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Analog Devices Inc. LT3690IUFE#PBF
- Part No.:
- LT3690IUFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 26-WFQFN Exposed Pad
- Datasheet:
-
LT3690IUFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 4A 26QFN
- Quantity:
- Payment:
- Shipping:
Inventory:655
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Product details
Overview
LT3690IUFE#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 infotainment power rails and industrial distributed supplies.
For engineers reviewing the LT3690IUFE#PBF datasheet, LT3690IUFE#PBF pinout, LT3690IUFE#PBF application, or LT3690IUFE#PBF equivalent, key selection criteria include input voltage range (3.9V–36V), output voltage adjustability (0.8V–20V), thermal performance in 4mm × 6mm QFN, and robust short-circuit protection with frequency foldback.
Technical Context
The LT3690IUFE#PBF uses current-mode control for fast transient response and loop stability, with internal slope compensation to maintain current limit accuracy across duty cycles. Its oscillator supports programmable frequency (170kHz–1.5MHz) via external RT resistor and synchronization to external clocks.
Operation includes low-ripple Burst Mode (70µA IQ at 12VIN→3.3VOUT), soft-start/tracking via SS pin, power-good flag signaling 90% VOUT regulation, and overvoltage lockout protecting against 60V transients. Thermal shutdown and frequency foldback provide overload protection.
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; current limit 5.5A–6.6A typical with thermal derating |
| Switching Frequency | Programmable 170kHz–1.5MHz; set by RT resistor or external SYNC signal |
| 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 |
| Efficiency | Up to 92% at 12VIN→3.3VOUT/4A; optimized by synchronous 30mΩ LS switch |
| Thermal Resistance | θJC = 2.7°C/W; θJA = 40°C/W with exposed pad soldered to PCB |
Pinout & Package
LT3690IUFE#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 direct soldering to PCB copper for thermal management.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pins 1–4, 23–26, Exposed Pad 27) | Switch node | Connects to inductor and boost capacitor; carries full switching current; internal connection to HS emitter and LS drain |
| FB (Pin 9) | Feedback input | Regulated to 0.8V reference; sets output voltage via external resistor divider |
| RT (Pin 7) | Oscillator programming | Resistor-to-GND sets switching frequency from 170kHz to 1.5MHz |
| SS (Pin 11) | Soft-start/tracking control | Internal 2µA pull-up enables voltage ramp for controlled startup or output tracking |
| PG (Pin 18) | Power good flag | Open-collector output asserts high when FB reaches 90% of target voltage |
| EN (Pin 17) | Enable input | Logic-high (>1.5V) enables operation; logic-low disables with <1µA VIN current |
| UVLO (Pin 12) | Undervoltage lockout | 1.25V threshold; resistor divider from VIN programs wake-up voltage and hysteresis |
| BST (Pin 22) | Boost capacitor connection | Provides >VIN gate drive for HS NPN switch; requires external ceramic capacitor |
| VCCINT (Pin 20) | LS driver supply | Internally generated ~5V supply for low-side N-channel gate driver; bypassed with CVCC |
| BIAS (Pin 19) | Boost diode anode | Connects to VOUT or other ≥3V rail to improve efficiency by powering internal bias regulator |
| GND (Pins 6, 10, 16, 21, Exposed Pad 28) | Ground reference | Multiple GND pins and exposed pad reduce impedance and improve thermal conduction |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Integrated 30mΩ N-channel LS switch eliminates external Schottky diode, reducing BOM count and improving efficiency |
| Burst Mode operation | 70µA quiescent current at light load while maintaining <15mVP-P output ripple |
| Robust protection suite | Short-circuit protection via LS current sensing, frequency foldback during overload, and thermal shutdown at 150°C junction |
| Flexible power sequencing | SS pin supports soft-start ramp or tracking to external voltage rail for coordinated system power-up |
| Wide input transient tolerance | OVLO circuit disables switching above ~38V, enabling safe operation under 60V non-repetitive transients |
Applications
| Automotive Infotainment Power | Industrial Distributed Supply |
|---|---|
Use Scenario: Powering DSPs, displays, and audio codecs in vehicle head units with 12V battery input subject to load dump transients. IC Role / Device Role / Timing Role: Primary 3.3V/5V buck converter delivering up to 4A with OVLO protection against 60V transients. Use Value: Eliminates need for external TVS and Schottky diode; maintains regulation during cold-crank (4.5V) and load-dump (60V) events. | Use Scenario: Local regulation of 24V factory bus to 5V/3.3V for PLC I/O modules and sensor interfaces. IC Role / Device Role / Timing Role: High-efficiency point-of-load regulator with programmable UVLO to prevent brownout during line sags. Use Value: 70µA Burst Mode IQ extends uptime in battery-backed systems; 4mm × 6mm QFN fits dense industrial PCB layouts. |
| Telecom Base Station Bias | Test Equipment Power Management |
Use Scenario: Generating stable 5V bias for RF front-end amplifiers in remote radio units powered from 48V telecom supply. IC Role / Device Role / Timing Role: Synchronous buck regulator operating at 600kHz with tight output ripple (<15mVP-P) for noise-sensitive analog circuits. Use Value: Low EMI due to constant-frequency PWM and integrated power switches reduces filtering requirements. | Use Scenario: Programmable output voltage source in automated test equipment requiring precise 0.8V–20V regulation with tracking capability. IC Role / Device Role / Timing Role: Adjustable buck controller supporting voltage tracking between multiple rails during power-up sequences. Use Value: SS pin enables accurate output voltage ramping and inter-rail coordination without external DACs or controllers. |
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 | Higher 42V max input; 3.5A output; 2.2MHz sync capability; lower 2.5µA IQ in Silent Switcher mode | Better suited for ultra-low-noise applications requiring spread-spectrum switching and minimal EMI | Select LT8610EUDE#PBF when EMI compliance is critical and input exceeds 36V |
| TPS54560QPWPRQ1 | Automotive-grade (AEC-Q100); 60V max input; 5A output; integrated boot diode; no BST pin required | Designed for automotive environments with extended temperature and qualification requirements | Select TPS54560QPWPRQ1 when AEC-Q100 qualification and 60V continuous operation are mandatory |
Compared with LT8610EUDE#PBF and TPS54560QPWPRQ1, the LT3690IUFE#PBF offers superior thermal resistance (θJC = 2.7°C/W) and programmable UVLO for custom brownout thresholds, making it optimal for space-constrained industrial designs needing robust 36V operation and precise enable sequencing.
Availability
LT3690IUFE#PBF is available at Aetrix Electronics and suitable for automotive infotainment power, industrial distributed supplies, and telecom base station bias requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LT3690IUFE#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 automation, and communications markets.
The LT3690IUFE#PBF belongs to Analog Devices' Power by Linear™ family of monolithic DC/DC regulators, designed specifically for wide-input industrial and automotive power conversion where reliability, thermal performance, and transient robustness are critical.
FAQ
What is the maximum continuous input voltage rating for the LT3690IUFE#PBF?
The LT3690IUFE#PBF supports continuous input voltages up to 36V. Its absolute maximum rating allows non-repetitive 60V transients for ≤1 second when junction temperature remains below 125°C. Operation above 36V triggers overvoltage lockout, halting switching to protect internal circuitry while sustaining the transient.
How does the LT3690IUFE#PBF achieve 70µA quiescent current in light-load conditions?
The LT3690IUFE#PBF achieves 70µA quiescent current using low-ripple Burst Mode® operation, where the controller shuts down all switching and bias circuitry between energy bursts. This minimizes VIN current draw while maintaining output regulation and keeping peak-to-peak ripple below 15mV in typical 12VIN→3.3VOUT configurations.
Can the LT3690IUFE#PBF be synchronized to an external clock, and what is its valid frequency range?
Yes, the LT3690IUFE#PBF can be synchronized to an external clock applied to the SYNC pin. The valid synchronization range is 170kHz to 1.5MHz with 20%–80% duty cycle. When not used for synchronization, tying SYNC to GND selects Burst Mode, while connecting it to VOUT selects standard PWM operation.
What thermal design considerations apply to the LT3690IUFE#PBF's exposed pads?
The LT3690IUFE#PBF has two exposed pads: Pin 27 (SW) and Pin 28 (GND), both requiring direct soldering to large PCB copper areas. Proper thermal land pattern and solder coverage are essential to achieve θJC = 2.7°C/W and prevent thermal shutdown under 4A load at elevated ambient temperatures.
Does the LT3690IUFE#PBF require an external Schottky diode for catch operation?
No, the LT3690IUFE#PBF does not require an external Schottky diode. It integrates a 30mΩ N-channel MOSFET as the synchronous low-side switch, eliminating conduction losses and heat generation associated with discrete diodes. This integration improves full-load efficiency and simplifies layout.
LT3690IUFE#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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 26-QFN (4x6)
LT3690IUFE#PBF FAQ
1.How can I place an order for LT3690IUFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3690IUFE#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 LT3690IUFE#PBF reliable?
The price and inventory of LT3690IUFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3690IUFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3690IUFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3690IUFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3690IUFE#PBF?
LT3690IUFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3690IUFE#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 LT3690IUFE#PBF?
For technical support, including LT3690IUFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3690IUFE#PBF requirements.
6.How does Aetrix verify that LT3690IUFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3690IUFE#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 LT3690IUFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3690IUFE#PBF?
All LT3690IUFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3690IUFE#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 LT3690IUFE#PBF part is unused and in its original packaging.
Return procedure for LT3690IUFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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