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Analog Devices Inc. LT1507IS8#PBF
- Part No.:
- LT1507IS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1507IS8#PBF.pdf
- Description:
- IC REG BUCK ADJ 1.5A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,381
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Product details
Overview
LT1507IS8#PBF from Analog Devices (formerly Linear Technology) is a 500kHz monolithic buck-mode switching regulator in an 8-lead SOIC package, featuring a fixed 3.3V output, 1.5A internal NPN power switch, 0.3Ω typical on-resistance, and cycle-by-cycle current limiting. It operates from 4V to 15V input and delivers regulated 3.3V at up to 1.25A in portable computing and battery-powered systems.
For engineers reviewing the LT1507IS8#PBF datasheet, LT1507IS8#PBF pinout, LT1507IS8#PBF application, or LT1507IS8#PBF equivalent, key selection considerations include its fixed 3.3V output configuration, 500kHz constant-frequency current-mode control, shutdown current of 20µA, thermal shutdown protection, and compatibility with surface-mount inductors as small as 2µH.
Technical Context
The LT1507IS8#PBF implements a current-mode, constant-frequency buck topology with an internal 500kHz oscillator and dual-loop control: an error amplifier sets the peak switch current threshold via the VC pin, while a current-sense amplifier monitors switch conduction on a cycle-by-cycle basis. This architecture ensures fast transient response and stable loop compensation without external slope compensation below 700kHz.
It uses a bipolar NPN power switch driven by a BOOST pin voltage elevated above VIN-enabling saturation and minimizing conduction loss (0.3Ω typical)-and integrates undervoltage lockout (2.38V) and micropower shutdown (0.4V threshold) on the SHDN pin. The SENSE pin (labeled FB/SENSE) connects directly to the 3.3V output for fixed-voltage operation and enables foldback current limiting and frequency reduction during short-circuit conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 500kHz ±40kHz - enables compact magnetics and reduces EMI filtering burden |
| Output Voltage | 3.3V ±1.5% - factory-trimmed fixed output eliminates external feedback resistors |
| Max Output Current | 1.25A at VOUT=3.3V, VIN=5V - limited by thermal design and inductor selection |
| Input Voltage Range | 4V to 15V - supports single-cell Li-ion (4.2V) and multi-cell battery inputs |
| Shutdown Current | 20µA - enables long battery life in standby mode |
| Switch On Resistance | 0.3Ω typical - minimizes conduction loss and improves efficiency at high load |
| Thermal Shutdown | 125°C junction - protects device under overload or poor PCB heatsinking |
Pinout & Package
LT1507IS8#PBF is housed in an 8-lead plastic SOIC (S8) package with standard 1.27mm pitch and exposed pad not present. Thermal resistance θJA is 120°C/W depending on PCB layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BOOST (1) | Boost capacitor drive | Supplies elevated gate drive to saturate internal NPN switch; requires external diode + capacitor |
| VIN (2) | Main power input | Accepts 4V–15V DC; powers internal bias circuitry and switch driver |
| VSW (3) | Switch collector node | Connects to inductor; swings from VIN to ~–0.7V (clamped by catch diode) |
| SHDN (4) | Shutdown control | Logic-level input: ≥2.38V disables switching; ≤0.4V forces micropower shutdown |
| SYNC (5) | External clock synchronization | Accepts 570kHz–1MHz logic-level signal; overrides internal oscillator |
| GND (6) | Power and signal reference | Common return for input, output, and internal circuits; must be low-impedance |
| FB/SENSE (7) | Output voltage sense | Direct connection to 3.3V output; enables foldback current limit and frequency shift below 1.5V |
| VC (8) | Error amplifier output | Drives peak-current comparator; used for loop compensation or current clamping |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 3.3V output | Eliminates external feedback divider, reducing BOM count and layout sensitivity |
| Saturated NPN switch | 0.3Ω on-resistance enables >85% efficiency at 1A, outperforming conventional bipolar designs |
| Current-mode control | Provides inherent cycle-by-cycle overcurrent protection and simplifies loop compensation |
| 500kHz constant frequency | Allows use of small, low-profile inductors (as low as 2µH) and reduces output capacitor size |
| Two-threshold shutdown | 2.38V UVLO prevents startup until input stabilizes; 0.4V deep-sleep cuts supply current to 20µA |
Applications
| Portable Computing Power | Battery-Powered Instrumentation |
|---|---|
Use Scenario: Regulating 5V USB or Li-ion battery rail down to clean 3.3V for microcontroller, FPGA I/O, and sensor interfaces in handheld test equipment. IC Role / Device Role / Timing Role: Primary step-down DC/DC converter delivering stable 3.3V at up to 1.25A with fast load transient response. Use Value: High 500kHz switching frequency enables compact 2–5µH inductors and low-ESR tantalum output capacitors, minimizing board area. | Use Scenario: Powering low-power data loggers and wireless sensor nodes operating from two AA cells (2.4–3.2V) boosted to 5V, then stepped down to 3.3V. IC Role / Device Role / Timing Role: Fixed-output buck regulator interfacing with boost stage; provides regulated supply during variable battery discharge. Use Value: 4V minimum input allows operation down to near-end-of-life battery voltage; 20µA shutdown current extends operational lifetime. |
| Distributed Power Subsystem | Battery Charger Auxiliary Rail |
Use Scenario: Generating local 3.3V rail from a 12V intermediate bus in industrial controllers or telecom line cards. IC Role / Device Role / Timing Role: Point-of-load regulator with thermal shutdown and current limiting for fault-tolerant distributed power. Use Value: Full cycle-by-cycle current limiting and 125°C thermal shutdown protect against sustained overloads without external circuitry. | Use Scenario: Providing isolated 3.3V supply for charger management ICs, status LEDs, and communication interfaces in multi-bay Li-ion chargers. IC Role / Device Role / Timing Role: Secondary regulator powered from main charging rail; must remain active during charge termination and safety monitoring. Use Value: Synchronizable 500kHz operation avoids beat frequencies with primary charger switching noise, improving EMC performance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3605EMS8E#PBF | 4MHz synchronous buck, 3.3V fixed, 1.2A, integrated MOSFETs; no BOOST pin required | Higher efficiency at light loads due to synchronous rectification; lower quiescent current (25µA) | Preferred for new designs requiring higher efficiency and smaller solution size; requires different layout and no external catch diode |
| TPS54331DR | 3.5MHz adjustable buck, 3.5A, integrated FETs; requires external feedback resistors for 3.3V | Wider input range (3.5–28V); higher current capability but larger thermal footprint | Selected when higher output current or wider input range is needed; adds BOM complexity for fixed 3.3V use |
Compared with LTC3605EMS8E#PBF and TPS54331DR, the LT1507IS8#PBF offers proven bipolar-switch reliability, simpler BOOST-based saturation drive, and direct pin compatibility within the LT1507 family-but lacks synchronous rectification and requires an external catch diode.
Availability
LT1507IS8#PBF is available at Aetrix Electronics and suitable for portable computing, battery-powered instrumentation, and distributed power subsystems requiring stable component supply across extended temperature ranges (–40°C to 85°C).
Supply support for LT1507IS8#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LT1507IS8#PBF belongs to Linear's legacy monolithic buck regulator product line, designed specifically for low-input-voltage, high-efficiency DC/DC conversion in space-constrained portable and battery-operated applications.
FAQ
What is the operating temperature range for the LT1507IS8#PBF?
The LT1507IS8#PBF is rated for an industrial ambient temperature range of –40°C to +85°C. Its maximum junction temperature is 125°C, and thermal shutdown activates at that threshold to prevent damage. The "I" grade designation in LT1507IS8#PBF explicitly confirms this extended temperature capability, distinguishing it from the commercial-grade "C" version (0°C to 70°C).
Does the LT1507IS8#PBF require an external catch diode, and why?
Yes, the LT1507IS8#PBF requires an external Schottky catch diode (e.g., 1N5818) connected between VSW and GND. Because it uses a single NPN power switch-not a synchronous MOSFET pair-the diode provides the return path for inductor current during the switch OFF time. Omitting it will cause destructive voltage spikes and failure. The diode's forward voltage directly impacts efficiency and thermal performance.
Can the LT1507IS8#PBF be synchronized to an external clock, and what is the valid frequency range?
Yes, the LT1507IS8#PBF can be synchronized using the SYNC pin (Pin 5). It accepts logic-level input signals with 10%–90% duty cycle across a range of 570kHz to 1MHz. Synchronization eliminates beat frequencies in multi-regulator systems and aids EMI compliance. For frequencies above 700kHz and duty cycles >50%, external slope compensation may be required per the datasheet.
How does the LT1507IS8#PBF implement short-circuit protection?
The LT1507IS8#PBF provides short-circuit protection through three coordinated mechanisms: (1) cycle-by-cycle current limiting trips at ~1.5A, (2) feedback pin (SENSE) foldback reduces switch current limit when output voltage drops below 1.5V, and (3) frequency foldback lowers switching frequency ~5:1 when SENSE falls below 1V. These features collectively limit power dissipation in the IC, catch diode, and inductor during sustained faults.
What is the purpose of the BOOST pin on the LT1507IS8#PBF, and how is it implemented?
The BOOST pin (Pin 1) on the LT1507IS8#PBF supplies an elevated voltage to the base drive of the internal NPN power switch, enabling full saturation and minimizing VCE(sat). It is implemented with an external flying capacitor (e.g., 3.3nF) and diode (e.g., 1N914) that charge to VIN + VF during switch OFF time. This technique achieves ~0.3Ω effective on-resistance-comparable to a low-RDS(on) MOSFET-while retaining bipolar process advantages.
LT1507IS8#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:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 16V
- Voltage - Output (Min/Fixed):
- 2.42V
- Voltage - Output (Max):
- 14.88V
- Current - Output:
- 1.5A
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1507IS8#PBF FAQ
1.How can I place an order for LT1507IS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1507IS8#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 LT1507IS8#PBF reliable?
The price and inventory of LT1507IS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1507IS8#PBF is usually 5 days.
3.What payment methods are accepted for LT1507IS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1507IS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1507IS8#PBF?
LT1507IS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1507IS8#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 LT1507IS8#PBF?
For technical support, including LT1507IS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1507IS8#PBF requirements.
6.How does Aetrix verify that LT1507IS8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1507IS8#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 LT1507IS8#PBF meets industry standards.
7.What is the process for return or replacement of LT1507IS8#PBF?
All LT1507IS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1507IS8#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 LT1507IS8#PBF part is unused and in its original packaging.
Return procedure for LT1507IS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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