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Analog Devices Inc. LTC1778EGN#TRPBF
- Part No.:
- LTC1778EGN#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC1778EGN#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK/BCK-BST 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:9,422
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Product details
Overview
LTC1778EGN#TRPBF from Analog Devices (formerly Linear Technology) is a wide-input synchronous step-down controller optimized for CPU and high-step-down-ratio DC/DC conversion. It delivers true valley current mode control without an external sense resistor, supports 4V–36V input and 0.8V–(0.9)×VIN output, achieves ≤100ns minimum on-time, and integrates dual N-channel MOSFET gate drivers with ±1% 0.8V reference - enabling stable ceramic-output designs in notebook and distributed power systems.
For engineers reviewing the LTC1778EGN#TRPBF datasheet, LTC1778EGN#TRPBF pinout, LTC1778EGN#TRPBF application, or LTC1778EGN#TRPBF equivalent, key selection criteria include its no-RSENSE current sensing architecture, programmable soft-start via RUN/SS, PGOOD output monitoring, adjustable switching frequency via ION resistor, and operation across –40°C to +85°C ambient.
Technical Context
The LTC1778EGN#TRPBF implements a valley current mode control loop using the bottom MOSFET's RDS(ON) as the current sense element, eliminating external sense resistors. Its one-shot timer sets tON proportional to ideal duty cycle, enabling near-constant switching frequency over input voltage variation.
Fault protection includes foldback current limiting, output overvoltage detection (±7.5% window), undervoltage lockout (3.4V–3.5V hysteresis), and optional short-circuit shutdown timer. Discontinuous mode operation at light loads improves efficiency, while forced continuous mode (via FCB pin) reduces EMI and supports secondary winding regulation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 36V - supports wide industrial and computing supply rails without pre-regulation. |
| Output Voltage Range | 0.8V to (0.9)×VIN - enables direct CPU core rail generation down to sub-1V levels. |
| Reference Voltage Accuracy | ±1% at 0.8V - ensures tight output regulation critical for low-voltage microprocessor supplies. |
| Min On-Time (tON(MIN)) | ≤100ns - allows high step-down ratios (e.g., 24V→1.2V at 500kHz) without pulse-skipping instability. |
| PGOOD Threshold | ±7.5% VFB window - provides reliable power-good signaling for system sequencing and fault reporting. |
| Shutdown Current (IQ) | <30µA - enables ultra-low-power standby states in battery-backed or energy-sensitive systems. |
| Operating Temp Range | –40°C to +85°C - qualified for commercial-grade embedded and portable computing applications. |
Pinout & Package
Package: 16-lead narrow SSOP (GN), 0.15mm max height, JEDEC MS-012AC compliant, RoHS-compliant lead finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN/SS (Pin 1) | Run enable & soft-start timing input | Capacitor-to-ground sets soft-start ramp time (~3s/µF); <0.8V forces shutdown. |
| PGOOD (Pin 2) | Open-drain power-good monitor | Pulled low when VOUT deviates >±7.5% from regulation point - used for system reset or sequencing control. |
| VRNG (Pin 3) | Sense voltage range configuration | Sets nominal current-sense threshold (50mV–200mV) via resistive divider from INTVCC - determines max valley current limit. |
| FCB (Pin 4) | Forced continuous mode control | Ground = continuous conduction at light load; INTVCC = discontinuous mode; enables EMI reduction and secondary regulation. |
| ITH (Pin 5) | Error amplifier compensation & current threshold | Voltage (0–2.4V) sets valley current comparator threshold - directly controls current limit and loop stability. |
| SGND (Pin 6) | Signal ground reference | Star-point connection for feedback divider, compensation network, and small-signal components - isolates noise from PGND. |
| ION (Pin 7) | On-time current programming | Resistor from VIN sets switching frequency; tON ∝ 1/IION - enables input-voltage-compensated constant-frequency operation. |
| VFB (Pin 8) | Feedback voltage input | Connects to resistive divider from VOUT; error amplifier compares to 0.8V internal reference - primary regulation node. |
| EXTVCC (Pin 9) | External bias supply input | Accepts 4.5–7V supply to power INTVCC; bypasses internal LDO - improves efficiency when secondary rail available. |
| VIN (Pin 10) | Main input power supply | 4V–36V input rail; requires RC filter (1Ω + 0.1µF) to PGND for noise suppression and ESD protection. |
| INTVCC (Pin 11) | Internal 5V regulator output | Supplies gate drivers and control logic; requires ≥4.7µF low-ESR tantalum capacitor to PGND for stability. |
| BG (Pin 12) | Bottom gate driver output | Drives gate of synchronous N-MOSFET between PGND and INTVCC - supports logic-level MOSFETs only. |
| PGND (Pin 13) | Power ground return | Low-impedance return path for bottom MOSFET source, CIN(–), and CVCC(–) - must be connected at single point to SGND. |
| SW (Pin 14) | Switch node | Connects to inductor and source of top MOSFET; swings from ~–0.4V to VIN - critical for bootstrap capacitor charging. |
| TG (Pin 15) | Top gate driver output | Drives top N-MOSFET gate with swing equal to INTVCC superimposed on SW - requires external bootstrap diode and capacitor. |
| BOOST (Pin 16) | Bootstrap capacitor positive terminal | Connects to (+) of CB; floats up to VIN + INTVCC - enables high-side N-MOSFET drive without charge pump. |
Key Features
| Feature | Design Value |
|---|---|
| No external sense resistor | Uses bottom MOSFET RDS(ON) for current sensing - eliminates power loss, board space, and cost of discrete sense resistor. |
| Valley current mode control | Enables stable operation at very low duty cycles (<5%) and fast transient response without slope compensation. |
| Programmable soft-start | RUN/SS pin accepts external capacitor to control startup dV/dt and prevent inrush current - supports multi-rail sequencing. |
| Ceramic-capacitor compatible | Stable with low-ESR ceramic output capacitors - reduces solution size and improves reliability vs. electrolytic alternatives. |
| Dual N-MOSFET synchronous drive | Integrated TG/BG drivers with 2Ω pull-up/pull-down - supports efficient high-current buck stages without external drivers. |
Applications
| Processor Core Power Supply | Industrial Distributed Power |
|---|---|
Use Scenario: Providing tightly regulated 1.2V/10A core voltage to Intel/AMD CPUs in notebooks and embedded controllers. IC Role / Device Role / Timing Role: Primary step-down controller managing valley current sensing, gate drive timing, and PGOOD sequencing. Use Value: Enables high-efficiency, compact, no-RSENSE design meeting ±1% output accuracy and <50µs load transient recovery per spec. | Use Scenario: Generating isolated 3.3V/5A rails from 24V industrial bus in PLCs and motor drives. IC Role / Device Role / Timing Role: High-input synchronous buck controller with robust UVLO, OVP, and thermal-safe shutdown. Use Value: Delivers stable output under wide input variation (18–36V) and maintains regulation during brownouts via 3.4V UVLO threshold. |
| Telecom Intermediate Bus Converter | Medical Imaging Power Module |
Use Scenario: Converting 48V telecom rectified bus to 12V intermediate rail for downstream POL converters. IC Role / Device Role / Timing Role: High-step-down ratio controller operating at 200–500kHz with minimal tON(MIN) limitation. Use Value: Achieves 24V→12V conversion at 92% peak efficiency with ceramic output caps - reducing heat and footprint vs. two-stage solutions. | Use Scenario: Supplying low-noise 5V/3A auxiliary power for FPGA-based image processing subsystems. IC Role / Device Role / Timing Role: Synchronous buck controller with forced continuous mode (FCB) to suppress EMI in sensitive analog signal chains. Use Value: Eliminates discontinuous-mode switching noise via FCB pin control - meets CISPR-32 Class B conducted emissions limits. |
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#PBF | Wider VIN (4–60V), integrated MOSFET drivers with higher peak current (4A), no PGOOD but includes EXTVCC and TRACK pins. | Supports higher input voltages and more complex multi-phase or tracking configurations; lacks dedicated PGOOD output. | Select when input exceeds 36V or when enhanced gate drive strength is required; verify PGOOD functionality is handled externally. |
| MP2918GL-Z | Lower IQ (15µA shutdown), integrated MOSFET drivers, fixed 0.6V reference, no VRNG or FCB pins - simplified feature set. | Targeted at cost-sensitive consumer applications; lacks programmable current sense range and forced continuous mode. | Choose for basic high-efficiency buck control where VRNG flexibility and EMI control via FCB are not required. |
Compared with LTC3891EMSE#PBF and MP2918GL-Z, the LTC1778EGN#TRPBF offers unique no-RSENSE valley current control with PGOOD, VRNG-adjustable current limit, and FCB-enabled EMI optimization - making it optimal for precision CPU and industrial intermediate bus supplies where those features are essential.
Availability
LTC1778EGN#TRPBF is available at Aetrix Electronics and suitable for notebook computers, distributed power systems, and telecom intermediate bus converters requiring stable component supply, long-term lifecycle support, and guaranteed commercial-temperature performance.
Supply support for LTC1778EGN#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 LTC1778EGN#TRPBF belongs to ADI's legacy Linear Technology power management portfolio, designed specifically for high-efficiency, high-step-down-ratio synchronous buck controllers targeting CPU core and intermediate bus applications.
FAQ
What is the function of the VRNG pin on the LTC1778EGN#TRPBF?
The VRNG pin on the LTC1778EGN#TRPBF sets the nominal current-sense voltage threshold by scaling the bottom MOSFET's RDS(ON) drop - configured via resistive divider from INTVCC to yield 50mV–200mV nominal sense range. This directly defines the maximum valley current limit (IOUT(MAX) ≈ 0.133×VVRNG/RDS(ON)), enabling precise current limiting without external components. The LTC1778EGN#TRPBF defaults to 70mV when VRNG is grounded.
Does the LTC1778EGN#TRPBF require an external sense resistor?
No, the LTC1778EGN#TRPBF does not require an external sense resistor. It uses the on-resistance (RDS(ON)) of the external bottom N-channel MOSFET as the current-sensing element - measuring the voltage between PGND and SW pins. This eliminates power loss, board area, and cost associated with discrete sense resistors while maintaining accurate valley current mode control. The LTC1778EGN#TRPBF achieves this via its proprietary no-RSENSE architecture.
How is switching frequency programmed on the LTC1778EGN#TRPBF?
Switching frequency on the LTC1778EGN#TRPBF is programmed by connecting a resistor (RON) from VIN to the ION pin - setting the one-shot timer current. Frequency scales inversely with RON and is approximately constant over input voltage due to tON ∝ 1/IION. For example, a 100kΩ resistor yields ~300kHz at VIN=15V and VOUT=2.5V. The LTC1778EGN#TRPBF datasheet provides RON vs. f curves for common output voltages.
What is the purpose of the PGOOD pin on the LTC1778EGN#TRPBF?
The PGOOD pin on the LTC1778EGN#TRPBF is an open-drain output that signals valid regulation: it pulls low when the feedback voltage (VFB) deviates more than ±7.5% from the 0.8V reference, indicating out-of-regulation condition. This enables safe power sequencing, system reset assertion, or fault logging in host systems. The LTC1778EGN#TRPBF asserts PGOOD only after soft-start completion and sustained regulation - critical for reliable CPU and FPGA power-up.
Can the LTC1778EGN#TRPBF operate with ceramic output capacitors?
Yes, the LTC1778EGN#TRPBF is explicitly designed to be stable with low-ESR ceramic output capacitors - a key advantage over many older controllers requiring bulk electrolytic or tantalum caps. Its valley current mode architecture and internal compensation eliminate need for external type-II or type-III networks. Stability is maintained across full load and temperature ranges when using ≥100µF ceramic capacitance with appropriate layout - reducing size, improving reliability, and lowering output ripple in the LTC1778EGN#TRPBF design.
LTC1778EGN#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, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Buck-Boost
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 4V ~ 36V
- Frequency - Switching:
- -
- Duty Cycle (Max):
- -
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- 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
LTC1778EGN#TRPBF FAQ
1.How can I place an order for LTC1778EGN#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1778EGN#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 LTC1778EGN#TRPBF reliable?
The price and inventory of LTC1778EGN#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1778EGN#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1778EGN#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1778EGN#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1778EGN#TRPBF?
LTC1778EGN#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1778EGN#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 LTC1778EGN#TRPBF?
For technical support, including LTC1778EGN#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1778EGN#TRPBF requirements.
6.How does Aetrix verify that LTC1778EGN#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1778EGN#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 LTC1778EGN#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1778EGN#TRPBF?
All LTC1778EGN#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1778EGN#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 LTC1778EGN#TRPBF part is unused and in its original packaging.
Return procedure for LTC1778EGN#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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