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Analog Devices Inc. LT3689EMSE-5#TRPBF
- Part No.:
- LT3689EMSE-5#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3689EMSE-5#TRPBF.pdf
- Description:
- IC REG BUCK 5V 700MA 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,341
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Product details
Overview
LT3689EMSE-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, operating from 3.6V to 36V input and delivering a fixed 5.0V ±1% output. It features 85µA quiescent current in Burst Mode®, programmable undervoltage lockout (EN/UVLO), and robust 60V transient tolerance-designed for automotive ECU power rails requiring reliable microprocessor supervision.
For engineers reviewing the LT3689EMSE-5#TRPBF datasheet, LT3689EMSE-5#TRPBF pinout, LT3689EMSE-5#TRPBF application, or LT3689EMSE-5#TRPBF equivalent, key selection criteria include its fixed 5V output, 16-pin MSOP package with exposed pad, independent POR and watchdog timing via external capacitors (CPOR/CWDT), and compatibility with high-voltage industrial and automotive supply domains where input transients up to 60V must be tolerated without latch-up.
Technical Context
The LT3689EMSE-5#TRPBF implements constant-frequency current-mode PWM control with frequency programmability (350kHz–2.2MHz via RT resistor) and automatic transition to low-ripple Burst Mode® below ~10mA load. Its internal bipolar NPN switch supports 700mA continuous output with cycle-by-cycle current limiting and thermal shutdown.
Supervisory functions are hardware-decoupled: the POR circuit asserts RST low when VOUT drops below 90% of 5.0V and holds it for a capacitor-programmed delay (tRST = 2.3ms/nF on CPOR); the watchdog operates in timeout or window mode (selected by W/T pin), with upper/lower boundaries set by CWDT (tWDU = 18.2·CWDT, tWDL = 0.588·CWDT).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.00V ±1% - eliminates external feedback resistors; ensures stable MCU core/logic rail without calibration. |
| Input Voltage Range | 3.6V to 36V continuous, 60V transient tolerant - supports 12V/24V automotive batteries with cold-crank and load-dump immunity. |
| Quiescent Current | 85µA at 12VIN → 5VOUT in Burst Mode® - enables always-on systems with multi-year battery life in low-power states. |
| Switching Frequency | Adjustable 350kHz–2.2MHz via RT pin - allows optimization of inductor size (e.g., 12µH @ 700kHz) vs. EMI vs. efficiency trade-offs. |
| Reset Accuracy | RST triggers at 90% of 5.0V (±2%) with 17–21ms typical timeout (CPOR = 8.2nF) - guarantees deterministic microprocessor initialization timing. |
| Watchdog Modes | Pin-selectable timeout or window mode (W/T pin) - provides flexible fault detection: timeout for simple heartbeat, window for precise timing validation. |
| Package | 16-pin MSOP with exposed thermal pad - delivers θJC = 4.3°C/W for high-power-density layouts in space-constrained ECUs. |
Pinout & Package
LT3689EMSE-5#TRPBF uses a 16-lead plastic MSOP package with exposed pad (pin 17 = GND), rated for –40°C to 125°C junction temperature. The exposed pad must be soldered to PCB ground for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (WDO) | Watchdog output | Open-collector active-low signal; pulled weakly to VOUT (1µA), requires external pull-up for fast rise or higher VOH. |
| 2 (CWDT) | Watchdog timing capacitor | Connects to GND; sets tWDU/tWDL per tWDU = 18.2·CWDT (ms), tWDL = 0.588·CWDT (ms) - enables precise fault-window tuning. |
| 3 (CPOR) | Reset timeout capacitor | Connects to GND; sets tRST = 2.3ms/nF - defines minimum system boot stabilization time before RST deassertion. |
| 4 (RT) | Oscillator frequency set | Resistor-to-GND sets fSW from 350kHz–2.2MHz; e.g., 20.5kΩ yields 700kHz - balances efficiency, size, and EMI. |
| 5 (SYNC) | External clock sync input | Accepts logic-level signal ≥80ns pulse width; enables EMI reduction via frequency alignment with system clock domain. |
| 6 (OUT) | Bias supply / internal divider tap | Provides bias current path when >3V; internally connects to fixed 5V feedback network - no external resistors needed. |
| 7 (BST) | Bootstrap drive | Drives internal NPN switch gate above VIN via external capacitor; enables full saturation and <450mV VCESAT at 0.8A. |
| 8 (VIN) | Main power input | Supplies control circuitry and switch; withstands 60V non-repetitive transients - critical for automotive load-dump survival. |
| 9 (RST) | Power-on reset output | Open-collector active-low; asserts when VOUT < 4.5V and holds for CPOR-defined period - ensures clean MCU reset sequencing. |
| 10 (WDI) | Watchdog input | Receives microprocessor heartbeat signal; falling edges monitored for timing compliance in window or timeout mode. |
| 11 (W/T) | Watchdog mode select | Low = window mode (detects too-close/too-far WDI edges); high = timeout mode (detects missing transitions) - configures fault logic. |
| 12 (WDE) | Watchdog enable | High >1V disables watchdog; WDO floats high - allows runtime disable for debug or safe boot phases. |
| 13 (FB) | Feedback reference | Internally tied to 5V divider; for LT3689-5 variants, used only for phase-lead compensation - no external resistor required. |
| 14 (EN/UVLO) | Enable & UVLO input | 1.26V threshold with hysteresis; resistor divider enables programmable start-up voltage (e.g., 9V min) - prevents brownout operation. |
| 15 (DA) | Catch diode anode monitor | Current-sense input; disables switching if diode current >1.2A - protects against short-circuit overcurrent without external sensing. |
| 16 (SW) | Switch node | Drives external inductor/catch diode; peak current limited to 1.55A typical - defines maximum deliverable load under fault. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 5V output with 0.8V internal reference | Eliminates external feedback resistors, reducing BOM count and layout sensitivity while maintaining ±1% regulation accuracy. |
| Independent POR and watchdog timing | Separate CPOR and CWDT pins allow concurrent, non-interfering configuration of reset delay (17–21ms typical) and watchdog windows (e.g., 182ms/5.9ms). |
| 60V transient-tolerant input | Withstands automotive load-dump events without shutdown or damage, enabling direct connection to battery rails without pre-regulation. |
| Burst Mode® with <15mVP-P ripple | Maintains ultra-low 85µA IQ at light loads while holding output ripple below 15mV - critical for noise-sensitive analog/mixed-signal circuits. |
| Programmable EN/UVLO with hysteresis | Resistor-divider setup enables precise turn-on voltage (e.g., 9V) and hysteresis (≥2.8µA current delta) to prevent oscillation near threshold. |
| Thermal shutdown + current foldback | Combines junction-temperature cutoff with frequency foldback during overload - sustains regulation longer than thermal-only protection. |
Applications
| Automotive Engine Control Unit (ECU) | Industrial Programmable Logic Controller (PLC) |
|---|---|
Use Scenario: Powering 5V microcontroller, CAN transceiver, and sensor interface circuitry in under-hood engine management systems exposed to 12V battery fluctuations and 60V load-dump transients. IC Role / Device Role / Timing Role: Primary 5V DC-DC converter with integrated POR and watchdog - ensures deterministic MCU boot and continuous runtime supervision against software hangs. Use Value: Eliminates need for discrete supervisor IC and external 5V feedback network, reducing component count by ≥3 parts while guaranteeing 60V transient survival. |
Use Scenario: Supplying isolated I/O modules and real-time controllers in factory automation systems requiring stable 5V rails across wide input ranges (18–36V DC). IC Role / Device Role / Timing Role: Regulator + system supervisor - delivers regulated 5V and monitors controller health via configurable watchdog window mode to detect timing violations in cyclic tasks. Use Value: Enables single-chip power + supervision for safety-critical PLC modules, with programmable tWDL/tWDU allowing adaptation to task cycle times from 10ms to 500ms. |
| Medical Diagnostic Imaging Interface | Railway Signaling Power Module |
Use Scenario: Powering FPGA-based image processing subsystems in portable ultrasound devices where low-noise, low-quiescent-current 5V supply is essential for ADC performance. IC Role / Device Role / Timing Role: Low-ripple 5V regulator with Burst Mode® - maintains <15mVP-P output noise at standby while enabling rapid wake-up via EN/UVLO-controlled sequencing. Use Value: Achieves 85µA IQ and sub-15mV ripple simultaneously, meeting stringent EMC and SNR requirements without adding LDO post-regulation. |
Use Scenario: Providing fail-safe 5V power to signaling logic in EN 5012x-compliant railway control cabinets operating from 24V–110V DC traction batteries. IC Role / Device Role / Timing Role: High-reliability regulator with dual supervisory outputs - RST ensures clean boot after power restoration; WDO detects firmware lockup in SIL-2-rated subsystems. Use Value: Meets IEC 61000-4-5 Level 4 surge immunity (6kV) via 60V input rating and provides certified watchdog timing traceability through external CWDT/CPOR capacitors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator with integrated supervision applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3631EMSE#TRPBF | 40V max input, 500mA output, no integrated watchdog - only POR with 200ms fixed timeout. | Lacks window-mode watchdog and independent CWDT programming; suitable for simpler reset-only supervision. | Select when only basic POR is needed and 500mA output suffices; not suitable for complex microprocessor hang detection. |
| MAX20004AATEA/VY+ | 42V max input, 600mA output, integrated watchdog with fixed 1.6s timeout - no window mode or CPOR/CWDT adjustability. | Offers AEC-Q100 Grade-1 qualification but lacks programmable timing; uses internal RC for fixed delays. | Choose for automotive-qualified designs needing guaranteed reliability but accepting inflexible supervision timing. |
Compared with LTC3631EMSE#TRPBF and MAX20004AATEA/VY+, the LT3689EMSE-5#TRPBF uniquely combines fixed 5V output, 700mA capability, 60V transient tolerance, and fully programmable POR/watchdog timing - making it optimal for high-integrity embedded systems requiring adaptable, capacitor-tuned supervision.
Availability
LT3689EMSE-5#TRPBF is available at Aetrix Electronics and suitable for automotive electronic control units, industrial PLC power supplies, medical imaging interfaces, and railway signaling modules requiring stable component supply with long-term lifecycle support.
Supply support for LT3689EMSE-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, inheriting its legacy of high-performance power management ICs with emphasis on precision, ruggedness, and integration.
The LT3689EMSE-5#TRPBF belongs to Linear's "Supervisory Power" product line, designed specifically for automotive and industrial applications demanding combined regulation and microprocessor supervision in a single package.
FAQ
What is the output voltage tolerance of the LT3689EMSE-5#TRPBF?
The LT3689EMSE-5#TRPBF delivers a fixed 5.00V output with ±1% initial accuracy over temperature and line, verified across –40°C to 125°C. This is achieved via laser-trimmed internal feedback resistors referenced to a stable 0.800V bandgap, eliminating external component drift effects seen in adjustable regulators.
How does the LT3689EMSE-5#TRPBF handle input voltage transients up to 60V?
The LT3689EMSE-5#TRPBF withstands 60V non-repetitive transients by disabling switching when VIN exceeds 38V (typical OVP threshold), entering a safe high-impedance state while maintaining internal bias. The 60V absolute maximum rating on VIN and EN/UVLO pins ensures no latch-up or damage occurs, allowing direct battery-rail connection in automotive environments.
Can the watchdog timer on the LT3689EMSE-5#TRPBF operate in both timeout and window modes?
Yes, the LT3689EMSE-5#TRPBF watchdog supports both modes: setting the W/T pin low enables window mode (detects WDI edges too close or too far apart), while pulling W/T high selects timeout mode (detects missing transitions). Both modes use the same CWDT capacitor to set tWDU and tWDL, providing flexible fault coverage for diverse MCU architectures.
What is the purpose of the DA pin on the LT3689EMSE-5#TRPBF?
The DA pin on the LT3689EMSE-5#TRPBF monitors catch diode anode current. If diode current exceeds 1.2A (e.g., during output short-circuit), the DA comparator disables switching until current falls below threshold. This valley-current limiting protects the external diode and inductor without requiring additional sensing components.
Is the LT3689EMSE-5#TRPBF compatible with external synchronization?
Yes, the LT3689EMSE-5#TRPBF supports external clock synchronization via the SYNC pin, accepting logic-level signals with ≥80ns pulse widths. When synchronized, the internal oscillator locks to the external frequency, enabling EMI reduction through spectral spreading or alignment with system clocks - critical for noise-sensitive applications.
LT3689EMSE-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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LT3689EMSE-5#TRPBF FAQ
1.How can I place an order for LT3689EMSE-5#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3689EMSE-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 LT3689EMSE-5#TRPBF reliable?
The price and inventory of LT3689EMSE-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 LT3689EMSE-5#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3689EMSE-5#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3689EMSE-5#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3689EMSE-5#TRPBF?
LT3689EMSE-5#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3689EMSE-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 LT3689EMSE-5#TRPBF?
For technical support, including LT3689EMSE-5#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3689EMSE-5#TRPBF requirements.
6.How does Aetrix verify that LT3689EMSE-5#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3689EMSE-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 LT3689EMSE-5#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3689EMSE-5#TRPBF?
All LT3689EMSE-5#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3689EMSE-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 LT3689EMSE-5#TRPBF part is unused and in its original packaging.
Return procedure for LT3689EMSE-5#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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