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Analog Devices Inc. LTC3775IUD#TRPBF
- Part No.:
- LTC3775IUD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LTC3775IUD#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,500
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Product details
Overview
LTC3775IUD#TRPBF from Analog Devices (formerly Linear Technology) is a high-efficiency, voltage-mode synchronous step-down DC/DC controller driving all-N-channel MOSFETs from 4.5V to 38V input. It delivers precise 0.6V reference accuracy (±0.75%), supports 250kHz–1MHz programmable switching frequency, achieves <30ns minimum on-time for high step-down ratios, and features RDS(ON) or sense-resistor current sensing. It is used in telecom power supplies requiring fast transient response and stable 1.2V/15A POL regulation.
For engineers reviewing the LTC3775IUD#TRPBF datasheet, LTC3775IUD#TRPBF pinout, LTC3775IUD#TRPBF application, or LTC3775IUD#TRPBF equivalent, key selection criteria include its 16-pin 3mm × 3mm QFN package with exposed PGND pad, cycle-by-cycle peak current limit configuration via ILIMT/ILIMB pins, line feedforward compensation for wide-VIN stability, and forced continuous vs pulse-skipping mode selection via MODE/SYNC pin.
Technical Context
The LTC3775IUD#TRPBF implements leading-edge modulation voltage-mode control with a patented line feedforward circuit that maintains constant modulator gain across 4.5V–38V input, enabling stable loop behavior without recompensation. Its error amplifier provides 25MHz unity-gain bandwidth and 80dB open-loop gain, supporting Type 3 compensation for robust phase margin at LC double-pole frequencies.
It integrates dual high-current gate drivers (TG/BG) with 1.5Ω/1.0Ω pull-down and 2.5Ω/2.5Ω pull-up on-resistances, enabling direct drive of low-Qg N-channel MOSFETs. Cycle-by-cycle current limiting is implemented by monitoring voltage across top/bottom MOSFETs via SENSE and SW pins, with thresholds set independently by external resistors on ILIMT (100μA sink) and ILIMB (10μA source) pins.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4.5V to 38V - supports wide-input industrial and telecom rails without pre-regulation |
| Reference Voltage Accuracy | ±0.75% over temperature - ensures tight output regulation under thermal stress |
| Min On-Time | <30ns - enables 1.2V output from 24V input at 500kHz (5% duty cycle) |
| Switching Frequency | 250kHz to 1MHz - selectable via FREQ pin resistor for EMI/noise/efficiency trade-off |
| Current Sense Options | RDS(ON) or external sense resistor - balances efficiency vs current-limit accuracy |
| Shutdown Current | 14μA typical - minimizes system standby power loss |
| Package Thermal Resistance | θJA = 68°C/W (QFN) - requires exposed PGND pad soldering for thermal integrity |
Pinout & Package
The LTC3775IUD#TRPBF is housed in a thermally enhanced 16-lead (3mm × 3mm) plastic QFN package with exposed PGND pad (Pin 17), requiring PCB soldering for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ILIMT (Pin 1) | Top-side current limit threshold input | 100μA internal sink current sets VIN–SENSE trip point; resistor to VIN programs limit |
| ILIMB (Pin 2) | Bottom-side current limit threshold input | 10μA internal source current sets PGND–SW trip point; resistor to SGND programs limit |
| FB (Pin 3) | Error amplifier inverting input | Connects to VOUT divider; virtual ground node for precision feedback network |
| COMP (Pin 4) | Error amplifier output | Drives line feedforward and PWM comparator; RC network here sets loop stability |
| SS (Pin 5) | Soft-start voltage ramp control | 1μA internal current charges external capacitor; regulates VFB during startup |
| FREQ (Pin 6) | Oscillator frequency set | Resistor to SGND programs free-running frequency from 250kHz to 1MHz |
| SGND (Pin 7) | Signal ground reference | Kelvin return for FB, SS, COMP, MODE/SYNC; isolated from PGND to avoid noise coupling |
| BG (Pin 8) | Bottom gate driver output | Drives bottom N-MOSFET gate from PGND to INTVCC; 1.0Ω pull-down ensures fast turn-off |
| INTVCC (Pin 9) | Internal 5.2V LDO output | Powers gate drivers and logic; requires ≥4.7μF ceramic bypass to PGND |
| SENSE (Pin 10) | Top MOSFET current sense input | Connects to switch node for RDS(ON) sensing or to sense resistor drain for accuracy |
| VIN (Pin 11) | Main input supply | 4.5V–38V input rail; bypass with ≥1μF ceramic capacitor to PGND |
| SW (Pin 12) | Switch node connection | Connects to source of top MOSFET; feeds bottom current limit and reverse-current comparators |
| TG (Pin 13) | Top gate driver output | Floating driver powered by BOOST; drives top N-MOSFET gate referenced to SW |
| BOOST (Pin 14) | Top gate driver floating supply | Decoupled to SW via 0.1μF capacitor; Schottky diode from INTVCC creates charge pump |
| MODE/SYNC (Pin 15) | Operation mode select / sync input | Pull <1.2V for forced continuous mode; drive with external clock for synchronization |
| RUN/SHDN (Pin 16) | Enable/shutdown control | ≥1.22V enables operation; ≤0.74V forces shutdown with <14μA quiescent current |
| PGND (Exposed Pad) | Power ground return | Return path for BG driver and input/output capacitors; must be soldered to PCB thermal plane |
Key Features
| Feature | Design Value |
|---|---|
| Line feedforward compensation | Maintains constant loop gain across 4.5V–38V input, eliminating need for dynamic compensation |
| Programmable soft-start | External capacitor on SS pin enables controlled VOUT ramp-up, preventing inrush current damage |
| Cycle-by-cycle peak current limit | Independent top/bottom limits via ILIMT/ILIMB resistors enable asymmetric current protection |
| Synchronizable oscillator | Accepts external clock on MODE/SYNC pin for EMI reduction in multi-rail systems |
| Overvoltage protection | Dedicated MAX comparator disables TG and asserts BG on >10% VOUT overshoot |
Applications
| Telecom Point-of-Load | Industrial 24V-to-12V Conversion |
|---|---|
Use Scenario: Regulating 1.2V/15A for FPGA core supply in 48V telecom shelf with strict ripple and transient requirements. IC Role / Device Role / Timing Role: Voltage-mode synchronous buck controller managing top/bottom N-MOSFETs, providing line feedforward-stabilized feedback and 500kHz fixed-frequency operation. Use Value: <30ns min on-time enables 2.5% duty cycle from 48V input; ±0.75% reference ensures <9mV output deviation over temperature. | Use Scenario: Converting 24V factory automation bus to 12V for PLC I/O modules with high reliability and thermal resilience. IC Role / Device Role / Timing Role: High-VIN synchronous step-down controller with programmable 250kHz–1MHz frequency and forced continuous mode for low-noise operation. Use Value: 38V absolute max VIN rating and –40°C to 125°C operating range ensure robustness in harsh environments; exposed PGND pad lowers θJA to 68°C/W. |
| Automotive Infotainment | Test Equipment Power Rails |
Use Scenario: Generating 3.3V/8A from 12V battery rail for automotive head unit processor, surviving cold-crank (4.5V) and load-dump (38V) transients. IC Role / Device Role / Timing Role: Wide-input synchronous buck controller with UVLO hysteresis (via RUN/SHDN divider) and pulse-skipping mode for light-load efficiency. Use Value: 4.5V–38V input range covers full automotive transient profile; 14μA shutdown current preserves battery life during vehicle sleep mode. | Use Scenario: Providing adjustable 0.6V–12V output in bench power supply with precise current limiting and remote sensing capability. IC Role / Device Role / Timing Role: Programmable-frequency buck controller with RDS(ON)/sense-resistor flexibility and independent top/bottom current limit configuration. Use Value: ILIMT/ILIMB pins allow asymmetric current limits (e.g., 12A top / 15A bottom) for safe inductor saturation margin; FREQ pin enables optimal frequency selection per output voltage. |
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 |
|---|---|---|---|
| MP2918GL-Z | Fixed 600kHz frequency; no programmable FREQ pin; integrated MOSFET drivers only (no external FET control) | Targeted at compact, lower-power applications (<10A); lacks RDS(ON) sensing and line feedforward | Select MP2918GL-Z only for space-constrained designs where fixed frequency and integrated drive suffice |
| TPS546D24RQFT | PMIC with dual outputs; includes PMBus interface; 4.5V–18V input; no RDS(ON) sensing support | Designed for digital power management in server VRMs; requires external EEPROM and firmware | Choose TPS546D24RQFT when digital telemetry, sequencing, and multi-rail coordination are required |
Compared with MP2918GL-Z and TPS546D24RQFT, the LTC3775IUD#TRPBF offers superior wide-input flexibility (4.5V–38V), analog programmability (FREQ, ILIMT/ILIMB, MODE/SYNC), and line feedforward for unattended stability-making it optimal for high-reliability industrial and telecom POL where input transients and analog control precision are critical.
Availability
LTC3775IUD#TRPBF is available at Aetrix Electronics and suitable for telecom power supplies, industrial 24V-to-12V conversion, and automotive infotainment systems requiring stable component supply across extended temperature ranges.
Supply support for LTC3775IUD#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LTC3775IUD#TRPBF belongs to Linear's high-voltage synchronous buck controller product line, engineered for demanding POL applications in telecom infrastructure, industrial automation, and automotive systems where wide input range, fast transient response, and thermal resilience are essential.
FAQ
What is the maximum input voltage rating for the LTC3775IUD#TRPBF?
The LTC3775IUD#TRPBF has an absolute maximum input voltage (VIN) rating of 40V, with recommended operating range from 4.5V to 38V. Exceeding 40V risks permanent damage per Absolute Maximum Ratings. The device's 38V upper limit ensures compatibility with 24V and 48V industrial/telecom rails including load-dump transients.
How does the LTC3775IUD#TRPBF achieve fast line transient response?
The LTC3775IUD#TRPBF achieves fast line transient response through its patented line feedforward compensation circuit, which dynamically adjusts the PWM modulator gain to maintain constant loop gain across the full 4.5V–38V input range. This eliminates the need for complex loop recompensation and enables sub-microsecond correction of input voltage steps without output droop or overshoot.
Can the LTC3775IUD#TRPBF operate with pre-biased outputs?
Yes, the LTC3775IUD#TRPBF supports pre-biased start-up: during initial power-on, it defaults to pulse-skipping mode until the SS pin voltage reaches 0.54V, allowing VOUT to remain at its pre-biased level (if unloaded) until the soft-start ramp catches up. This prevents reverse current flow and ensures safe start-up into existing output voltages.
What is the purpose of the exposed pad (Pin 17) on the LTC3775IUD#TRPBF QFN package?
The exposed pad (Pin 17) on the LTC3775IUD#TRPBF is electrically connected to PGND and serves as the primary thermal and power ground return path. It must be soldered to a dedicated PCB copper pour to achieve the specified θJA = 68°C/W; failure to do so increases thermal resistance significantly and risks junction temperature exceedance under load.
How is current limit configured on the LTC3775IUD#TRPBF?
Current limit on the LTC3775IUD#TRPBF is configured independently for top and bottom MOSFETs using external resistors on ILIMT (100μA sink) and ILIMB (10μA source) pins. For example, a 120kΩ resistor from ILIMT to VIN sets a 12mV topside limit (100μA × 120kΩ), while a 100kΩ resistor from ILIMB to SGND sets a 1V bottom-side limit (10μA × 100kΩ), enabling asymmetric protection.
LTC3775IUD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 16-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 4.5V ~ 38V
- Frequency - Switching:
- 250kHz ~ 1MHz
- Duty Cycle (Max):
- 90%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QFN (3x3)
LTC3775IUD#TRPBF FAQ
1.How can I place an order for LTC3775IUD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3775IUD#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 LTC3775IUD#TRPBF reliable?
The price and inventory of LTC3775IUD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3775IUD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3775IUD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3775IUD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3775IUD#TRPBF?
LTC3775IUD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3775IUD#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 LTC3775IUD#TRPBF?
For technical support, including LTC3775IUD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3775IUD#TRPBF requirements.
6.How does Aetrix verify that LTC3775IUD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3775IUD#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 LTC3775IUD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3775IUD#TRPBF?
All LTC3775IUD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3775IUD#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 LTC3775IUD#TRPBF part is unused and in its original packaging.
Return procedure for LTC3775IUD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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