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Analog Devices Inc. LT3690HUFE#PBF
- Part No.:
- LT3690HUFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 26-WFQFN Exposed Pad
- Datasheet:
-
LT3690HUFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 4A 26QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,314
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Product details
Overview
LT3690HUFE#PBF 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 delivers regulated 3.3V/5V outputs for automotive power systems requiring high input transient tolerance up to 60V.
For engineers reviewing the LT3690HUFE#PBF datasheet, LT3690HUFE#PBF pinout, LT3690HUFE#PBF application, or LT3690HUFE#PBF equivalent, key selection criteria include its –40°C to 150°C operating junction temperature, 0.8V feedback reference, 170kHz–1.5MHz programmable frequency, and robust short-circuit protection with thermal shutdown.
Technical Context
The LT3690HUFE#PBF implements constant-frequency current-mode control with slope compensation, enabling fast transient response and stable loop behavior across wide input (3.9V–36V) and output (0.8V–20V) ranges. Its internal architecture integrates a bipolar NPN high-side switch and synchronous N-channel MOSFET low-side switch, eliminating external catch diodes.
Operation includes programmable soft-start via SS pin, power-good flag signaling at 90% of regulation, and frequency foldback during overload or startup. The device supports external synchronization (170kHz–1.5MHz), adjustable UVLO via resistor divider on UVLO pin, and dual bias sourcing (VIN or VOUT via BIAS pin) for efficiency optimization.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.9V to 36V continuous; withstands 60V non-repetitive transients |
| Output Current | Up to 4A DC load capability with thermal derating above 125°C junction |
| Switching Frequency | Programmable 170kHz–1.5MHz via RT resistor; supports external sync |
| Quiescent Current | 70µA in Burst Mode at 12VIN→3.3VOUT; <1µA in shutdown |
| Feedback Reference | 0.8V ±12mV over temperature; enables precise output voltage setting |
| Junction Temp Range | –40°C to +150°C (H-grade); validated for automotive under-hood use |
| Protection Features | Thermal shutdown, frequency foldback, short-circuit robustness, OVLO at ~38V |
Pinout & Package
LT3690HUFE#PBF is housed in a thermally enhanced 26-lead 4mm × 6mm plastic QFN package with two exposed pads: Pin 27 (SW) and Pin 28 (GND), both requiring soldering to PCB copper for thermal management (θJA = 40°C/W, θJC = 2.7°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 |
| GND (Pins 6, 10, 16, 21, Exposed Pad 28) | Power and signal ground | Common return for control logic, power switches, and feedback network |
| FB (Pin 9) | Feedback input | Servo point regulated to 0.8V; sets output voltage via resistor divider |
| EN (Pin 17) | Enable control | Active-high input; ≥1.5V enables regulation, ≤0.4V forces shutdown (<1µA IQ) |
| PG (Pin 18) | Power good flag | Open-collector output asserting when FB reaches 90% of target (e.g., 0.72V for 3.3V out) |
| RT (Pin 7) | Frequency programming | Resistor-to-GND sets oscillator frequency from 170kHz to 1.5MHz |
| SS (Pin 11) | Soft-start/tracking | Internal 2µA pull-up enables voltage ramp for controlled startup or output tracking |
| UVLO (Pin 12) | Undervoltage lockout | 1.25V threshold; resistor divider from VIN sets custom wake-up voltage |
| BST (Pin 22) | Bootstrap supply | Drives HS switch gate above VIN using external capacitor; requires ≥1.6V boost headroom |
| BIAS (Pin 19) | Bias supply input | Accepts external ≥3V source (e.g., VOUT) to improve efficiency vs. VIN-derived bias |
Key Features
| Feature | Design Value |
|---|---|
| Integrated synchronous switch | 30mΩ LS N-channel 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 |
| Robust thermal grade | H-grade qualification (–40°C to +150°C) supports automotive under-hood deployment |
| Programmable protections | User-configurable UVLO threshold and fixed 38V OVLO enable system-level fault resilience |
| Power good signaling | Open-drain PG output confirms regulation stability before downstream circuit activation |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering 3.3V/5V rails for display controllers, audio codecs, and CAN transceivers in vehicle head units. IC Role / Device Role / Timing Role: Primary buck converter delivering clean, regulated DC from 12V battery with transient immunity. Use Value: Withstands 60V load-dump transients without latch-off; H-grade temp range ensures reliability in dashboard environments. | Use Scenario: Generating isolated 5V and 3.3V supplies for digital I/O, analog sensor interfaces, and microcontroller cores in factory automation modules. IC Role / Device Role / Timing Role: High-efficiency point-of-load regulator with programmable UVLO for brown-out detection. Use Value: 70µA Burst Mode IQ extends standby time; 4A output supports multiple rail loads without external pass devices. |
| Distributed Telecom Supply | Ruggedized Medical Imaging Subsystem |
Use Scenario: Local 5V conversion from 24V/48V backplane in base station remote radio units. IC Role / Device Role / Timing Role: Synchronous buck regulator with sync input for EMI reduction across multiple converters. Use Value: 1.5MHz max switching frequency allows compact 2.2µH inductors; frequency foldback prevents current runaway during hot-swap events. | Use Scenario: Providing stable 3.3V for FPGA configuration, ADC references, and interface logic in portable ultrasound or X-ray subsystems. IC Role / Device Role / Timing Role: Safety-critical power stage with thermal shutdown and short-circuit protection. Use Value: Validated 150°C junction operation meets IEC 60601-1 thermal safety margins; PG flag enables safe power sequencing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8610EUDE#PBF | 42V input, 3.5A, 2MHz max, 2.5µA quiescent current; requires external bootstrap capacitor | Better suited for ultra-low IQ battery-powered systems; lacks programmable UVLO | Select LT8610EUDE#PBF when minimum no-load current is critical and 3.5A output suffices. |
| TPS54560QPWPRQ1 | 60V input, 5A, 100kHz–2.5MHz, 145µA IQ; AEC-Q100 qualified; no integrated BST diode | Higher input rating and automotive qualification; requires external bootstrap diode/capacitor | Choose TPS54560QPWPRQ1 for AEC-Q100 compliance and >36V input requirements. |
Compared with LT3690HUFE#PBF, LT8610EUDE#PBF offers lower quiescent current but reduced output current and no UVLO programming, while TPS54560QPWPRQ1 provides AEC-Q100 certification and higher input voltage tolerance at the cost of increased external component count and higher IQ.
Availability
LT3690HUFE#PBF is available at Aetrix Electronics and suitable for automotive infotainment, industrial PLC I/O modules, and distributed telecom supply applications requiring stable component supply across extended temperature and high-reliability environments.
Supply support for LT3690HUFE#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial, automotive, and communications markets.
The LT3690HUFE#PBF belongs to Analog Devices' Power by Linear™ family of monolithic DC/DC regulators, engineered for high-voltage industrial and automotive power conversion with emphasis on thermal robustness, transient immunity, and design simplicity.
FAQ
What is the maximum continuous input voltage rating for LT3690HUFE#PBF?
The LT3690HUFE#PBF supports continuous input voltages up to 36V. It tolerates non-repetitive 60V transients for up to 1 second when junction temperature remains below 125°C. Above 38V (typical), overvoltage lockout disables switching to protect downstream circuitry while sustaining the transient.
How does the LT3690HUFE#PBF achieve 70µA quiescent current?
The LT3690HUFE#PBF achieves 70µA quiescent current in Burst Mode operation by periodically disabling the control circuitry, oscillator, and gate drivers between energy bursts. This reduces dynamic power consumption while maintaining output regulation and keeping peak-to-peak ripple below 15mV in typical 12VIN→3.3VOUT configurations.
Can LT3690HUFE#PBF be synchronized to an external clock?
Yes, the LT3690HUFE#PBF supports external synchronization via the SYNC pin (Pin 5). An external clock signal with 20%–80% duty cycle and frequency between 170kHz and 1.5MHz can directly drive the SYNC pin to align switching edges, reducing EMI in multi-converter systems. Leaving SYNC unconnected defaults to internal oscillator operation.
What thermal considerations apply to LT3690HUFE#PBF in automotive applications?
The LT3690HUFE#PBF is rated for –40°C to +150°C junction temperature (H-grade), making it suitable for under-hood automotive use. Effective thermal design requires soldering both exposed pads (Pin 27/SW and Pin 28/GND) to large PCB copper areas. Thermal resistance is θJA = 40°C/W and θJC = 2.7°C/W, enabling reliable 4A operation with proper layout and airflow.
Does LT3690HUFE#PBF require an external Schottky diode?
No, the LT3690HUFE#PBF does not require an external Schottky diode. Its integrated synchronous rectifier uses a 30mΩ N-channel MOSFET as the low-side switch, replacing the traditional catch diode. This eliminates forward voltage drop losses and improves efficiency, especially at high load currents and low output voltages.
LT3690HUFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 26-WFQFN Exposed Pad
- Packaging:
- Tube
- 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#PBF FAQ
1.How can I place an order for LT3690HUFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3690HUFE#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 LT3690HUFE#PBF reliable?
The price and inventory of LT3690HUFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3690HUFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3690HUFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3690HUFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3690HUFE#PBF?
LT3690HUFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3690HUFE#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 LT3690HUFE#PBF?
For technical support, including LT3690HUFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3690HUFE#PBF requirements.
6.How does Aetrix verify that LT3690HUFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3690HUFE#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 LT3690HUFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3690HUFE#PBF?
All LT3690HUFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3690HUFE#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 LT3690HUFE#PBF part is unused and in its original packaging.
Return procedure for LT3690HUFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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