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Analog Devices Inc. LTC1504AIS8-3.3#PBF
- Part No.:
- LTC1504AIS8-3.3#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1504AIS8-3.3#PBF.pdf
- Description:
- IC REG BUCK 3.3V 500MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:4,080
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Product details
Overview
LTC1504AIS8-3.3#PBF from Analog Devices (formerly Linear Technology) is a fixed-output 3.3V, 500mA synchronous buck DC/DC regulator in SO-8 package, featuring 1.3Ω on-chip P/N-channel MOSFETs, 92% peak efficiency at 5V→3.3V, 100% duty cycle capability, internal 1% trimmed reference, and daisy-chainable control outputs for multi-rail sequencing in portable digital systems.
For engineers reviewing the LTC1504AIS8-3.3#PBF datasheet, LTC1504AIS8-3.3#PBF pinout, LTC1504AIS8-3.3#PBF application, or LTC1504AIS8-3.3#PBF equivalent, key selection considerations include input voltage range (4V–10V), IMAX-set current limit, SENSE-pin feedback architecture, thermal derating in SO-8, and compatibility with low-ESR output capacitors requiring RC compensation at COMP.
Technical Context
The LTC1504AIS8-3.3#PBF implements a synchronous buck topology with integrated 1.3Ω P-channel high-side and N-channel low-side switches, enabling bidirectional output current sourcing/sinking to maintain regulation during load transients. Its internal 200kHz sawtooth oscillator supports synchronization up to 500kHz and delivers 0–100% duty cycle control via COMP pin voltage modulation.
Feedback is implemented through direct SENSE pin connection to the 3.3V output node (not resistor divider), referenced to an internal 1.265V bandgap trimmed to ±1% over temperature. A secondary ILIM amplifier monitors SW-node voltage during Q1 conduction to compare against IMAX-set threshold, pulling current from SS pin to dynamically clamp COMP and limit peak inductor current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±3% (SENSE pin servoed to 3.3V; no external divider required) |
| Max Output Current | 500mA continuous at 5V input; limited by SO-8 thermal resistance (θJA = 90°C/W) and switch RDS(on) |
| Input Voltage Range | 4V to 10V (guaranteed operation; factory support available down to 2.7V) |
| Peak Efficiency | 92% at 5V→3.3V/500mA; enables minimal thermal dissipation in space-constrained layouts |
| Switching Frequency | 200kHz typical (130–300kHz over industrial temp range); synchronizable to external clock up to 500kHz |
| Current Limit | Adjustable via resistor from VCC to IMAX pin; sets threshold using internal 12µA current source |
| Duty Cycle Range | 0–100%; eliminates dropout at light loads and supports ultra-low-VIN–VOUT differentials |
Pinout & Package
Package: 8-lead plastic SO-8 (S8), exposed pad not present; θJA = 90°C/W; GND pin (Pin 4) serves as primary thermal path and must connect to large copper area.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IMAX (Pin 1) | Current limit threshold set | Internal 12µA sink pulls voltage across external RIMAX; compared to SW-node voltage during Q1 on-time to trigger ILIM loop |
| VCC (Pin 2) | Main power supply input | 4V–10V input; requires local low-ESR ceramic bypass (≥1µF) and bulk reservoir capacitor (22–100µF) to prevent reference corruption |
| SW (Pin 3) | Switching node | Drives external inductor; connects to drain of internal P-MOSFET and source of N-MOSFET; avoid shorting to GND/VCC |
| GND (Pin 4) | Power and signal ground | Low-impedance return for VCC bypass, COUT, and feedback; critical for thermal dissipation and noise immunity |
| SENSE (Pin 5) | Fixed-output voltage sense | Direct connection to 3.3V output; internal resistor divider loads external nodes; not FB-no external resistors needed |
| SHDN (Pin 6) | Active-low shutdown control | Pull ≤0.8V to disable; draws <1µA quiescent current; forces SW low to actively disconnect output |
| SS (Pin 7) | Soft-start and current-limit compensation | 0.1µF capacitor to GND sets ramp rate; also compensates ILIM loop; pulled down by ILIM during overload |
| COMP (Pin 8) | Error amplifier output | High-impedance node for external RC compensation; clamped by SS during startup/current limit; drives PWM comparator |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous buck architecture | Enables bidirectional output current (source/sink) for tight regulation during fast load transients without external diode |
| Integrated 1.3Ω power switches | Eliminates need for external MOSFETs; reduces BOM count and layout complexity while limiting conduction loss at 500mA |
| 100% duty cycle operation | Supports ultra-low dropout (e.g., 4.0V→3.3V) and maintains regulation even when VIN approaches VOUT |
| Adjustable current limit | Single resistor from VCC to IMAX sets threshold; avoids destructive overloads while allowing safe short-circuit tolerance >30 seconds |
| Internal 1% reference | Ensures ±3% total output accuracy over line/load/temp; removes need for external trimming or calibration |
Applications
| Portable Digital Systems | Active Termination |
|---|---|
Use Scenario: Powering FPGA I/O banks or microcontroller core logic in handheld test equipment with 5V main rail. IC Role / Device Role / Timing Role: Primary 3.3V point-of-load regulator delivering stable 500mA with fast transient response to digital switching noise. Use Value: 92% efficiency minimizes battery drain; 100% duty cycle sustains operation as battery discharges below 4.5V. | Use Scenario: Providing termination voltage for high-speed parallel buses (e.g., SCSI, PCI-X) requiring precise 3.3V with low noise. IC Role / Device Role / Timing Role: Low-noise, low-ripple 3.3V supply referenced directly to bus VTT; SENSE pin ensures minimal trace-length sensitivity. Use Value: Internal 1% reference and synchronous rectification reduce output ripple to <20mVpp, meeting JEDEC VTT tolerance specs. |
| Auxiliary Voltage Supplies | Minimum Part Count Switchers |
Use Scenario: Generating isolated 3.3V rail for analog sensor front-ends in industrial data acquisition modules. IC Role / Device Role / Timing Role: Secondary regulator fed from main 5V supply; SHDN pin enables coordinated power-up sequencing with MCU. Use Value: Daisy-chainable SHDN/SS pins allow synchronized start-up across multiple LTC1504AIS8-3.3#PBF units without external logic. | Use Scenario: Replacing linear regulators in cost-sensitive consumer electronics where board space and BOM count are critical. IC Role / Device Role / Timing Role: Complete switching solution requiring only four external components: CIN, COUT, L, and RIMAX. Use Value: Eliminates external MOSFETs, gate drivers, and feedback resistors-reducing footprint by >40% vs discrete buck designs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62067DSGR | 3.3V fixed, 600mA, 2.5V–6V input, 2.5MHz switching, WSON-8 package | Higher frequency enables smaller L/C but increases EMI sensitivity; lacks 100% duty cycle and IMAX-adjustable current limit | Preferred for compact, high-density layouts where input voltage stays ≥2.5V and fast transient response outweighs dropout requirements |
| MP2108DQ-LF-Z | 3.3V fixed, 600mA, 2.5V–6V input, 1.5MHz, QFN-10 package with enable and power-good | Includes PG pin and tighter output accuracy (±2%), but no SENSE-pin architecture or daisy-chain capability | Chosen when system-level power sequencing and fault reporting are required, and SO-8 thermal performance is not limiting |
Compared with TPS62067DSGR and MP2108DQ-LF-Z, the LTC1504AIS8-3.3#PBF offers superior dropout performance (100% duty cycle), robust short-circuit survivability (>30s), and simplified feedback (no divider), making it optimal for 4–10V industrial inputs where reliability and thermal margin are prioritized over footprint.
Availability
LTC1504AIS8-3.3#PBF is available at Aetrix Electronics and suitable for portable digital systems, active termination networks, auxiliary voltage supplies, and minimum-part-count switcher designs requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC1504AIS8-3.3#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 full technical support, documentation, and manufacturing continuity for all Linear legacy products including the LTC series.
The LTC1504AIS8-3.3#PBF belongs to Linear's precision monolithic DC/DC regulator family, engineered for high-efficiency, low-noise power conversion in space- and thermal-constrained industrial and portable applications where simplicity, reliability, and wide-input operation are essential.
FAQ
What is the guaranteed input voltage range for LTC1504AIS8-3.3#PBF?
The LTC1504AIS8-3.3#PBF is specified for guaranteed operation from 4V to 10V. While the device may function down to 2.7V, Analog Devices states that full parameter guarantees-including output accuracy, efficiency, and current limit-require contacting the factory for characterization data at sub-4V inputs.
How does the SENSE pin differ from FB in LTC1504AIS8-3.3#PBF?
The LTC1504AIS8-3.3#PBF uses SENSE (Pin 5), not FB, because it is the fixed 3.3V version. SENSE connects directly to the output node and is internally servoed to 3.3V, eliminating external resistors. In contrast, FB is used only on adjustable versions (e.g., LTC1504AIS8) and references 1.265V, requiring a resistor divider to set VOUT.
Can LTC1504AIS8-3.3#PBF operate with 100% duty cycle, and what design benefit does that provide?
Yes, the LTC1504AIS8-3.3#PBF supports 100% duty cycle operation, confirmed by DCMAX = 100% in its electrical characteristics table. This allows regulation with minimal dropout-e.g., sustaining 3.3V output from a decaying 4.0V input-critical for battery-powered systems where input voltage collapses near end-of-life.
What external components are absolutely required for basic operation of LTC1504AIS8-3.3#PBF?
A functional LTC1504AIS8-3.3#PBF circuit requires exactly four external components: input bypass capacitor (≥22µF tantalum or OS-CON), output capacitor (≥47µF low-ESR), power inductor (e.g., 47–100µH), and current limit resistor (RIMAX) from VCC to IMAX. No feedback resistors are needed due to the fixed 3.3V SENSE architecture.
How does the current limit function in LTC1504AIS8-3.3#PBF, and is it accurate enough for constant-current applications?
The LTC1504AIS8-3.3#PBF current limit uses an internal ILIM amplifier comparing SW-node voltage (proportional to Q1 conduction loss) against IMAX-set threshold. It is designed for fault protection-not precision current regulation-due to RDS(on) variation with temperature and part-to-part tolerance. Analog Devices explicitly states it is not intended for accurate constant-current output.
LTC1504AIS8-3.3#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 10V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 500mA
- Frequency - Switching:
- 200kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC1504AIS8-3.3#PBF FAQ
1.How can I place an order for LTC1504AIS8-3.3#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1504AIS8-3.3#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 LTC1504AIS8-3.3#PBF reliable?
The price and inventory of LTC1504AIS8-3.3#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1504AIS8-3.3#PBF is usually 5 days.
3.What payment methods are accepted for LTC1504AIS8-3.3#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1504AIS8-3.3#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1504AIS8-3.3#PBF?
LTC1504AIS8-3.3#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1504AIS8-3.3#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 LTC1504AIS8-3.3#PBF?
For technical support, including LTC1504AIS8-3.3#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1504AIS8-3.3#PBF requirements.
6.How does Aetrix verify that LTC1504AIS8-3.3#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1504AIS8-3.3#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 LTC1504AIS8-3.3#PBF meets industry standards.
7.What is the process for return or replacement of LTC1504AIS8-3.3#PBF?
All LTC1504AIS8-3.3#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1504AIS8-3.3#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 LTC1504AIS8-3.3#PBF part is unused and in its original packaging.
Return procedure for LTC1504AIS8-3.3#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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