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Analog Devices Inc. LTC3561AIDD#PBF
- Part No.:
- LTC3561AIDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3561AIDD#PBF.pdf
- Description:
- IC REG BUCK ADJ 1A 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:309
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Product details
Overview
LTC3561AIDD#PBF from Analog Devices (formerly Linear Technology) is a constant-frequency, current-mode synchronous step-down DC/DC converter optimized for medium-power portable applications. It operates from 2.5V to 5.5V input, delivers up to 1A output current, supports user-configurable switching frequency up to 4MHz, and regulates output voltage from 0.8V to 5.5V with ±2% feedback reference accuracy. Its integrated 0.15Ω P-channel and 0.13Ω N-channel MOSFETs enable high-efficiency conversion in space-constrained devices such as digital cameras and cellular handsets.
For engineers reviewing the LTC3561AIDD#PBF datasheet, LTC3561AIDD#PBF pinout, LTC3561AIDD#PBF application, or LTC3561AIDD#PBF equivalent, key selection considerations include its 8-lead 3mm × 3mm DFN package with exposed PGND pad, 100% duty-cycle dropout operation, <1µA shutdown current, 330µA quiescent current, and OPTI-LOOP® compensation architecture enabling stable ceramic-capacitor-based designs across wide load and temperature ranges.
Technical Context
The LTC3561AIDD#PBF implements a peak-current-mode control architecture with external compensation via the ITH pin, allowing loop optimization for diverse output capacitor types and load transients. Its oscillator frequency is set by an external resistor from SHDN/RT to ground, supporting precise timing control from ~200kHz to 4MHz.
It features dual power rails-PVIN for high-current switch path and SVIN for signal circuitry-with strict SVIN ≥ PVIN requirement. The device integrates undervoltage lockout (UVLO at 2.1V), short-circuit protection, and thermal shutdown, while maintaining stable regulation down to 0.8V output with 0.784V–0.816V internal reference tolerance over temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 5.5V - supports single-cell Li-ion, Li-polymer, and multi-cell alkaline/NiMH battery inputs without pre-regulation. |
| Output Voltage Range | 0.8V to 5.5V - adjustable via external resistive divider; 0.8V nominal feedback reference enables low-voltage core rail generation. |
| Max Output Current | 1A continuous - limited by internal MOSFET RDS(ON) (0.15Ω top / 0.13Ω bottom) and thermal design in 3mm × 3mm DFN. |
| Switching Frequency | Up to 4MHz - enables use of sub-2mm-height inductors and compact ceramic capacitors; RT-resistor programmable. |
| Efficiency | Up to 96% - achieved at mid-load with 3.6VIN/1.8VOUT, enabled by synchronous rectification and low RDS(ON). |
| Quiescent Current | 330µA - minimizes no-load power loss in battery-powered standby modes. |
| Shutdown Current | <1µA - ensures negligible battery drain during system sleep or off-state. |
| Feedback Reference | 0.8V ±2% - tight tolerance enables accurate output regulation; measured at VFB pin under specified conditions. |
Pinout & Package
Package: 8-lead 3mm × 3mm plastic DFN with exposed PGND pad (Pin 9), rated for –40°C to +125°C junction temperature. Exposed pad must be soldered to PCB ground plane for thermal and electrical performance.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 SHDN/RT | Combined shutdown control and oscillator timing input | Pulling to SVIN disables all functions; resistor to ground sets fOSC (200kHz–4MHz); also resets soft-start on re-enable. |
| 2 SGND | Signal ground reference | Reference node for VFB, ITH, and internal analog circuitry; must be tied to PGND via low-impedance path. |
| 3 SW | Switch node | Connects to inductor; swings between PVIN and PGND; requires careful layout to minimize EMI and ringing. |
| 4 PGND | Main power ground | Return path for high-current switch and output capacitor; shares exposed pad (Pin 9) for thermal conduction. |
| 5 PVIN | Main power supply input | High-current input for power switches; must be decoupled locally to PGND with low-ESR ceramic capacitor. |
| 6 SVIN | Signal power supply | Supplies bias for control circuitry; must be ≥ PVIN and decoupled to SGND; defines absolute max ratings for other pins. |
| 7 VFB | Feedback input | Monitors output via resistive divider; 0.8V reference sets regulation point; input current ≤ ±0.1µA minimizes divider error. |
| 8 ITH | Error amplifier output / compensation node | Controls peak inductor current; external RC network sets loop dynamics; provides direct access to closed-loop response. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Integrated 0.15Ω P-MOSFET and 0.13Ω N-MOSFET eliminate external diode, enabling >95% efficiency at 1A and reducing thermal footprint. |
| OPTI-LOOP® compensation | ITH pin provides full access to error amplifier output, enabling custom pole-zero placement for optimal transient response with ceramic, tantalum, or polymer output capacitors. |
| 100% duty-cycle dropout | P-MOSFET remains fully on when VIN ≤ VOUT + IOUT×RDS(ON), sustaining regulated output down to input voltages near VOUT - critical for battery end-of-life operation. |
| Ceramic-capacitor stability | Current-mode architecture and internal slope compensation ensure unconditional stability with zero-ESR ceramic output capacitors, eliminating need for tantalum or electrolytic alternatives. |
| Low-noise shutdown | <1µA shutdown current and controlled soft-start (0.8ms ramp) prevent inrush current and supply rail disturbance during power sequencing. |
| Robust protection suite | Includes UVLO (2.1V), cycle-by-cycle current limiting (1.3–2.5A), thermal shutdown, and short-circuit foldback - no external components required. |
Applications
| Digital Cameras | Cellular Handsets |
|---|---|
Use Scenario: Powering image sensor core voltage (1.2V/1.8V) and ISP logic rails from single Li-ion cell (2.8–4.2V). IC Role / Device Role / Timing Role: Primary step-down regulator delivering tightly regulated, low-noise 1A output with fast load transient response to handle burst-mode sensor readout. Use Value: Enables compact camera module design using 2.2µH inductor and 10µF ceramic output capacitor, with 96% efficiency at 3.6VIN/1.8VOUT and <100mV output droop during 1A load steps. |
Use Scenario: Supplying application processor I/O and memory interface rails (2.8V/3.3V) in LTE smartphones with dynamic load profiles. IC Role / Device Role / Timing Role: High-frequency (2.5MHz) buck converter minimizing inductor size while maintaining regulation during RF transmit bursts. Use Value: 4MHz capability allows 1.0µH inductor height ≤1.2mm (e.g., Sumida CR5D11-1R0), reducing board area by 35% vs. 1MHz designs without sacrificing efficiency (>92% at 1A). |
| Notebook Subsystems | Handheld Test Instruments |
Use Scenario: Generating 5V auxiliary rail for USB peripherals or display backlight drivers from 3.3V system bus. IC Role / Device Role / Timing Role: Boost-capable buck (VOUT > VIN possible via external charge pump) delivering 500mA at 5V with minimal BOM count. Use Value: Adjustable 0.8–5.5V output range and 0.8V reference enable precise 5.0V ±2% regulation; 330µA quiescent current extends battery runtime in always-on subsystems. |
Use Scenario: Powering precision ADC front-end and microcontroller core in portable multimeters or oscilloscopes. IC Role / Device Role / Timing Role: Low-noise, low-ripple power source with excellent line/load regulation (<0.2% load reg, <0.2%/V line reg) for analog signal chain integrity. Use Value: Stable 1.8V output with <10mV p-p ripple (10µF X7R + 1µF ceramic) and 0.784–0.816V reference tolerance ensures <0.1% measurement accuracy drift over temperature. |
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 |
|---|---|---|---|
| TPS62130ARGTR | Fixed 3.3V output (non-adjustable); 3MHz max fSW; 0.12Ω/0.11Ω RDS(ON); 1.2A rating; 2.7–6V input. | Best suited for fixed-rail systems where output voltage doesn't require adjustment; lacks ITH pin for loop tuning. | Select when 3.3V output suffices and board space is constrained - smaller 2mm × 2mm QFN, but less flexible compensation. |
| MAX17504ATP+T | Wider input (4.5–60V); 0.5A output; 100kHz–2.2MHz fSW; requires external MOSFETs; includes PMBus interface. | Targeted at industrial/high-voltage DC-DC needs, not low-voltage portable applications. | Choose only for 12–48V input systems requiring digital monitoring; not a functional substitute for LTC3561AIDD#PBF's 2.5–5.5V/1A portable profile. |
Compared with TPS62130ARGTR and MAX17504ATP+T, the LTC3561AIDD#PBF uniquely combines 2.5V minimum input, 1A output, 4MHz programmability, and accessible ITH compensation in a thermally enhanced 3mm × 3mm DFN - making it the only option among the three qualified for Li-ion-powered devices requiring adjustable sub-1V core rails and aggressive size constraints.
Availability
LTC3561AIDD#PBF is available at Aetrix Electronics and suitable for digital cameras, cellular handsets, and handheld test instruments requiring stable component supply with guaranteed –40°C to +125°C operation and lead-free compliance.
Supply support for LTC3561AIDD#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision instrumentation, communications, and power conversion markets.
The LTC3561AIDD#PBF belongs to Linear's µPower synchronous buck converter family, engineered specifically for space- and efficiency-critical portable electronics where battery life, thermal density, and PCB real estate are primary design constraints.
FAQ
What is the maximum supported switching frequency for LTC3561AIDD#PBF?
The LTC3561AIDD#PBF supports oscillator frequencies up to 4MHz, set by an external resistor from the SHDN/RT pin to ground. While 4MHz operation is guaranteed by design, production testing is performed at lower frequencies (e.g., 2.5MHz typical), and duty cycle limitations apply at the upper end - fO(MAX) ≈ 6.67 × VOUT/VIN(MAX) MHz. For VOUT = 1.8V and VIN(MAX) = 5.5V, max usable frequency is ~2.2MHz.
Does LTC3561AIDD#PBF require an external catch diode?
No, the LTC3561AIDD#PBF does not require an external catch diode because it integrates synchronous N-channel and P-channel MOSFETs. An optional Schottky diode may marginally improve light-load efficiency in pulse-skipping mode, but its parasitic capacitance and leakage typically negate benefits - and the datasheet explicitly states it is unnecessary in most applications.
How is output voltage set on LTC3561AIDD#PBF?
Output voltage on the LTC3561AIDD#PBF is set by a resistive divider from VOUT to SGND, with the midpoint connected to the VFB pin. Using the formula VOUT ≈ 0.8V × (1 + R2/R1), a standard 16.9kΩ (R1) and 549kΩ (R2) divider yields 2.5V. Feedback pin input current is ≤ ±0.1µA, so divider current should be 10–100× higher (e.g., 5–50µA) to minimize error.
What is the purpose of the separate PVIN and SVIN pins on LTC3561AIDD#PBF?
PVIN supplies high-current paths for the internal power switches, while SVIN powers the control circuitry (error amplifier, oscillator, logic). SVIN must be ≥ PVIN to ensure proper biasing and define absolute maximum ratings for all signal pins. This separation reduces noise coupling from switching currents into sensitive analog blocks, improving regulation accuracy and transient immunity.
Can LTC3561AIDD#PBF operate with ceramic output capacitors only?
Yes, the LTC3561AIDD#PBF is explicitly designed for stable operation with ceramic output capacitors. Its current-mode architecture, internal slope compensation, and OPTI-LOOP® compensation via the ITH pin eliminate the need for ESR-based zero generation - unlike voltage-mode controllers. X5R or X7R dielectrics are recommended to mitigate temperature/voltage coefficient effects.
LTC3561AIDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-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):
- 2.5V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 5V
- Current - Output:
- 1A
- Frequency - Switching:
- 2.5MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-DFN (3x3)
LTC3561AIDD#PBF FAQ
1.How can I place an order for LTC3561AIDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3561AIDD#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 LTC3561AIDD#PBF reliable?
The price and inventory of LTC3561AIDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3561AIDD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3561AIDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3561AIDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3561AIDD#PBF?
LTC3561AIDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3561AIDD#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 LTC3561AIDD#PBF?
For technical support, including LTC3561AIDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3561AIDD#PBF requirements.
6.How does Aetrix verify that LTC3561AIDD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3561AIDD#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 LTC3561AIDD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3561AIDD#PBF?
All LTC3561AIDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3561AIDD#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 LTC3561AIDD#PBF part is unused and in its original packaging.
Return procedure for LTC3561AIDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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