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Analog Devices Inc. LT3686AEDD#PBF
- Part No.:
- LT3686AEDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3686AEDD#PBF.pdf
- Description:
- IC REG BUCK ADJ 1.2A 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:137
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Product details
Overview
LT3686AEDD#PBF from Analog Devices (formerly Linear Technology) is a 3.6V–37V input, 1.2A synchronous step-down DC/DC converter in a thermally enhanced 10-lead 3mm × 3mm DFN package. It delivers regulated 3.3V or adjustable output with internal power switch, 2.5MHz max switching frequency, and active BD-pin load for fixed-frequency operation at light loads - ideal for automotive infotainment power rails and industrial 24V distributed supplies.
For engineers reviewing the LT3686AEDD#PBF datasheet, LT3686AEDD#PBF pinout, LT3686AEDD#PBF application, or LT3686AEDD#PBF equivalent, key selection criteria include its 100ns minimum on-time, ±1% feedback reference (0.79V–0.815V), cycle-by-cycle current limit (1.85A–2.65A), overvoltage lockout (37V–39V), and synchronization capability up to 2.5MHz - all validated for –40°C to 125°C junction operation.
Technical Context
The LT3686AEDD#PBF uses current-mode PWM control with internal bipolar NPN power switch and integrated boost diode. Its oscillator is resistor-programmable (RT pin) from 300kHz to 2.5MHz, and it supports external synchronization via SYNC/MODE pin with ≥200ns pulse width and 0.8V/0.4V logic thresholds.
It implements dual protection architecture: cycle-by-cycle peak current limiting (via SW-to-VIN sensing) and DA-pin valley current limiting (1.2A–1.7A), plus thermal shutdown, overvoltage lockout (60V transient), and precision UVLO (3.4V–3.6V). The BD pin enables constant-frequency operation below 100mA by regulating an active load when SYNC/MODE > 0.8V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 37V continuous; withstands 60V transients - supports 24V industrial and 12V/24V automotive battery inputs without external clamping. |
| Output Current | 1.2A maximum continuous - sufficient for powering microcontrollers, CAN transceivers, and sensor interfaces from single-stage conversion. |
| Switching Frequency | 300kHz to 2.5MHz, RT-programmable - enables use of sub-10µH inductors and avoids AM band interference (≥1.8MHz). |
| Feedback Reference | 0.790V to 0.815V (±1.25%) - ensures ≤1.5% output voltage error across temperature and line/load conditions. |
| Min On-Time | 100ns typical - allows 16VIN→3.3VOUT conversion at 2MHz without pulse-skipping in continuous mode. |
| Quiescent Current | <1µA in shutdown (VEN/UVLO < 0.4V) - preserves battery life in always-on automotive modules. |
| Overvoltage Lockout | 37V to 39V threshold - protects downstream circuitry during load-dump events in automotive systems. |
Pinout & Package
LT3686AEDD#PBF is housed in a 10-lead, 3mm × 3mm plastic DFN package with exposed thermal pad (Pin 11 = GND). The package features 43°C/W junction-to-ambient thermal resistance and requires soldering of the exposed pad to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pins 1,2) | Power input supply | Supplies internal regulator and power switch; must be locally bypassed with ≥2.2µF X7R ceramic capacitor. |
| BD (Pin 3) | Active load control terminal | Regulates ~30–40mA active load when SYNC/MODE > 0.8V to maintain fixed frequency at light loads. |
| FB (Pin 4) | Feedback node | Regulated to 0.8V reference; sets output voltage via resistor divider (e.g., R2 = 10kΩ, R1 = (VOUT/0.8 − 1) × R2). |
| SS (Pin 5) | Soft-start and tracking input | Charged by internal 2µA current source; ramps FB and frequency simultaneously; resets during UVLO/OVLO/thermal fault. |
| RT (Pin 6) | Oscillator programming | Resistor to GND sets frequency (e.g., 15.4kΩ → 2.1MHz); min 300kHz, max 2.5MHz. |
| EN/UVLO (Pin 7) | Enable and programmable UVLO | Pull <0.4V to shut down (IQ < 1µA); 1.28V threshold enables accurate input undervoltage lockout. |
| SYNC/MODE (Pin 8) | Clock sync and BD mode select | Accepts external clock ≥200ns pulse width; >0.8V enables BD active load, <0.4V disables it. |
| BOOST (Pin 9) | Switch driver bootstrap | Provides >VIN drive voltage to internal NPN switch via external capacitor and internal diode. |
| DA (Pin 10) | Catch diode anode sense | Monitors diode current; triggers frequency foldback if valley current exceeds 1.2A–1.7A to limit fault energy. |
| SW (Pin 11) | Switch node | Connects to inductor, catch diode cathode, and BOOST capacitor; carries high di/dt switching waveform. |
| GND (Exposed Pad) | Primary ground return | Only GND connection; must be soldered to large PCB copper area for thermal management and noise control. |
Key Features
| Feature | Design Value |
|---|---|
| Internal compensation | Eliminates need for external compensation network - reduces BOM count and layout sensitivity. |
| Constant frequency at light loads | BD-pin active load maintains full switching frequency down to ~10mA - ensures predictable EMI profile and low audio-band ripple. |
| Synchronization capability | Accepts external clock up to 2.5MHz with 0.4V/0.8V logic thresholds - enables coherent multi-rail timing in complex systems. |
| Robust short-circuit protection | Dual current limiting (SW peak + DA valley) and thermal shutdown - sustains 37V input into 0Ω load without damage. |
| Thermally enhanced DFN | 10-lead 3mm × 3mm package with exposed pad (JA = 43°C/W) - enables 1.2A operation without heatsink in compact layouts. |
Applications
| Automotive Infotainment Power | Industrial 24V Point-of-Load |
|---|---|
|
Use Scenario: Powering DSPs, display controllers, and USB hubs in head units with 12V/24V battery input and strict EMI limits. IC Role / Device Role / Timing Role: Primary 3.3V/5V step-down regulator with 2MHz fixed-frequency operation to avoid AM band interference. Use Value: 100ns min on-time enables direct 24V→3.3V conversion at 2MHz; BD active load eliminates audible noise during standby. |
Use Scenario: Local regulation for PLC I/O modules powered from 24V industrial bus with wide input transients. IC Role / Device Role / Timing Role: High-input-voltage buck converter with 37V OVLO and cycle-by-cycle current limiting for field-side robustness. Use Value: Withstands 60V load-dump transients; internal boost diode and compensation reduce component count by 3 parts vs discrete solutions. |
| Battery-Powered Telematics | Wall Adapter Powered IoT Gateway |
|
Use Scenario: Power management for LTE/CAN-based vehicle trackers operating from 9–36V battery with low quiescent current requirement. IC Role / Device Role / Timing Role: Always-on buck regulator with <1µA shutdown current and programmable UVLO for brownout prevention. Use Value: EN/UVLO pin programmable to 9V turn-on threshold; 1.2A output supports modem + MCU + GPS without secondary stages. |
Use Scenario: Step-down stage after 12V wall adapter in smart home gateways requiring clean 3.3V for Wi-Fi/BLE SoCs. IC Role / Device Role / Timing Role: Compact, high-efficiency DC/DC with internal compensation and soft-start for inrush control. Use Value: SS pin enables controlled startup into large capacitive loads; 2.2µF input cap suffices due to low EMI design. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3686EMSE#PBF | Same IC die in 12-lead MSOP package (JA = 40°C/W); includes additional thermal pad (Pin 13) and higher pin count for optional features. | Preferred where board space permits larger footprint and enhanced thermal performance is needed for sustained 1.2A at high ambient. | Select LT3686AEDD#PBF for space-constrained automotive modules; choose LT3686EMSE#PBF for industrial designs needing margin at 125°C ambient. |
| LT8610ACIMSE#PBF | 42V input, 3.5A, 2MHz synchronous buck; Silent Switcher architecture; lower EMI, higher current, but no BD-pin active load. | Better suited for noise-sensitive RF sections or higher-current loads; lacks light-load fixed-frequency mode. | Choose LT3686AEDD#PBF when predictable light-load ripple and AM-band avoidance are critical; select LT8610ACIMSE#PBF for ultra-low EMI or >1.2A needs. |
Compared with LT3686EMSE#PBF, the LT3686AEDD#PBF offers identical electrical specs in a 30% smaller footprint and 7% higher thermal resistance - optimal for dense automotive PCBs. Versus LT8610ACIMSE#PBF, it trades higher current and lower EMI for unique BD-pin light-load control and simpler layout, making it superior for cost-sensitive, audio-immune 1.2A applications.
Availability
LT3686AEDD#PBF is available at Aetrix Electronics and suitable for automotive infotainment, industrial 24V point-of-load, and battery-powered telematics requiring stable component supply, long-term lifecycle support, and AEC-Q200-aligned reliability.
Supply support for LT3686AEDD#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 acquired Linear Technology in 2017 and maintains its high-reliability analog power portfolio. Linear's DC/DC regulators are engineered for rugged operation in automotive, industrial, and aerospace environments.
The LT3686A belongs to Linear's high-voltage monolithic buck converter family, designed specifically for 24V/36V industrial and 12V/24V automotive systems requiring wide VIN range, robust fault protection, and minimal external components.
FAQ
What is the absolute maximum input voltage rating for the LT3686AEDD#PBF?
The LT3686AEDD#PBF has an absolute maximum VIN rating of 60V for nonrepetitive one-second transients and 55V for continuous operation. Its overvoltage lockout activates at 37V–39V, protecting downstream circuitry during automotive load-dump events while allowing normal 36V industrial operation.
Does the LT3686AEDD#PBF require an external catch diode?
No - the LT3686AEDD#PBF integrates a boost diode and does not require an external catch diode. However, an external Schottky diode (e.g., MBRM140) is required between SW and GND to provide the freewheeling path; the DA pin monitors its anode current for valley-current limiting.
How does the BD pin function in the LT3686AEDD#PBF?
The BD pin on the LT3686AEDD#PBF enables a regulated active load (~30–40mA) when SYNC/MODE > 0.8V. This maintains constant switching frequency at light loads (<100mA), eliminating pulse-skipping noise and ensuring output ripple remains above the audio band - critical for automotive cabin electronics.
Can the LT3686AEDD#PBF synchronize to an external clock?
Yes - the LT3686AEDD#PBF accepts external synchronization via the SYNC/MODE pin. It supports clock frequencies up to 2.5MHz with ≥200ns high/low pulse widths and logic thresholds of 0.4V (low) and 0.8V (high), enabling timing coherence across multi-rail power systems.
What is the guaranteed operating junction temperature range for the LT3686AEDD#PBF?
The LT3686AEDD#PBF is specified for –40°C to 125°C junction temperature. This grade ('E' suffix) is assured by design and characterization across the full range, making it suitable for under-hood automotive and industrial environments without derating.
LT3686AEDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN 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):
- 3.6V
- Voltage - Input (Max):
- 37V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 37V
- Current - Output:
- 1.2A
- Frequency - Switching:
- 300kHz ~ 2.5MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT3686AEDD#PBF FAQ
1.How can I place an order for LT3686AEDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3686AEDD#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 LT3686AEDD#PBF reliable?
The price and inventory of LT3686AEDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3686AEDD#PBF is usually 5 days.
3.What payment methods are accepted for LT3686AEDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3686AEDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3686AEDD#PBF?
LT3686AEDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3686AEDD#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 LT3686AEDD#PBF?
For technical support, including LT3686AEDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3686AEDD#PBF requirements.
6.How does Aetrix verify that LT3686AEDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3686AEDD#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 LT3686AEDD#PBF meets industry standards.
7.What is the process for return or replacement of LT3686AEDD#PBF?
All LT3686AEDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3686AEDD#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 LT3686AEDD#PBF part is unused and in its original packaging.
Return procedure for LT3686AEDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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