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Analog Devices Inc. LT1576IS8-5#PBF
- Part No.:
- LT1576IS8-5#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1576IS8-5#PBF.pdf
- Description:
- IC REG BUCK 5V 1.5A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:182
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Product details
Overview
LT1576IS8-5#PBF from Analog Devices (formerly Linear Technology) is a fixed 5V, 1.25A monolithic step-down switching regulator in fused-lead SO-8 package. It features 200kHz constant-frequency current-mode control, 0.2Ω switch on-resistance, 1.16mA effective supply current, and integrated shutdown with 20µA quiescent draw. Designed for battery-powered systems requiring stable 5V rail generation from 6V–25V input.
For engineers reviewing the LT1576IS8-5#PBF datasheet, LT1576IS8-5#PBF pinout, LT1576IS8-5#PBF application, or LT1576IS8-5#PBF equivalent, key selection criteria include fixed 5V output accuracy (±2%), SENSE-pin-based feedback architecture, fused-ground thermal performance (θJA = 80°C/W), and cycle-by-cycle current limiting with foldback protection during short-circuit events.
Technical Context
The LT1576IS8-5#PBF implements current-mode control with internal 1.21V reference and dedicated SENSE pin (replacing FB) for direct 5V output monitoring. Its 200kHz oscillator enables predictable EMI filtering while supporting external synchronization up to 400kHz via SYNC pin on compatible variants - though LT1576IS8-5#PBF uses SHDN on Pin 8.
Thermal management is enhanced by a fused ground lead connected to PCB ground plane, reducing θJA to 80°C/W. The BOOST pin drives an external capacitor-diode network to saturate the internal NPN switch, achieving 0.2Ω on-resistance and >88% efficiency at 5V/1.25A - significantly improved over standard bipolar buck designs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.0V ±2% (SENSE pin monitors output directly; no external divider required) |
| Max Output Current | 1.25A continuous at VIN = 10V, L = 33µH; derates to 1.12A at VIN = 15V due to ripple current limits |
| Switch On Resistance | 0.2Ω typical (enables high efficiency with low conduction loss; measured at ISW = 1.5A) |
| Switching Frequency | 200kHz nominal (±20kHz over temp; supports frequency foldback to ~40kHz under short-circuit) |
| Reference Accuracy | ±1.2% over full temperature range (G-grade spec: 4.90V–5.10V at all conditions) |
| Shutdown Current | 20µA max (ensures ultra-low power-off drain in portable systems) |
| Input Voltage Range | 6V to 25V (minimum validated running voltage is 5.5V; startup requires ≥5.0V) |
Pinout & Package
Fused-lead 8-lead plastic SOIC (SO-8) package with exposed ground lead thermally bonded to die attach pad. Ground pin (Pin 4) is fused to reduce thermal resistance to PCB ground plane (θJA = 80°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VSW (Pin 1) | Switch emitter node | Connects to inductor; driven to VIN during on-time; clamped negative by catch diode during off-time (max –0.8V) |
| VIN (Pin 2) | Power switch collector & bias source | Supplies internal circuitry when BIAS pin is open; high dI/dt node requiring local bypass cap and short trace to GND |
| BOOST (Pin 3) | Switch driver boost supply | Accepts external capacitor-diode charge pump to drive switch into saturation; improves efficiency vs conventional bipolar design |
| GND (Pin 4) | Signal and power reference | Fused lead reduces thermal resistance; must be tied directly to load ground point to avoid load regulation error |
| BIAS (Pin 5) | Efficiency-optimized bias source | When tied to regulated 5V output, shifts internal bias current from VIN to VOUT, improving efficiency by >10% at high VIN/VOUT ratios |
| VC (Pin 6) | Error amplifier output & current limit comparator input | Used for loop compensation; also serves as current clamp point; shutdown threshold is 0.37V (active low) |
| SENSE (Pin 7) | Fixed-output voltage monitor | Replaces FB pin in -5 variants; connects directly to 5V output; triggers foldback if voltage drops below 0.7V |
| SHDN (Pin 8) | Enable/disable control | Two-threshold logic: 2.42V UVLO lockout, 0.37V full shutdown; draws only 20µA in shutdown state |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 5V output with SENSE pin | Eliminates external resistor divider; improves accuracy and stability by removing FB bias current error and trace impedance effects |
| Fused-lead SO-8 thermal design | Reduces junction-to-ambient thermal resistance to 80°C/W when mounted on large copper pour, extending ambient operating range |
| Current-mode control with slope compensation | Enables fast transient response and inherent cycle-by-cycle current limiting; nonlinear slope compensation preserves current limit across duty cycle range |
| Frequency and current foldback | Automatically reduces switching frequency (~5:1) and peak switch current (<0.77A) when SENSE < 0.7V, limiting power dissipation during short-circuit faults |
| BOOST-driven saturated NPN switch | Achieves 0.2Ω on-resistance and >88% efficiency at 5V/1.25A - outperforming standard bipolar buck regulators by ~13 percentage points |
Applications
| Portable Computers | Battery-Powered Systems |
|---|---|
Use Scenario: Generating clean 5V rail for USB peripherals and logic from single-cell Li-ion (8.4V–12.6V) or multi-cell alkaline packs. IC Role / Device Role / Timing Role: Primary step-down regulator delivering regulated 5V at up to 1.25A with tight load/line regulation and low-noise operation. Use Value: Fixed 5V output eliminates resistor tolerance errors; fused SO-8 package maintains thermal headroom during CPU burst loads. | Use Scenario: Powering microcontroller subsystems, sensors, and RF modules in handheld test equipment and portable medical devices. IC Role / Device Role / Timing Role: Main DC-DC converter providing stable 5V supply with ultra-low shutdown current (20µA) to extend battery life. Use Value: Shutdown threshold (0.37V) ensures deep sleep mode activation; BIAS pin connection to VOUT improves light-load efficiency by >10%. |
| Battery Charger | Distributed Power |
Use Scenario: Supplying isolated 5V bias for charger controller ICs and gate drivers in multi-bay Li-ion charging stations. IC Role / Device Role / Timing Role: Auxiliary power supply converting 12V–24V bus to precise 5V rail with robust short-circuit foldback. Use Value: SENSE-pin foldback protects against sustained overload during cell balancing; BOOST pin enables high efficiency even at 24V input. | Use Scenario: Local point-of-load regulation in industrial PLC backplanes where 24V or 48V distribution buses feed multiple 5V subsystems. IC Role / Device Role / Timing Role: Compact, thermally robust buck converter delivering 5V/1.25A per module with minimal board space. Use Value: Fused SO-8 package allows direct mounting to heatsinked ground planes; 200kHz switching simplifies EMI filter design. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fixed-output buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3605EDE-5#PBF | 4MHz synchronous buck; 3A output; integrated MOSFETs; no BOOST pin required | Higher frequency enables smaller inductors/caps; lacks fused-lead thermal enhancement | Preferred for space-constrained designs needing >1.25A or higher efficiency; not drop-in due to different pinout and control scheme |
| LM2678SX-5.0/NOPB | 63kHz nonsynchronous buck; 5A output; external diode; 0.32Ω switch RDS(on) | Lower switching frequency increases inductor size; higher quiescent current (50mA vs 1.16mA) | Suitable for cost-sensitive, non-portable applications where thermal performance is less critical than raw current capability |
Compared with LTC3605EDE-5#PBF and LM2678SX-5.0/NOPB, LT1576IS8-5#PBF delivers optimal balance of thermal robustness (fused SO-8), low-light-load current (1.16mA), and fault resilience (foldback + UVLO) for mid-power portable and industrial 5V rails - without requiring synchronous rectification or sacrificing layout simplicity.
Availability
LT1576IS8-5#PBF is available at Aetrix Electronics and suitable for portable computers, battery-powered systems, battery chargers, and distributed power architectures requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT1576IS8-5#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.
The LT1576 family was designed specifically for noise-sensitive, thermally constrained buck applications requiring fixed 5V or adjustable outputs with superior transient response and integrated protection - targeting portable, industrial, and instrumentation markets.
FAQ
What is the output voltage tolerance of the LT1576IS8-5#PBF over temperature and line conditions?
The LT1576IS8-5#PBF guarantees a 5V output with ±2% total accuracy across all operating conditions. Per datasheet specifications, the SENSE pin voltage is 4.94V to 5.06V at room temperature and 4.90V to 5.10V over the full –40°C to 125°C junction temperature range. This includes effects of line regulation (0.03%/V), load regulation, and initial tolerance - making LT1576IS8-5#PBF suitable for applications requiring stable 5V logic rails without post-regulation.
Can the LT1576IS8-5#PBF operate with input voltages below 6V?
The absolute minimum input voltage for reliable operation of the LT1576IS8-5#PBF is 5.5V (typical), with guaranteed startup at 5.0V. Operation below 5.5V may result in degraded regulation, reduced output current capability, or failure to maintain 5V under load. The device's undervoltage lockout (UVLO) activates at 2.42V on the SHDN pin, but this does not govern VIN behavior - the internal bias regulator requires sufficient VIN headroom to sustain 2.9V internal rails.
How does the SENSE pin on the LT1576IS8-5#PBF differ from the FB pin on the adjustable LT1576 variants?
The SENSE pin on LT1576IS8-5#PBF replaces the FB pin and connects directly to the regulated 5V output, eliminating external resistive dividers. Internally, it interfaces with the same error amplifier but uses factory-trimmed on-die resistors to set the 5V target. Crucially, SENSE also enables foldback protection: when voltage drops below 0.7V, LT1576IS8-5#PBF automatically reduces switching frequency and peak current limit - a feature not active on FB-pin variants unless externally implemented.
What is the purpose of the BOOST pin on the LT1576IS8-5#PBF, and what external components are required?
The BOOST pin on LT1576IS8-5#PBF supplies a boosted gate drive voltage to the internal NPN power switch, enabling saturation and achieving 0.2Ω on-resistance. It requires an external charge-pump network: a Schottky diode (e.g., 1N5818) from VIN to BOOST, and a 100pF capacitor from BOOST to SW. This configuration lifts BOOST ~5V above VIN during switch on-time, reducing conduction losses and raising efficiency to >88% - a key differentiator versus standard bipolar buck regulators.
Does the LT1576IS8-5#PBF support external synchronization, and if not, what alternatives exist?
The LT1576IS8-5#PBF does not support external synchronization because Pin 8 is configured as SHDN, not SYNC. Synchronization is only available on -SYNC variants (e.g., LT1576IS8-5#PBF-SYNC), where SHDN is replaced by SYNC. For designs requiring synchronized switching, users must select the -SYNC variant or implement clock dithering via the SHDN pin - though the latter is not recommended for precise phase alignment. LT1576IS8-5#PBF retains full functionality for standalone operation with its native 200kHz oscillator.
LT1576IS8-5#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):
- 5V
- Voltage - Input (Max):
- 25V
- Voltage - Output (Min/Fixed):
- 5V
- Voltage - Output (Max):
- -
- Current - Output:
- 1.5A
- Frequency - Switching:
- 200kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1576IS8-5#PBF FAQ
1.How can I place an order for LT1576IS8-5#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1576IS8-5#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 LT1576IS8-5#PBF reliable?
The price and inventory of LT1576IS8-5#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1576IS8-5#PBF is usually 5 days.
3.What payment methods are accepted for LT1576IS8-5#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1576IS8-5#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1576IS8-5#PBF?
LT1576IS8-5#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1576IS8-5#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 LT1576IS8-5#PBF?
For technical support, including LT1576IS8-5#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1576IS8-5#PBF requirements.
6.How does Aetrix verify that LT1576IS8-5#PBF is sourced from the original manufacturer or authorized distributors?
All LT1576IS8-5#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 LT1576IS8-5#PBF meets industry standards.
7.What is the process for return or replacement of LT1576IS8-5#PBF?
All LT1576IS8-5#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1576IS8-5#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 LT1576IS8-5#PBF part is unused and in its original packaging.
Return procedure for LT1576IS8-5#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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