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Analog Devices Inc. LT3640EFE#TRPBF
- Part No.:
- LT3640EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3640EFE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ DL 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,240
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Product details
Overview
LT3640EFE#TRPBF from Analog Devices (formerly Linear Technology) is a dual-channel monolithic buck switching regulator IC with integrated power-on reset and window-mode watchdog timer. It delivers 1.3A from its high-voltage nonsynchronous channel (4V–35V input, 3.3V/0.8A typical output) and 1.1A from its low-voltage synchronous channel (2.5V–5.5V input, 1.8V/0.8A typical output), operating at adjustable 350kHz–2.5MHz frequency with Burst Mode® for light-load efficiency. It serves as primary power management in automotive ECU and industrial control subsystems.
For engineers reviewing the LT3640EFE#TRPBF datasheet, LT3640EFE#TRPBF pinout, LT3640EFE#TRPBF application, or LT3640EFE#TRPBF equivalent, key selection criteria include its dual-input voltage ranges, programmable reset/watchdog timing via external capacitors, 290µA quiescent current, 55V transient input tolerance, and thermally enhanced 28-pin TSSOP package with exposed GND pad.
Technical Context
The LT3640EFE#TRPBF integrates two independent current-mode buck regulators sharing a single adjustable oscillator. The high-voltage channel uses an internal 2.4A NPN switch with nonsynchronous rectification and 36.5V OVLO; the low-voltage channel employs internal synchronous MOSFETs (PMOS/NMOS) with cycle-by-cycle current limiting and valley-current foldback during overload.
Its power-on reset (RST1/RST2) and window-mode watchdog (WDO/WDI/CWDT) are independently programmable via external capacitors, with RST timeout ≥8ms and watchdog boundaries of 1.68–35ms. Soft-start is implemented via SS1/SS2 pins with 1.4–2.5µA charge current, and regulation references are 1.265V (FB1) and 600mV (FB2).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range (HV) | 4V to 35V continuous; 55V non-repetitive 1s transient - enables direct battery-fed operation in 12V/24V automotive systems. |
| Input Voltage Range (LV) | 2.5V to 5.5V - supports post-regulation from HV output or independent 3.3V/5V rails. |
| Switching Frequency | 350kHz to 2.5MHz, set by RT resistor or SYNC pin - allows optimization of inductor size vs. efficiency in space-constrained designs. |
| Quiescent Current | 290µA typical - sustains low-power standby modes without compromising wake-up responsiveness. |
| Output Current (HV) | 1.3A maximum - sufficient to power microcontrollers, FPGAs, or sensor interfaces requiring 3.3V/1.8V rails. |
| Output Current (LV) | 1.1A maximum - supports higher-current digital loads on secondary rail with synchronous efficiency >90% at 2MHz. |
| Watchdog Type | Window mode (tWDL = 1.68–2.2ms, tWDU = 27–35ms) - detects both stuck and runaway µP behavior, enhancing system reliability. |
Pinout & Package
The LT3640EFE#TRPBF is housed in a thermally enhanced 28-pin plastic TSSOP package (FE) with exposed GND pad (Pin 29), θJA = 30°C/W, requiring PCB soldering of the exposed pad for thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB1 (Pin 6) | High-voltage feedback reference input | Regulated to 1.265V; sets VOUT1 via resistor divider - determines accuracy and stability of primary output. |
| FB2 (Pin 1) | Low-voltage feedback reference input | Regulated to 600mV; sets VOUT2 via resistor divider - enables precise 1.8V/1.2V generation for core logic supplies. |
| EN/UVLO (Pin 3) | Enable and undervoltage lockout input | 1.26V threshold with 2µA hysteresis - provides programmable VIN brownout protection and shutdown control. |
| RST1 / RST2 (Pins 9, 8) | Open-drain reset outputs | Asserted until FB1 >1.165V or FB2 >550mV, then timed by CPOR capacitor - ensures sequenced µP startup. |
| WDO / WDI / WDE (Pins 10, 14, 13) | Watchdog interface | WDO open-drain flag; WDI accepts µP pulses; WDE enables watchdog - implements fail-safe monitoring of host processor activity. |
| SW1 (Pin 19) | High-voltage switch node | Connects to inductor and catch diode cathode - carries high dI/dt; requires careful layout to minimize EMI and voltage spikes. |
| VIN2 (Pin 24) | Low-voltage channel input supply | Powers LV regulator and internal circuitry when >3V - enables flexible two-stage or independent supply configurations. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent buck regulation | Enables simultaneous 3.3V/1.8V generation from separate inputs or cascaded topology - reduces BOM count and board area. |
| Programmable window-mode watchdog | Rejects both too-frequent and too-infrequent µP pulses - prevents false resets while catching firmware hangs or clock faults. |
| Burst Mode® operation | Maintains >85% efficiency at 1mA load - extends battery life in always-on industrial sensors without sacrificing light-load ripple performance. |
| Thermally optimized TSSOP-28 | Exposed GND pad and θJC = 8°C/W - supports 1.3A/1.1A continuous output in compact industrial enclosures without forced air. |
| Robust fault protection | Cycle-by-cycle current limit, short-circuit tolerant, 55V transient survival - eliminates need for external TVS or fuse in harsh automotive environments. |
Applications
| Automotive Engine Control Unit (ECU) | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering MCU, CAN transceiver, and analog front-end from 12V battery with cold-crank resilience. IC Role / Device Role / Timing Role: Primary dual-rail power manager delivering regulated 3.3V (MCU core) and 1.8V (sensor interface), with watchdog supervision of firmware execution. Use Value: 55V transient tolerance withstands load-dump events; programmable RST1/RST2 ensures deterministic boot sequencing after ignition. | Use Scenario: Generating isolated 3.3V and 1.8V rails for FPGA configuration and ADC drivers in DIN-rail mounted controllers. IC Role / Device Role / Timing Role: Dual-output DC/DC converter with soft-start (SS1/SS2) and PGOOD signaling to enable downstream logic only after stable regulation. Use Value: 290µA quiescent current minimizes standby loss; Burst Mode® maintains <20mVpp ripple at 10mA load for noise-sensitive analog circuits. |
| Medical Diagnostic Sensor Hub | Telecom Remote Radio Unit (RRU) |
Use Scenario: Supplying low-noise 1.8V for precision ADCs and 3.3V for wireless SoC in portable ultrasound probe. IC Role / Device Role / Timing Role: High-efficiency dual buck regulator with independent soft-start and reset timing to meet IEC 60601-1 safety sequencing requirements. Use Value: Synchronous LV channel achieves >92% efficiency at 2MHz, reducing thermal load in sealed enclosures; FB2 600mV reference improves low-VOUT accuracy. | Use Scenario: Providing bias rails for GaN PA drivers and baseband processors in outdoor 5G small cells powered by -48V telecom supply. IC Role / Device Role / Timing Role: HV channel steps -48V (via intermediate 12V) to 3.3V; LV channel generates 1.8V for digital ASICs, with watchdog guarding firmware integrity. Use Value: Adjustable 350kHz–2.5MHz frequency avoids sensitive RF bands; OVLO prevents damage during power surge events on long cable runs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3640EFE#TRPBF | Same die, identical electrical specs and pinout - rebranded part after Analog Devices acquisition of Linear Technology. | No functional difference; same qualification, temperature range (–40°C to 125°C), and packaging. | Select when sourcing under updated Analog Devices part numbering; full drop-in replacement with identical documentation. |
| TPS65270PWP | Single 3.6V–18V input, dual synchronous buck (1.5A/1.5A); no integrated watchdog or POR; fixed 500kHz/1MHz options. | Lacks window watchdog, programmable reset, and wide HV input - suitable only where supervisory functions are handled externally. | Choose for cost-sensitive, non-safety-critical applications without µP monitoring needs; requires external reset IC and timing components. |
Compared with LTC3640EFE#TRPBF (identical function) and TPS65270PWP (no watchdog/POR), the LT3640EFE#TRPBF uniquely combines dual-rail regulation, 55V transient robustness, and integrated window-mode supervision in one TSSOP package - eliminating discrete timing components and improving system-level reliability.
Availability
LT3640EFE#TRPBF is available at Aetrix Electronics and suitable for automotive electronic control units, industrial PLC modules, and medical sensor hubs requiring stable component supply across extended temperature and high-reliability environments.
Supply support for LT3640EFE#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 LT3640EFE#TRPBF belongs to ADI's Power by Linear™ portfolio of highly integrated DC/DC converters, designed specifically for demanding automotive, industrial, and medical applications requiring robustness, precision, and embedded system supervision.
FAQ
What is the maximum input voltage the LT3640EFE#TRPBF can withstand without damage?
The LT3640EFE#TRPBF features an overvoltage lockout (OVLO) that disables switching at 36.5V (typical), but it can survive non-repetitive 1-second transients up to 55V on the VIN pin. Continuous operation must remain within 4V–35V for the high-voltage channel. This 55V rating makes the LT3640EFE#TRPBF suitable for automotive load-dump conditions without external clamping.
Does the LT3640EFE#TRPBF support synchronization to an external clock?
Yes, the LT3640EFE#TRPBF supports external synchronization via the SYNC pin (Pin 4), accepting TTL/CMOS clock signals from 350kHz to 2.5MHz. The internal oscillator frequency must be set at least 20% lower than the minimum external clock frequency using the RT resistor. The LT3640EFE#TRPBF ignores SYNC until FB1 exceeds 1.165V, ensuring stable startup before synchronization begins.
How is the power-on reset timeout period set for the LT3640EFE#TRPBF?
The power-on reset timeout for both channels (RST1 and RST2) is set by the capacitor connected to the CPOR pin (Pin 12). With CPOR = 220pF, the typical timeout is 9.5ms. The reset asserts when FB1 rises above 1.165V or FB2 above 550mV, then releases after the CPOR-timed interval. This ensures deterministic µP initialization after output regulation is achieved in the LT3640EFE#TRPBF.
Can the LT3640EFE#TRPBF operate with only the low-voltage channel enabled?
No - the LT3640EFE#TRPBF requires the high-voltage channel to be active and regulating (FB1 >1.165V) before enabling the low-voltage channel. EN2 (Pin 27) can disable the LV channel, but VIN2 must exceed 2.3V and FB1 must be in regulation first. If FB1 drops below 1.165V (e.g., due to HV overload), the LT3640EFE#TRPBF automatically discharges SS2 and disables the LV channel to prevent instability.
What is the purpose of the DA pin on the LT3640EFE#TRPBF?
The DA (Diode Anode) pin (Pin 18) senses current through the external catch diode in the high-voltage buck stage. It enables valley-current limiting and extends the oscillator cycle if diode current remains above the limit, providing robust short-circuit protection independent of peak current sensing. This feature enhances fault tolerance during output shorts at high input voltages in the LT3640EFE#TRPBF.
LT3640EFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 2
- Voltage - Input (Min):
- 2.5V
- Voltage - Input (Max):
- 35V
- Voltage - Output (Min/Fixed):
- 0.6V, 1.265V
- Voltage - Output (Max):
- 33.97V
- Current - Output:
- 1.1A, 1.3A
- Frequency - Switching:
- 500kHz ~ 2MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSSOP-EP
LT3640EFE#TRPBF FAQ
1.How can I place an order for LT3640EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3640EFE#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 LT3640EFE#TRPBF reliable?
The price and inventory of LT3640EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3640EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3640EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3640EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3640EFE#TRPBF?
LT3640EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3640EFE#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 LT3640EFE#TRPBF?
For technical support, including LT3640EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3640EFE#TRPBF requirements.
6.How does Aetrix verify that LT3640EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3640EFE#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 LT3640EFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3640EFE#TRPBF?
All LT3640EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3640EFE#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 LT3640EFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3640EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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