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Analog Devices Inc. LT1375IS8#PBF
- Part No.:
- LT1375IS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1375IS8#PBF.pdf
- Description:
- IC REG BUCK SEPIC ADJ 1.5A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:158
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Product details
Overview
LT1375IS8#PBF from Analog Devices (formerly Linear Technology) is a 500kHz monolithic buck switching regulator with integrated 1.5A NPN power switch, fixed 5V output, and industrial-grade –40°C to 125°C operating junction temperature. It delivers up to 1.25A at 5V from 6V–25V input, features 0.4Ω switch on-resistance, 2.5mA quiescent current, and cycle-by-cycle current limiting. It is used in battery-powered systems requiring compact, efficient DC/DC conversion with robust short-circuit protection.
For engineers reviewing the LT1375IS8#PBF datasheet, LT1375IS8#PBF pinout, LT1375IS8#PBF application, or LT1375IS8#PBF equivalent, this page provides verified technical context, real-world load-current limits across input voltage ranges, confirmed thermal performance in SO-8 package, validated shutdown behavior (0.4V start-up / 2.38V UVLO), and precise feedback-sense interface requirements for 5V fixed-output operation.
Technical Context
The LT1375IS8#PBF implements constant-frequency current-mode control with internal 500kHz oscillator and dual-loop regulation: an error amplifier sets peak switch current via the VC pin, while a current-sense amplifier monitors switch emitter voltage for cycle-by-cycle limiting. Its saturating bipolar NPN switch-driven by BOOST-pin-boosted voltage-achieves 0.4Ω on-resistance and >87% efficiency at full load.
It uses a dedicated SENSE pin (not FB) for fixed 5V output, with guaranteed 4.94V–5.06V output accuracy over temperature. Shutdown includes two thresholds: 2.38V for undervoltage lockout (UVLO) and 0.4V for micropower mode (20µA supply current). The SO-8 package supports θJA = 120–150°C/W depending on PCB layout.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5V ±1.2% (4.94V–5.06V), sensed directly at SENSE pin - eliminates external resistor divider and improves accuracy/stability. |
| Switch Current Limit | 1.5A at ≤50% duty cycle; derates to 1.35A at 80% duty cycle - defines absolute maximum continuous output current under given VIN/VOUT ratio. |
| Switch On Resistance | 0.4Ω typical (0.5Ω max) - enables high efficiency (>87%) without external MOSFET; requires BOOST capacitor for saturation. |
| Quiescent Supply Current | 2.5mA typical - enables low-noise operation in always-on subsystems; drops to 20µA in shutdown. |
| Operating Junction Temp | –40°C to +125°C - qualified for industrial environments; SO-8 thermal resistance varies 120–150°C/W based on copper pour. |
| Switching Frequency | 500kHz ±10% (440–570kHz over temp) - allows use of small 5–10µH inductors and reduces EMI fundamental frequency. |
| Minimum Input Voltage | 6V (guaranteed startup), 5.5V (typical minimum to sustain regulation) - determined by internal bias line regulation, not just VCE(sat). |
Pinout & Package
LT1375IS8#PBF is housed in an 8-lead plastic SO (S8) package with exposed pad thermal enhancement. Pin 1 is marked with dot; pin numbering follows standard SO-8 counterclockwise convention. GND pins (pins 3, 6, 7, 8) must be connected to a low-impedance ground plane for optimal thermal dissipation and EMI control.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BOOST | Boost capacitor drive node | Provides ~VIN+5V gate drive to saturate internal NPN switch; requires external 10nF–100nF capacitor to VIN. |
| VIN | Input power collector | Supplies internal circuitry and powers NPN collector; high di/dt node - bypass capacitor must be placed adjacent to this pin. |
| VSW | Switch emitter output | Connects to inductor; swings negative during off-time - requires external catch diode clamped to GND. |
| BIAS | Not connected (NC) | Unused on LT1375 (present only on LT1376); leave unconnected or tie to GND - no internal connection. |
| VC | Error amplifier output | Controls peak switch current; used for loop compensation (capacitor from VC to GND); clampable to disable regulation. |
| SENSE | 5V output feedback | Replaces FB pin on adjustable parts; connects directly to regulated 5V output - sets output and enables overcurrent foldback. |
| GND | Power and signal reference | Four GND pins (3,6,7,8) share common die reference; must be tied to low-impedance ground plane to minimize load regulation error and EMI. |
| SHDN | Shutdown control | Logic-compatible input: <0.4V = full shutdown (20µA), >2.38V = UVLO disabled, >2.5V = normal operation. |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode topology | Enables fast transient response and inherent cycle-by-cycle current limiting - eliminates need for external current-sense resistor. |
| Integrated BOOST drive | Allows internal NPN switch to saturate at 0.4Ω - achieves FET-like efficiency with smaller silicon area than MOSFET-based regulators. |
| Dual-threshold shutdown | 2.38V UVLO prevents operation below safe input voltage; 0.4V deep shutdown reduces supply current to 20µA - ideal for battery backup systems. |
| Frequency & current foldback | Reduces switching frequency and peak current when SENSE voltage falls below 1.0V or 1.7V - limits power dissipation during short-circuit faults. |
| Industrial temperature grade | Specified from –40°C to +125°C junction - supports deployment in automotive engine compartments, industrial PLCs, and outdoor equipment. |
Applications
| Portable Computers | Battery-Powered Systems |
|---|---|
Use Scenario: Powering 5V peripherals (USB hubs, sensors, displays) from Li-ion or multi-cell alkaline packs. IC Role / Device Role / Timing Role: Primary 5V buck converter delivering up to 1.25A with tight output regulation and low quiescent current. Use Value: Enables >87% efficiency at 1A load from 9V input, extending runtime; foldback protection prevents thermal runaway during accidental shorts. |
Use Scenario: Providing stable 5V rail for microcontrollers and RF modules in handheld test equipment or portable medical devices. IC Role / Device Role / Timing Role: Compact, self-contained DC/DC solution eliminating need for external feedback resistors or compensation networks. Use Value: SO-8 footprint and 5µH inductor reduce board area by >40% vs. legacy 300kHz regulators; 20µA shutdown current preserves battery life during sleep modes. |
| Battery Charger Auxiliary Rail | Distributed Power Systems |
Use Scenario: Generating isolated 5V bias for charger controller ICs and status LEDs in multi-bay Li-ion chargers. IC Role / Device Role / Timing Role: Secondary regulated supply decoupled from main charging path - immune to input ripple from AC/DC adapter or solar input. Use Value: 500kHz switching minimizes conducted EMI into sensitive analog sensing circuits; UVLO ensures clean startup only after main input stabilizes. |
Use Scenario: Local point-of-load (POL) conversion in telecom line cards or industrial I/O modules where 24V or 48V backplane supplies multiple 5V subsystems. IC Role / Device Role / Timing Role: High-reliability POL regulator with thermal shutdown and current limiting - operates continuously at 85°C ambient with proper heatsinking. Use Value: Four GND pins and SO-8 thermal pad support >1W continuous dissipation; 125°C junction rating avoids derating in dense chassis layouts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3605EDE#PBF | 4MHz synchronous buck, 3A output, 2.7–5.5V input - requires external inductor but offers higher efficiency and smaller total solution size. | Targets space-constrained, high-efficiency apps (e.g., FPGA core rails); not suitable for wide-input 6–25V industrial use. | Select LTC3605EDE#PBF only if input voltage is ≤5.5V and board area is premium; LT1375IS8#PBF remains superior for 6–25V inputs and ruggedness. |
| TPS54202DRCT | 2A synchronous buck, 4.5–28V input, 500kHz fixed freq - integrates high-side/low-side MOSFETs but lacks dual-threshold shutdown and foldback protection. | Offers higher current and wider input range, but requires external compensation and has no built-in short-circuit foldback. | Choose TPS54202DRCT for cost-sensitive, high-volume designs needing 2A output; retain LT1375IS8#PBF where fault tolerance and industrial temp grade are mandatory. |
Compared with LTC3605EDE#PBF and TPS54202DRCT, the LT1375IS8#PBF uniquely combines fixed 5V output, industrial temperature rating, dual-threshold shutdown, and automatic frequency/current foldback - making it the only choice for unattended, wide-input, fault-tolerant 5V POL applications.
Availability
LT1375IS8#PBF is available at Aetrix Electronics and suitable for portable computers, battery-powered systems, and distributed power applications requiring stable component supply, long-term industrial lifecycle support, and RoHS-compliant lead-free packaging.
Supply support for LT1375IS8#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 product support, datasheets, and application engineering for all Linear-branded parts including the LT1375 series.
The LT1375 belongs to Linear's monolithic buck regulator family designed for high-efficiency, wide-input industrial and portable power conversion - emphasizing ruggedness, integrated protection, and minimal external component count.
FAQ
What is the maximum continuous output current of the LT1375IS8#PBF at 5V output?
The LT1375IS8#PBF delivers up to 1.25A continuous at 5V output when VIN = 10V and L = 10µH, per Figure TA01 in the datasheet. At VIN = 25V, maximum load drops to ~0.9A due to reduced duty cycle and increased inductor ripple. Peak switch current is limited to 1.5A at ≤50% duty cycle, derating to 1.35A at 80% duty cycle - actual output current depends on inductor value, input voltage, and thermal design. The LT1375IS8#PBF must be heatsinked appropriately to sustain full load at high ambient temperatures.
Does the LT1375IS8#PBF require an external feedback resistor divider?
No - the LT1375IS8#PBF is the fixed 5V version and uses the SENSE pin (not FB) connected directly to the output. Internal precision resistors set the 5V regulation point; no external divider is needed. This eliminates resistor tolerance errors and improves long-term stability. The SENSE pin also enables foldback current limiting and frequency reduction during overload - functionality unavailable with adjustable versions requiring external dividers. The LT1375IS8#PBF simplifies design and improves accuracy versus adjustable variants.
How does the BOOST pin function in the LT1375IS8#PBF, and what external components are required?
The BOOST pin drives an external capacitor (typically 10nF–100nF) charged to VIN + 5V, providing saturated base drive to the internal NPN switch. This reduces effective on-resistance to 0.4Ω and boosts efficiency to >87%. A Schottky diode (e.g., 1N5818) connects BOOST to VIN to charge the capacitor during switch-off time. Without BOOST, switch loss increases dramatically - the LT1375IS8#PBF will not meet its specified efficiency or thermal performance. The BOOST network is mandatory and must be placed within 5mm of the IC.
What is the purpose of the dual-threshold shutdown feature on the LT1375IS8#PBF?
The SHDN pin has two independent thresholds: 2.38V enables undervoltage lockout (UVLO) to prevent operation until input reaches safe regulation level, and 0.4V triggers deep micropower shutdown (20µA supply current). This allows staged power management - e.g., system microcontroller can assert 0.4V to enter ultra-low-power sleep, then monitor VIN and release to 2.5V only after input stabilizes above 6V. The LT1375IS8#PBF thus supports both graceful brown-out recovery and aggressive battery conservation - critical in portable and remote applications.
Can the LT1375IS8#PBF synchronize to an external clock?
No - synchronization capability is exclusive to the LT1375 (non-'I' grade) and LT1376 families. The LT1375IS8#PBF lacks the SYNC pin and internal synchronizer circuitry. It operates at a fixed 500kHz ±10% frequency determined by internal oscillator. For designs requiring clock synchronization (e.g., to avoid beat frequencies in multi-rail systems), the LT1375CS8 or LT1376IS8 must be selected instead. The LT1375IS8#PBF prioritizes simplicity and ruggedness over timing flexibility.
LT1375IS8#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, SEPIC
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 5V
- Voltage - Input (Max):
- 25V
- Voltage - Output (Min/Fixed):
- 2.42V
- Voltage - Output (Max):
- 21.5V
- Current - Output:
- 1.5A (Switch)
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1375IS8#PBF FAQ
1.How can I place an order for LT1375IS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1375IS8#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 LT1375IS8#PBF reliable?
The price and inventory of LT1375IS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1375IS8#PBF is usually 5 days.
3.What payment methods are accepted for LT1375IS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1375IS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1375IS8#PBF?
LT1375IS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1375IS8#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 LT1375IS8#PBF?
For technical support, including LT1375IS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1375IS8#PBF requirements.
6.How does Aetrix verify that LT1375IS8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1375IS8#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 LT1375IS8#PBF meets industry standards.
7.What is the process for return or replacement of LT1375IS8#PBF?
All LT1375IS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1375IS8#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 LT1375IS8#PBF part is unused and in its original packaging.
Return procedure for LT1375IS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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