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Analog Devices Inc. LT1506IS8-3.3#PBF
- Part No.:
- LT1506IS8-3.3#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1506IS8-3.3#PBF.pdf
- Description:
- IC REG BUCK 3.3V 4.5A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,469
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Product details
Overview
LT1506IS8-3.3#PBF from Analog Devices (formerly Linear Technology) is a fixed 3.3V, 4.5A monolithic synchronous-buck switching regulator in SO-8 package, featuring 500kHz constant-frequency current-mode control, 4V minimum input voltage, 0.07Ω internal switch on-resistance, and cycle-by-cycle current limiting - deployed in portable computers and battery-powered systems.
For engineers reviewing the LT1506IS8-3.3#PBF datasheet, LT1506IS8-3.3#PBF pinout, LT1506IS8-3.3#PBF application, or LT1506IS8-3.3#PBF equivalent, key selection criteria include verified 3.3V fixed output accuracy (±1.5%), thermal shutdown protection, shutdown current ≤50µA, boost-capacitor-driven saturation architecture, and SO-8 fused-ground package compatibility with standard PCB layouts.
Technical Context
The LT1506IS8-3.3#PBF implements a current-mode buck topology with internal 4.5A NPN power switch, 500kHz oscillator, and integrated slope compensation to prevent subharmonic oscillation at duty cycles >50%. Its error amplifier delivers 2000µMho transconductance and 400V/V gain, driving the VC pin to modulate peak switch current.
Fixed-output operation uses the SENSE pin (replacing FB) tied directly to VOUT for 3.3V regulation with ±1.5% tolerance over temperature and line. The BOOST pin enables switch saturation via external capacitor/diode, reducing conduction loss and enabling >89% efficiency at 4A load with 5V→3.3V conversion.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±1.5% (guaranteed across –40°C to 125°C junction) |
| Max Output Current | 4.5A at ≤50% duty cycle; derates to 3.7A at 80% duty cycle due to slope compensation |
| Switch On-Resistance | 0.07Ω typical (measured at 4.5A), enabling low conduction loss and high efficiency |
| Switching Frequency | 500kHz ±8% (460–540kHz), enabling compact 1.8–10µH inductor selection |
| Min Input Voltage | 4.0V (guaranteed; supports single-cell Li-ion and 5V rail start-up) |
| Shutdown Current | ≤50µA (measured at VSHDN = 0V, TJ = 25°C), enabling ultra-low-power standby |
| Thermal Protection | Internal thermal shutdown active above 125°C junction, with automatic recovery |
Pinout & Package
LT1506IS8-3.3#PBF is housed in an 8-lead plastic SO package with fused ground pin (Pin 4) connected internally to the exposed tab for enhanced thermal performance (θJA = 80°C/W). Ground plane attachment to Pin 4 is mandatory for thermal reliability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Input supply and switch collector | Accepts 4V–15V; carries high dI/dt; requires local 100µF tantalum + 0.68µF ceramic bypass |
| BOOST (Pin 2) | Switch drive voltage booster | Must be biased 5V above VIN via external capacitor/diode to saturate internal NPN switch |
| GND (Pin 4) | Power and signal reference | Fused ground pin attached to internal tab; must connect to large copper area for thermal dissipation |
| VSW (Pin 5) | Switch emitter node | Drives external catch diode (e.g., MBRS330T3); clamped to –0.8V max negative swing |
| SHDN (Pin 6) | Enable/disable control | Logic-low (≤0.37V) disables switching; 2.38V threshold provides accurate UVLO lockout |
| VC (Pin 7) | Error amplifier output / current limit setpoint | 0.9–2.1V range; used for loop compensation; can clamp to shut down regulator |
| SENSE (Pin 8) | Fixed-output voltage sense | Replaces FB pin; connects directly to 3.3V output; sets regulation point at 3.3V ±1.5% |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode control | Enables fast transient response and inherent stability without external compensation components |
| Integrated slope compensation | Prevents subharmonic oscillation above 50% duty cycle while preserving 4.5A peak switch current |
| Boost-driven saturation | Reduces effective switch resistance to 0.07Ω, improving efficiency by >14% vs conventional bipolar designs |
| Cycle-by-cycle current limiting | Provides full short-circuit protection with foldback to <3A under VFB <1V, limiting IC and diode power dissipation |
| Thermal shutdown + UVLO | Two independent protections: 125°C thermal cutoff and 2.38V input undervoltage lockout |
Applications
| Portable Computers | Battery-Powered Systems |
|---|---|
Use Scenario: Core logic voltage regulation in subnotebook motherboards with 5V input rails. IC Role / Device Role / Timing Role: Primary 3.3V buck converter delivering up to 4.5A with tight load transient response. Use Value: Enables use of 1.8µH inductors and eliminates need for external MOSFET drivers, reducing BOM count and board area. | Use Scenario: Power management in handheld medical monitors operating from single Li-ion cell (3.0–4.2V). IC Role / Device Role / Timing Role: Step-down regulator maintaining stable 3.3V for microcontroller and sensor interface despite input droop. Use Value: 4.0V minimum input allows operation down to near end-of-discharge; 20µA shutdown current extends battery life. |
| Battery Charger | Distributed Power |
Use Scenario: Auxiliary 3.3V rail generation in multi-chemistry smart battery chargers (NiMH/Li-ion). IC Role / Device Role / Timing Role: Isolated auxiliary supply powering charge controller MCU and communication interfaces. Use Value: Thermal shutdown prevents overheating during high-current charging phases; fused GND pin ensures robust grounding under high ripple currents. | Use Scenario: Local DC-DC conversion in industrial IoT gateways with 12V backplane input. IC Role / Device Role / Timing Role: Point-of-load regulator supplying 3.3V to Ethernet PHY and wireless SoC subsystems. Use Value: 500kHz switching frequency allows small 3.3µH inductors and low-profile TPS tantalum output capacitors (ESR <0.1Ω). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3605EDE-3.3#PBF | 4A, 3MHz synchronous buck; integrated MOSFETs; 2.5V–5.5V input; no BOOST pin required | Higher frequency enables smaller inductors but lower max input voltage; no external diode needed | Select when board space is critical and input voltage stays below 5.5V; not suitable for 12V input rails. |
| TPS54331DR | 3A, 570kHz non-synchronous buck; 3.5V–28V input; external diode; 0.13Ω HS-FET RDS(on) | Wider input range and higher voltage tolerance; lower current rating and lower efficiency at 4A | Select for cost-sensitive 12V-input systems where 3A output suffices and thermal margin is adequate. |
Compared with LTC3605EDE-3.3#PBF and TPS54331DR, the LT1506IS8-3.3#PBF uniquely combines 4.5A capability, 4V–15V input flexibility, and BOOST-assisted saturation for highest efficiency in mid-power 3.3V applications - making it optimal where input voltage varies widely and thermal headroom is constrained.
Availability
LT1506IS8-3.3#PBF is available at Aetrix Electronics and suitable for portable computers, battery-powered systems, and distributed power applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT1506IS8-3.3#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 and manufacturing continuity for legacy Linear power products.
The LT1506 series was designed specifically for high-efficiency, medium-current DC-DC conversion in space-constrained portable and battery-operated equipment where low input voltage operation and thermal robustness are critical.
FAQ
What is the guaranteed output voltage tolerance for LT1506IS8-3.3#PBF across temperature and line?
The LT1506IS8-3.3#PBF guarantees a fixed 3.3V output with ±1.5% tolerance over the full –40°C to 125°C junction temperature range and 4.3V to 15V input voltage range. This is confirmed by the "Sense Voltage (Fixed 3.3V)" specification: 3.25V (min), 3.3V (typ), 3.35V (max) at TJ = 25°C, with G-grade min/max values of 3.23V and 3.37V across temperature.
Can LT1506IS8-3.3#PBF operate from a 3.6V input source?
No - the LT1506IS8-3.3#PBF has a guaranteed minimum input voltage of 4.0V (with 4.3V typical), as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. Operation below 4.0V is not characterized and may result in loss of regulation, oscillator instability, or failure to start. For 3.6V input, consider alternatives like the LTC3605EDE-3.3#PBF.
What is the purpose of the BOOST pin on LT1506IS8-3.3#PBF, and what happens if it's left unconnected?
The BOOST pin on LT1506IS8-3.3#PBF supplies an elevated drive voltage to saturate the internal NPN power switch, reducing its effective on-resistance to 0.07Ω. If left unconnected, the switch operates in linear mode with ~1.5V VCE drop, degrading efficiency to ~75% and risking thermal overload at full load. A 1.5nF capacitor and Schottky diode (e.g., 1N914) must connect BOOST to VIN to enable saturation.
Does LT1506IS8-3.3#PBF support synchronization to an external clock?
No - the standard LT1506IS8-3.3#PBF uses the SHDN pin (Pin 6) for enable/disable control and does not include SYNC functionality. Synchronization is only available on variants marked "-SYNC" (e.g., LT1506IS8-SYNC), where the SHDN pin is replaced by SYNC. Using an external clock with LT1506IS8-3.3#PBF is not supported and may cause erratic operation.
What thermal derating applies to LT1506IS8-3.3#PBF in SO-8 package without a heatsink?
The LT1506IS8-3.3#PBF in SO-8 package has θJA = 80°C/W with standard PCB layout (no heatsink). At ambient 25°C and 4.5A load, junction temperature rise is ~288°C - exceeding the 125°C maximum. Therefore, full 4.5A output requires the fused GND pin (Pin 4) soldered to ≥1 square inch of internal ground plane or external copper pour. Without this, continuous output current must be reduced to ~2.2A to maintain TJ ≤125°C.
LT1506IS8-3.3#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):
- 15V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 4.5A
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1506IS8-3.3#PBF FAQ
1.How can I place an order for LT1506IS8-3.3#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1506IS8-3.3#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 LT1506IS8-3.3#PBF reliable?
The price and inventory of LT1506IS8-3.3#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1506IS8-3.3#PBF is usually 5 days.
3.What payment methods are accepted for LT1506IS8-3.3#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1506IS8-3.3#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1506IS8-3.3#PBF?
LT1506IS8-3.3#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1506IS8-3.3#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 LT1506IS8-3.3#PBF?
For technical support, including LT1506IS8-3.3#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1506IS8-3.3#PBF requirements.
6.How does Aetrix verify that LT1506IS8-3.3#PBF is sourced from the original manufacturer or authorized distributors?
All LT1506IS8-3.3#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 LT1506IS8-3.3#PBF meets industry standards.
7.What is the process for return or replacement of LT1506IS8-3.3#PBF?
All LT1506IS8-3.3#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1506IS8-3.3#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 LT1506IS8-3.3#PBF part is unused and in its original packaging.
Return procedure for LT1506IS8-3.3#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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