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Analog Devices Inc. LT3690IUFE#TRPBF
- Part No.:
- LT3690IUFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 26-WFQFN Exposed Pad
- Datasheet:
-
LT3690IUFE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 4A 26QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,877
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Product details
Overview
LT3690IUFE#TRPBF from Analog Devices is a 36V, 4A synchronous step-down DC/DC regulator with 1.5MHz programmable switching frequency, 70µA quiescent current in Burst Mode, and integrated 30mΩ low-side N-channel MOSFET. It delivers regulated 3.3V/5V outputs for industrial power supplies and automotive systems requiring wide-input, high-efficiency conversion.
For engineers reviewing the LT3690IUFE#TRPBF datasheet, LT3690IUFE#TRPBF pinout, LT3690IUFE#TRPBF application, or LT3690IUFE#TRPBF equivalent, key selection criteria include input voltage range (3.9V–36V), output voltage adjustability (0.8V–20V), thermal performance in the 4mm × 6mm QFN package, and robust protection features including overvoltage lockout, power good flag, and short-circuit current limiting.
Technical Context
The LT3690IUFE#TRPBF employs current-mode control with internal slope compensation for fast transient response and stable loop behavior across duty cycles. Its oscillator supports frequency programming from 170kHz to 1.5MHz via an external RT resistor and synchronization to external clocks within the same range.
It integrates dual power switches - a 90mΩ high-side NPN bipolar transistor and a 30mΩ low-side N-channel MOSFET - enabling synchronous rectification without an external Schottky diode. Protection includes frequency foldback during overload, thermal shutdown, and active current limit clamping at the VC pin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.9V to 36V continuous; withstands 60V transients for ≤1s |
| Output Current | Up to 4A DC load capability with thermal derating above 125°C junction |
| Switching Frequency | Programmable 170kHz–1.5MHz; enables compact magnetics and layout optimization |
| Quiescent Current | 70µA typical in Burst Mode at 12VIN→3.3VOUT, enabling battery-backed standby operation |
| Feedback Reference | 0.8V ±12mV over temperature; sets output accuracy and enables precise resistor-divider design |
| Power Good Flag | Open-collector PG asserts when FB reaches 90% of target; valid only if VIN > 3.9V, EN high, UVLO active |
| Thermal Package | 4mm × 6mm QFN-26 with exposed SW (Pin 27) and GND (Pin 28) pads; θJC = 2.7°C/W |
Pinout & Package
The LT3690IUFE#TRPBF is housed in a thermally enhanced 26-lead plastic QFN package (4mm × 6mm) with two exposed pads: Pin 27 (SW) and Pin 28 (GND), both requiring solder connection to PCB copper for thermal management.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pins 1–4, 23–26, Exposed Pad 27) | Switch node | Drives inductor and boost capacitor; connects internally to all SW pins and exposed pad; negative swing during off-time must be managed by layout |
| GND (Pins 6, 10, 16, 21, Exposed Pad 28) | Ground reference | Common return for control circuitry, power stage, and feedback; exposed pad provides primary thermal path |
| FB (Pin 9) | Feedback input | Regulated to 0.8V; determines output voltage via external resistor divider; bias current flows out (–40nA max) |
| EN (Pin 17) | Enable control | Active-high logic input; ≥1.5V enables regulation; ≤0.4V forces shutdown (<1µA IQ) |
| PG (Pin 18) | Power good indicator | Open-collector output; pulled low until VOUT reaches 90% of setpoint; requires external pull-up |
| RT (Pin 7) | Oscillator frequency set | Resistor-to-GND sets switching frequency from 170kHz to 1.5MHz per Table 1 in datasheet |
| VC (Pin 8) | Error amplifier output | Controls peak switch current; RC compensation network required for loop stability |
| SS (Pin 11) | Soft-start/tracking | 2µA internal current source charges external capacitor for controlled ramp; also supports output tracking |
| UVLO (Pin 12) | Undervoltage lockout | 1.25V threshold; resistor divider from VIN sets turn-on voltage with hysteresis |
| BST (Pin 22) | Boost supply | Drives high-side switch via external capacitor; requires ≥1.6V above SW to ensure full saturation |
| BIAS (Pin 19) | Bias supply input | Accepts external ≥3V source (e.g., VOUT); reduces VIN current draw and improves efficiency |
| VCCINT (Pin 20) | Internal driver supply | Provides gate drive for LS MOSFET; requires 1µF ceramic capacitor to GND (Pin 21) |
| SYNC (Pin 5) | Frequency sync input | Accepts external clock (170kHz–1.5MHz, 20–80% duty); ties to GND for Burst Mode, to VOUT for PWM |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Integrated 30mΩ low-side N-MOSFET eliminates external Schottky diode, reducing conduction loss and board area |
| Burst Mode operation | Maintains <15mVP-P output ripple while achieving 70µA IQ at light loads, extending battery life in always-on systems |
| Robust input protection | Overvoltage lockout triggers at ~38.2V (typical), allowing safe operation through 60V transients without damage |
| Programmable undervoltage lockout | Resistor-divider on UVLO pin sets custom startup threshold with hysteresis, preventing brownout oscillation |
| Thermally optimized package | Exposed SW and GND pads enable direct thermal coupling to PCB; θJC = 2.7°C/W supports high-power density designs |
Applications
| Industrial Power Supplies | Automotive Infotainment Systems |
|---|---|
Use Scenario: Distributed 5V/3.3V rails powering PLC I/O modules, sensors, and fieldbus interfaces in harsh factory environments. IC Role / Device Role / Timing Role: Primary buck regulator converting 24V DC bus to isolated, tightly regulated low-voltage supplies. Use Value: 36V max input and 60V transient tolerance eliminate need for upstream TVS clamping; 4A output sustains peak sensor burst currents. | Use Scenario: Powering display controllers, audio codecs, and USB hubs in vehicle head units with variable battery voltage (9V–16V). IC Role / Device Role / Timing Role: Main DC/DC converter delivering stable 3.3V/5V under cold-crank (6.5V min) and load-dump (38V+ transients) conditions. Use Value: Programmable UVLO ensures reliable startup at low battery; PG flag enables safe system boot sequencing and fault reporting. |
| Distributed Supply Regulation | Test & Measurement Equipment |
Use Scenario: Local point-of-load regulation on multi-layer PCBs where centralized PSUs feed intermediate bus voltages (12V/24V). IC Role / Device Role / Timing Role: High-efficiency, low-noise buck converter placed near FPGA or ADC to minimize IR drop and EMI. Use Value: 1.5MHz switching allows use of 2.2µH inductors and small ceramic caps; Burst Mode maintains low noise during idle periods. | Use Scenario: Precision analog front-end power in portable oscilloscopes and signal generators requiring ultra-low output ripple. IC Role / Device Role / Timing Role: Secondary regulator generating clean 3.3V for SAR ADCs and reference buffers from a noisy 12V rail. Use Value: <15mVP-P ripple in Burst Mode and 0.8V reference with ±12mV drift ensure sub-LSB measurement accuracy. |
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#TRPBF | Higher 42V input rating, 3.5A output, 200kHz–3MHz sync range, lower 2.5µA IQ in Silent Switcher mode | Better suited for ultra-low-noise applications; lacks programmable UVLO and PG flag | Select when input transients exceed 36V or EMI-sensitive layouts require Silent Switcher architecture |
| TPS54560QDGQRQ1 | 4.5V–60V input, 5A output, integrated FETs, but higher 145µA IQ and no Burst Mode; AEC-Q100 qualified | Designed for automotive under-hood use; lacks BIAS pin for efficiency optimization | Select for AEC-Q100-compliant designs requiring >36V operation and higher current, accepting higher quiescent power |
Compared with LT8610EUDE#TRPBF and TPS54560QDGQRQ1, the LT3690IUFE#TRPBF offers superior light-load efficiency via Burst Mode, flexible UVLO programming, and a dedicated PG flag-making it optimal for industrial and non-AEC-Q100 automotive infotainment where precision sequencing and standby power matter most.
Availability
LT3690IUFE#TRPBF is available at Aetrix Electronics and suitable for industrial power supplies, automotive infotainment systems, and distributed supply regulation requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT3690IUFE#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 industrial, automotive, communications, and healthcare markets.
The LT3690IUFE#TRPBF belongs to Analog Devices' Power by Linear™ family of monolithic DC/DC regulators, engineered for wide-input, high-current applications demanding robustness, efficiency, and ease of design-in across harsh environments.
FAQ
What is the maximum continuous input voltage rating for the LT3690IUFE#TRPBF?
The LT3690IUFE#TRPBF supports continuous input voltages up to 36V. It can withstand non-repetitive 60V transients for up to 1 second while junction temperature remains below 125°C. Above ~38.2V, overvoltage lockout disables switching to protect downstream circuitry, though the device remains undamaged.
How does the LT3690IUFE#TRPBF achieve 70µA quiescent current?
The LT3690IUFE#TRPBF achieves 70µA typical quiescent current using low-ripple Burst Mode® operation. In light-load conditions, the controller shuts down most internal circuitry between switching bursts, maintaining regulation while minimizing VIN current draw - critical for battery-powered or always-on systems.
Can the LT3690IUFE#TRPBF be synchronized to an external clock?
Yes, the LT3690IUFE#TRPBF supports external synchronization via the SYNC pin (Pin 5). It accepts logic-level clocks from 170kHz to 1.5MHz with 20–80% duty cycle. When not used, SYNC can be tied to GND for Burst Mode or to VOUT for standard PWM operation - no additional components needed.
What thermal considerations apply to the LT3690IUFE#TRPBF's exposed pads?
The LT3690IUFE#TRPBF has two exposed pads: Pin 27 (SW) and Pin 28 (GND). Both must be soldered to large PCB copper areas. The SW pad carries high di/dt current and serves as the primary thermal path for the high-side switch; the GND pad provides low-inductance return and heatsinking for the entire IC. Thermal resistance from junction to case (θJC) is 2.7°C/W.
Does the LT3690IUFE#TRPBF require an external Schottky diode?
No, the LT3690IUFE#TRPBF does not require an external Schottky diode. It integrates a 30mΩ low-side N-channel MOSFET for synchronous rectification, eliminating conduction losses and heat generation associated with discrete diodes. This integration reduces solution size, improves full-load efficiency, and simplifies bill-of-materials.
LT3690IUFE#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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 26-QFN (4x6)
LT3690IUFE#TRPBF FAQ
1.How can I place an order for LT3690IUFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3690IUFE#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 LT3690IUFE#TRPBF reliable?
The price and inventory of LT3690IUFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3690IUFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3690IUFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3690IUFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3690IUFE#TRPBF?
LT3690IUFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3690IUFE#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 LT3690IUFE#TRPBF?
For technical support, including LT3690IUFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3690IUFE#TRPBF requirements.
6.How does Aetrix verify that LT3690IUFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3690IUFE#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 LT3690IUFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3690IUFE#TRPBF?
All LT3690IUFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3690IUFE#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 LT3690IUFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3690IUFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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