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Analog Devices Inc. LT1372IN8#PBF
- Part No.:
- LT1372IN8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LT1372IN8#PBF.pdf
- Description:
- IC REG BUCK BOOST ADJ 1.5A 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,644
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Product details
Overview
LT1372IN8#PBF from Analog Devices (formerly Linear Technology) is a monolithic 500kHz current-mode switching regulator IC in 8-pin PDIP package, integrating a 1.5A power switch, oscillator, error amplifier, and protection circuitry. It operates in boost, buck, flyback, inverting, and Cuk topologies, supports ±2.7V to 25V input, regulates positive or negative outputs, and delivers up to 0.29A at 12V in boost configuration for laptop supplies and CCFL backlight drivers.
For engineers reviewing the LT1372IN8#PBF datasheet, LT1372IN8#PBF pinout, LT1372IN8#PBF application, or LT1372IN8#PBF equivalent, key selection considerations include its 500kHz fixed switching frequency, 1.245V internal reference, –40°C to 125°C industrial temperature rating, shutdown current of 12µA, and dual feedback capability for bipolar output regulation.
Technical Context
The LT1372IN8#PBF uses peak-current-mode control with adaptive anti-saturation driver logic, enabling immediate line transient response and simplified loop compensation. Its error amplifier features nonlinear transconductance (700–2300 µmho) that increases tenfold above 40mV error to suppress startup/overload overshoot.
Oscillator frequency shifting (5:1 reduction when FB < 0.6V) protects external components during overload; the S/S pin provides logic-level shutdown (threshold 0.6–2.0V) and synchronization (600–800kHz range). Internal 2.3V LDO powers all circuitry, supporting operation down to 2.7V input.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 500 kHz typical - enables use of compact 4.7 µH inductors and reduces board space vs lower-frequency regulators. |
| Input Voltage Range | 2.7 V to 25 V - supports single-cell Li-ion to multi-cell battery and industrial supply rails without external pre-regulation. |
| Output Switch Current Limit | 1.5 A typical - sets maximum deliverable load current in boost/buck configurations; duty-cycle dependent (e.g., 1.3 A at 80% DC). |
| Reference Voltage | 1.245 V ±15 mV - precise internal bandgap reference used directly for positive-output feedback divider design. |
| Negative Reference Voltage | –2.490 V ±50 mV - enables direct negative-output regulation via NFB pin without external op-amps. |
| Quiescent Current | 4 mA typical - minimizes no-load power loss in battery-powered systems like portable computers. |
| Shutdown Supply Current | 12 µA typical - allows ultra-low-power standby mode for energy-sensitive embedded applications. |
| Operating Temperature | –40°C to +125°C - qualified for industrial environments including automotive under-hood and factory automation. |
Pinout & Package
LT1372IN8#PBF is housed in an 8-lead plastic DIP (N8) package with 0.3-inch width, JEDEC MS-001AC compliant, thermal resistance θJA = 100°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (Pin 1) | Error amplifier output / compensation node | Accepts RC network for loop compensation; clamping controls soft-start and current limit; voltage range 0.8–1.9 V reflects load condition. |
| FB (Pin 2) | Positive output voltage sense input | Inverting input of main error amp; referenced to 1.245 V; bias current ≤550 nA affects high-resistor-divider accuracy. |
| NFB (Pin 3) | Negative output voltage sense input | Connects to inverting input of dedicated negative-feedback amp via 100 kΩ resistor; regulates at –2.49 V with –30 µA bias current. |
| S/S (Pin 4) | Shutdown and synchronization input | Logic-compatible pin: low = shutdown (12 µA IQ); AC-coupled square wave (600–800 kHz) synchronizes switching. |
| VIN (Pin 5) | Power input supply | Bypass with ≥10 µF capacitor; triggers undervoltage lockout below 2.5 V to prevent erratic operation. |
| GND S (Pin 6) | Clean analog ground reference | Reference point for internal reference, error amps, and NFB circuitry; must be isolated from high-current GND paths. |
| GND (Pin 7) | Power switch emitter return | Carries full switch current (up to 1.5 A); requires direct connection to low-impedance ground plane. |
| VSW (Pin 8) | Power switch collector output | High-di/dt node connecting to inductor/diode; trace length must be minimized to reduce EMI and voltage spikes. |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode control architecture | Enables stable operation across wide VIN/VOUT ranges and simplifies compensation with single-pole-zero network on VC pin. |
| Dual feedback capability (FB + NFB) | Allows simultaneous regulation of positive and negative outputs in flyback or inverting converters without external amplifiers. |
| Nonlinear error amplifier transconductance | Increases 10× above 40 mV error to suppress output overshoot during startup and overload recovery. |
| Oscillator frequency shifting | Reduces switching frequency 5:1 when FB < 0.6 V, limiting peak switch current and protecting external magnetics during overload. |
| Adaptive anti-saturation driver | Dynamically adjusts base drive to minimize switch saturation voltage and enable fast turn-off, improving efficiency at high loads. |
| Logic-level shutdown with resetable delay | 12 µA shutdown current and 5–25 µs delay prevent false triggering during sync signal transitions. |
Applications
| Laptop Computer Power Supply | CCFL Backlight Driver |
|---|---|
Use Scenario: Generating 12 V or 19 V from 3.3 V or 5 V system rail in ultraportable notebooks with strict board area constraints. IC Role / Device Role / Timing Role: Primary DC/DC boost controller managing power conversion, feedback regulation, and thermal-safe current limiting. Use Value: Delivers 0.29 A at 12 V using only 0.5 in² board space with 4.7 µH inductor and surface-mount passives per typical application circuit. | Use Scenario: Driving cold cathode fluorescent lamps in LCD displays requiring high-voltage AC output with tight current regulation. IC Role / Device Role / Timing Role: High-frequency current-mode controller operating in flyback topology to generate isolated high-voltage AC via transformer secondary. Use Value: Enables lamp dimming via FB pin modulation and provides inherent short-circuit protection through pulse-by-pulse current limiting. |
| Inverting Power Supply | Multiple Output Flyback Supply |
Use Scenario: Generating –5 V or –12 V from a 5 V or 12 V source in mixed-signal systems needing clean negative rails for op-amps or ADCs. IC Role / Device Role / Timing Role: Inverting topology controller using NFB pin to regulate negative output while maintaining single-chip simplicity. Use Value: Eliminates need for external inverting op-amp or charge pump; achieves ±1% output accuracy over temperature using –2.49 V internal reference. | Use Scenario: Providing isolated +5 V and –5 V outputs from a single 12 V input in industrial PLC modules with safety isolation requirements. IC Role / Device Role / Timing Role: Dual-polarity feedback controller regulating both outputs simultaneously via FB and NFB pins in flyback configuration. Use Value: Prevents either output from overvoltage during unbalanced loading-e.g., if +5 V is heavily loaded, –5 V remains regulated while +5 V sags slightly. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1372CS8#PBF | Same die, 8-lead SOIC package (S8), θJA = 120°C/W, commercial 0°C to 70°C rating | Suitable for cost-sensitive consumer electronics where industrial temp range and DIP form factor are unnecessary | Select when surface-mount assembly, smaller footprint, or lower thermal mass is prioritized over extended temperature operation. |
| LT1377IS8#PBF | Same architecture but 1 MHz switching frequency, 0.35 A max output in boost, industrial temp, SOIC package | Better suited for ultra-compact designs requiring smallest possible inductors (e.g., 2.2 µH) and higher ripple frequency filtering | Choose when board space is critical and load current ≤0.35 A; note higher switching losses may reduce efficiency at high VIN/VOUT ratios. |
Compared with LT1372CS8#PBF, the LT1372IN8#PBF offers wider –40°C to 125°C operation and through-hole mounting for prototyping or high-reliability industrial use; versus LT1377IS8#PBF, it trades higher output current capability (0.29 A vs 0.35 A) for lower switching frequency (500 kHz), easing EMI filtering and reducing gate drive losses.
Availability
LT1372IN8#PBF is available at Aetrix Electronics and suitable for laptop computer supplies, CCFL backlight drivers, inverting power supplies, and multiple-output flyback converters requiring stable component supply across industrial temperature ranges and long production lifecycles.
Supply support for LT1372IN8#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 support for legacy Linear switching regulator products.
The LT1372 product line was designed for high-efficiency, multi-topology DC/DC conversion in space-constrained industrial and portable applications, emphasizing ease of use, robust protection, and bipolar output capability without external components.
FAQ
What is the maximum output current achievable with the LT1372IN8#PBF in a 5V-to-12V boost configuration?
The LT1372IN8#PBF delivers up to 0.29 A continuous output current in a 5V-to-12V boost converter per the manufacturer's typical performance data. This limit arises from the 1.5 A switch current rating, duty cycle constraints, and thermal dissipation in the 8-lead PDIP package at 125°C junction temperature. Peak currents may exceed this briefly under transient loads, but sustained operation above 0.29 A risks thermal shutdown or reduced reliability.
Can the LT1372IN8#PBF regulate both positive and negative outputs simultaneously?
Yes, the LT1372IN8#PBF supports dual-polarity regulation using both FB and NFB pins in flyback or inverting topologies. When both pins are active, the IC prevents either output from exceeding its setpoint - e.g., in a dual-output flyback, heavy loading on the positive rail causes the negative rail to regulate tightly while the positive rail sags slightly. The FB pin load must remain below 250 µA when NFB is used to maintain accuracy.
What is the purpose of the VC pin on the LT1372IN8#PBF, and how is it used in circuit design?
On the LT1372IN8#PBF, the VC pin serves three critical functions: it is the error amplifier output for loop compensation, the node for adjusting current limit via external clamping, and the point for implementing soft-start with a capacitor. A series RC network from VC to ground sets loop stability; pulling VC below 0.8 V forces zero duty cycle (idle mode); and coupling a capacitor to VC introduces controlled voltage ramp-up during startup to limit inrush current.
Does the LT1372IN8#PBF require an external synchronization signal to operate, or is it self-oscillating?
The LT1372IN8#PBF is fully self-oscillating at 500 kHz and does not require external synchronization. The S/S pin is optional: leaving it open, tying it to VIN, or pulling it high enables normal operation. External synchronization (600–800 kHz square wave) is supported for EMI reduction or system-level timing alignment but is not mandatory. Applying sync before FB reaches 0.7 V at startup may cause instability.
How does the LT1372IN8#PBF handle overload or short-circuit conditions?
The LT1372IN8#PBF employs pulse-by-pulse current limiting with blanking time (130–260 ns) to protect the internal switch during overloads. Under sustained overload, oscillator frequency shifting reduces switching frequency 5:1 when FB drops below 0.6 V, lowering peak switch current and preventing thermal runaway. Unlike some regulators, it lacks hiccup mode or auto-restart - output collapses until fault clears and FB recovers above threshold.
LT1372IN8#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-Up, Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Boost, Cuk, Flyback, Forward Converter, SEPIC
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.7V
- Voltage - Input (Max):
- 30V
- Voltage - Output (Min/Fixed):
- 1.245V
- Voltage - Output (Max):
- 35V (Switch)
- Current - Output:
- 1.5A (Switch)
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LT1372IN8#PBF FAQ
1.How can I place an order for LT1372IN8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1372IN8#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 LT1372IN8#PBF reliable?
The price and inventory of LT1372IN8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1372IN8#PBF is usually 5 days.
3.What payment methods are accepted for LT1372IN8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1372IN8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1372IN8#PBF?
LT1372IN8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1372IN8#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 LT1372IN8#PBF?
For technical support, including LT1372IN8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1372IN8#PBF requirements.
6.How does Aetrix verify that LT1372IN8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1372IN8#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 LT1372IN8#PBF meets industry standards.
7.What is the process for return or replacement of LT1372IN8#PBF?
All LT1372IN8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1372IN8#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 LT1372IN8#PBF part is unused and in its original packaging.
Return procedure for LT1372IN8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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