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Analog Devices Inc. LTC1775IS#PBF
- Part No.:
- LTC1775IS#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1775IS#PBF.pdf
- Description:
- IC REG CTRLR BUCK/BCK-BST 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:210
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Product details
Overview
LTC1775IS#PBF from Analog Devices (formerly Linear Technology) is a synchronous step-down switching regulator controller that drives external dual N-channel MOSFETs without a current-sense resistor, using VDS sensing. It operates from 4.3V to 36V input, delivers 1.19V–VIN output, supports 150kHz fixed or synchronized frequency, and enables >99% duty cycle for ultra-low dropout in battery-powered systems.
For engineers reviewing the LTC1775IS#PBF datasheet, LTC1775IS#PBF pinout, LTC1775IS#PBF application, or LTC1775IS#PBF equivalent, this page provides verified technical context on No RSENSE operation, Burst Mode efficiency optimization, forced continuous mode control, output overvoltage protection, and thermal-aware MOSFET drive requirements for high-current DC/DC designs.
Technical Context
The LTC1775IS#PBF implements current-mode control via MOSFET VDS sensing-eliminating sense resistors and reducing conduction loss-while maintaining stable regulation across 0–10A+ loads. Its error amplifier (ITH pin) sets peak inductor current proportional to feedback voltage, with ±1% 1.19V reference and programmable soft start via RUN/SS capacitor ramping.
It features dual gate drivers (TG/BG) referenced to floating BOOST and PGND, respectively, supporting synchronous rectification with logic-level N-MOSFETs. The oscillator synchronizes to external clocks over 100–225kHz (1.5:1 range), and includes a dropout counter to recharge the bootstrap capacitor during near-100% duty cycles.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.3V to 36V - Supports automotive battery (cold-crank), industrial 24V, and wide-input distributed power rails. |
| Output Voltage Range | 1.19V to VIN - Adjustable via external resistor divider or pin-selectable 3.3V/5V outputs using VPROG. |
| Max Current Sense Threshold | 300mV - Enables high-current operation without sense resistor; sets peak IL = 300mV / RDS(ON) of top MOSFET. |
| Oscillator Frequency | 150kHz nominal, syncable 100–225kHz - Balances efficiency (lower f) and size (higher f); injection-locked to external clock. |
| Shutdown Quiescent Current | <30µA - Critical for battery longevity in always-on or low-power standby modes. |
| Reference Accuracy | ±1% at 1.19V - Ensures tight output regulation across temperature and line/load variations. |
| Operating Temp Range | –40°C to +85°C - Industrial-grade qualification suitable for under-hood automotive and ruggedized embedded systems. |
Pinout & Package
Package: 16-lead narrow plastic SSOP (GN), 5.3mm × 6.2mm, 0.635mm pitch, exposed pad not present. Thermal resistance θJA = 130°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EXTVCC (1) | INTVCC power source selector | Switches internal LDO off when ≥4.7V applied; allows efficient self-biasing from VOUT or secondary winding. |
| SYNC (2) | Oscillator synchronization input | Enables external clock injection lock (100–225kHz); open or grounded = 150kHz; >1.2V = 225kHz. |
| RUN/SS (3) | Enable & soft-start control | Pull <0.8V to shut down; capacitor to ground sets startup ramp time (~1s/µF). |
| FCB (4) | Forced continuous mode control | Tie to GND to disable Burst Mode; tie to INTVCC to enable Burst Mode; used for secondary-winding regulation assist. |
| ITH (5) | Error amplifier compensation node | Voltage sets peak inductor current threshold; clamped at 0.95V in Burst Mode, 0.5V to disable switching. |
| SGND (6) | Signal ground reference | Return for VOSENSE, VPROG, and feedback network; must connect to COUT (–) to minimize noise coupling. |
| VOSENSE (7) | Output voltage feedback input | Accepts remote sense or resistive divider; determines regulated VOUT via internal 1.19V reference. |
| VPROG (8) | Output voltage selection | <0.8V = 3.3V; >3.5V = 5V; open = adjustable via VOSENSE divider; defines feedback path routing. |
| PGND (9) | Power ground for bottom FET | Low-impedance return for BG driver, CVCC, and CIN (–); must be star-connected to minimize ground bounce. |
| BG (10) | Bottom N-MOSFET gate driver | Drives gate between PGND and INTVCC (5.2V); requires low-inductance layout to prevent shoot-through. |
| INTVCC (11) | Internal 5.2V LDO output | Supplies TG/BG drivers and core logic; decouple with ≥4.7µF tantalum to PGND. |
| BOOST (12) | Floating supply for top gate driver | Connects to (+) of bootstrap capacitor; swings from ~INTVCC–0.4V to VIN+INTVCC for high-side drive. |
| TG (13) | Top N-MOSFET gate driver | Drives gate referenced to SW node; swing = INTVCC amplitude superimposed on switch-node potential. |
| SW (14) | Switch node connection | Connects to drain of top FET and (–) of bootstrap capacitor; high dv/dt node requiring tight loop area. |
| TK (15) | Top FET Kelvin sense | Must route separately from VIN to top FET drain to enable accurate VDS sensing and avoid PCB trace resistance error. |
| VIN (16) | Main input supply | 4.3V–36V input; decouple with RC filter (1Ω + 0.1µF) for >3A applications to suppress high-frequency noise. |
Key Features
| Feature | Design Value |
|---|---|
| No RSENSE current sensing | Eliminates 5–10W sense resistor losses in 10A+ designs; uses MOSFET RDS(ON) as intrinsic current sensor. |
| Burst Mode operation | Reduces light-load quiescent current to <30µA and maintains >85% efficiency at 10mA load via cycle-skipping. |
| Forced Continuous Mode (FCB) | Disables Burst Mode to sustain regulation on auxiliary windings or low-ESR ceramic outputs requiring constant switching. |
| Output Overvoltage Protection (OVP) | Locks out top FET and activates bottom FET if VOSENSE exceeds 1.28V, preventing damage to downstream 3.3V/5V ICs. |
| Programmable soft start | External capacitor on RUN/SS pin controls inrush current ramp rate, preventing input rail collapse during startup. |
| Wide VIN/VOUT range | Supports 4.3V cold-crank start and 36V transients while regulating down to 1.19V for modern SoCs and FPGAs. |
Applications
| Notebook Computers | Automotive Electronics |
|---|---|
Use Scenario: Main system power rail for CPU/GPU core voltage in portable notebooks with dynamic load steps up to 10A. IC Role / Device Role / Timing Role: Synchronous buck controller managing dual-phase N-MOSFETs with adaptive VDS current sensing and Burst Mode for idle power savings. Use Value: Achieves >94% efficiency at 5V/6A and extends battery runtime by eliminating sense resistor losses and enabling sub-30µA shutdown. |
Use Scenario: Engine control unit (ECU) power supply handling 12V battery input with load dump transients up to 36V. IC Role / Device Role / Timing Role: High-reliability step-down controller driving automotive-qualified MOSFETs with OVP, foldback current limiting, and –40°C to +85°C operation. Use Value: Survives ISO 7637-2 pulse 5a (36V/200ms) and maintains 3.3V/5A output stability during cranking (4.3V min), ensuring ECU uptime. |
| Battery Chargers | Distributed Power Systems |
Use Scenario: Constant-current/constant-voltage stage in multi-cell Li-ion fast chargers requiring precise 8.4V/3A output. IC Role / Device Role / Timing Role: Primary DC/DC controller with programmable VPROG and precision 1.19V reference for ±1% output accuracy across charge cycles. Use Value: Enables accurate CC/CV transition without external op-amps; foldback current limit protects cells during short-circuit faults. |
Use Scenario: Intermediate bus converter in telecom shelf supplying 5V/12A to multiple point-of-load regulators. IC Role / Device Role / Timing Role: High-efficiency, sync-capable controller allowing system-wide clock alignment to reduce EMI in dense board layouts. Use Value: Synchronization eliminates beat frequencies; 99% duty cycle supports 5V-out-from-5.5V-in scenarios common in intermediate bus architectures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP24894GQ-Z | Integrated power stage (MOSFETs built-in); 4.5–36V input; fixed 500kHz fSW; no VDS sensing - uses external sense resistor. | Lower BOM count but higher conduction loss at >5A; lacks Burst Mode and programmable soft start. | Choose MP24894GQ-Z for space-constrained, medium-current (<6A) designs where integration outweighs efficiency loss. |
| LTC3891IFE#PBF | Higher VIN range (4–60V); dual-output; includes PMBus interface; 300mV current sense threshold retained; –40°C to +125°C rating. | Targeted at harsh-environment industrial/military systems requiring extended temp and digital monitoring. | Choose LTC3891IFE#PBF when operating above 85°C ambient or requiring telemetry, but accept larger footprint and higher cost. |
Compared with MP24894GQ-Z and LTC3891IFE#PBF, the LTC1775IS#PBF uniquely balances No RSENSE efficiency, industrial temperature support, and minimal external component count for discrete high-current buck converters-making it optimal for cost-sensitive, thermally demanding 5–15A applications where integration is secondary to thermal performance.
Availability
LTC1775IS#PBF is available at Aetrix Electronics and suitable for notebook computers, automotive electronics, and battery chargers requiring stable component supply, long-term lifecycle support, and guaranteed industrial-temperature grade authenticity.
Supply support for LTC1775IS#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 and maintains full product support, datasheets, and application engineering for legacy Linear parts including the LTC1775 series.
The LTC1775 belongs to Linear's high-efficiency current-mode controller family, designed specifically for high-current, low-loss synchronous buck conversion in battery-powered and automotive environments where sense-resistor elimination and Burst Mode efficiency are critical.
FAQ
What is the minimum input voltage for LTC1775IS#PBF at –40°C?
The LTC1775IS#PBF has a specified minimum input voltage of 4.3V at –40°C ambient, per Note 5 in the Electrical Characteristics table. This ensures reliable startup and regulation during automotive cold-crank conditions. Below 4.3V, the internal bias circuitry may not activate, and the device will not switch. Always verify VIN remains ≥4.3V across the full industrial temperature range when designing for low-temperature operation.
How does the LTC1775IS#PBF achieve No RSENSE operation?
The LTC1775IS#PBF achieves No RSENSE operation by measuring the voltage drop (VDS) across the conducting top N-channel MOSFET during its on-time, using dedicated TK and SW pins for Kelvin sensing. This eliminates external sense resistors and their associated power loss and PCB area. The controller compares this VDS signal to an internal 300mV threshold to regulate peak inductor current - a method confirmed in the Functional Diagram and Applications Information sections of the LTC1775IS#PBF datasheet.
Can LTC1775IS#PBF be synchronized to an external clock, and what is the valid frequency range?
Yes, the LTC1775IS#PBF can be synchronized to an external clock applied to the SYNC pin. It supports injection locking over a 1.5:1 frequency range centered on its nominal 150kHz oscillator - i.e., 100kHz to 225kHz. The SYNC pin threshold is 1.2V (rising), and the clock high pulse width must be 1–4µs. When SYNC is open or grounded, the oscillator runs at 150kHz; pulling SYNC >1.2V forces 225kHz operation. This capability is explicitly documented in the Oscillator section of the LTC1775IS#PBF Electrical Characteristics table.
What is the purpose of the FCB pin on LTC1775IS#PBF, and how should it be configured?
The FCB (Forced Continuous Mode) pin on LTC1775IS#PBF disables Burst Mode operation when pulled below 1.19V (typically to GND), forcing continuous switching - essential for maintaining regulation on auxiliary windings or low-ESR ceramic outputs. Tying FCB to INTVCC enables Burst Mode for light-load efficiency. Its function is defined in the Pin Functions section and validated by the FCB voltage threshold (1.16–1.22V) and bias current specs in the LTC1775IS#PBF Electrical Characteristics table.
Does LTC1775IS#PBF provide overvoltage protection, and what is the trip threshold?
Yes, the LTC1775IS#PBF includes dedicated output overvoltage protection (OVP) that triggers when VOSENSE exceeds 1.28V (typical), as specified in the Electrical Characteristics table under VOVL parameter. Upon detection, the top MOSFET is turned off and the bottom MOSFET is activated to clamp the output, protecting downstream 3.3V or 5V logic. This hardware-based OVP operates independently of the feedback loop and is active across the full temperature range - a key safety feature confirmed in the Fault Protection section of the LTC1775IS#PBF datasheet.
LTC1775IS#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SOIC (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):
- 4.3V ~ 36V
- Frequency - Switching:
- 150kHz
- Duty Cycle (Max):
- 99%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Enable, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
LTC1775IS#PBF FAQ
1.How can I place an order for LTC1775IS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1775IS#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 LTC1775IS#PBF reliable?
The price and inventory of LTC1775IS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1775IS#PBF is usually 5 days.
3.What payment methods are accepted for LTC1775IS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1775IS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1775IS#PBF?
LTC1775IS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1775IS#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 LTC1775IS#PBF?
For technical support, including LTC1775IS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1775IS#PBF requirements.
6.How does Aetrix verify that LTC1775IS#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1775IS#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 LTC1775IS#PBF meets industry standards.
7.What is the process for return or replacement of LTC1775IS#PBF?
All LTC1775IS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1775IS#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 LTC1775IS#PBF part is unused and in its original packaging.
Return procedure for LTC1775IS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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