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Analog Devices Inc. LTC3646HDE#PBF
- Part No.:
- LTC3646HDE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LTC3646HDE#PBF.pdf
- Description:
- IC REG BUCK ADJ 1A 14DFN
- Quantity:
- Payment:
- Shipping:
Inventory:109
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Product details
Overview
LTC3646HDE#PBF from Analog Devices (formerly Linear Technology) is a 40V input, 1A synchronous step-down DC/DC converter with integrated high-side and synchronous power FETs, ±1% reference accuracy, Burst Mode® operation for ultra-low 140µA no-load quiescent current, and 2.0V–30V programmable output voltage range - deployed in industrial point-of-load and automotive intermediate bus supplies.
For engineers reviewing the LTC3646HDE#PBF datasheet, LTC3646HDE#PBF pinout, LTC3646HDE#PBF application, or LTC3646HDE#PBF equivalent, key selection criteria include its –40°C to 150°C guaranteed junction temperature rating, 4.0V–40V wide input range, controlled on-time architecture enabling large step-down ratios without overvoltage risk, and selectable 200kHz–3.0MHz switching frequency via RT resistor or external sync clock.
Technical Context
The LTC3646HDE#PBF implements a current-mode, monolithic synchronous buck topology with valley-current sensing and patented controlled on-time architecture. Its on-time calculation tON = VON/(VIN × fO) enables constant-frequency operation across wide VIN–VOUT ratios while maintaining stability without external compensation in many cases.
It integrates dual MOSFETs (200mΩ high-side, 120mΩ low-side at 5.5V), a 5.0V INTVCC regulator (±2% tolerance), PGOOD with 7.5% over/under-voltage window, and robust protection including SVIN/PVIN overvoltage lockout (43.5V trip), short-circuit current limiting (1.2A typ), and thermal shutdown. MODE/SYNC pin selects between Burst Mode® (high efficiency at light load) and forced continuous mode (low ripple).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.0V to 40V - supports direct connection to 24V/36V industrial rails and automotive battery transients up to 40V. |
| Output Current | 1A guaranteed - delivers full rated load continuously at TJ ≤ 150°C with proper PCB thermal design. |
| Output Voltage Range | 2.0V to 30V - set via resistive divider on VFB; compatible with FPGA core, I/O, and analog subsystems. |
| Reference Voltage | 0.6V ±1% - enables precise regulation; line/load regulation <0.12% ensures stable output under dynamic conditions. |
| Quiescent Current | 140µA typical in Burst Mode® - extends battery life in always-on systems; drops to 8µA in shutdown. |
| Switching Frequency | 200kHz to 3.0MHz - adjustable via RT resistor or external clock; 2.25MHz default when RT tied to INTVCC. |
| Package | 14-lead 3mm × 4mm DFN - thermally enhanced exposed pad (PGND) with θJA = 43°C/W. |
Pinout & Package
Package: 14-lead (4mm × 3mm) plastic DFN with exposed thermal pad (Pin 15 = PGND). Requires soldering of exposed pad 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 error amplifier; must be isolated from noisy power ground until joined at single point. |
| VFB (Pin 2) | Feedback Input | Connects to resistor divider; compares output voltage against 0.6V internal reference to regulate VOUT. |
| ITH (Pin 3) | Error Amplifier Output / Compensation Node | Loop compensation point; connect RC network for stability; tie to INTVCC for internal compensation. |
| RT (Pin 4) | Oscillator Frequency Programming | Resistor to SGND sets switching frequency (200kHz–3.0MHz); floating not allowed. |
| VON (Pin 5) | On-Time Proportional Input | Connected to VOUT to scale on-time inversely with input voltage, enabling constant frequency across wide VIN ranges. |
| PGOOD (Pin 6) | Power Good Open-Drain Output | Asserts low when VFB deviates >7.5% from 0.6V; includes 30µs filter to suppress transient glitches. |
| MODE/SYNC (Pin 7) | Operating Mode Control / Clock Input | Tie to INTVCC for Burst Mode®, to GND for forced continuous mode, or drive with external clock for synchronization. |
| PVIN (Pin 8) | Main Power Switch Supply | High-voltage input for top FET; requires ≥10µF low-ESR ceramic capacitor to PGND. |
| SW (Pin 9) | Switch Node | Connects to inductor and boost capacitor; carries high di/dt; layout critical for EMI and efficiency. |
| BOOST (Pin 10) | Bootstrap Supply | Generates gate drive voltage for high-side FET via SW–BOOST capacitor; swing = INTVCC to PVIN + INTVCC. |
| INTVCC (Pin 11) | Internal 5.0V Regulator Output | Supplies control circuitry; decouple with ≥4.7µF low-ESR capacitor to PGND; disabled when RUN = low. |
| EXTVCC (Pin 12) | External Bias Input | Optional 4.5V–6.0V supply for lower quiescent current; tie to SGND if unused. |
| RUN (Pin 13) | Enable Input | Active-high enable; threshold = 1.21V (typ); hysteresis = 110mV prevents chatter during slow-rising supplies. |
| SVIN (Pin 14) | Control Circuitry Supply | Must match PVIN for accurate on-time calculation; decouple with >1µF low-ESR capacitor to SGND. |
| PGND (Pin 15) | Power Ground / Thermal Pad | Exposed pad; must be soldered to large PCB copper area for thermal dissipation and low-impedance return path. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode® Operation | Reduces no-load IQ to 140µA while maintaining ±1% output regulation - essential for battery-backed or energy-harvesting systems. |
| Controlled On-Time Architecture | Enables stable 2.0V–30V output from 40V input without risk of overvoltage during startup or transients - eliminates need for external OVP clamps. |
| Integrated Dual Power FETs | 200mΩ/120mΩ RDS(ON) at 5.5V reduces conduction loss and eliminates external MOSFET selection - simplifies BOM and layout. |
| Wide Temperature Grade | –40°C to 150°C guaranteed operation (H-grade) - qualified for under-hood automotive, industrial motor drives, and harsh-environment power supplies. |
| Robust Protection Suite | Includes SVIN overvoltage lockout (43.5V), short-circuit current limit (1.2A), thermal shutdown, and PGOOD with glitch filtering - enables unattended operation in mission-critical systems. |
Applications
| Industrial Point-of-Load Supply | Automotive Intermediate Bus Converter |
|---|---|
|
Use Scenario: Powering FPGA I/O banks and auxiliary logic in programmable logic controllers (PLCs) operating from 24V DC rails with strict thermal constraints. IC Role / Device Role / Timing Role: Primary synchronous buck regulator delivering regulated 3.3V/1.8V at up to 1A with minimal board space and thermal overhead. Use Value: 95% peak efficiency and 140µA Burst Mode® IQ extend system uptime during standby; 150°C rating ensures reliability in sealed enclosures. |
Use Scenario: Converting 12V/24V vehicle battery to stable 5V for infotainment head units and ADAS camera modules subject to cold-crank and load-dump transients. IC Role / Device Role / Timing Role: High-input-voltage buck converter with integrated OVP and short-circuit protection, eliminating discrete protection components. Use Value: 40V absolute max input and SVIN OV lockout (43.5V) withstand 12V system load-dump spikes; PGOOD enables safe microcontroller boot sequencing. |
| Telecom Intermediate Bus Converter | Test & Measurement Equipment Power |
|
Use Scenario: Generating 12V intermediate rail from 48V telecom backplane in modular base station cards requiring low EMI and high efficiency. IC Role / Device Role / Timing Role: Synchronous step-down controller supporting 200kHz–3.0MHz frequency selection to avoid sensitive RF bands and minimize filter size. Use Value: External clock synchronization (via MODE/SYNC) enables coherent switching across multiple converters - reducing beat frequencies and conducted emissions. |
Use Scenario: Providing low-noise, tightly regulated 2.5V/3.3V for precision ADCs and DACs in portable oscilloscopes and signal analyzers with battery backup. IC Role / Device Role / Timing Role: Low-quiescent-current buck regulator with ±1% reference and <0.12% load regulation for metrology-grade voltage stability. Use Value: Internal 0.6V reference drift <±10mV over –40°C to 150°C ensures consistent accuracy across environmental stress testing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8610EMSE#PBF | 42V input, 3.5A output, Silent Switcher® architecture; higher current, lower IQ (2.5µA), but fixed 3.3V/5V options only. | Preferred where ultra-low EMI is mandatory (e.g., RF-sensitive test equipment); less flexible VOUT programming than LTC3646HDE#PBF. | Select LT8610EMSE#PBF when EMI compliance is primary and output voltage is fixed; retain LTC3646HDE#PBF for adjustable 2–30V outputs with Burst Mode® efficiency. |
| TPS54340DDAR | 40V input, 3.5A output, current-mode control; no integrated BOOT diode path, higher min. on-time (130ns vs. 30ns), no PGOOD. | Suitable for cost-sensitive industrial supplies where 150°C rating and PGOOD monitoring are not required. | Choose TPS54340DDAR for higher current at lower cost in commercial-temp designs; LTC3646HDE#PBF remains optimal for extended temp, precision regulation, and system monitoring. |
Compared with LT8610EMSE#PBF and TPS54340DDAR, the LTC3646HDE#PBF uniquely combines 150°C operation, 2–30V programmable output, 140µA Burst Mode® IQ, and integrated PGOOD - making it the preferred choice for ruggedized, field-deployable power systems requiring flexibility and long-term reliability.
Availability
LTC3646HDE#PBF is available at Aetrix Electronics and suitable for industrial PLCs, automotive ADAS modules, telecom base station cards, and test equipment requiring stable component supply across extended temperature and long product lifecycles.
Supply support for LTC3646HDE#PBF 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 LTC3646HDE#PBF belongs to Linear's high-voltage monolithic buck regulator family, designed specifically for robust, compact, and efficient point-of-load conversion in harsh environments - emphasizing thermal resilience, wide VIN capability, and integrated protection.
FAQ
What is the maximum junction temperature specification for the LTC3646HDE#PBF?
The LTC3646HDE#PBF is specified for guaranteed operation from –40°C to 150°C junction temperature. This H-grade rating is confirmed in the Absolute Maximum Ratings table and Order Information section, distinguishing it from E-grade (–40°C to 85°C) and I-grade (–40°C to 125°C) variants. Derating curves in the datasheet show lifetime reduction above 125°C, but full electrical specifications remain valid up to 150°C.
Does the LTC3646HDE#PBF support output voltages below 2.0V?
No - the LTC3646HDE#PBF is the standard version with a 2.0V to 30V output voltage range. For 0.6V to 15V operation, the pin-compatible LTC3646-1 variant (e.g., LTC3646HDE-1#PBF) must be used. The datasheet explicitly separates these two families in the FEATURES and ELECTRICAL CHARACTERISTICS tables, and the VOUT range is not adjustable beyond these hard limits by external components.
How does the LTC3646HDE#PBF achieve high efficiency at light loads?
The LTC3646HDE#PBF achieves high light-load efficiency via Burst Mode® operation, which reduces no-load quiescent current to 140µA typical. In this mode, the controller discontinues switching cycles when output current falls near zero, allowing the output capacitor to supply load current until regulation error triggers the next burst - minimizing switching and gate drive losses while maintaining ±1% output accuracy.
Can the LTC3646HDE#PBF be synchronized to an external clock?
Yes - the MODE/SYNC pin accepts an external clock signal (0.2MHz to 3.0MHz) to synchronize switching frequency. When driven externally, the LTC3646HDE#PBF operates in forced continuous mode and adjusts its on-time to match the applied clock. An RT resistor must still be connected to set the internal oscillator's nominal frequency for proper loop behavior during sync transitions.
What is the purpose of the VON pin on the LTC3646HDE#PBF?
The VON pin provides the on-time controller with real-time output voltage information, enabling the controlled on-time architecture. By connecting VON directly to VOUT, the device calculates tON = VON/(VIN × fO), ensuring constant switching frequency and stable regulation even with large VIN/VOUT ratios - preventing overvoltage during startup or line transients without requiring external compensation.
LTC3646HDE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 14-WFDFN Exposed Pad
- Packaging:
- Tube
- 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#PBF FAQ
1.How can I place an order for LTC3646HDE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3646HDE#PBF 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#PBF reliable?
The price and inventory of LTC3646HDE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3646HDE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3646HDE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3646HDE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3646HDE#PBF?
LTC3646HDE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3646HDE#PBF 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#PBF?
For technical support, including LTC3646HDE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3646HDE#PBF requirements.
6.How does Aetrix verify that LTC3646HDE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3646HDE#PBF 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#PBF meets industry standards.
7.What is the process for return or replacement of LTC3646HDE#PBF?
All LTC3646HDE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3646HDE#PBF, 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#PBF part is unused and in its original packaging.
Return procedure for LTC3646HDE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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