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Analog Devices Inc. LT1375CN8#PBF
- Part No.:
- LT1375CN8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LT1375CN8#PBF.pdf
- Description:
- IC REG BUCK SEPIC ADJ 1.5A 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,856
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Product details
Overview
LT1375CN8#PBF from Analog Devices (formerly Linear Technology) is a monolithic 500kHz current-mode step-down switching regulator with an integrated 1.5A NPN power switch, 2.42V reference, and fixed 5V output. It delivers up to 1.25A at 5V from 6V–25V input, features cycle-by-cycle current limiting, 0.4Ω switch on-resistance, and 20µA shutdown current. It is used in battery-powered systems requiring compact, efficient DC/DC conversion.
For engineers reviewing the LT1375CN8#PBF datasheet, LT1375CN8#PBF pinout, LT1375CN8#PBF application, or LT1375CN8#PBF equivalent, key selection criteria include input voltage range (6–25V), output current capability (1.25A @ 5V), thermal resistance (θJA = 100°C/W in PDIP), synchronous capability (LT1375 only), and fixed-output configuration without external feedback resistors.
Technical Context
The LT1375CN8#PBF implements constant-frequency current-mode control using an internal 500kHz oscillator and peak-current sensing. Its bipolar NPN switch is driven via an external BOOST capacitor to achieve saturation, reducing conduction loss and enabling >87% efficiency. The architecture includes built-in slope compensation to prevent subharmonic oscillation at duty cycles above 50%.
It integrates undervoltage lockout (2.38V UVLO threshold), thermal shutdown, and dual-threshold shutdown (0.4V full micropower, 2.38V standby). Unlike the LT1376, it lacks a BIAS pin but supports external synchronization (580–900kHz) via the SYNC pin and uses a fixed 5V SENSE configuration instead of adjustable FB.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5V ±1.2% (guaranteed over temperature and line) |
| Max Output Current | 1.25A continuous at VIN ≥ 7.5V, L = 10µH (derates at higher duty cycles) |
| Switching Frequency | 500kHz nominal; externally synchronizable from 580kHz to 900kHz |
| Input Voltage Range | 6V to 25V (minimum start-up voltage 5.5V; operation below 7.5V has restrictions) |
| Shutdown Current | 20µA typical (75µA max over full temperature range) |
| Switch On-Resistance | 0.4Ω typical (0.5Ω max), enabling low conduction loss with BOOST capacitor |
| Thermal Resistance | θJA = 100°C/W in 8-pin PDIP package; requires adequate PCB copper for thermal management |
Pinout & Package
LT1375CN8#PBF is housed in an 8-pin plastic DIP (N8) package with through-hole mounting. Pin 1 is marked by a notch or dot; leads are tin-lead (Pb-free per #PBF suffix) and RoHS-compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1: BOOST | Boost capacitor drive node | Connects to external diode-capacitor network to generate ~VIN+5V for switch saturation; critical for low RON and high efficiency |
| 2: VIN | Power switch collector & IC supply | Primary input connection; powers internal circuitry and carries high di/dt switching current; requires local 100µF solid tantalum bypass |
| 3: VSW | Switch emitter node | Connects to inductor; swings negative during off-time; clamped by external catch diode (e.g., 1N5818) |
| 4: BIAS | Not connected (NC) | No internal connection; must be left unconnected or grounded - not present in LT1375 (only LT1376) |
| 5: VC | Error amplifier output / current limit comparator input | Used for loop compensation (capacitor to GND); also serves as current clamp point; 1V–2V swing under load |
| 6: FB/SENSE | Fixed 5V output sense input | Internally connected to 5V output; monitors regulation; triggers foldback protection if voltage drops below 1.7V |
| 7: GND | Power and signal reference | Must tie directly to low-impedance ground plane; separates power return from load ground to avoid regulation error and EMI |
| 8: SHDN | Logic-level shutdown control | Active-low; 0.4V threshold for full shutdown, 2.38V for UVLO standby; drives <50µA in shutdown |
Key Features
| Feature | Design Value |
|---|---|
| Constant 500kHz switching | Enables use of small 5µH inductors and reduces EMI filtering burden vs. lower-frequency regulators |
| Saturating switch design | 0.4Ω on-resistance achieved via BOOST pin drive - improves efficiency over standard bipolar designs by >12% |
| External synchronization support | Allows noise-sensitive systems to lock switching frequency to external clock (580–900kHz), avoiding beat frequencies |
| Cycle-by-cycle current limiting | Guarantees 1.5A peak switch current limit across temperature and input voltage - protects against short-circuit faults |
| Foldback protection | Reduces switching frequency and current limit when output collapses (<1.7V FB), limiting power dissipation during sustained shorts |
Applications
| Portable Computers | Battery-Powered Systems |
|---|---|
Use Scenario: Powering 5V logic rails and peripherals in laptops and handheld PCs with wide-input battery packs (7–25V). IC Role / Device Role / Timing Role: Primary 5V buck converter delivering regulated power to USB controllers, display interfaces, and I/O subsystems. Use Value: Delivers 1.25A at >87% efficiency with minimal external components - reduces board area and thermal load in space-constrained enclosures. | Use Scenario: Converting variable battery voltage (e.g., 2-cell Li-ion or 4-cell NiMH) to stable 5V for microcontrollers and sensors. IC Role / Device Role / Timing Role: Main system regulator providing clean, efficient 5V supply with low quiescent current (20µA shutdown) to extend battery life. Use Value: Enables >100-hour standby via micropower shutdown and maintains regulation down to 6V input - compatible with aging or partially discharged batteries. |
| Battery Charger Control | Distributed Power Architectures |
Use Scenario: Supplying 5V bias to charge management ICs and status LEDs in multi-bay smart chargers. IC Role / Device Role / Timing Role: Auxiliary 5V rail generator supporting charger controller logic, communication interfaces (I²C/SMBus), and indicator circuits. Use Value: Fixed 5V output eliminates need for feedback resistors; SYNC capability allows synchronization with main charging controller clock to reduce conducted EMI. | Use Scenario: Providing localized 5V power in modular industrial equipment with distributed 24V backplane supplies. IC Role / Device Role / Timing Role: Point-of-load (POL) regulator converting 24V intermediate bus to 5V for FPGA I/O banks, ADC references, and digital isolators. Use Value: High-frequency operation (500kHz) permits compact 5µH inductors - simplifies mechanical layout and enables dense, multi-rail PCB designs. |
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, integrated MOSFETs, 2.5–5.5V input - no BOOST requirement | Requires lower input voltage; better suited for 3.3V/5V intermediate bus systems, not wide-input battery apps | Select for higher efficiency at light loads and smaller solution size where input ≤5.5V; not drop-in for LT1375CN8#PBF's 6–25V range |
| LM2678SX-5.0/NOPB | 63kHz nonsynchronous buck, 5A output, 8–40V input, 0.32Ω switch - larger inductor needed (33–100µH) | Lower switching frequency increases EMI filter size; higher current rating suits heavier loads but sacrifices transient response | Select when cost sensitivity outweighs size/efficiency; acceptable where 500kHz EMI is problematic and board space allows larger magnetics |
Compared with LTC3605EDE#PBF and LM2678SX-5.0/NOPB, the LT1375CN8#PBF uniquely balances wide 6–25V input compatibility, 500kHz fixed-frequency operation, and simple BOOST-based bipolar switch design - making it optimal for legacy battery-powered systems where input range and component count are primary constraints.
Availability
LT1375CN8#PBF is available at Aetrix Electronics and suitable for portable computers, battery-powered instrumentation, and distributed power systems requiring stable component supply, long-lifecycle availability, and through-hole manufacturability.
Supply support for LT1375CN8#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 parts including the LT1375 series.
The LT1375 belongs to Linear's monolithic current-mode buck regulator product line, designed specifically for compact, high-efficiency DC/DC conversion in battery-operated and wide-input industrial equipment where simplicity, reliability, and thermal robustness are prioritized over ultra-high switching frequencies or synchronous rectification.
FAQ
What is the minimum input voltage required for LT1375CN8#PBF to start regulation?
The LT1375CN8#PBF has a guaranteed minimum start-up input voltage of 5.5V. Below this, internal bias lines may not regulate properly, causing unstable oscillator frequency or reference voltage. Operation at 6V–25V is fully specified; inputs below 7.5V require attention to inductor sizing and may reduce maximum output current. The 2.38V UVLO threshold on the SHDN pin provides additional input monitoring capability.
Can LT1375CN8#PBF be synchronized to an external clock, and what is its sync range?
Yes, the LT1375CN8#PBF supports external synchronization via its dedicated SYNC pin. It accepts logic-level signals (10–90% duty cycle) and locks to frequencies from 580kHz to 900kHz. This feature is exclusive to the LT1375 family - the LT1376 variant does not include SYNC. Synchronization helps eliminate beat frequencies in multi-regulator systems and simplifies EMI compliance testing.
What is the role of the BOOST pin on LT1375CN8#PBF, and what happens if it's omitted?
The BOOST pin on LT1375CN8#PBF drives an external capacitor-diode network to generate ~VIN+5V, which saturates the internal NPN power switch and achieves 0.4Ω on-resistance. If omitted or improperly configured, the switch operates in linear mode, increasing conduction loss, reducing efficiency by >12%, and risking thermal overload at full load. A 10nF ceramic capacitor and 1N5817/1N5818 Schottky diode are mandatory.
Does LT1375CN8#PBF require external feedback resistors for its 5V output?
No. The LT1375CN8#PBF is the fixed 5V version (denoted by "-5" in part numbering convention); its internal resistor divider connects the FB/SENSE pin directly to the output, eliminating external feedback components. This simplifies layout, improves accuracy (±1.2% over temperature), and enhances reliability versus adjustable variants that depend on external resistor tolerance and layout parasitics.
How does LT1375CN8#PBF protect against short-circuit conditions?
The LT1375CN8#PBF employs dual-foldback protection triggered by the FB/SENSE pin voltage. When output collapses below 1.7V, it reduces peak switch current limit; below 1.0V, it lowers switching frequency by ~5:1. This limits power dissipation in both the IC and external components during sustained shorts. Combined with cycle-by-cycle current limiting (1.5A max) and thermal shutdown, it ensures safe operation without external fault-handling circuitry.
LT1375CN8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- 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:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LT1375CN8#PBF FAQ
1.How can I place an order for LT1375CN8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1375CN8#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 LT1375CN8#PBF reliable?
The price and inventory of LT1375CN8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1375CN8#PBF is usually 5 days.
3.What payment methods are accepted for LT1375CN8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1375CN8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1375CN8#PBF?
LT1375CN8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1375CN8#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 LT1375CN8#PBF?
For technical support, including LT1375CN8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1375CN8#PBF requirements.
6.How does Aetrix verify that LT1375CN8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1375CN8#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 LT1375CN8#PBF meets industry standards.
7.What is the process for return or replacement of LT1375CN8#PBF?
All LT1375CN8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1375CN8#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 LT1375CN8#PBF part is unused and in its original packaging.
Return procedure for LT1375CN8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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