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Analog Devices Inc. LT3689HMSE-5#TRPBF
- Part No.:
- LT3689HMSE-5#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3689HMSE-5#TRPBF.pdf
- Description:
- IC REG BUCK 5V 700MA 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,054
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Product details
Overview
LT3689HMSE-5#TRPBF from Analog Devices (formerly Linear Technology) is a 700mA monolithic step-down switching regulator with integrated power-on reset (POR) and pin-selectable watchdog timer (window or timeout mode), operating from 3.6V to 36V input, delivering fixed 5V output with 0.8% feedback voltage accuracy and 85µA quiescent current in Burst Mode®. It supports automotive ECU and industrial power supply applications requiring high transient immunity (60V) and reliable microprocessor supervision.
For engineers reviewing the LT3689HMSE-5#TRPBF datasheet, LT3689HMSE-5#TRPBF pinout, LT3689HMSE-5#TRPBF application, or LT3689HMSE-5#TRPBF equivalent, this page delivers verified technical context, package-specific pin functions, real-world timing behavior (tRST = 157ms, tWDU = 182ms), thermal-rated operation up to 150°C junction, and validated alternative options for fixed 5V supervisory buck conversion.
Technical Context
The LT3689HMSE-5#TRPBF implements constant-frequency current-mode PWM control with programmable 350kHz–2.2MHz switching via RT resistor, frequency foldback during overload, and internal NPN power switch with 1.55A typical current limit. Its POR comparator asserts RST when VOUT drops below 90% of 5V (i.e., 4.5V), with reset delay set by CPOR capacitor (e.g., 68nF → 157ms).
Watchdog operation is configurable via W/T pin: timeout mode triggers WDO low if no WDI transition occurs within tWDU (18.2 × CWDT), while window mode requires successive WDI falling edges spaced between tWDL (0.588 × CWDT) and tWDU - both periods independently adjustable with external capacitors. The device sustains 60V non-repetitive transients without latch-off.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.00V ±1% (guaranteed over –40°C to 150°C junction) |
| Input Voltage Range | 3.6V to 36V continuous; withstands 60V/1s transients (no shutdown) |
| Quiescent Current | 85µA at 12VIN→5VOUT in Burst Mode® (enables ultra-low standby power) |
| Switch Current Limit | 1.55A typical (protects against short-circuit with valley-current limiting via DA pin) |
| Reset Threshold Accuracy | 90% of VOUT ±2% (i.e., 4.5V ±0.1V at 5V output; ensures clean µP boot) |
| Watchdog Timing Range | tWDU = 18.2 × CWDT (ms), tWDL = 0.588 × CWDT (ms); CWDT = 1nF–100nF |
| Thermal Rating | Junction temperature range: –40°C to +150°C (H-grade MSOP package) |
Pinout & Package
LT3689HMSE-5#TRPBF uses a 16-pin MSOP package with exposed pad (pin 17 = GND), θJA = 43°C/W, requiring soldered thermal pad for rated performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (WDO) | Watchdog output | Open-collector active-low signal; pulled low on watchdog fault; weak pull-up to VOUT |
| 2 (CWDT) | Watchdog timing capacitor | Sets tWDU and tWDL via external capacitor (e.g., 10nF → tWDU = 182ms, tWDL = 5.9ms) |
| 3 (CPOR) | Reset delay capacitor | Sets tRST = 2.3ms/nF (e.g., 68nF → 157ms); ensures stable µP release after power ramp |
| 4 (RT) | Oscillator frequency set | Resistor to GND programs fSW from 350kHz to 2.2MHz (e.g., 20.5kΩ → 700kHz) |
| 5 (SYNC) | External clock sync input | Accepts logic-level signal ≥80ns pulse width; enables deterministic switching in noise-sensitive systems |
| 6 (OUT) | Bias supply / feedback reference | Provides bias current path; internally connected to fixed 5V divider; reduces VIN quiescent draw when VOUT > 3V |
| 7 (BST) | Bootstrap drive | Supplies gate drive >VIN to internal NPN switch via external capacitor; enables full saturation |
| 8 (VIN) | Main power input | Supplies internal circuitry and switch; rated to 60V transient; UVLO threshold = 3.7V (rising) |
| 9 (RST) | Power-on reset output | Open-collector active-low; asserted until VOUT > 4.5V then held for tRST; weak pull-up to VOUT |
| 10 (WDI) | Watchdog input | Receives µP watchdog pulses; edge-triggered; glitch-immune with 300ns minimum pulse width |
| 11 (W/T) | Watchdog mode select | Low = window mode (dual-boundary detection); high = timeout mode (single upper-boundary) |
| 12 (WDE) | Watchdog enable | Pulled >1V to disable watchdog; WDO remains high; allows runtime watchdog deactivation |
| 13 (FB) | Feedback reference | Regulated to 0.800V ±12mV; for LT3689HMSE-5#TRPBF, internally tied to fixed 5V divider |
| 14 (EN/UVLO) | Enable / undervoltage lockout | 1.26V threshold with 2.8µA hysteresis; resistor divider enables programmable UVLO with hysteresis |
| 15 (DA) | Catch diode anode monitor | Current-sense input; disables switching if diode current >1.2A (short-circuit protection) |
| 16 (SW) | Switch node | Connects to inductor, catch diode cathode, and BST capacitor; carries high di/dt switching current |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 5V output with 0.8V reference | Eliminates external feedback resistors; reduces BOM count and layout sensitivity for 5V rails |
| Programmable POR and watchdog timing | Capacitor-based tRST and tWDU/tWDL allow precise coordination with µP boot sequence and firmware watchdog intervals |
| 60V transient tolerance | Enables direct connection to 24V/36V automotive or industrial bus without external TVS or clamping |
| Burst Mode® operation | Maintains <15mVP-P output ripple at light load while achieving 85µA IQ - critical for battery-backed systems |
| H-grade 150°C junction rating | Validated for under-hood automotive ECU and high-ambient industrial environments without derating |
| Internal NPN switch with DA current limit | Provides robust short-circuit protection by monitoring catch diode current - avoids reliance on external sense resistors |
Applications
| Automotive Engine Control Unit (ECU) | Industrial PLC Power Management |
|---|---|
Use Scenario: Powering microcontroller, CAN transceiver, and sensor interface in engine bay with 12V/24V battery input subject to load dump (60V). IC Role / Device Role / Timing Role: Primary 5V buck regulator with POR ensuring clean µP reset after ignition-on, and watchdog monitoring firmware execution integrity. Use Value: Eliminates need for discrete reset IC and external TVS; 150°C rating avoids thermal derating in sealed enclosures. |
Use Scenario: Generating stable 5V rail for logic and I/O in programmable logic controller modules operating in factory-floor cabinets (70°C ambient). IC Role / Device Role / Timing Role: Integrated power + supervision IC providing regulated 5V, power-good signaling (RST), and field-programmable watchdog timeout (via CWDT). Use Value: Reduces board space vs. separate DC/DC + supervisor; capacitor-programmable timing avoids firmware updates for timing changes. |
| Railway Signaling Power Supply | Medical Diagnostic Equipment |
Use Scenario: Converting 36V nominal railway battery to 5V for safety-critical control logic with EN/UVLO hysteresis preventing brownout oscillation. IC Role / Device Role / Timing Role: High-input-voltage buck converter with programmable undervoltage lockout and fail-safe reset assertion on output droop. Use Value: 36V max continuous input matches railway spec; 60V transient rating meets EN 50155 surge requirements. |
Use Scenario: Powering FPGA configuration and ADC interface in portable ultrasound units where standby power and reliability are critical. IC Role / Device Role / Timing Role: Low-IQ 5V supply with POR holding reset until stable VOUT, plus watchdog guarding against firmware hang during image acquisition. Use Value: 85µA Burst Mode® IQ extends battery life; open-collector RST/WDO allow wired-OR with other system supervisors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fixed-output supervisory buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3631EMSE#TRPBF | 40V input, 500mA output, no integrated watchdog or POR; requires external reset IC | Lacks built-in supervision; suitable only when discrete reset/watchdog already present | Select if lower cost is prioritized and supervision is handled elsewhere; not drop-in for LT3689HMSE-5#TRPBF's integrated features |
| TPS62130ARGTR | 6V max input, 3A output, no POR/watchdog, 2.2MHz fixed frequency; requires external components for supervision | Cannot replace LT3689HMSE-5#TRPBF in 24V+ systems due to VIN limit; lacks timing supervision | Choose only for low-input-voltage, high-current apps where supervision is unnecessary or implemented externally |
Compared with LTC3631EMSE#TRPBF and TPS62130ARGTR, LT3689HMSE-5#TRPBF uniquely integrates 36V operation, fixed 5V output, POR, and configurable watchdog in one H-grade MSOP package - eliminating four external components (buck controller, reset IC, watchdog IC, TVS) in automotive and industrial designs.
Availability
LT3689HMSE-5#TRPBF is available at Aetrix Electronics and suitable for automotive electronic control units, industrial PLCs, and railway signaling power supplies requiring stable component supply with guaranteed 150°C operation and long-term lifecycle support.
Supply support for LT3689HMSE-5#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 acquired Linear Technology in 2017 and maintains its high-reliability analog and power management portfolio with rigorous automotive and industrial qualification standards.
The LT3689 product line was designed specifically for microprocessor-supervised power conversion in harsh environments - integrating regulation, reset, and watchdog functions to reduce system-level component count and improve functional safety compliance.
FAQ
What is the maximum input voltage rating for LT3689HMSE-5#TRPBF?
The LT3689HMSE-5#TRPBF operates continuously from 3.6V to 36V input and withstands non-repetitive 60V transients for up to 1 second without damage or latch-off. Above 38V (typical), switching halts to protect downstream circuitry while maintaining safe bias operation - a key feature for automotive load-dump resilience.
How does the watchdog timer function in window mode on LT3689HMSE-5#TRPBF?
In window mode (W/T pin low), LT3689HMSE-5#TRPBF monitors WDI falling edges: WDO pulls low if two consecutive edges occur either too close (< tWDL) or too far apart (> tWDU). This detects both runaway loops and frozen firmware - unlike timeout mode, which only catches complete stalls. Timing is set solely by CWDT capacitor value.
What is the purpose of the DA pin on LT3689HMSE-5#TRPBF?
The DA pin on LT3689HMSE-5#TRPBF senses current through the external catch diode anode. If DA current exceeds 1.2A (typical), the IC disables switching until current falls below threshold - providing valley-current limiting during output short-circuit events without requiring external current-sense resistors or complex protection circuitry.
Can LT3689HMSE-5#TRPBF be synchronized to an external clock?
Yes, LT3689HMSE-5#TRPBF supports external synchronization via the SYNC pin. A logic-level signal with ≥80ns positive/negative pulse width can override the internal oscillator. The RT resistor must be selected so the internal fSW is at least 20% below the lowest expected sync frequency to ensure reliable locking and avoid beat frequencies.
What is the guaranteed junction temperature range for LT3689HMSE-5#TRPBF?
LT3689HMSE-5#TRPBF is an H-grade part with guaranteed operation from –40°C to +150°C junction temperature. This is validated across process corners and wafer lots - enabling use in under-hood automotive ECUs and high-ambient industrial controls without thermal derating or additional heatsinking beyond standard MSOP pad soldering.
LT3689HMSE-5#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3.6V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 5V
- Voltage - Output (Max):
- -
- Current - Output:
- 700mA
- Frequency - Switching:
- 500kHz ~ 2MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LT3689HMSE-5#TRPBF FAQ
1.How can I place an order for LT3689HMSE-5#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3689HMSE-5#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 LT3689HMSE-5#TRPBF reliable?
The price and inventory of LT3689HMSE-5#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3689HMSE-5#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3689HMSE-5#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3689HMSE-5#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3689HMSE-5#TRPBF?
LT3689HMSE-5#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3689HMSE-5#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 LT3689HMSE-5#TRPBF?
For technical support, including LT3689HMSE-5#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3689HMSE-5#TRPBF requirements.
6.How does Aetrix verify that LT3689HMSE-5#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3689HMSE-5#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 LT3689HMSE-5#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3689HMSE-5#TRPBF?
All LT3689HMSE-5#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3689HMSE-5#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 LT3689HMSE-5#TRPBF part is unused and in its original packaging.
Return procedure for LT3689HMSE-5#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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