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Analog Devices Inc. LT3690HUFE#TRPBF
- Part No.:
- LT3690HUFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 26-WFQFN Exposed Pad
- Datasheet:
-
LT3690HUFE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 4A 26QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,351
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Product details
Overview
LT3690HUFE#TRPBF from Analog Devices is a 36V, 4A, 1.5MHz synchronous step-down switching regulator with 70µA quiescent current in Burst Mode, integrated 30mΩ N-channel low-side switch, and programmable undervoltage lockout. It operates from 3.9V to 36V input, delivers 0.8V–20V adjustable output, and features power good flag and thermal shutdown-used in automotive power supplies requiring high transient immunity.
For engineers reviewing the LT3690HUFE#TRPBF datasheet, LT3690HUFE#TRPBF pinout, LT3690HUFE#TRPBF application, or LT3690HUFE#TRPBF equivalent, key selection criteria include its –40°C to 150°C junction temperature rating, 4mm × 6mm QFN-26 package with exposed SW/GND pads, 1.5MHz max switching frequency, and robust short-circuit protection with frequency foldback.
Technical Context
The LT3690HUFE#TRPBF implements constant-frequency current-mode control with internal slope compensation, enabling fast transient response and stable loop behavior across wide duty cycles. Its dual-switch architecture integrates a 90mΩ high-side NPN and a 30mΩ low-side N-channel MOSFET, eliminating external catch diodes while supporting synchronous rectification.
Operation includes programmable soft-start via SS pin, tracking capability, and selectable Burst Mode (via SYNC pin) for ultra-low IQ operation. Protection features include overvoltage lockout (38.2V typ), thermal shutdown, current-limit foldback, and power-good signaling at 90% of regulated output voltage.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.9V to 36V continuous; withstands 60V transients for ≤1s without damage |
| Output Current | Up to 4A DC load; current limit threshold 5.5A–6.6A (typ) |
| Switching Frequency | Programmable 170kHz–1.5MHz via RT resistor; supports external synchronization |
| Quiescent Current | 70µA in Burst Mode (12VIN→3.3VOUT); <1µA in shutdown |
| Feedback Reference | 0.792V–0.808V (–40°C to 150°C); enables precise output regulation |
| Thermal Rating | Junction temperature range –40°C to 150°C (H-grade); θJC = 2.7°C/W |
| Package | 26-lead 4mm × 6mm QFN with exposed SW (Pin 27) and GND (Pin 28) pads |
Pinout & Package
LT3690HUFE#TRPBF is housed in a thermally enhanced 4mm × 6mm plastic QFN package with 26 signal leads plus two exposed thermal pads: Pin 27 (SW) and Pin 28 (GND). Both exposed pads must be soldered to PCB copper for optimal thermal performance (θJA = 40°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pins 1–4, 23–26, Exposed Pad 27) | Switch node | Drain of LS MOSFET and emitter of HS NPN; connects to inductor and BST capacitor; carries full switching current |
| FB (Pin 9) | Feedback input | Regulates output by servoing to 0.8V reference; connects to resistor divider tap |
| RT (Pin 7) | Oscillator programming | Sets switching frequency via resistor to GND (10kΩ → 1.5MHz; 32.4kΩ → 600kHz) |
| EN (Pin 17) | Enable control | Active-high logic input; ≥1.5V enables regulator; ≤0.4V disables with <1µA VIN current |
| PG (Pin 18) | Power good flag | Open-collector output asserting when VOUT reaches 90% of target; valid only if VIN > 3.9V, UVLO high, EN high |
| UVLO (Pin 12) | Undervoltage lockout | 1.25V internal threshold; external resistor divider sets custom wake-up voltage and hysteresis |
| BST (Pin 22) | Bootstrap supply | Drives HS NPN gate via external capacitor; requires ≥1.6V above SW to ensure saturation |
| BIAS (Pin 19) | Internal regulator bias | Connects to VOUT (≥3V) to improve efficiency by powering internal circuitry from output rail |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous buck topology | Integrated 30mΩ LS N-MOSFET eliminates Schottky diode, reducing conduction loss and board area |
| Burst Mode® operation | Maintains <15mVP-P output ripple at light loads while achieving 70µA IQ, extending battery life |
| Robust transient protection | Withstands 60V input transients and includes OVLO (38.2V typ), UVLO, and thermal shutdown |
| Programmable soft-start & tracking | SS pin supports controlled ramp-up or voltage tracking using external capacitor or resistor divider |
| High-temperature operation | H-grade qualification (–40°C to 150°C) enables use in under-hood automotive and industrial environments |
Applications
| Automotive Infotainment Power Supply | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powers 3.3V/5V rails for MCU, CAN transceivers, and display controllers in head units exposed to 60V load-dump events. IC Role / Device Role / Timing Role: Primary synchronous buck regulator delivering up to 4A with programmable UVLO and OVLO thresholds. Use Value: Eliminates need for external TVS and discrete MOSFETs; H-grade rating ensures reliability at 150°C junction temperature. | Use Scenario: Generates isolated 5V and 3.3V supplies for analog input conditioning and digital logic in DIN-rail mounted controllers. IC Role / Device Role / Timing Role: High-efficiency step-down converter operating from 24VDC industrial bus with low-noise Burst Mode for sensor front-ends. Use Value: 70µA quiescent current extends uptime during brownouts; PG flag enables system-level power sequencing. |
| Distributed Telecom Backup Supply | Ruggedized Medical Imaging Subsystem |
Use Scenario: Provides 12V-to-3.3V conversion for FPGA configuration and memory in 48V telecom systems with strict EMI limits. IC Role / Device Role / Timing Role: Synchronizable buck regulator allowing clock alignment with system master oscillator to reduce beat frequencies. Use Value: 1.5MHz max switching frequency enables compact 2.2µH inductors; RT pin allows precise EMI tuning. | Use Scenario: Supplies imaging sensor array and ADC interface in portable ultrasound devices requiring low-noise, high-reliability power. IC Role / Device Role / Timing Role: Main DC/DC converter with soft-start and tracking to coordinate power-up with FPGA and analog front-end. Use Value: 0.8V feedback reference enables tight regulation tolerance; BIAS pin connection to VOUT improves light-load efficiency by >5%. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3639EMSE#PBF | 40V input, 3A output, 3mm × 4mm MSOP; no integrated BST diode; requires external bootstrap cap | Lower current, smaller package; lacks PG flag and programmable UVLO | Choose for space-constrained designs where 3A suffices and PG/UVLO are not required |
| MPQ4420AGL-A-Z | 36V input, 2A output, 170kHz–2.2MHz sync range; 200mΩ/120mΩ FETs; no BIAS pin | Lower current, higher RDS(on); no BIAS option reduces efficiency at light loads | Prefer for cost-sensitive industrial applications where 2A output and simplified biasing are acceptable |
Compared with LTC3639EMSE#PBF and MPQ4420AGL-A-Z, the LT3690HUFE#TRPBF offers higher output current (4A vs 3A/2A), superior thermal performance (θJC = 2.7°C/W), and unique BIAS pin functionality that improves light-load efficiency-making it optimal for high-reliability automotive and industrial systems demanding extended temperature operation.
Availability
LT3690HUFE#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC I/O modules, and distributed telecom backup supplies requiring stable component supply across extended temperature ranges.
Supply support for LT3690HUFE#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, and automotive markets.
The LT3690HUFE#TRPBF belongs to the LT® monolithic switching regulator product line, engineered for rugged, high-input-voltage DC/DC conversion in harsh environments including automotive under-hood and industrial control cabinets.
FAQ
What is the maximum junction temperature rating for LT3690HUFE#TRPBF?
The LT3690HUFE#TRPBF is rated for operation from –40°C to +150°C junction temperature, qualifying it as an H-grade device per Analog Devices' specification. This exceeds standard industrial grade (–40°C to +125°C) and supports deployment in under-hood automotive and high-ambient industrial applications where thermal margins are critical. The LT3690HUFE#TRPBF achieves this via optimized die design and the 4mm × 6mm QFN package with low-thermal-resistance exposed pads.
How does the BIAS pin improve efficiency in LT3690HUFE#TRPBF?
The BIAS pin on the LT3690HUFE#TRPBF allows the internal bias regulator to draw power from the output rail (typically ≥3V) instead of VIN, reducing power dissipation in the internal LDO and improving overall efficiency-especially at light loads and high input voltages. When BIAS is connected to VOUT, the LT3690HUFE#TRPBF achieves up to 5% higher efficiency versus VIN-only biasing. This feature is confirmed in the Electrical Characteristics table (page 3) and Application Information section (page 11).
Can LT3690HUFE#TRPBF operate with input voltages above 36V?
Yes-the LT3690HUFE#TRPBF tolerates non-repetitive 60V transients for up to 1 second while junction temperature remains below 125°C, per Absolute Maximum Ratings (page 2). However, continuous operation above 36V is not permitted: when VIN exceeds ~38.2V (OVLO threshold), the part disables switching to protect itself, causing VOUT to fall out of regulation. For sustained >36V operation, external clamping or pre-regulation is required.
What is the purpose of the exposed SW pad (Pin 27) in LT3690HUFE#TRPBF?
The exposed SW pad (Pin 27) on the LT3690HUFE#TRPBF is electrically connected to all SW signal pins (1–4, 23–26) and serves as the primary current return path for the high-side NPN and low-side MOSFET switches. It must be soldered to a large PCB copper pour to achieve the specified θJC = 2.7°C/W thermal resistance. Failure to connect this pad compromises thermal performance and risks premature thermal shutdown or reliability degradation under 4A load conditions.
Does LT3690HUFE#TRPBF support output voltage tracking?
Yes-the LT3690HUFE#TRPBF supports output voltage tracking via the SS (soft-start) pin. By connecting a resistor divider from a master supply rail to the SS pin, the LT3690HUFE#TRPBF's output will ramp in proportion to that rail during startup. This ensures controlled sequencing between multiple regulators in complex systems. Tracking behavior is explicitly documented in the PIN FUNCTIONS section (page 9) and APPLICATIONS INFORMATION (page 12), confirming direct functional support-not just soft-start capability.
LT3690HUFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 26-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3.9V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 20V
- Current - Output:
- 4A
- Frequency - Switching:
- 138kHz ~ 1.5MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 26-QFN (4x6)
LT3690HUFE#TRPBF FAQ
1.How can I place an order for LT3690HUFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3690HUFE#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 LT3690HUFE#TRPBF reliable?
The price and inventory of LT3690HUFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3690HUFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3690HUFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3690HUFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3690HUFE#TRPBF?
LT3690HUFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3690HUFE#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 LT3690HUFE#TRPBF?
For technical support, including LT3690HUFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3690HUFE#TRPBF requirements.
6.How does Aetrix verify that LT3690HUFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3690HUFE#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 LT3690HUFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3690HUFE#TRPBF?
All LT3690HUFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3690HUFE#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 LT3690HUFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3690HUFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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