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Analog Devices Inc. LTC1778IGN#PBF
- Part No.:
- LTC1778IGN#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC1778IGN#PBF.pdf
- Description:
- IC REG CTRLR BUCK/BCK-BST 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:247
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Product details
Overview
LTC1778IGN#PBF from Analog Devices (formerly Linear Technology) is a wide-input synchronous step-down controller optimized for CPU power delivery in high step-down ratio applications. 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 features dual N-channel MOSFET gate drive with programmable soft-start and output overvoltage protection - used in notebook computers and distributed power systems.
For engineers reviewing the LTC1778IGN#PBF datasheet, LTC1778IGN#PBF pinout, LTC1778IGN#PBF application, or LTC1778IGN#PBF equivalent, key selection criteria include its no-RSENSE architecture, valley current mode operation, 16-pin SSOP package, ±1% 0.8V reference, and compatibility with ceramic output capacitors for fast transient response in CPU core voltage regulation.
Technical Context
The LTC1778IGN#PBF implements a valley current mode control architecture where inductor valley current is sensed via bottom MOSFET RDS(ON), eliminating need for a discrete sense resistor. Its one-shot timer sets top MOSFET on-time based on ION pin current and (for LTC1778-1 variants) VON pin voltage, enabling frequency stabilization across input and output voltage variations.
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 including 5V, 12V, 24V, and 28V inputs. |
| Output Voltage Range | 0.8V to (0.9)×VIN - enables direct CPU core voltage regulation down to sub-1V levels with adaptive tracking. |
| Reference Voltage Accuracy | ±1% at 0.8V - ensures tight output regulation critical for low-voltage microprocessor power domains. |
| Minimum On-Time | ≤100ns - enables stable operation at high step-down ratios (e.g., 24V→1.2V) without pulse-skipping artifacts. |
| Switching Frequency Control | Externally programmable via RON resistor - allows optimization of inductor size vs. efficiency tradeoff (typical range: 200–300kHz). |
| Gate Drive Capability | TG/ BG drivers with 2–3Ω pull-up/pull-down resistance - supports fast switching of logic-level N-MOSFETs with <20ns rise/fall times. |
| Shutdown Current | <30µA - enables ultra-low-power system standby states without compromising startup reliability. |
Pinout & Package
Package: 16-lead narrow-body plastic SSOP (GN), 0.150" body width, 0.025" lead pitch, RoHS-compliant, moisture sensitivity level 3.
| 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); voltage <0.8V forces shutdown. |
| PGOOD (Pin 2) | Open-drain power-good monitor | Pulled low when VFB deviates >±7.5% from 0.8V - provides system-level power sequencing feedback. |
| VRNG (Pin 3) | Sense voltage range configuration | Sets nominal current sense threshold (50–200mV) by resistive divider from INTVCC - determines max valley current limit. |
| FCB (Pin 4) | Forced continuous mode control | Ground = continuous conduction; 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; also serves as EA output for loop compensation. |
| SGND (Pin 6) | Signal ground reference | Isolated small-signal ground node - must connect to PGND at single point to avoid noise coupling into feedback path. |
| ION (Pin 7) | On-time current programming | Resistor from VIN sets one-shot timer current - primary means of setting switching frequency and stabilizing fSW vs. VIN. |
| VFB (Pin 8) | Feedback input | Connects to resistive divider from VOUT; internal 0.8V reference enables precise output voltage regulation. |
| EXTVCC (Pin 9) | External bias supply input | Accepts 4.5–7V external supply to power INTVCC - bypasses internal LDO for higher efficiency in multi-rail systems. |
| VIN (Pin 10) | Main input supply | Primary power input (4–36V); requires RC filter (1Ω + 0.1µF) to PGND for noise suppression. |
| INTVCC (Pin 11) | Internal 5V regulator output | Supplies gate drivers and control circuitry; requires ≥4.7µF low-ESR tantalum capacitor to PGND. |
| BG (Pin 12) | Bottom gate driver output | Drives source-follower-connected N-MOSFET gate between PGND and INTVCC - supports synchronous rectification. |
| PGND (Pin 13) | Power ground return | High-current return path for bottom MOSFET source, CIN(–), and CVCC(–) - must be low-inductance connection to minimize switching noise. |
| SW (Pin 14) | Switch node | Connects to drain of top MOSFET and source of bottom MOSFET; swings from ~–0.5V to VIN - node for bootstrap capacitor (–) terminal. |
| TG (Pin 15) | Top gate driver output | Drives high-side N-MOSFET gate with swing equal to INTVCC superimposed on SW node voltage - requires bootstrap capacitor. |
| BOOST (Pin 16) | Bootstrap capacitor positive terminal | Connects to (+) terminal of bootstrap capacitor CB; swings from ~INTVCC–0.5V to VIN+INTVCC - enables high-side gate drive above VIN. |
Key Features
| Feature | Design Value |
|---|---|
| No external sense resistor required | 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 load transient response without subharmonic oscillation. |
| Stable with ceramic output capacitors | Eliminates need for high-ESR electrolytic or tantalum capacitors - reduces size, improves reliability, and lowers output ripple. |
| Dual N-channel synchronous drive | Integrated TG/BG drivers support efficient synchronous rectification - avoids Schottky diode losses and thermal derating issues. |
| Programmable soft-start | External CSS capacitor controls output voltage ramp rate - prevents inrush current and enables controlled power sequencing in multi-rail systems. |
| Output overvoltage protection | Hardware-based OVP trips within microseconds if VOUT exceeds +7.5% - protects downstream ICs during fault conditions without software intervention. |
Applications
| Server CPU Core Power | Notebook Processor VRM |
|---|---|
Use Scenario: Regulating 1.0V–1.3V core voltage for Intel Xeon or AMD EPYC processors under dynamic load from 0A to 120A. IC Role / Device Role / Timing Role: Primary step-down controller managing valley current mode, gate timing, and PGOOD signaling for PMBus-compatible VRM. Use Value: ≤100ns tON(MIN) enables stable 24V→1.2V conversion; no-RSENSE architecture reduces BOM cost and thermal footprint in dense server PCB layouts. | Use Scenario: Providing 0.8V–1.5V adaptive core voltage to mobile CPUs in ultrabooks with battery input ranging 7V–21V. IC Role / Device Role / Timing Role: Synchronous buck controller with programmable soft-start and PGOOD for coordinated power-up with chipset and memory rails. Use Value: Wide 4V–36V input range accommodates Li-ion battery pack voltage sag; ceramic-capable design meets thin-profile mechanical constraints. |
| Distributed Telecom Power | Industrial FPGA Power Supply |
Use Scenario: Generating 3.3V or 5V intermediate bus from –48V telecom rectified input using isolated front-end followed by LTC1778IGN#PBF post-regulator. IC Role / Device Role / Timing Role: High-efficiency synchronous buck controller operating in discontinuous mode at light loads to meet Energy Star standby requirements. Use Value: Micropower shutdown (<30µA) and forced continuous mode (FCB) reduce no-load losses and EMI in multi-output telecom shelves. | Use Scenario: Delivering 0.85V core voltage to Xilinx Kintex or Intel Arria FPGAs with rapid load transients up to 10A/µs in factory automation controllers. IC Role / Device Role / Timing Role: Valley current mode controller providing fast transient response and output overvoltage protection for reconfigurable logic power domains. Use Value: Stable ceramic-capacitor operation and ±1% reference ensure FPGA configuration integrity; PGOOD signal enables FPGA INIT_B coordination. |
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 |
|---|---|---|---|
| MP2482DK-LF-Z | Fixed 500kHz frequency, integrated MOSFETs, no PGOOD, lower input range (4.5–30V) | Targeted at space-constrained consumer DC/DC modules; lacks programmable soft-start and valley current mode | Choose MP2482DK-LF-Z only when board area is critical and fixed-frequency operation suffices. |
| TPS54620RGYR | Current-mode controller with integrated 30V MOSFETs, 4.5–17V input, no VRNG pin, different pinout | Designed for mid-range industrial supplies; lacks no-RSENSE capability and wide 4–36V input support | Prefer TPS54620RGYR when integrated power stage simplifies layout but accept reduced input voltage headroom. |
Compared with MP2482DK-LF-Z and TPS54620RGYR, the LTC1778IGN#PBF uniquely combines no-RSENSE valley current control, 4–36V input, and PGOOD monitoring - making it optimal for high-reliability CPU and FPGA core power where precision, flexibility, and fault reporting are essential.
Availability
LTC1778IGN#PBF is available at Aetrix Electronics and suitable for notebook computers, distributed power systems, and industrial FPGA power supplies requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.
Supply support for LTC1778IGN#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, 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 LTC1778IGN#PBF belongs to ADI's legacy Linear Technology power management portfolio, specifically designed for high-efficiency, high-step-down-ratio CPU and FPGA core voltage regulation in computing and telecom infrastructure.
FAQ
What is the operating temperature range for the LTC1778IGN#PBF?
The LTC1778IGN#PBF is specified for operation from –40°C to +125°C ambient temperature, with junction temperature limited to 125°C. This extended industrial temperature grade makes LTC1778IGN#PBF suitable for demanding environments such as base station power supplies and ruggedized computing platforms where thermal margins are constrained.
Does the LTC1778IGN#PBF require an external sense resistor?
No, the LTC1778IGN#PBF does not require an external sense resistor. It uses the RDS(ON) of the external bottom N-channel MOSFET to sense inductor valley current - a feature confirmed in the datasheet's "No Sense Resistor Required" headline and functional diagram. This eliminates sense resistor power loss and improves efficiency in high-current applications.
How is switching frequency set on the LTC1778IGN#PBF?
Switching frequency on the LTC1778IGN#PBF is set by connecting a resistor RON from VIN to the ION pin (Pin 7). The on-time tON is inversely proportional to ION current, resulting in approximately constant frequency across input voltage variation. Typical RON values range from 10kΩ to 100kΩ for 200–300kHz operation, as shown in Figures 3a and 3b of the LTC1778IGN#PBF datasheet.
What is the function of the VRNG pin on the LTC1778IGN#PBF?
The VRNG pin (Pin 3) on the LTC1778IGN#PBF sets the nominal current sense voltage range - it scales the maximum allowable valley current threshold from 50mV to 200mV depending on the applied voltage (0.5V–2V). This directly determines the peak inductor current limit and must be configured with a resistive divider from INTVCC to match the selected bottom MOSFET's RDS(ON) and maximum load current.
Can the LTC1778IGN#PBF be used with ceramic output capacitors?
Yes, the LTC1778IGN#PBF is explicitly designed to be stable with low-ESR ceramic output capacitors - a key feature highlighted in its "Stable with Ceramic COUT" bullet. This eliminates the need for high-ESR electrolytic or tantalum capacitors, reducing board area, improving reliability, and lowering output voltage ripple in high-frequency switching applications.
LTC1778IGN#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, 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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SSOP
LTC1778IGN#PBF FAQ
1.How can I place an order for LTC1778IGN#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1778IGN#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 LTC1778IGN#PBF reliable?
The price and inventory of LTC1778IGN#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1778IGN#PBF is usually 5 days.
3.What payment methods are accepted for LTC1778IGN#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1778IGN#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1778IGN#PBF?
LTC1778IGN#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1778IGN#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 LTC1778IGN#PBF?
For technical support, including LTC1778IGN#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1778IGN#PBF requirements.
6.How does Aetrix verify that LTC1778IGN#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1778IGN#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 LTC1778IGN#PBF meets industry standards.
7.What is the process for return or replacement of LTC1778IGN#PBF?
All LTC1778IGN#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1778IGN#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 LTC1778IGN#PBF part is unused and in its original packaging.
Return procedure for LTC1778IGN#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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