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Analog Devices Inc. LTC3646HDE#TRPBF
- Part No.:
- LTC3646HDE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LTC3646HDE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 1A 14DFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,044
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Product details
Overview
LTC3646HDE#TRPBF from Analog Devices (formerly Linear Technology) is a 40V, 1A synchronous step-down DC/DC converter with integrated high-side and synchronous power FETs, ±1% reference accuracy, 4.0V–40V input range, and 2.0V–30V adjustable output voltage - deployed in industrial point-of-load and automotive intermediate bus supplies.
For engineers reviewing the LTC3646HDE#TRPBF datasheet, LTC3646HDE#TRPBF pinout, LTC3646HDE#TRPBF application, or LTC3646HDE#TRPBF equivalent, key selection criteria include guaranteed 1A output current, Burst Mode® operation delivering 140µA no-load quiescent current, programmable 200kHz–3.0MHz switching frequency, –40°C to 150°C junction temperature rating, and DFN-14 (3mm × 4mm) thermally enhanced package with exposed PGND pad.
Technical Context
The LTC3646HDE#TRPBF implements a current-mode, controlled-on-time architecture that dynamically calculates switch on-time as tON = VON/(VIN × fO) to maintain constant frequency across wide input-output ratios. It integrates valley-current sensing, internal 5.0V INTVCC regulator, and dual overvoltage protection (SVIN/PVIN at 43.5V/46V).
Its control loop uses an error amplifier (300µS transconductance) referenced to a 0.6V bandgap, with external compensation via ITH pin and selectable operation modes: Burst Mode® for ultra-low IQ or forced continuous mode for low-noise applications. PGOOD provides open-drain status with ±7.5% output window detection and 30µs filter time.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.0V to 40V - supports 24V/36V automotive and industrial rails without pre-regulation |
| Output Current | 1A guaranteed - sustains full load across –40°C to 150°C junction temperature |
| Output Voltage Range | 2.0V to 30V - set via resistor divider on VFB; compatible with 3.3V, 5V, 12V, and 24V systems |
| Quiescent Current | 140µA typical in Burst Mode® - enables >10-year battery life in always-on monitoring circuits |
| Switching Frequency | 200kHz to 3.0MHz - adjustable via RT resistor or synchronizable to external clock for EMI control |
| Reference Voltage Accuracy | ±1% over –40°C to 150°C - ensures stable regulation under thermal stress in engine bay or industrial enclosures |
| Package | 14-lead 3mm × 4mm DFN with exposed PGND pad - θJA = 43°C/W; requires PCB thermal pad for rated 150°C operation |
Pinout & Package
Package: 14-lead (3mm × 4mm) plastic DFN with exposed thermal pad (Pin 15 = PGND), rated for –40°C to 150°C operating junction temperature. Exposed pad must be soldered to PCB ground plane for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SGND (Pin 1) | Analog ground reference | Low-noise return path for feedback and compensation; separate from PGND to minimize noise coupling |
| VFB (Pin 2) | Feedback input | Connects to resistor divider; compares output to 0.6V reference to regulate VOUT within ±1% |
| ITH (Pin 3) | Error amplifier output / compensation node | Setpoint for valley current limit; external RC network adjusts loop bandwidth and phase margin |
| RT (Pin 4) | Oscillator frequency programming | Resistor to SGND sets fSW from 200kHz to 3.0MHz; connect to INTVCC for fixed 2.25MHz |
| VON (Pin 5) | On-time voltage input | Connected to VOUT to enable constant-frequency operation across wide VIN/VOUT ratios |
| PGOOD (Pin 6) | Open-drain power-good indicator | Pulled low if VFB deviates >7.5% from 0.6V; includes 30µs glitch filter for transient immunity |
| MODE/SYNC (Pin 7) | Mode selection / external clock input | Tied to INTVCC = Burst Mode®; tied to GND = forced continuous; driven by clock = sync mode |
| PVIN (Pin 8) | Main power switch supply | High-voltage input for top FET; decouple with ≥10µF low-ESR capacitor to PGND |
| SW (Pin 9) | Switch node | Connects to inductor and boost capacitor; carries high dv/dt switching waveform |
| BOOST (Pin 10) | Bootstrap supply for high-side gate drive | Capacitor between BOOST and SW generates gate drive voltage above PVIN |
| INTVCC (Pin 11) | Internal 5.0V regulator output | Power source for control circuitry; decouple with ≥4.7µF low-ESR capacitor to PGND |
| EXTVCC (Pin 12) | External bias supply input | Accepts 4.5V–6.0V supply to reduce power loss vs. INTVCC; tie to SGND if unused |
| RUN (Pin 13) | Enable input | Active-high; threshold 1.21V with 110mV hysteresis; enables full operation when asserted |
| SVIN (Pin 14) | Control circuit supply input | Must match PVIN voltage to ensure accurate on-time calculation and frequency stability |
| PGND (Pin 15, exposed pad) | Power ground return | Primary thermal and current return path; must be soldered to large PCB copper area |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode® operation | Reduces no-load IQ to 140µA while maintaining ±1% VOUT regulation - critical for always-on automotive modules |
| Controlled-on-time architecture | Enables stable 200kHz–3.0MHz operation across 4.0V–40V input and 2.0V–30V output - eliminates risk of overvoltage during startup or transients |
| Integrated 1.2A valley-current limit | Guarantees short-circuit robustness without external current-sense components - withstands sustained output shorts |
| Two independent overvoltage protections | SVIN/PVIN OVLO at 43.5V/46V prevents damage from load-dump transients in 24V automotive systems |
| Thermally enhanced DFN package | θJA = 43°C/W with exposed PGND pad - supports 1A continuous output at 150°C junction temperature |
| PGOOD with filtered window detection | ±7.5% output window with 30µs deglitching - avoids false fault signals during dynamic load steps |
Applications
| Automotive Engine Control Unit (ECU) | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering microcontroller, CAN transceiver, and sensor interface in under-hood ECU exposed to 125°C ambient and 36V load-dump transients. IC Role / Device Role / Timing Role: Primary 5V/1A point-of-load regulator with SVIN/PVIN OVLO and 150°C-rated operation. Use Value: Eliminates need for external TVS and pre-regulator; maintains regulation during cold-crank (4.0V) and load-dump (40V+). |
Use Scenario: Generating isolated 3.3V rail for FPGA configuration and communication peripherals in DIN-rail mounted PLC. IC Role / Device Role / Timing Role: High-efficiency, low-noise buck converter with forced continuous mode option for EMI-sensitive digital logic. Use Value: 95% peak efficiency reduces thermal load in sealed enclosures; programmable fSW enables EMI compliance tuning. |
| Telecom Remote Radio Head (RRH) | Medical Patient Monitor Front-End |
Use Scenario: Converting 48V backplane to 12V intermediate bus in outdoor 5G RRH units operating at –40°C to 85°C ambient. IC Role / Device Role / Timing Role: Intermediate bus converter with wide input range and robust thermal performance. Use Value: 40V max input accommodates 48V nominal with ripple; 150°C rating allows derated operation at elevated case temperatures. |
Use Scenario: Supplying analog front-end ADCs and precision op-amps in portable patient monitors requiring ultra-low standby power. IC Role / Device Role / Timing Role: Low-quiescent-current buck regulator enabling multi-year battery life in sleep mode. Use Value: 140µA Burst Mode® IQ extends battery runtime without compromising fast wake-up response. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8610EMSE#TRPBF | 42V input, 3.5A output, 2.5µA IQ, Silent Switcher® architecture | Higher current, lower IQ, superior EMI performance; requires larger layout due to dual-switch topology | Select for noise-sensitive applications where <10mVpp ripple and CISPR-22 Class B compliance are mandatory |
| TPS54240DGQR | 40V input, 2.5A output, 145µA IQ, external MOSFETs, 100kHz–2.5MHz fSW | Higher current but discrete FETs increase BOM count and layout complexity; no integrated PGOOD | Select when 2.5A output or design flexibility with external FETs outweighs integration benefits |
Compared with LT8610EMSE#TRPBF, LTC3646HDE#TRPBF offers tighter output voltage accuracy (±1% vs ±2%) and simpler layout but higher EMI emissions; compared with TPS54240DGQR, it delivers full integration and guaranteed 1A performance in a smaller footprint but lacks programmable soft-start and current limit.
Availability
LTC3646HDE#TRPBF is available at Aetrix Electronics and suitable for automotive engine control units, industrial PLC I/O modules, and telecom remote radio heads requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC3646HDE#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) is a global leader in high-performance analog, mixed-signal, and power management ICs, serving industrial, automotive, communications, and healthcare markets.
The LTC3646 family was designed as a rugged, high-voltage synchronous buck controller for demanding environments - emphasizing wide VIN range, high temperature reliability, and integrated protection features for automotive and industrial point-of-load conversion.
FAQ
What is the maximum junction temperature rating for the LTC3646HDE#TRPBF?
The LTC3646HDE#TRPBF is specified for operation from –40°C to 150°C junction temperature, confirmed by datasheet ordering information and absolute maximum ratings. This H-grade variant is validated for continuous operation at 150°C with appropriate PCB thermal design - unlike E-grade (85°C) or I-grade (125°C) versions. The exposed PGND pad must be soldered to a sufficient copper area to achieve θJA = 43°C/W and sustain 1A load at elevated ambient temperatures.
Does the LTC3646HDE#TRPBF support external synchronization of its switching frequency?
Yes, the LTC3646HDE#TRPBF supports external clock synchronization via the MODE/SYNC pin. When an external clock signal (0.2MHz–3.0MHz) is applied to this pin, the device locks its switching frequency to the input clock and operates in forced continuous mode. An RT resistor must still be connected to set the internal oscillator's target frequency - ensuring stable lock even during clock transients. This capability enables EMI reduction in noise-sensitive systems like medical or test equipment.
How does the LTC3646HDE#TRPBF handle output short-circuit conditions?
The LTC3646HDE#TRPBF incorporates valley-current limiting with a typical 1.2A threshold and built-in short-circuit protection. During an output short, it limits peak inductor current to ~1.2A plus half the ripple, reduces switching frequency, and maintains safe thermal operation without latch-off. The device automatically recovers once the fault clears - no external circuitry or reset required. This behavior is verified across the full –40°C to 150°C temperature range per datasheet electrical characteristics.
Can the LTC3646HDE#TRPBF be used with an external 5V bias supply instead of its internal INTVCC regulator?
Yes, the LTC3646HDE#TRPBF supports external bias via the EXTVCC pin. When a clean 4.5V–6.0V supply is available, connecting it to EXTVCC powers the low-voltage control circuitry and disables the internal 5.0V INTVCC regulator - reducing total power dissipation and improving light-load efficiency. If unused, EXTVCC must be tied to SGND. This feature is explicitly documented in the Pin Functions and Applications Information sections of the datasheet.
What is the purpose of the VON pin on the LTC3646HDE#TRPBF, and how must it be connected?
The VON pin on the LTC3646HDE#TRPBF provides the on-time control loop with real-time output voltage information, enabling constant-frequency operation across wide input-output ratios. It must be connected directly to the regulated output (VOUT) - not through a resistor divider - to ensure accurate tON calculation per the formula tON = VON/(VIN × fO). This connection is mandatory for stable regulation and is validated in all typical application circuits shown in the datasheet.
LTC3646HDE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 14-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):
- 4V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 2V
- Voltage - Output (Max):
- 30V
- Current - Output:
- 1A
- Frequency - Switching:
- 200kHz ~ 3MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-DFN (4x3)
LTC3646HDE#TRPBF FAQ
1.How can I place an order for LTC3646HDE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3646HDE#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 LTC3646HDE#TRPBF reliable?
The price and inventory of LTC3646HDE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3646HDE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3646HDE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3646HDE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3646HDE#TRPBF?
LTC3646HDE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3646HDE#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 LTC3646HDE#TRPBF?
For technical support, including LTC3646HDE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3646HDE#TRPBF requirements.
6.How does Aetrix verify that LTC3646HDE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3646HDE#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 LTC3646HDE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3646HDE#TRPBF?
All LTC3646HDE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3646HDE#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 LTC3646HDE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3646HDE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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