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Analog Devices Inc. LTC3809EDD#PBF
- Part No.:
- LTC3809EDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LTC3809EDD#PBF.pdf
- Description:
- IC REG CTRLR BUCK 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,854
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Product details
Overview
LTC3809EDD#PBF from Analog Devices (formerly Linear Technology) is a synchronous step-down DC/DC controller IC that drives external complementary P- and N-channel MOSFETs without requiring a current sense resistor. It features constant-frequency current-mode control, 550kHz default switching frequency, 0.6V ±1.5% reference, and supports input voltages from 2.75V to 9.8V for battery-powered portable instruments and distributed power systems.
For engineers reviewing the LTC3809EDD#PBF datasheet, LTC3809EDD#PBF pinout, LTC3809EDD#PBF application, or LTC3809EDD#PBF equivalent, key selection considerations include its No RSENSE™ architecture, selectable Burst Mode®/pulse-skipping/forced continuous operation, spread spectrum modulation for EMI reduction, auxiliary winding regulation capability, and thermal performance in the 3mm × 3mm DFN package with exposed ground pad.
Technical Context
The LTC3809EDD#PBF implements a constant-frequency current-mode control loop using VDS sensing across the external P-channel MOSFET to eliminate the need for a discrete sense resistor. Its internal error amplifier compares feedback at VFB to a precision 0.6V reference, while the ITH pin sets peak current threshold via voltage-controlled comparator.
It integrates a true PLL with capture range of 200kHz–1MHz for external synchronization, supports spread spectrum modulation (460kHz–635kHz), and provides three operating modes-Burst Mode®, pulse-skipping, and forced continuous-selected via the SYNC/MODE pin. The IPRG pin configures maximum current sense voltage thresholds (85mV/125mV/204mV) to match MOSFET RDS(ON) and duty cycle requirements.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.75V to 9.8V - supports single/dual Li-ion batteries and intermediate bus rails |
| Output Voltage Range | 0.6V to VIN - enables low-voltage core supplies and adjustable point-of-load regulation |
| Reference Voltage | 0.6V ±1.5% - ensures tight output regulation accuracy over temperature and line/load |
| Switching Frequency | Up to 750kHz (programmable) - allows use of compact 2.2μH inductors and ceramic capacitors |
| Quiescent Current | 9μA in shutdown - extends battery life in always-on portable systems |
| Peak Gate Drive Current | 1A (TG/BG) - ensures fast MOSFET turn-on/off for high-efficiency synchronous rectification |
| Thermal Package | 10-lead 3mm × 3mm DFN with exposed GND pad - θJA = 43°C/W enables >2A output with minimal heatsinking |
Pinout & Package
The LTC3809EDD#PBF is housed in a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed ground pad (Pin 11), which must be soldered to PCB ground for electrical integrity and thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PLLLPF (1) | Frequency set / PLL filter node | Selects oscillator frequency (300/550/750kHz) when unsynchronized; serves as loop filter for external sync clock |
| SYNC/MODE (2) | Multi-function control input | Enables external clock sync, selects Burst Mode®/pulse-skipping/forced continuous, activates spread spectrum, and accepts auxiliary winding feedback |
| VFB (3) | Feedback input | Compares resistive divider output against 0.6V reference to regulate VOUT; input bias <50nA minimizes divider error |
| ITH (4) | Error amp output / current threshold | Sets peak inductor current limit; nominal 0.7V–2.0V range enables precise load-current scaling |
| RUN (5) | Enable/shutdown control | Pulling below 1.1V disables all circuitry; releases internal soft-start ramp on enable |
| IPRG (6) | Current sense threshold select | Configures ΔVSENSE(MAX) to 85mV/125mV/204mV - matches MOSFET RDS(ON) and duty cycle for stable current limiting |
| BG (7) | N-channel gate driver output | Drives bottom MOSFET gate from PGND to VIN; 50ns fall time ensures fast turn-off and prevents shoot-through |
| TG (8) | P-channel gate driver output | Drives top MOSFET gate from PGND to VIN; 40ns rise/fall times support high-frequency switching |
| VIN (9) | Power supply input | Powers internal circuitry and gate drivers; also serves as positive input to differential current comparator |
| SW (10) | Switch node connection | Connects to MOSFET drains and inductor; serves as negative input to current comparator and reverse-current detector |
Key Features
| Feature | Design Value |
|---|---|
| No RSENSE™ architecture | Eliminates current sense resistor losses and board area; uses MOSFET VDS for accurate, efficient current sensing |
| Selectable spread spectrum modulation | Reduces EMI peak emissions by spreading 550kHz fundamental across 460–635kHz band - simplifies EMC compliance |
| True PLL synchronization | Locks internal oscillator to external clock (250–750kHz); suppresses Burst Mode during sync to prevent noise coupling |
| 100% duty cycle dropout operation | Maintains regulation as VIN approaches VOUT - critical for battery end-of-discharge in portable Li-ion systems |
| Auxiliary winding regulation | Uses SYNC/MODE pin to monitor secondary-side winding voltage - enables isolated flyback-derived outputs without optocoupler |
Applications
| 1-Cell or 2-Cell Li-ion Power Management | Portable Test & Measurement Instruments |
|---|---|
Use Scenario: Regulating 2.5V or 3.3V from a 3.0–4.2V lithium-ion cell in handheld oscilloscopes or multimeters. IC Role / Device Role / Timing Role: Synchronous buck controller providing high-efficiency, low-noise power conversion with programmable light-load behavior. Use Value: Burst Mode® delivers >85% efficiency at 10mA load; 100% duty cycle extends runtime below 3.0V; DFN package saves PCB space. | Use Scenario: Generating stable 1.8V and 1.2V core supplies for ARM Cortex-M microcontrollers and ADCs in portable data loggers. IC Role / Device Role / Timing Role: Precision voltage regulator with 0.6V ±1.5% reference and excellent transient response for mixed-signal SoCs. Use Value: Constant-frequency current-mode control ensures <100ns load-step recovery; low 9μA shutdown current preserves battery charge between measurements. |
| Distributed DC Power Systems | Low-EMI Industrial Sensors |
Use Scenario: Point-of-load conversion from 5V or 3.3V intermediate bus to 2.5V FPGA I/O banks in modular PLC backplanes. IC Role / Device Role / Timing Role: High-density synchronous controller enabling compact, thermally efficient local regulation. Use Value: 750kHz operation allows ≤2.2μH inductors; exposed DFN pad dissipates >1W with minimal thermal resistance. | Use Scenario: Powering analog front-ends and RF transceivers in wireless sensor nodes where conducted/radiated EMI must meet CISPR-22 Class B limits. IC Role / Device Role / Timing Role: EMI-optimized DC/DC controller with spread spectrum and synchronized PWM to avoid spectral peaks. Use Value: Spread spectrum reduces 550kHz harmonic amplitudes by >10dB; external sync eliminates beat frequencies in multi-rail systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3850EDD#PBF | Higher 800kHz max frequency; includes integrated 5V LDO bias rail; no IPRG pin - fixed 50mV current sense threshold | Requires external 5V bias for gate drive; less flexible current limit configuration for ultra-low RDS(ON) MOSFETs | Choose for higher-frequency designs needing integrated bias supply; not drop-in due to different current sensing scheme |
| MP2315DJ-LF-Z | Integrated power stage (no external MOSFETs); 2A rated; fixed 500kHz frequency; no spread spectrum or PLL sync | Limited to ≤2A output; no external MOSFET optimization; lacks advanced light-load and EMI features | Choose for cost-sensitive, lower-current applications where board space is constrained and EMI requirements are moderate |
Compared with LTC3850EDD#PBF and MP2315DJ-LF-Z, the LTC3809EDD#PBF offers unique flexibility in current sense threshold selection (via IPRG), true PLL synchronization, and spread spectrum modulation - making it optimal for noise-sensitive, battery-critical, or thermally constrained designs requiring external MOSFET optimization.
Availability
LTC3809EDD#PBF is available at Aetrix Electronics and suitable for portable instrumentation, Li-ion powered devices, and distributed DC power systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC3809EDD#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 and maintains its high-performance analog and power management product lines with rigorous reliability testing and automotive-grade qualification options.
The LTC3809EDD#PBF belongs to Linear's No RSENSE™ synchronous controller family, designed specifically for high-efficiency, low-EMI DC/DC conversion in space-constrained, battery-operated, and noise-sensitive applications.
FAQ
What is the function of the IPRG pin on the LTC3809EDD#PBF?
The IPRG pin on the LTC3809EDD#PBF selects the maximum allowable peak current sense voltage (ΔVSENSE(MAX)) across the external P-channel MOSFET: floating = 125mV, tied to GND = 85mV, tied to VIN = 204mV. This setting directly determines the peak inductor current limit based on the MOSFET's RDS(ON), enabling robust current protection and stable operation across varying duty cycles. The LTC3809EDD#PBF uses this to maintain control loop stability and prevent overcurrent under light- or heavy-load conditions.
Does the LTC3809EDD#PBF support 100% duty cycle operation, and how is it implemented?
Yes, the LTC3809EDD#PBF supports true 100% duty cycle operation to maintain regulation during low-input conditions, such as end-of-discharge in Li-ion batteries. When VIN approaches VOUT, the controller extends the top-gate (TG) on-time beyond one oscillator period until the inductor current reaches the threshold set by the ITH pin. This allows the output to track VIN minus only the P-MOSFET RDS(ON) drop and inductor DCR, extending usable battery life. The LTC3809EDD#PBF achieves this without external components or mode switching.
How does spread spectrum modulation reduce EMI in the LTC3809EDD#PBF?
The LTC3809EDD#PBF implements spread spectrum modulation by dithering its internal 550kHz oscillator frequency between 460kHz and 635kHz using a dedicated modulation scheme controlled via the SYNC/MODE and PLLLPF pins. This spreads energy across a wider bandwidth, reducing peak spectral amplitude by up to 10dB compared to fixed-frequency operation - easing compliance with FCC Part 15 and CISPR-22 radiated emission limits. The LTC3809EDD#PBF applies this modulation only in pulse-skipping mode, preserving light-load efficiency.
Can the LTC3809EDD#PBF synchronize to an external clock, and what is its lock range?
Yes, the LTC3809EDD#PBF includes a true phase-locked loop (PLL) that synchronizes its internal oscillator to an external clock applied to the SYNC/MODE pin. Its guaranteed lock range is 250kHz to 750kHz, with typical capture range extending from 200kHz to 1MHz. During synchronization, Burst Mode® is automatically disabled to prevent interference, and the PLLLPF pin functions as the loop filter node. The LTC3809EDD#PBF maintains tight phase alignment and jitter performance across temperature and supply variations.
What package type and thermal characteristics apply to the LTC3809EDD#PBF?
The LTC3809EDD#PBF is supplied in a 10-lead 3mm × 3mm plastic DFN package with exposed ground pad (Pin 11), designated as the DD package. Its thermal resistance is θJA = 43°C/W under standard JEDEC 2-layer board conditions. The exposed pad must be soldered to a minimum 100mm² copper pour for optimal thermal performance and electrical grounding. This package enables the LTC3809EDD#PBF to deliver >2A continuous output current with acceptable junction temperature rise in compact portable designs.
LTC3809EDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 2.75V ~ 9.8V
- Frequency - Switching:
- 460kHz ~ 635kHz
- Duty Cycle (Max):
- 100%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Enable
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LTC3809EDD#PBF FAQ
1.How can I place an order for LTC3809EDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3809EDD#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 LTC3809EDD#PBF reliable?
The price and inventory of LTC3809EDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3809EDD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3809EDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3809EDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3809EDD#PBF?
LTC3809EDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3809EDD#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 LTC3809EDD#PBF?
For technical support, including LTC3809EDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3809EDD#PBF requirements.
6.How does Aetrix verify that LTC3809EDD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3809EDD#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 LTC3809EDD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3809EDD#PBF?
All LTC3809EDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3809EDD#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 LTC3809EDD#PBF part is unused and in its original packaging.
Return procedure for LTC3809EDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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