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Analog Devices Inc. LTC1778EGN-1#TRPBF
- Part No.:
- LTC1778EGN-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC1778EGN-1#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK/BCK-BST 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:5,349
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Product details
Overview
LTC1778EGN-1#TRPBF from Analog Devices (formerly Linear Technology) is a wide-input synchronous step-down controller optimized for high step-down ratio CPU and point-of-load power supplies. It delivers true valley current mode control without an external sense resistor, supports 4V–36V input, 0.8V–(0.9)VIN output, ≤100ns minimum on-time, and adjustable switching frequency via ION pin resistor. Used in notebook computers and distributed power systems.
For engineers reviewing the LTC1778EGN-1#TRPBF datasheet, LTC1778EGN-1#TRPBF pinout, LTC1778EGN-1#TRPBF application, or LTC1778EGN-1#TRPBF equivalent, key selection criteria include its no-RSENSE architecture, VON-adjustable on-time for constant-frequency operation across VOUT changes, dual N-MOSFET synchronous drive, and 16-pin narrow SSOP package with validated thermal performance up to 85°C ambient.
Technical Context
The LTC1778EGN-1#TRPBF implements valley current mode control using the bottom MOSFET's RDS(ON) as the current sense element, eliminating need for discrete sense resistors. Its one-shot timer sets tON proportional to VON/IION, enabling stable frequency under varying VIN and VOUT when VON is tied to output or INTVCC.
Fault protection includes foldback current limiting, output overvoltage comparator (±7.5% threshold), undervoltage lockout (3.4V–4.0V), and optional short-circuit shutdown timer. Discontinuous mode is selectable via FCB pin, and soft-start is programmable with external capacitor on RUN/SS.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 36V - supports wide industrial and computing input rails including 5V, 12V, 24V, and 28V bus systems. |
| Output Voltage Range | 0.8V to (0.9)×VIN - enables low-voltage CPU core regulation down to sub-1V with tight tracking. |
| Reference Voltage Accuracy | ±1% at 0.8V - ensures precise output regulation critical for sensitive digital loads. |
| Min On-Time (tON(MIN)) | ≤100ns - allows stable operation at high step-down ratios (e.g., 24V→1.2V @ 5% duty cycle) without dropout. |
| Switching Frequency Control | Adjustable via external RON on ION pin - enables optimization of efficiency vs. size tradeoffs; typical range 200–300kHz. |
| Current Sense Method | No external RSENSE; uses bottom MOSFET RDS(ON) - reduces BOM cost, PCB area, and power loss versus discrete sensing. |
| Package | 16-pin narrow SSOP (GN) - 5.0mm × 6.2mm footprint with 0.65mm pitch; thermally enhanced for 130°C/W θJA. |
Pinout & Package
Package: 16-lead plastic narrow SSOP (GN), RoHS-compliant, rated for –40°C to +85°C operating ambient temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN/SS (Pin 1) | Run enable & soft-start timing input | Capacitor-to-ground sets ramp time (~3s/µF); <0.8V forces shutdown; internal 1.2µA charge current enables controlled startup sequencing. |
| VON (Pin 2) | On-time voltage reference input | Adjusts tON comparator trip point (0.7V–2.4V clamped); tying to VOUT or INTVCC enables constant-frequency operation across load/VOUT changes. |
| VRNG (Pin 3) | Sense voltage range configuration | Sets nominal current sense threshold (50mV–200mV) by scaling bottom MOSFET RDS(ON) voltage; defaults to 70mV if grounded. |
| FCB (Pin 4) | Forced continuous mode control | Tie to ground for forced CCM at light load; tie to INTVCC for DCM; enables secondary-winding regulation in multi-output designs. |
| ITH (Pin 5) | Error amplifier output & current limit threshold | 0V–2.4V control voltage sets valley current limit; also serves as compensation node for loop stability. |
| SGND (Pin 6) | Signal ground reference | Low-noise return for feedback, compensation, and control circuitry; must be star-connected to PGND at single point. |
| ION (Pin 7) | On-time current programming | Resistor from VIN sets tON current; determines switching frequency; ~0.7V bias minimizes VIN dependency error. |
| VFB (Pin 8) | Feedback voltage input | Connects to resistive divider from VOUT; compares against 0.8V internal reference to regulate output voltage. |
| EXTVCC (Pin 9) | External VCC supply input | Accepts 4.5V–7V; disables internal LDO and powers INTVCC directly when >4.7V - improves efficiency in multi-rail systems. |
| VIN (Pin 10) | Main input supply | 4V–36V input rail; requires RC filter (1Ω + 0.1µF) to PGND for noise suppression and EMI reduction. |
| 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; 1–2Ω pull-down/pull-up resistance supports fast switching. |
| PGND (Pin 13) | Power ground return | High-current return path for bottom MOSFET source, CIN (–), and CVCC (–); must be low-inductance connection to minimize noise. |
| SW (Pin 14) | Switch node | Connects to source of top MOSFET and (–) terminal of bootstrap capacitor CB; swings from ~–0.5V to VIN. |
| TG (Pin 15) | Top gate driver output | Drives gate of high-side N-MOSFET with floating 5V swing referenced to SW node; supports bootstrap operation. |
| BOOST (Pin 16) | Bootstrap capacitor positive terminal | Connects to (+) terminal of CB; swings from ~4.5V to VIN+5V; requires Schottky diode (e.g., CMDSH-3) for recharge path. |
Key Features
| Feature | Design Value |
|---|---|
| Valley current mode control | Enables stable operation at ultra-low duty cycles (<5%) without external sense resistor, reducing component count and conduction losses. |
| VON-adjustable on-time | Allows dynamic tON tuning to maintain constant switching frequency during VOUT transients or load steps - critical for EMI-sensitive applications. |
| Dual N-channel MOSFET drive | Integrated 2A peak TG/BG drivers support logic-level MOSFETs; eliminates need for external level shifters or gate driver ICs. |
| Discontinuous/continuous mode select | FCB pin enables seamless transition between DCM (high light-load efficiency) and CCM (low output ripple, better transient response). |
| Programmable soft-start & fault protection | External CSS capacitor controls startup slew rate; built-in OVP, UVLO, foldback current limiting, and optional short-circuit timer ensure robust system reliability. |
Applications
| Notebook CPU Core Power | Distributed Telecom Power |
|---|---|
Use Scenario: Regulating 1.2V/10A core voltage for Intel/AMD mobile processors from 19V adapter input. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing valley current sensing, adaptive on-time, and fast transient response. Use Value: Eliminates RSENSE loss (up to 1W saved), achieves <20µs load-step recovery, and maintains regulation during deep sleep-to-active transitions. | Use Scenario: Generating 3.3V/5A auxiliary rail from 48V telecom backplane in base station power modules. IC Role / Device Role / Timing Role: High-input step-down controller with wide VIN range and ceramic-capacitor stability. Use Value: Supports 48V input derating (36V max), enables compact layout with 180µF ceramic output capacitance, and sustains >92% efficiency at full load. |
| Industrial PLC I/O Power | Automotive Infotainment SoC Supply |
Use Scenario: Providing isolated 1.8V/3A supply for FPGA I/O banks in programmable logic controllers with 24V field bus input. IC Role / Device Role / Timing Role: Robust buck controller with ±1% reference, programmable current limit, and -40°C to +85°C operation. Use Value: Guarantees accurate I/O voltage under wide temperature swings; VRNG pin allows precise current limit calibration across MOSFET RDS(ON) variation. | Use Scenario: Delivering 1.1V/8A core power to automotive-grade application processors (e.g., Qualcomm SA8155) from 12V battery rail. IC Role / Device Role / Timing Role: Automotive-qualified synchronous controller with UVLO (3.4V), overvoltage protection, and micropower shutdown (<30µA). Use Value: Survives cold-crank (4.5V) and load-dump (36V) events; PGOOD-equivalent monitoring via VFB window detection ensures safe processor boot. |
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), but no VON pin; requires external RSENSE. | Preferred for ultra-high-input systems (e.g., 48V industrial) where sense resistor tolerance is acceptable. | Select LTC3891 when input exceeds 36V or higher gate drive strength is needed; avoid if RSENSE-free operation is mandatory. |
| MP2918GL-Z | Lower IQ (25µA shutdown), same 4–36V range, but fixed 600kHz frequency and no VON/VRNG adjustment; uses external current sense. | Suitable for cost-sensitive, fixed-frequency consumer power supplies where design simplicity outweighs adjustability. | Choose MP2918 for production-cost optimization in non-CPU applications; not recommended for dynamic VOUT or precision current limit needs. |
Compared with LTC3891EMSE#PBF and MP2918GL-Z, the LTC1778EGN-1#TRPBF uniquely combines no-RSENSE operation, VON-based on-time adjustability, and VRNG-configurable current sensing - making it optimal for high-efficiency, high-precision CPU and SoC power where board space and thermal budget are constrained.
Availability
LTC1778EGN-1#TRPBF is available at Aetrix Electronics and suitable for notebook computing, distributed telecom power, and industrial PLC I/O power requiring stable component supply, long-term lifecycle support, and guaranteed RoHS compliance.
Supply support for LTC1778EGN-1#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 power management semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC1778EGN-1#TRPBF belongs to ADI's legacy Linear Technology Power Management product line, designed specifically for high-efficiency, high-step-down-ratio DC/DC conversion in space-constrained computing and communications equipment.
FAQ
What is the key functional difference between LTC1778EGN-1#TRPBF and the standard LTC1778EGN?
The LTC1778EGN-1#TRPBF replaces the PGOOD open-drain output pin of the LTC1778EGN with a VON (on-time voltage) input pin. This allows direct adjustment of the one-shot timer's trip point to stabilize switching frequency across output voltage changes or load transients - a critical feature for EMI-sensitive and dynamically scaled CPU power rails. The LTC1778EGN-1#TRPBF retains all other specifications including no-RSENSE operation, 4V–36V input, and 16-pin GN package.
Does LTC1778EGN-1#TRPBF require an external current sense resistor?
No, the LTC1778EGN-1#TRPBF does not require an external current sense resistor. It uses the RDS(ON) of the external bottom N-channel MOSFET as the current sensing element, measuring the voltage between PGND and SW pins. The VRNG pin configures the nominal sense voltage (50mV–200mV), and the ITH pin sets the actual current limit threshold - enabling accurate valley current mode control while eliminating RSENSE power loss and PCB area.
What is the minimum on-time specification for LTC1778EGN-1#TRPBF and why does it matter?
The LTC1778EGN-1#TRPBF has a guaranteed minimum on-time (tON(MIN)) of ≤100ns. This enables stable regulation at very high step-down ratios - for example, converting 24V input to 1.2V output requires only a 5% duty cycle, which demands sub-100ns on-time at typical 300kHz frequencies. Without this capability, the controller would drop out of regulation during low-VIN or high-VOUT conditions, making the LTC1778EGN-1#TRPBF essential for modern low-voltage, high-input applications.
How is switching frequency set on LTC1778EGN-1#TRPBF?
Switching frequency on the LTC1778EGN-1#TRPBF is set by an external resistor RON connected from VIN to the ION pin, combined with the voltage applied to the VON pin. The on-time is calculated as tON = (10pF × VON) / IION, where IION ≈ (VIN − 0.7V) / RON. Tying VON to INTVCC (2.4V) or VOUT enables constant-frequency operation across input or output variations. Typical RON values range from 100kΩ to 1MΩ for 200–300kHz operation.
Can LTC1778EGN-1#TRPBF operate with ceramic output capacitors?
Yes, the LTC1778EGN-1#TRPBF is explicitly designed to be stable with ceramic output capacitors. Its valley current mode architecture and internal compensation provide sufficient phase margin even with low-ESR ceramic capacitors (e.g., 180µF ×2 X5R). This eliminates the need for large, high-ESR electrolytic or tantalum capacitors, reducing solution size, improving reliability, and enabling faster transient response - as verified in Figure 1 and Application Note 1778fb.
LTC1778EGN-1#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-1#TRPBF FAQ
1.How can I place an order for LTC1778EGN-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1778EGN-1#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-1#TRPBF reliable?
The price and inventory of LTC1778EGN-1#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-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1778EGN-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1778EGN-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1778EGN-1#TRPBF?
LTC1778EGN-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1778EGN-1#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-1#TRPBF?
For technical support, including LTC1778EGN-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1778EGN-1#TRPBF requirements.
6.How does Aetrix verify that LTC1778EGN-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1778EGN-1#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-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1778EGN-1#TRPBF?
All LTC1778EGN-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1778EGN-1#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-1#TRPBF part is unused and in its original packaging.
Return procedure for LTC1778EGN-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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