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Analog Devices Inc. LTC3561EDD
- Part No.:
- LTC3561EDD
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3561EDD.pdf
- Description:
- IC REG BUCK ADJ 1A 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,686
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Product details
Overview
LTC3561EDD from Analog Devices (formerly Linear Technology) is a constant-frequency, synchronous step-down DC/DC converter optimized for medium-power portable applications. It operates from 2.63V to 5.5V input, delivers up to 1.4A peak output current, supports adjustable output voltage from 0.8V to 5V, and features internal 0.11Ω P/N-channel MOSFETs in an 8-pin 3mm × 3mm DFN package - used in notebook computers and cellular phones for efficient battery-powered rail generation.
For engineers reviewing the LTC3561EDD datasheet, LTC3561EDD pinout, LTC3561EDD application, or LTC3561EDD equivalent, key selection criteria include its 4MHz max switching frequency capability, 240µA no-load quiescent current, 100% duty-cycle dropout operation, thermal derating via θJA = 43°C/W, and compatibility with ceramic output capacitors without external compensation components.
Technical Context
The LTC3561EDD implements a current-mode control architecture with external RT resistor–programmed oscillator frequency (up to 4MHz), enabling precise transient response tuning across wide load and capacitor ranges. Its dual MOSFET power stage uses a P-channel high-side switch and N-channel synchronous rectifier, both with matched 0.11Ω RDS(ON) at 3.3V.
Operation includes pulse-skipping at light loads to maintain low 240µA quiescent current, digital soft-start over 1024 clock cycles, and undervoltage lockout at 2.5V. The ITH pin provides direct access to the error amplifier output for loop compensation and external soft-start control.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.63V to 5.5V - supports single-cell Li-ion, Li-polymer, and regulated 3.3V/5V rails. |
| Output Voltage Range | 0.8V to 5V - set by external resistive divider; 0.8V feedback reference enables low-VOUT regulation. |
| Max Output Current | 1.4A peak - sufficient for core logic, memory, and interface ICs in portable systems. |
| Switching Frequency | Up to 4MHz - allows use of 2.2µH inductors ≤2mm height and compact ceramic capacitors. |
| RDS(ON) (Top/Bottom) | 0.11Ω each at VIN = 3.3V - minimizes conduction loss and enables >95% efficiency at 1A. |
| Quiescent Current | 240µA - extends battery runtime in standby and low-power modes. |
| Shutdown Current | <1µA - ensures negligible drain during system sleep or off-state. |
| Junction Temp Limit | 125°C - protected by internal thermal shutdown; θJA = 43°C/W defines PCB thermal design requirement. |
Pinout & Package
Package: 8-lead 3mm × 3mm plastic DFN (DD package) with exposed thermal pad (Pin 9) requiring solder connection to PCB ground for rated thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SHDN/RT (Pin 1) | Oscillator timing & shutdown control | Resistor-to-ground sets fOSC; pulled to SVIN to disable regulator - dual-function pin reduces component count. |
| SGND (Pin 2) | Signal ground reference | Reference node for feedback, compensation, and small-signal circuitry - must be isolated from PGND to avoid noise coupling. |
| SW (Pin 3) | Switch node | Connects to inductor; swings between PVIN and PGND - requires short, low-inductance trace for EMI control. |
| PGND (Pin 4) | Power ground return | Main return path for high-current inductor and output capacitor - must connect directly to COUT(–) and CIN(–). |
| PVIN (Pin 5) | Main power input | Supplies high-side switch; requires local 10µF ceramic decoupling to PGND for stability. |
| SVIN (Pin 6) | Signal power supply | Bias source for internal analog circuitry; must be ≥ PVIN and decoupled to SGND - enables independent noise isolation. |
| VFB (Pin 7) | Feedback input | Monitors output via resistive divider; 0.8V reference enables accurate VOUT setting with minimal divider current (<0.1µA). |
| ITH (Pin 8) | Error amplifier output | Provides direct access to control loop; used for compensation, soft-start ramping, and closed-loop response analysis. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous 1.4A buck topology | Eliminates external Schottky diode - reduces board area, improves efficiency, and enables 100% duty cycle in dropout. |
| 4MHz max switching frequency | Permits ultra-compact 2.2µH inductors and low-profile ceramic capacitors - ideal for space-constrained mobile designs. |
| 0.11Ω internal MOSFETs | Minimizes I²R losses at full load - achieves 95% peak efficiency with 3.3VIN/2.5VOUT @ 1A. |
| 240µA quiescent current | Extends battery life in always-on subsystems - critical for wireless LAN and camera modules in standby. |
| Digital soft-start (1024 cycles) | Prevents inrush current and output overshoot during power-up - eliminates need for external soft-start circuitry. |
| Stable with ceramic output capacitors | Removes dependency on tantalum or polymer caps - lowers BOM cost and improves reliability across temperature. |
Applications
| Wireless LAN Power | Notebook Computers |
|---|---|
Use Scenario: Powering 2.5V or 3.3V WLAN baseband and RF transceivers in smartphones and tablets. IC Role / Device Role / Timing Role: Primary step-down regulator supplying clean, low-noise DC power to sensitive RF sections. Use Value: Pulse-skipping mode maintains 240µA IQ during idle periods, extending battery life between data transmissions. | Use Scenario: Generating 1.8V core voltage for embedded controllers or 3.3V I/O rails in ultraportable notebooks. IC Role / Device Role / Timing Role: High-efficiency point-of-load converter operating from shared 5V or 3.3V system bus. Use Value: 4MHz operation enables use of 2.2µH/2mm-height inductors - saves PCB area without sacrificing transient response. |
| Digital Cameras | Cellular Phones |
Use Scenario: Supplying 2.8V image sensor bias and 1.2V processor core in compact camera modules. IC Role / Device Role / Timing Role: Compact, thermally efficient buck converter mounted adjacent to ASICs on dense camera flex PCBs. Use Value: Exposed thermal pad (Pin 9) soldered to ground plane ensures junction temperature stays below 125°C even at 1.4A continuous load. | Use Scenario: Regulating 1.2V application processor cores and 2.5V memory interfaces in LTE/5G handsets. IC Role / Device Role / Timing Role: Synchronous buck converter supporting dynamic voltage scaling (DVS) and rapid load transients. Use Value: Current-mode architecture with ITH access enables optimized loop compensation for fast load-step recovery (<10µs). |
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 |
|---|---|---|---|
| TPS62231DRYT | Fixed 3.3V output; 1.8A max; 3.5MHz max fSW; 12µA IQ; 6-pin WSON | Not adjustable - unsuitable where multiple output voltages required | Select when fixed 3.3V rail and ultra-low IQ are prioritized over flexibility. |
| MP2143DJ-LF-Z | Adjustable 0.8–6V; 3A max; 2MHz max fSW; 300µA IQ; 8-pin SOIC-EP | Larger SOIC package; lower fSW limits inductor size reduction vs. LTC3561EDD | Choose for higher current needs where board space permits larger inductors and thermal pad layout. |
Compared with TPS62231DRYT and MP2143DJ-LF-Z, the LTC3561EDD uniquely balances 1.4A capability, 4MHz operation, and 240µA quiescent current in a 3mm × 3mm DFN - making it optimal for space- and battery-life–constrained portable designs requiring adjustable output voltage.
Availability
LTC3561EDD is available at Aetrix Electronics and suitable for notebook computers, cellular phones, and digital cameras requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LTC3561EDD 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 precision analog and power management product lines. Linear's legacy includes industry-leading DC/DC converters known for high integration, efficiency, and robustness.
The LTC3561EDD belongs to Linear's high-frequency synchronous buck converter family, designed specifically for battery-powered portable electronics where small size, low quiescent current, and ceramic-capacitor compatibility are mandatory.
FAQ
What is the maximum supported switching frequency for the LTC3561EDD?
The LTC3561EDD supports up to 4MHz switching frequency, achieved by selecting an appropriate RT resistor (e.g., ~324kΩ for 1MHz, down to ~82kΩ for 4MHz). This 4MHz operation is guaranteed by design but not production-tested due to duty-cycle limitations at extreme VIN/VOUT ratios - refer to Figure 1 and Applications Information section of the datasheet for RT selection guidance.
Does the LTC3561EDD require external diodes or compensation components?
No, the LTC3561EDD does not require external diodes - its integrated synchronous P/N-channel MOSFETs eliminate body-diode conduction losses. While basic operation only needs input/output capacitors and an inductor, external compensation (RC network on ITH) is recommended to optimize transient response for specific output capacitor types and load conditions - the front-page schematic provides a validated starting point.
How is thermal performance defined for the LTC3561EDD?
Thermal performance of the LTC3561EDD is defined by θJA = 43°C/W and θJC = 3°C/W, with the exposed pad (Pin 9) required to be soldered to a PCB ground plane. Junction temperature is calculated as TJ = TA + (PD × 43°C/W). Exceeding 125°C triggers thermal shutdown - proper copper pour and via count under the pad are essential for sustained 1.4A operation at elevated ambient temperatures.
Can the LTC3561EDD operate in dropout mode, and what happens to efficiency?
Yes, the LTC3561EDD operates in dropout mode with 100% duty cycle when VIN approaches VOUT, turning on the P-channel MOSFET continuously. Efficiency drops in dropout due to increased conduction loss across the top switch RDS(ON) and inductor DCR, but regulation is maintained - output tracks input minus these IR drops. Load-step capability also decreases near dropout, so applications demanding large transients there should consider alternative topologies.
What is the purpose of the separate SVIN and PVIN pins on the LTC3561EDD?
The LTC3561EDD separates SVIN (signal power) and PVIN (power input) to isolate noise-sensitive analog circuitry (error amplifier, reference, oscillator) from high-current switching paths. SVIN must be ≥ PVIN and decoupled to SGND, while PVIN connects to the main input capacitor and PGND. This separation improves PSRR, reduces jitter in oscillator timing, and enhances overall regulation accuracy - especially critical in RF and audio subsystems.
LTC3561EDD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.625V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 5V
- Current - Output:
- 1A
- Frequency - Switching:
- 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-DFN (3x3)
LTC3561EDD FAQ
1.How can I place an order for LTC3561EDD through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3561EDD 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 LTC3561EDD reliable?
The price and inventory of LTC3561EDD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3561EDD is usually 5 days.
3.What payment methods are accepted for LTC3561EDD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3561EDD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3561EDD?
LTC3561EDD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3561EDD 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 LTC3561EDD?
For technical support, including LTC3561EDD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3561EDD requirements.
6.How does Aetrix verify that LTC3561EDD is sourced from the original manufacturer or authorized distributors?
All LTC3561EDD 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 LTC3561EDD meets industry standards.
7.What is the process for return or replacement of LTC3561EDD?
All LTC3561EDD units undergo pre-shipment inspection (PSI). If there is an issue with LTC3561EDD, 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 LTC3561EDD part is unused and in its original packaging.
Return procedure for LTC3561EDD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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