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Analog Devices Inc. LTC3646EDE#PBF
- Part No.:
- LTC3646EDE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LTC3646EDE#PBF.pdf
- Description:
- IC REG BUCK ADJ 1A 14DFN
- Quantity:
- Payment:
- Shipping:
Inventory:596
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Product details
Overview
LTC3646EDE#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, 0.6V feedback voltage, and programmable 200kHz–3MHz switching frequency. It operates in Burst Mode® (140µA no-load IQ) or forced continuous mode and supports output voltages from 2.0V to 30V - ideal for intermediate bus regulation in industrial power supplies.
For engineers reviewing the LTC3646EDE#PBF datasheet, LTC3646EDE#PBF pinout, LTC3646EDE#PBF application, or LTC3646EDE#PBF equivalent, key selection criteria include its 4.0V–40V input range, internal compensation capability, 14-lead 3mm × 4mm DFN package with exposed PGND pad, and robust short-circuit and overvoltage protection for high-reliability 12V/24V/36V systems.
Technical Context
The LTC3646EDE#PBF implements a current-mode, controlled-on-time architecture that maintains constant frequency across wide VIN–VOUT ratios while avoiding output overvoltage risk. Its valley-current sensing and on-time calculation (tON = VON/(VIN·fO)) enable stable operation down to 2.0V output from 40V input without external timing components.
It integrates dual MOSFET drivers, a 5.0V INTVCC regulator (±2% load regulation), PGOOD with 70-cycle filtering, and independent SVIN/PVIN monitoring for overvoltage lockout at 43.5V (2.5V hysteresis). The MODE/SYNC pin selects between Burst Mode® (high efficiency at light loads) and forced continuous mode (low ripple), with external clock synchronization support up to 3.0MHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.0V to 40V - supports automotive cold-crank (4.5V) and industrial 36V bus without pre-regulation |
| Output Current | 1A guaranteed - sustains full load across –40°C to +85°C junction temperature |
| Feedback Reference | 0.6V ±1% - enables precise output setting from 2.0V to 30V using standard resistor dividers |
| No-Load Quiescent Current | 140µA typical in Burst Mode® - extends battery life in always-on systems |
| Switching Frequency | 200kHz to 3.0MHz (resistor-programmable or external sync) - balances EMI, size, and efficiency |
| Top/Bottom RDS(ON) | 200mΩ / 120mΩ at 5.5V - minimizes conduction loss at 1A, enabling >95% peak efficiency |
| Package | 14-lead 3mm × 4mm DFN with exposed PGND pad - θJA = 43°C/W, supports >1.5W dissipation at 25°C ambient |
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 for feedback and error amplifier; must be isolated from noisy PGND paths |
| VFB (Pin 2) | Feedback input | Connects to resistor divider; compares output to 0.6V reference to regulate VOUT |
| ITH (Pin 3) | Error amplifier output & compensation node | Loop stability set by external R/C network; tie to INTVCC for internal compensation |
| RT (Pin 4) | Oscillator programming input | Resistor to SGND sets fSW from 200kHz–3MHz; connect to INTVCC for 2.25MHz default |
| VON (Pin 5) | On-time voltage input | Connected to VOUT to scale tON proportionally - enables wide VIN/VOUT ratios without overvoltage |
| PGOOD (Pin 6) | Open-drain power-good indicator | Pulled low if VFB deviates >7.5% from 0.6V; includes 15–30µs filter to suppress transient glitches |
| MODE/SYNC (Pin 7) | Operating mode control | Ground = forced continuous; INTVCC = Burst Mode®; external clock = synchronized forced continuous |
| PVIN (Pin 8) | Main power switch supply | High-voltage input (up to 45V absolute max); decouple with ≥10µF low-ESR capacitor to PGND |
| SW (Pin 9) | Switch node | Connects to inductor and boost capacitor; carries high di/dt; requires tight layout and ground stitching |
| BOOST (Pin 10) | Bootstrap supply for high-side gate driver | Capacitor between BOOST and SW generates gate drive voltage; swing = INTVCC to PVIN + INTVCC |
| INTVCC (Pin 11) | Internal 5.0V regulator output | Supplies control circuitry; decouple with ≥4.7µF low-ESR cap; disabled when RUN = low |
| EXTVCC (Pin 12) | External bias input | Accepts 4.5V–6.0V supply to reduce power loss; tie to SGND if unused |
| RUN (Pin 13) | Enable input | Active-high; threshold = 1.21V (110mV hysteresis); leakage <1µA enables high-impedance control |
| SVIN (Pin 14) | Secondary input monitor | Tracks PVIN for overvoltage protection; must equal PVIN to maintain accurate on-time calculation |
| PGND (Pin 15, Exposed Pad) | Power ground return | Primary return path for high-current switches; must be soldered to large PCB ground plane |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode® operation | Reduces no-load IQ to 140µA while maintaining ±1% output regulation - critical for battery-backed systems |
| Controlled-on-time architecture | Enables stable 2.0V–30V output from 40V input without risk of overvoltage during startup or transients |
| Integrated 5.0V INTVCC regulator | Provides regulated bias for internal logic; supports up to 5mA load with <0.5% load regulation |
| Independent SVIN/PVIN OV protection | Detects >43.5V on SVIN and suspends switching within microseconds - protects MOSFETs from transient spikes |
| Valley-current limit with negative current detection | 1.2A valley limit (±0.3A negative limit) prevents inductor saturation and enables safe forced continuous operation |
| PGOOD with filtered response | 15–30µs glitch rejection window ensures reliable system sequencing without false fault assertions |
Applications
| Industrial PLC Power Supply | Automotive Body Control Module |
|---|---|
Use Scenario: Regulating 24V intermediate bus to 5V/3.3V for microcontroller, CAN transceiver, and sensor interfaces in harsh factory environments. IC Role / Device Role / Timing Role: Primary buck regulator delivering 1A at ±1% accuracy with Burst Mode® for standby current reduction. Use Value: 40V input rating withstands load-dump transients; 140µA no-load IQ extends backup battery life; integrated OV protection eliminates need for external TVS. |
Use Scenario: Converting 12V vehicle battery to 3.3V for infotainment MCU and memory in body electronics modules. IC Role / Device Role / Timing Role: Synchronous step-down converter operating from cold-crank (4.5V) to load-dump (40V) conditions. Use Value: Wide 4.0V–40V input range covers full automotive voltage envelope; 14-lead DFN enables compact layout; PGOOD enables safe processor reset sequencing. |
| Point-of-Load Telecom Supply | Test Equipment Auxiliary Rail |
Use Scenario: Generating 12V/5V rails from 48V backplane in modular telecom line cards requiring low noise and fast transient response. IC Role / Device Role / Timing Role: High-efficiency intermediate bus converter supporting forced continuous mode for ripple-sensitive analog circuits. Use Value: 200kHz–3MHz frequency adjustment optimizes EMI filtering; internal compensation reduces BOM count; 95% peak efficiency lowers thermal load. |
Use Scenario: Providing stable 15V/–5V auxiliary supplies for op-amp biasing and DAC references in benchtop test instruments. IC Role / Device Role / Timing Role: Precision-regulated buck stage with 0.6V reference and ±1% accuracy for metrology-grade voltage generation. Use Value: 0.6V reference enables direct use of standard 1% resistors; low 140µA IQ minimizes self-heating drift; EXTVCC option improves efficiency when 5V rail is available. |
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, 2.2MHz fixed frequency, 2.5µA quiescent current in Silent Switcher mode | Higher current, lower IQ, but narrower 3.4V–42V input range and no VON-based on-time scaling | Prefer LT8610EMSE#PBF for ultra-low-IQ battery systems needing >1A; LTC3646EDE#PBF better for wide-VIN ratio stability and 2.0V–30V flexibility |
| TPS54240DGQR | 40V input, 2.5A, adjustable 100kHz–2.5MHz, 145µA IQ, no integrated BOOT diode or PGOOD filter | Higher current, wider frequency range, but lacks PGOOD glitch immunity and requires external bootstrap diode | Choose TPS54240DGQR for cost-sensitive 2.5A designs where external components are acceptable; LTC3646EDE#PBF preferred for integrated reliability features and simplified layout |
Compared with LT8610EMSE#PBF and TPS54240DGQR, the LTC3646EDE#PBF delivers superior wide-ratio regulation stability via VON-scaled on-time control, built-in PGOOD filtering, and seamless Burst Mode®/continuous mode transition - making it optimal for precision intermediate bus applications where output accuracy and transient immunity are prioritized over raw current or ultra-low IQ.
Availability
LTC3646EDE#PBF is available at Aetrix Electronics and suitable for industrial PLC power supplies, automotive body control modules, and telecom point-of-load converters requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.
Supply support for LTC3646EDE#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 medical markets.
The LTC3646EDE#PBF belongs to Linear's high-voltage monolithic buck regulator product line, designed specifically for robust, wide-input-range DC/DC conversion in space-constrained, high-reliability systems where input transients and output accuracy are critical.
FAQ
What is the maximum input voltage rating for the LTC3646EDE#PBF?
The LTC3646EDE#PBF has an absolute maximum PVIN/SVIN rating of 45V, with guaranteed operation from 4.0V to 40V. Its overvoltage lockout triggers at 43.5V (with 2.5V hysteresis), protecting internal MOSFETs during load-dump events. This makes LTC3646EDE#PBF suitable for 24V and 36V industrial buses and automotive applications where transient spikes exceed nominal rail voltage.
Does the LTC3646EDE#PBF support external frequency synchronization?
Yes, the LTC3646EDE#PBF supports external clock synchronization via the MODE/SYNC pin. When an external clock signal (0.2MHz–3.0MHz) is applied, the device adjusts its top-switch on-time to match the input frequency and operates in forced continuous mode. An RT resistor must still be connected to set the internal oscillator's baseline frequency for proper lock range - confirming full synchronization capability for LTC3646EDE#PBF in noise-sensitive systems.
How does the VON pin function in the LTC3646EDE#PBF?
The VON pin in the LTC3646EDE#PBF provides the on-time controller with real-time output voltage information. When connected directly to VOUT, it enables the patented controlled-on-time architecture to scale tON proportionally to VOUT/VIN - ensuring stable regulation across extreme step-down ratios (e.g., 40V→2V) without risk of output overvoltage. This direct VON feedback is a defining feature of LTC3646EDE#PBF that differentiates it from fixed-frequency current-mode controllers.
What is the thermal performance of the LTC3646EDE#PBF in its DFN package?
The LTC3646EDE#PBF in the 14-lead 3mm × 4mm DFN package has a junction-to-ambient thermal resistance (θJA) of 43°C/W when mounted on a standard 2-layer PCB with the exposed PGND pad fully soldered to a 1in² copper area. At 1A load and 12V input, typical power dissipation is ~0.3W, resulting in <15°C junction rise above ambient - well within its –40°C to +85°C operating range. This validated thermal performance confirms LTC3646EDE#PBF suitability for compact, convection-cooled designs.
Can the LTC3646EDE#PBF operate with only internal compensation?
Yes, the LTC3646EDE#PBF supports internal compensation by connecting the ITH pin directly to INTVCC. This configuration eliminates external compensation components and is optimized for standard 3.3V/5V outputs with typical inductor/capacitor values. For non-standard VOUT, wide temperature ranges, or demanding transient response, external R-C compensation on the ITH node is recommended - but the internal option provides immediate, robust operation for LTC3646EDE#PBF in general-purpose applications.
LTC3646EDE#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)
LTC3646EDE#PBF FAQ
1.How can I place an order for LTC3646EDE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3646EDE#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 LTC3646EDE#PBF reliable?
The price and inventory of LTC3646EDE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3646EDE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3646EDE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3646EDE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3646EDE#PBF?
LTC3646EDE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3646EDE#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 LTC3646EDE#PBF?
For technical support, including LTC3646EDE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3646EDE#PBF requirements.
6.How does Aetrix verify that LTC3646EDE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3646EDE#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 LTC3646EDE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3646EDE#PBF?
All LTC3646EDE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3646EDE#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 LTC3646EDE#PBF part is unused and in its original packaging.
Return procedure for LTC3646EDE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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