My Inquiry
My Account
Analog Devices Inc. LT3686HDD#TRPBF
- Part No.:
- LT3686HDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3686HDD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 1.2A 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,629
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT3686HDD#TRPBF from Analog Devices (formerly Linear Technology) is a 3.6V to 37V input, 1.2A synchronous step-down DC/DC regulator in a 10-lead 3mm × 3mm DFN package with exposed thermal pad. It delivers regulated 3.3V or adjustable output voltage using current-mode PWM control, features internal 1.2A bipolar NPN switch, integrated boost diode, and operates up to 2.5MHz. It is designed for automotive battery regulation and industrial 24V supply conversion where high transient immunity and compact layout are critical.
For engineers reviewing the LT3686HDD#TRPBF datasheet, LT3686HDD#TRPBF pinout, LT3686HDD#TRPBF application, or LT3686HDD#TRPBF equivalent, key selection criteria include its –40°C to 150°C guaranteed junction temperature rating, 100ns minimum on-time enabling 16V-to-3.3V conversion at 2MHz, overvoltage lockout up to 39V, adjustable frequency (300kHz–2.5MHz), and BD-pin active load for fixed-frequency light-load operation.
Technical Context
The LT3686HDD#TRPBF implements peak-current-mode control with cycle-by-cycle current limiting and DA-pin valley-current sensing for fault protection. Its oscillator is resistor-programmable via the RT pin, supporting precise frequency setting from 300kHz to 2.5MHz, and includes frequency foldback during soft-start and overload conditions.
It integrates an internal boost diode and requires an external boost capacitor to drive the bipolar NPN power switch; the BOOST pin must remain ≥2.2V above SW for full saturation. The BD pin enables an internal active load when MODE > 0.8V, maintaining constant switching frequency down to zero load and reducing output ripple above audio/AM bands.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 37V - supports direct connection to 24V industrial rails and automotive batteries with 55V transient tolerance. |
| Output Current | 1.2A continuous - sufficient for powering microcontrollers, sensors, and interface ICs in embedded systems. |
| Switching Frequency | 300kHz to 2.5MHz - programmable via RT resistor; enables use of sub-10µH inductors and ultra-compact PCB layouts. |
| Feedback Reference | 0.790V to 0.815V - precision 0.8V reference with ±1.5% tolerance over temperature, enabling accurate output voltage setting. |
| Min On-Time | 100ns - allows high VIN/VOUT ratios (e.g., 16V→3.3V) at 2MHz without pulse-skipping in continuous mode. |
| Junction Temp Range | –40°C to +150°C - fully specified and guaranteed for under-hood automotive and high-temperature industrial environments. |
| Quiescent Current (Shutdown) | <1µA - enables long-term battery-powered operation with negligible standby drain. |
Pinout & Package
LT3686HDD#TRPBF is housed in a 10-lead 3mm × 3mm plastic DFN package with exposed GND pad (Pin 11), requiring soldering to PCB copper for thermal management. Thermal resistance θJA = 43°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Main power input | Supplies internal regulator and power switch; must be locally bypassed with ≥2.2µF ceramic capacitor. |
| BD (Pin 2) | Boost diode cathode node | Tied to VOUT to enable internal active load; regulates ~30–40mA load when MODE > 0.8V to prevent pulse-skipping. |
| FB (Pin 3) | Feedback sense input | Regulated to 0.8V reference; sets output voltage via R1/R2 divider (VOUT = 0.8 × (1 + R1/R2)). |
| SS (Pin 4) | Soft-start & tracking control | Internal 2µA current source charges external capacitor; ramps FB and frequency simultaneously for controlled startup. |
| RT (Pin 5) | Oscillator programming | Resistor to GND sets switching frequency (e.g., 15.4kΩ → 2.1MHz); determines minimum practical inductor value. |
| EN/UVLO (Pin 6) | Enable & undervoltage lockout | 1.27V threshold enables operation; can be programmed with resistor divider for custom UVLO; <0.4V forces shutdown. |
| MODE (Pin 7) | Active load control | High (>0.8V) enables BD-pin active load; low (<0.4V) disables it for burst-mode efficiency at light loads. |
| BOOST (Pin 8) | Bootstrap drive voltage | Charged via internal diode and external capacitor; must exceed SW by ≥2.2V to fully saturate NPN switch. |
| DA (Pin 9) | Catch diode anode monitor | Detects valley current in external Schottky diode; triggers frequency foldback if >1.7A to limit fault current. |
| SW (Pin 10) | Power switch output | Connects to inductor, catch diode anode, and boost capacitor; carries high di/dt switching current. |
| GND (Pin 11, Exposed Pad) | Primary ground reference | Only ground connection; must be soldered to large PCB copper area for thermal and EMI performance. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated boost diode | Eliminates need for external bootstrap diode; reduces BOM count and layout complexity in high-side NPN driver stage. |
| Constant frequency at light load | BD-pin active load maintains full switching frequency down to zero load, ensuring predictable EMI profile and low output ripple above AM band. |
| Overvoltage lockout (OVLO) | 37V–39V trip threshold protects against 24V system transients and load-dump events without external clamping. |
| Internal compensation | Reduces external component count by embedding loop compensation network; simplifies design while maintaining stability across operating conditions. |
| Cycle-by-cycle current limit | Guarantees robust short-circuit protection with 1.85A–2.65A switch current limit, slope-compensated for duty-cycle stability. |
Applications
| Automotive Infotainment Power Supply | Industrial PLC I/O Module Regulator |
|---|---|
Use Scenario: Powers 3.3V logic and communication interfaces (CAN, LIN, UART) in head-unit or display control units exposed to 12V/24V battery rails with load-dump transients. IC Role / Device Role / Timing Role: Primary buck converter delivering stable 3.3V from unregulated vehicle battery; provides clean, low-noise supply for sensitive analog and digital circuitry. Use Value: 150°C rated junction temperature ensures reliability in sealed enclosures; 55V absolute max input withstands ISO 7637-2 pulse 5a; fixed-frequency light-load operation avoids audible noise. | Use Scenario: Regulates 5V or 3.3V from 24V factory floor distributed supply for sensor signal conditioning, ADC references, and microcontroller cores in modular I/O cards. IC Role / Device Role / Timing Role: High-input-voltage step-down regulator with fast transient response and low quiescent current for always-on monitoring functions. Use Value: 100ns min on-time enables efficient 24V→3.3V conversion at 2MHz; internal compensation accelerates design; exposed pad ensures thermal margin in convection-cooled chassis. |
| Portable Test Equipment Power | Smart Sensor Node DC/DC Stage |
Use Scenario: Supplies 3.3V to FPGA configuration, ADC, and RF front-end in handheld calibration tools powered by Li-ion or wall adapter (9–24V). IC Role / Device Role / Timing Role: Wide-input buck regulator with programmable frequency and soft-start for flexible power architecture and inrush control. Use Value: Adjustable frequency (300kHz–2.5MHz) allows optimization for size vs. efficiency; <1µA shutdown current extends battery life between measurements. | Use Scenario: Powers ultra-low-power MCU, BLE radio, and analog front-end in battery-operated predictive maintenance sensors deployed in HVAC or motor drives. IC Role / Device Role / Timing Role: Primary DC/DC converter providing regulated 3.3V from primary 3.6–36V input; manages light-load efficiency and EMI in dense wireless modules. Use Value: BD/MODE-controlled fixed-frequency mode eliminates sub-audible ripple; 1.2A capability supports future firmware upgrades with higher peripheral usage. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3630EMSE#PBF | 4.5V–60V input, 1.2A, 3mm × 4mm MSOP; no BD pin or active load; lower max frequency (2MHz); requires external bootstrap diode. | Suitable for higher-input-voltage industrial systems but lacks fixed-frequency light-load capability and automotive transient robustness. | Select when input exceeds 37V or MSOP package preferred; avoid if AM-band EMI compliance or zero-load ripple matters. |
| MPQ4420AGL-AEC1-Z | 3.3V–60V input, 2A, AEC-Q200 qualified; 12-lead QFN; no BD pin; uses MOSFET switch; typical IQ = 25µA (shutdown = 1.5µA). | Better suited for AEC-Q200-compliant automotive modules needing >1.2A, but lacks active load and has higher light-load IQ than LT3686HDD#TRPBF. | Choose for production automotive programs requiring AEC-Q200 certification and higher current; not drop-in due to different pinout and control scheme. |
Compared with LTC3630EMSE#PBF and MPQ4420AGL-AEC1-Z, the LT3686HDD#TRPBF uniquely combines guaranteed 150°C operation, BD-pin active load for ripple-free light-load behavior, and integrated boost diode-making it optimal for space-constrained, thermally demanding automotive and industrial buck applications where EMI predictability and transient resilience are non-negotiable.
Availability
LT3686HDD#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC I/O modules, and portable test equipment requiring stable component supply across extended temperature ranges and high-reliability manufacturing.
Supply support for LT3686HDD#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, formed through the acquisition of Linear Technology in 2017.
The LT3686 product line was developed by Linear Technology specifically for wide-input-voltage, high-temperature, compact-footprint DC/DC conversion in automotive and industrial environments-emphasizing robustness, EMI control, and ease of layout.
FAQ
What is the maximum guaranteed junction temperature for LT3686HDD#TRPBF?
The LT3686HDD#TRPBF is fully specified and guaranteed over a junction temperature range of –40°C to +150°C, making it suitable for under-hood automotive applications and high-temperature industrial enclosures where thermal derating is critical. This rating is explicitly confirmed in the Absolute Maximum Ratings table and Operating Junction Temperature Range note for the "H" grade device.
How does the BD pin function in LT3686HDD#TRPBF, and what is required to enable it?
The BD pin in LT3686HDD#TRPBF serves as the cathode node for the internal boost Schottky diode and enables an active load feature when MODE > 0.8V. To activate it, tie BD directly to VOUT and ensure MODE is pulled above 0.8V (e.g., with a resistor to VIN). This causes the LT3686HDD#TRPBF to regulate ~30–40mA into BD, preventing pulse-skipping and maintaining constant 2MHz (or set) frequency even at zero load.
Can LT3686HDD#TRPBF operate at 2MHz with a 16V input and 3.3V output?
Yes, LT3686HDD#TRPBF can operate at 2MHz with 16V input and 3.3V output because its minimum on-time is guaranteed at 100ns - sufficient to achieve the required ~20.6% duty cycle (D ≈ (3.3V + 0.4V)/(16V − 0.67V + 0.4V) ≈ 0.206) without entering pulse-skipping mode. This is validated in the Typical Performance Characteristics (Figure 3 and Figure 16).
What is the purpose of the DA pin in LT3686HDD#TRPBF, and how does it affect operation?
The DA pin in LT3686HDD#TRPBF monitors valley current in the external catch diode. When DA current exceeds 1.7A, the LT3686HDD#TRPBF reduces switching frequency to limit inductor valley current and protect against overcurrent during faults like output short-circuit. This complements the peak switch current limit and improves robustness in high-VIN fault conditions.
Does LT3686HDD#TRPBF require an external bootstrap diode?
No, LT3686HDD#TRPBF does not require an external bootstrap diode because it integrates a dedicated boost Schottky diode internally. The BOOST pin is driven through this internal diode from the BD pin (typically tied to VOUT), eliminating one external component and simplifying layout - a key differentiator from many competing buck controllers.
LT3686HDD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN 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):
- 3.6V
- 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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT3686HDD#TRPBF FAQ
1.How can I place an order for LT3686HDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3686HDD#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 LT3686HDD#TRPBF reliable?
The price and inventory of LT3686HDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3686HDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3686HDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3686HDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3686HDD#TRPBF?
LT3686HDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3686HDD#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 LT3686HDD#TRPBF?
For technical support, including LT3686HDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3686HDD#TRPBF requirements.
6.How does Aetrix verify that LT3686HDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3686HDD#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 LT3686HDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3686HDD#TRPBF?
All LT3686HDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3686HDD#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 LT3686HDD#TRPBF part is unused and in its original packaging.
Return procedure for LT3686HDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3686HDD#TRPBF Tags
-
TPS562201DDCR
Texas Instruments
-
MC34063ABD-TR
STMicroelectronics
-
TPS561201DDCR
Texas Instruments
-
MC33063ADR
Texas Instruments
-
MC34063ADR
Texas Instruments
-
TPS560200DBVR
Texas Instruments
-
AP3012KTR-G1
Diodes Incorporated
-
TLV61048DBVR
Texas Instruments
-
AZ34063UMTR-G1
Diodes Incorporated
-
TPS562200DDCR
Texas Instruments
-
AP62300TWU-7
Diodes Incorporated
-
MC34063EBD-TR
STMicroelectronics
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
