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Analog Devices Inc. LTC3561EDD#TRPBF
- Part No.:
- LTC3561EDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3561EDD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 1A 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,185
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Product details
Overview
LTC3561EDD#TRPBF from Analog Devices (formerly Linear Technology) is a constant-frequency, synchronous step-down DC/DC converter designed 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-channel/N-channel MOSFETs - used in wireless LAN power supplies, notebook computers, and cellular phone core logic rails.
For engineers reviewing the LTC3561EDD#TRPBF datasheet, LTC3561EDD#TRPBF pinout, LTC3561EDD#TRPBF application, or LTC3561EDD#TRPBF equivalent, key selection criteria include its 4MHz max switching frequency, 240µA no-load quiescent current, 100% duty-cycle dropout operation, ceramic-capacitor compatibility, and external compensation via ITH pin for transient optimization across load and capacitor variations.
Technical Context
The LTC3561EDD#TRPBF employs a current-mode control architecture with an externally programmable oscillator (via SHDN/RT pin resistor), enabling precise loop tuning and stable operation with ceramic output capacitors. Its dual-MOSFET synchronous rectification eliminates external diode losses and supports discontinuous conduction mode at light loads.
Dropout behavior is implemented by holding the P-channel top switch fully on (100% duty cycle), allowing VOUT to track VIN minus RDS(ON) drop and inductor DCR - critical for battery-powered systems nearing end-of-discharge. The ITH pin serves as both error amplifier output and current limit threshold control point, enabling feedforward compensation and soft-start extension.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.63V to 5.5V - supports single-cell Li-ion (2.7–4.2V), USB 3.3V, and regulated 5V rails without pre-regulation. |
| Output Voltage Range | 0.8V to 5V - set by external resistor divider; 0.8V feedback reference enables low-voltage core supply generation (e.g., 1.2V, 1.8V, 2.5V). |
| Max Switch Current | 1.4A peak - sufficient for powering 1A continuous digital IC cores (e.g., ARM Cortex-A/M series, FPGA I/O banks). |
| RDS(ON) (Top/Bottom) | 0.11Ω each at 3.3V - minimizes conduction loss; enables >95% efficiency at 1A/2.5V out from 3.3V in. |
| Quiescent Current | 240µA - extends battery runtime in standby; drops to <1µA in shutdown. |
| Switching Frequency | Up to 4MHz - allows use of 2.2µH inductors ≤2mm height and compact 22µF ceramic output capacitors. |
| Operating Temp | –40°C to 85°C ambient - qualified for industrial and consumer portable equipment environments. |
Pinout & Package
Package: 8-lead (3mm × 3mm) plastic DFN with exposed thermal pad (Pin 9), requiring solder connection to PCB ground for thermal performance (θJA = 43°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SHDN/RT (1) | Oscillator timing & shutdown control | Resistor to ground sets fOSC; pulled to SVIN to disable regulator - enables power sequencing and dynamic frequency scaling. |
| SGND (2) | Signal ground reference | Reference node for feedback (VFB), error amp (ITH), and compensation network - must be isolated from high-current PGND paths. |
| SW (3) | Switch node | Connects to inductor; swings between PVIN and PGND - requires tight layout to minimize EMI and ringing. |
| PGND (4) | Power ground return | Return path for input/output capacitors and bottom MOSFET - must be low-inductance copper pour tied to exposed pad. |
| PVIN (5) | Main power input | Supplies top MOSFET and high-side gate driver - requires local 10µF ceramic decoupling to PGND. |
| SVIN (6) | Signal power supply | Bias rail for control circuitry; must be ≥ PVIN and decoupled to SGND - ensures stable reference and error amp operation. |
| VFB (7) | Feedback input | Monitors resistive divider output; 0.8V reference enables precise output regulation - input bias current ±0.1µA minimizes divider loss. |
| ITH (8) | Error amplifier output / current limit control | DC-coupled loop test point; voltage sets peak inductor current - enables OPTI-LOOP compensation and external soft-start ramping. |
Key Features
| Feature | Design Value |
|---|---|
| Constant-frequency current-mode control | Enables predictable EMI profile and stable loop response across wide load/capacitor ranges via external compensation at ITH pin. |
| 100% duty-cycle dropout operation | Maintains regulation down to VIN ≈ VOUT, extending usable battery life in Li-ion discharge tail without brownout. |
| Ultra-low quiescent current (240µA) | Reduces no-load power loss in always-on subsystems (e.g., RTC, sensor interface) - critical for multi-week standby in IoT devices. |
| Synchronous MOSFETs (0.11Ω) | Eliminates external Schottky diode; improves full-load efficiency by ~8–10% vs. asynchronous buck, especially at low VOUT. |
| Ceramic capacitor stability | Compensated for zero-ESR output caps - avoids need for tantalum or polymer alternatives, reducing BOM cost and height. |
Applications
| Wireless LAN Baseband Power | Notebook CPU Core Rail |
|---|---|
Use Scenario: Powers IEEE 802.11ac baseband ICs (e.g., QCA9377, BCM4356) requiring 1.2V @ 800mA with fast load transients during packet bursts. IC Role / Device Role / Timing Role: Primary step-down regulator delivering tightly regulated core voltage; responds within 3–4 cycles to 200mA–1A load steps. Use Value: 240µA quiescent current extends battery life during idle scan intervals; 4MHz operation shrinks inductor footprint to fit ultra-thin M.2 WLAN modules. | Use Scenario: Supplies Intel Atom or AMD Ryzen Embedded V1000 CPU cores (1.0–1.35V, up to 1.2A) in fanless industrial notebooks. IC Role / Device Role / Timing Role: Main core voltage regulator with programmable soft-start for controlled power-up sequencing and inrush limiting. Use Value: External ITH compensation allows tuning for low-ESR ceramic caps used in space-constrained designs; 0.8V reference supports precise 1.1V core setting. |
| Digital Camera Image Sensor Bias | Cellular Phone Application Processor |
Use Scenario: Generates clean 2.8V bias for CMOS image sensors (e.g., Sony IMX586) with minimal noise coupling into analog pixel readout paths. IC Role / Device Role / Timing Role: Low-noise synchronous buck supplying sensor analog/digital rails; uses pulse-skipping mode to reduce audible noise during video capture. Use Value: 0.11Ω RDS(ON) limits voltage drop under 1A pulsed loads; SGND/PGND separation prevents digital switching noise from corrupting sensor ADC references. | Use Scenario: Powers Qualcomm Snapdragon or MediaTek Dimensity application processors (1.05–1.4V @ 1.4A peak) in 5G smartphones during bursty modem activity. IC Role / Device Role / Timing Role: High-efficiency intermediate bus converter stepping 3.8V battery to processor core voltage; supports dynamic voltage scaling via VFB divider control. Use Value: 4MHz switching enables 2.2µH inductor ≤2mm height - essential for thin bezel smartphone PCB stacking; <1µA shutdown current preserves battery during off-state. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62130ARGTR | Fixed 3.3V or adjustable 0.9–3.3V output; 3MHz max fSW; 0.12Ω RDS(ON); 17µA IQ in DCM | Optimized for lower-VOUT and ultra-low IQ in always-on apps; lacks 4MHz capability and 5.5V input support | Select when prioritizing sub-20µA quiescent current over wide input range and high-frequency size reduction. |
| MP2143DJ-LF-Z | 2.5–5.5V input; 0.8–5V output; 1.2A peak; 2MHz max fSW; 0.14Ω RDS(ON); 350µA IQ | Lower peak current and frequency; higher RDS(ON) reduces efficiency at 1A; no 100% duty-cycle dropout | Choose for cost-sensitive consumer designs where 1.2A and 2MHz suffice and thermal margin is ample. |
Compared with TPS62130ARGTR and MP2143DJ-LF-Z, the LTC3561EDD#TRPBF uniquely combines 4MHz operation, 5.5V input, 1.4A peak current, and true 100% duty-cycle dropout - making it optimal for space-constrained, battery-extending portable systems demanding wide input flexibility and fast transient response.
Availability
LTC3561EDD#TRPBF is available at Aetrix Electronics and suitable for wireless LAN power supplies, notebook computer core rails, and cellular phone application processor domains requiring stable component supply, long-lifecycle availability, and consistent parametric performance across production batches.
Supply support for LTC3561EDD#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC3561EDD#TRPBF belongs to ADI's Power by Linear™ family of high-efficiency DC/DC converters, engineered specifically for portable and battery-powered applications where small solution size, low quiescent current, and robust transient performance are critical design requirements.
FAQ
What is the maximum operating frequency of the LTC3561EDD#TRPBF, and how is it set?
The LTC3561EDD#TRPBF supports a maximum switching frequency of 4MHz, guaranteed by design but not production-tested. Frequency is set by an external resistor (RT) connected between the SHDN/RT pin and ground. For example, a 324kΩ resistor yields 1MHz typical operation; values down to ~100kΩ enable operation near 4MHz. Duty cycle limitations apply at high frequencies per the equation fO(MAX) ≈ 6.67 × (VOUT/VIN(MAX)) MHz.
Does the LTC3561EDD#TRPBF support 100% duty-cycle operation, and what is its benefit?
Yes, the LTC3561EDD#TRPBF supports true 100% duty-cycle operation in dropout mode, where the P-channel top switch remains continuously on. This allows the output voltage to track the input voltage minus only the RDS(ON) drop and inductor DCR - extending usable battery life in single-cell Li-ion systems as voltage declines below the regulated output level.
What is the role of the ITH pin on the LTC3561EDD#TRPBF, and how is it used in design?
The ITH pin on the LTC3561EDD#TRPBF is the error amplifier output and current limit threshold control point. It enables OPTI-LOOP external compensation for optimizing transient response across load and capacitor variations. It also serves as a DC-coupled test point for closed-loop analysis and can be ramped externally to extend soft-start time beyond the internal 1024-cycle digital ramp.
Can the LTC3561EDD#TRPBF operate with all-ceramic input and output capacitors?
Yes, the LTC3561EDD#TRPBF is explicitly designed for stable operation with ceramic capacitors. Its current-mode architecture and external compensation via the ITH pin allow robust loop stability even with zero-ESR ceramics. However, layout best practices - including SGND/PGND separation, short SW traces, and proper decoupling - remain essential to prevent ringing or instability.
What thermal considerations apply to the LTC3561EDD#TRPBF in high-duty-cycle applications?
In dropout or high-duty-cycle operation (e.g., VIN ≈ VOUT), power dissipation increases due to higher conduction loss in the top MOSFET. The exposed thermal pad (Pin 9) must be soldered to a solid PCB ground plane to achieve θJA = 43°C/W. Junction temperature must stay ≤125°C; exceeding ~150°C triggers thermal shutdown, turning off both switches and floating the SW node.
LTC3561EDD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-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):
- 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#TRPBF FAQ
1.How can I place an order for LTC3561EDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3561EDD#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 LTC3561EDD#TRPBF reliable?
The price and inventory of LTC3561EDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3561EDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3561EDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3561EDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3561EDD#TRPBF?
LTC3561EDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3561EDD#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 LTC3561EDD#TRPBF?
For technical support, including LTC3561EDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3561EDD#TRPBF requirements.
6.How does Aetrix verify that LTC3561EDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3561EDD#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 LTC3561EDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3561EDD#TRPBF?
All LTC3561EDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3561EDD#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 LTC3561EDD#TRPBF part is unused and in its original packaging.
Return procedure for LTC3561EDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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