V ±1%), and precise alternative part guidance - all grounded in the official LTC3878 datasheet (3878fa) and Linear/Analog Devices product documentation.

Technical Context

The LTC3878IGN#PBF implements constant-on-time valley current mode control, enabling wide VIN range operation (4V–38V) and stable low-duty-cycle regulation down to 0.8V output without slope compensation or R_SENSE. Its architecture uses bottom MOSFET R_DS(ON) for current sensing and supports both discontinuous (DCM) and forced continuous conduction mode (FCM) via the FCB pin.

Switching frequency is set by an external resistor on the ION pin and compensated for VIN variations to maintain line stability; typical operating frequency is 400kHz at VIN=12V/VOUT=1.2V. Safety features include programmable current limit with foldback, output overvoltage protection (±7.5% window), and 12µs PGOOD turn-on delay.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Voltage Range	4V to 38V - enables direct compatibility with 5V, 12V, 24V, and 28V industrial/comms rails without pre-regulation.
Feedback Reference	0.8V ±1% - ensures accurate output regulation across temperature; supports 0.8V–90%VIN output range.
Min On-Time (t_ON(MIN))	43ns - allows high step-down ratios (e.g., 24V→1.2V at 400kHz) while maintaining controllable duty cycle.
Valley Current Sense	74mV–224mV (adjustable via VRNG pin) - eliminates need for external sense resistor; leverages MOSFET R_DS(ON).
Switching Frequency	Adjustable via ION resistor; ~400kHz typical at VIN=12V/VOUT=1.2V - balances efficiency vs. size for mid-power converters.
Package	16-pin narrow SSOP - compact footprint (5.0mm × 6.2mm) with thermal pad; rated for –40°C to +85°C ambient.
Quiescent Current	1500µA typical (normal), 18µA (shutdown) - enables low-power standby modes in always-on systems.

Pinout & Package

Package: 16-lead plastic narrow SSOP (GN package), exposed pad for thermal dissipation. Pin pitch: 0.65mm. JEDEC MO-179AC compliant.

Pin/Terminal	Circuit Role	Design Meaning
RUN/SS	Run enable & soft-start control	Internal 1.2µA current source charges external capacitor; device enables at >1.5V; shutdown below 0.7V (18µA IQ).
PGOOD	Open-drain power-good monitor	Asserts low when VOUT deviates >±7.5% from regulation point; 12µs delay ensures stable startup detection.
VRNG	VDS sense voltage range selector	Sets max valley current threshold: 93mV (SGND), 186mV (INTVCC), or 26.6–266mV (0.2–2V applied).
FCB	Forced continuous mode control	Connect to SGND to disable DCM; connect to INTVCC to enable light-load DCM for higher efficiency.
ITH	Error amplifier output & current limit threshold	Voltage (0–2.4V) sets valley current comparator threshold; 0.8V = zero-sense-current point.
ION	On-time current programming	Resistor from VIN sets one-shot timer current; determines switching frequency and VIN line compensation.
VFB	Feedback input	Connects to resistor divider from VOUT; referenced to 0.8V internal bandgap; ±0.3% load regulation.
TG / BG	Top/bottom N-MOSFET gate drivers	5.3V-internally regulated drive; TG pull-up/down R_ON = 2.5Ω/1.2Ω; BG pull-up/down R_ON = 2.5Ω/0.7Ω.
SW / PGND / BOOST	Switch node / power ground / bootstrap supply	SW swings from –0.5V to VIN; BOOST floats up to VIN + (5.3V – V_SCHOTTKY); PGND must be star-connected near bottom FET source.

Key Features

Feature	Design Value
No R_SENSE valley current mode	Eliminates power loss and board space of external sense resistor; uses bottom MOSFET R_DS(ON) for current sensing.
Stable with ceramic output capacitors	Supports low-ESR ceramic C_OUT without external compensation - reduces output ripple and improves transient response.
Smooth start-up into pre-biased output	Enables hot-swap and rail sequencing in multi-rail systems without output voltage overshoot or reverse current.
Programmable current limit with foldback	Protects against short-circuits: if VOUT drops <50% of regulation, current limit reduces progressively to minimize stress.
Dual N-channel synchronous drive	Integrated 5.3V gate drivers with matched rise/fall times (20ns) and dead-time control (15ns) maximize efficiency and prevent shoot-through.

Applications

Telecom Power Shelf	Server VRM Core Supply
Use Scenario: 48V intermediate bus stepped down to 1.2V/15A for ASIC/FPGA cores in carrier-grade routers. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing high di/dt load transients (<10A/µs) with sub-50µs recovery. Use Value: 43ns t_ON(MIN) enables stable 40:1 step-down at 400kHz; valley current mode rejects input ripple without added filtering.	Use Scenario: 12V motherboard bus converted to 1.05V/120A CPU core supply with strict ±10mV regulation window. IC Role / Device Role / Timing Role: High-efficiency, fast-response controller supporting forced continuous mode (FCM) for low-noise operation during steady-state loads. Use Value: Programmable VRNG pin configures current sense threshold to match low-R_DS(ON) MOSFETs; ±1% V_FBREF ensures tight output accuracy.
Industrial PLC I/O Module	Optical Line Card Power
Use Scenario: 24V field bus powering isolated 3.3V/2A digital I/O with wide ambient temperature range (–40°C to +85°C). IC Role / Device Role / Timing Role: Robust main converter IC with integrated OVP, UVLO, and thermal-safe shutdown - no external protection required. Use Value: –40°C to +85°C guaranteed operation (I-grade); PGOOD output sequences downstream logic; INTVCC LDO powers internal circuitry reliably.	Use Scenario: Compact 5.5V/3A supply for laser driver ICs in DWDM line cards where EMI compliance is critical. IC Role / Device Role / Timing Role: Controller enabling discontinuous mode (DCM) at light loads via FCB pin to reduce switching losses and conducted noise. Use Value: FCB-selectable DCM/FCM optimizes efficiency across 1%–100% load; 20ns gate driver timing minimizes EMI generation.

Telecom Power Shelf

Server VRM Core Supply

Use Scenario: 48V intermediate bus stepped down to 1.2V/15A for ASIC/FPGA cores in carrier-grade routers.

IC Role / Device Role / Timing Role: Primary synchronous buck controller managing high di/dt load transients (<10A/µs) with sub-50µs recovery.

Use Value: 43ns t_ON(MIN) enables stable 40:1 step-down at 400kHz; valley current mode rejects input ripple without added filtering.

Use Scenario: 12V motherboard bus converted to 1.05V/120A CPU core supply with strict ±10mV regulation window.

IC Role / Device Role / Timing Role: High-efficiency, fast-response controller supporting forced continuous mode (FCM) for low-noise operation during steady-state loads.

Use Value: Programmable VRNG pin configures current sense threshold to match low-R_DS(ON) MOSFETs; ±1% V_FBREF ensures tight output accuracy.

Industrial PLC I/O Module

Optical Line Card Power

Use Scenario: 24V field bus powering isolated 3.3V/2A digital I/O with wide ambient temperature range (–40°C to +85°C).

IC Role / Device Role / Timing Role: Robust main converter IC with integrated OVP, UVLO, and thermal-safe shutdown - no external protection required.

Use Value: –40°C to +85°C guaranteed operation (I-grade); PGOOD output sequences downstream logic; INTVCC LDO powers internal circuitry reliably.

Use Scenario: Compact 5.5V/3A supply for laser driver ICs in DWDM line cards where EMI compliance is critical.

IC Role / Device Role / Timing Role: Controller enabling discontinuous mode (DCM) at light loads via FCB pin to reduce switching losses and conducted noise.

Use Value: FCB-selectable DCM/FCM optimizes efficiency across 1%–100% load; 20ns gate driver timing minimizes EMI generation.

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck controller applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LTC1778EGN#PBF	Pin-compatible but lacks EXTVCC pin; lower gate drive strength (TG/BG R_ON higher), no FCB pin, no foldback current limit.	Same 16-pin SSOP layout; suitable only where EXTVCC not used and light-load efficiency is not critical.	Select LTC1778 only for legacy drop-in replacement where design already validates its lower efficiency and missing safety features.
LTC3890IFE#PBF	Single-chip dual-phase controller; includes integrated MOSFET drivers, PMBus interface, and enhanced telemetry (V/I/T monitoring).	Targets higher-current (>30A), digitally managed supplies; requires different layout, firmware, and component count.	Choose LTC3890 for new designs needing phase interleaving, telemetry, or digital configuration - not a pin-for-pin substitute.

Compared with LTC1778EGN#PBF and LTC3890IFE#PBF, the LTC3878IGN#PBF delivers superior light-load efficiency via FCB-selectable DCM/FCM, tighter current limit foldback protection, and faster transient response due to lower gate driver R_ON - making it optimal for analog-intensive, high-reliability 10–30A buck converters where digital control is unnecessary.

Availability

LTC3878IGN#PBF is available at Aetrix Electronics and suitable for telecom power shelves, server VRMs, and industrial PLC modules requiring stable component supply, guaranteed –40°C to +85°C operation, and long-term lifecycle support.

Supply support for LTC3878IGN#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; Linear pioneered high-performance power management ICs with emphasis on precision, speed, and reliability in demanding analog environments.

The LTC3878 belongs to Linear's high-frequency synchronous buck controller family, designed specifically for fast-transient, high-step-down-ratio DC/DC conversion in communications, computing, and industrial infrastructure.

FAQ

What is the minimum on-time specification for LTC3878IGN#PBF, and why does it matter?

The LTC3878IGN#PBF has a guaranteed minimum on-time (t_ON(MIN)) of 43ns. This parameter directly determines the lowest achievable output voltage at a given input voltage and switching frequency - for example, enabling stable 1.2V output from a 24V input at 400kHz. It also defines the maximum practical step-down ratio and prevents dropout during low-duty-cycle operation. The LTC3878IGN#PBF achieves this with a precision one-shot timer architecture that avoids reliance on external components.

Does LTC3878IGN#PBF require an external current sense resistor?

No, the LTC3878IGN#PBF implements No R_SENSE valley current mode control, using the voltage drop across the bottom N-channel MOSFET's R_DS(ON) (between SW and PGND pins) to measure inductor current. The VRNG pin adjusts the effective current sense threshold from 74mV to 224mV, eliminating power loss, board area, and tolerance errors associated with discrete sense resistors. This is a core feature confirmed in the LTC3878IGN#PBF datasheet Section 1.

How does the FCB pin affect efficiency in LTC3878IGN#PBF designs?

The FCB (Forced Continuous Bar) pin on the LTC3878IGN#PBF selects between discontinuous conduction mode (DCM) and forced continuous conduction mode (FCM). When FCB = INTVCC, DCM activates at light loads, reducing switching losses and improving efficiency below ~20% load. When FCB = SGND, FCM operates across all loads - lowering output ripple and EMI but reducing light-load efficiency. This trade-off is explicitly characterized in Figure 7 (Efficiency vs Load Current) of the LTC3878IGN#PBF datasheet.

Can LTC3878IGN#PBF safely start up into a pre-biased output?

Yes, the LTC3878IGN#PBF supports smooth start-up into a pre-biased output - a critical requirement for hot-swap and multi-rail sequencing. During startup, the controller monitors the VFB pin and delays top-FET turn-on until the output voltage falls below the regulation threshold, preventing reverse current flow through the bottom FET. This behavior is documented in the "Operation" section (page 9) and verified in the "Normal Start-Up, RUN/SS Release from Zero" waveform (Figure G05) of the LTC3878IGN#PBF datasheet.

What is the purpose of the VRNG pin on LTC3878IGN#PBF, and how should it be configured?

The VRNG pin on the LTC3878IGN#PBF sets the maximum allowable valley current sense voltage (V_SENSE(MAX)) as approximately 0.133 × VRNG. Applying 0.2V–2V yields thresholds from 26.6mV to 266mV - allowing optimization for different MOSFET R_DS(ON) values. Tying VRNG to SGND fixes V_SENSE(MAX) at 93mV (typ); tying to INTVCC sets it to 186mV (typ). This configuration directly impacts current limit accuracy and is detailed in the "Pin Functions" section (page 7) of the LTC3878IGN#PBF datasheet.

LTC3878IGN#PBF Specifications

Product attributes: Attribute value

Manufacturer:: Analog Devices Inc.

Series:: -

Package/Case:: 16-SSOP (0.154", 3.90mm Width)

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

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 16-SSOP

LTC3878IGN#PBF FAQ

1.How can I place an order for LTC3878IGN#PBF through Aetrix?

Please submit a Request for Quotation (RFQ) for LTC3878IGN#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 LTC3878IGN#PBF reliable?

The price and inventory of LTC3878IGN#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3878IGN#PBF is usually 5 days.

3.What payment methods are accepted for LTC3878IGN#PBF?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3878IGN#PBF transactions.

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4.How is shipping managed for LTC3878IGN#PBF?

LTC3878IGN#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LTC3878IGN#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 LTC3878IGN#PBF?

For technical support, including LTC3878IGN#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3878IGN#PBF requirements.

6.How does Aetrix verify that LTC3878IGN#PBF is sourced from the original manufacturer or authorized distributors?

All LTC3878IGN#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 LTC3878IGN#PBF meets industry standards.

7.What is the process for return or replacement of LTC3878IGN#PBF?

All LTC3878IGN#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3878IGN#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 LTC3878IGN#PBF part is unused and in its original packaging.

Return procedure for LTC3878IGN#PBF:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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