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Analog Devices Inc. LT1371ISW#TRPBF
- Part No.:
- LT1371ISW#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
LT1371ISW#TRPBF.pdf
- Description:
- IC REG BUCK BOOST ADJ 3A 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:4,403
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Product details
Overview
LT1371ISW#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic 500kHz current-mode switching regulator IC with integrated 3A power switch, designed for boost, buck, flyback, inverting, and Cuk topologies. It regulates positive or negative outputs, features 1.245V reference voltage, 2.7V minimum input voltage, and 12µA shutdown current - used in laptop computer supplies and multiple-output flyback converters.
For engineers reviewing the LT1371ISW#TRPBF datasheet, LT1371ISW#TRPBF pinout, LT1371ISW#TRPBF application, or LT1371ISW#TRPBF equivalent, key selection considerations include its 20-pin SO Wide package, dual feedback capability (FB/NFB), external synchronization support (600–800kHz), nonlinear error amplifier transconductance for reduced startup overshoot, and thermal design implications of θJA = 50°C/W.
Technical Context
The LT1371ISW#TRPBF implements current-mode control with pulse-by-pulse switch current limiting, adaptive anti-saturation driver circuitry, and a 500kHz oscillator with frequency shifting (5:1 reduction under overload). Its error amplifier delivers nonlinear transconductance (1100–1900 µmho) and internal clamping (0.25–2.30V) to suppress output overshoot during startup or load recovery.
It supports dual polarity regulation via separate FB (1.245V reference) and NFB (–2.49V reference) pins, enabling independent positive/negative output sensing without duplicated circuitry. The VC pin serves triple function: error amplifier output, soft-start node, and current limit adjustment point - all accessible externally for loop compensation and protection tuning.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 450–550 kHz (typ. 500 kHz); enables use of compact 4.7µH inductors and reduces EMI filter size. |
| Integrated Switch Current Limit | 3.0–5.4 A (duty-cycle dependent); provides pulse-by-pulse overcurrent protection without external sense resistor. |
| Reference Voltage (FB) | 1.245 V ±1.2%; sets output voltage accuracy in positive configurations using standard resistor dividers. |
| Negative Reference (NFB) | –2.490 V ±20 mV; enables direct regulation of negative outputs with dedicated sensing path. |
| Quiescent Supply Current | 4 mA typ.; minimizes no-load power loss in battery-powered systems like laptops. |
| Shutdown Current | 12 µA typ.; extends battery life during system sleep modes. |
| Minimum Input Voltage | 2.7 V; supports single-cell Li-ion (3.0V nominal) and 3.3V rail operation with margin. |
| Error Amplifier Transconductance | 1100–1900 µmho; determines loop gain stability and transient response speed. |
Pinout & Package
LT1371ISW#TRPBF is housed in a 20-lead plastic SO Wide (SW) package with exposed ground pads (pins 4–7 and 14–17) for thermal conduction. Thermal resistance is θJA = 50°C/W (typ.) on double-sided PCB with 0.33 in² copper; mounting technique significantly impacts thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC | Error amplifier output / compensation node | External RC network sets loop stability; clamping controls soft-start and current limit. |
| FB | Positive output voltage feedback input | Connects to resistor divider for +VOUT regulation; bias current ≤550 nA affects accuracy. |
| NFB | Negative output voltage feedback input | Connects to resistor divider for –VOUT regulation; bias current ≈ –30 µA requires compensation. |
| SHDN | Active-low shutdown control | Pull low to reduce supply current to 12 µA; threshold 0.6–2.0 V ensures logic-level compatibility. |
| SYNC | External clock synchronization input | Accepts 600–800 kHz square wave to align switching; prevents beat frequencies in multi-regulator systems. |
| VIN | Main input supply (2.7–25 V) | Bypass with ≥10 µF low-ESR capacitor; undervoltage lockout triggers below 2.5 V. |
| VSW | Switch collector node | Carries high di/dt current; requires shortest possible trace to diode/capacitor to minimize EMI and ringing. |
| GND (x8) | Power and signal ground returns | Pins 4–7 and 14–17 are internally tied and thermally connected; must connect to solid ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode topology with adaptive anti-saturation driver | Enables rapid switch turn-off, reduces driver dissipation, and maintains efficiency across wide input/output ranges. |
| Nonlinear error amplifier transconductance | Doubles gain when FB exceeds VREF by 40 mV, suppressing output overshoot during startup or overload recovery. |
| Dual feedback architecture (FB + NFB) | Allows simultaneous regulation of positive and negative outputs using shared error amplifier core-no extra die area. |
| Oscillator frequency shifting (5:1 reduction) | Reduces switching frequency under overload, lowering peak switch current and protecting external components. |
| Logic-compatible SHDN and SYNC pins | Eliminates need for level-shifting circuitry; supports direct connection to microcontroller GPIO or clock sources. |
| Low dropout internal 2.3V bias regulator | Maintains stable internal operation down to VIN = 2.7 V, enabling reliable start-up from weak or depleted batteries. |
Applications
| Laptop Computer Power Supply | Multiple-Output Flyback Converter |
|---|---|
Use Scenario: Generating 12V/0.7A boost rail from 5V USB-C PD source in ultraportable notebooks. IC Role / Device Role / Timing Role: Primary controller implementing current-mode boost topology with synchronous rectification support. Use Value: 4mA quiescent current extends standby battery life; 500kHz switching allows <5mm-height inductor integration. |
Use Scenario: Isolated dual-output (±15V) supply for op-amp biasing in industrial data acquisition modules. IC Role / Device Role / Timing Role: Flyback controller regulating both rails independently via FB and NFB pins with cross-regulation. Use Value: Eliminates need for secondary-side optocouplers or TL431 references; reduces BOM count and layout area. |
| Inverting DC-DC Supply | Programmable Negative Bias Generator |
Use Scenario: Converting 3.3V logic rail to –5V for RS-232 transceivers in embedded IoT gateways. IC Role / Device Role / Timing Role: Inverting buck-boost controller using single inductor and Schottky diode. Use Value: –2.49V NFB reference enables precise negative output setting; 2.7V min VIN supports direct 3.3V rail operation. |
Use Scenario: Adjustable –1.25V to –15V bias supply for CCD sensor analog front-ends in medical imaging devices. IC Role / Device Role / Timing Role: Programmable inverting regulator with external resistor divider on NFB pin. Use Value: Nonlinear transconductance prevents output overshoot during fast DAC-setpoint transitions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3573EDD#TRPBF | Higher 2.5MHz switching frequency; integrated 1.5A switch; no NFB pin; requires external compensation. | Optimized for ultra-compact designs needing >1MHz operation; lacks native negative output regulation. | Select when board space is critical and only positive outputs are required; avoid if dual-polarity regulation is needed. |
| TPS54331DR | 3.5A switch; 570kHz fixed frequency; no NFB pin; integrated boot diode; different compensation scheme. | Designed for cost-sensitive consumer power supplies; supports only positive output configurations. | Choose for high-volume production where TI's ecosystem and lower unit cost outweigh missing NFB functionality. |
Compared with LT1371ISW#TRPBF, LT3573EDD#TRPBF offers higher frequency but sacrifices dual-polarity regulation, while TPS54331DR provides higher current and lower cost but eliminates negative output capability entirely - making LT1371ISW#TRPBF uniquely suited for mixed-rail industrial and test equipment designs.
Availability
LT1371ISW#TRPBF is available at Aetrix Electronics and suitable for laptop computer supplies, multiple-output flyback converters, inverting DC-DC supplies, programmable negative bias generators, and industrial isolated power modules requiring stable component supply across extended temperature and long product lifecycles.
Supply support for LT1371ISW#TRPBF 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 its legacy of high-performance analog and power management ICs with rigorous reliability testing and long-term product support.
The LT1371ISW#TRPBF belongs to Linear's high-frequency current-mode switching regulator family, engineered for flexible topology implementation (boost/buck/flyback/inverting) in space-constrained, efficiency-critical applications such as portable computing and precision instrumentation.
FAQ
What is the maximum output current achievable with LT1371ISW#TRPBF in a boost configuration?
The LT1371ISW#TRPBF integrates a 3A switch with current limit ranging from 3.0A to 5.4A depending on duty cycle. In a typical 5V-to-12V boost converter, practical continuous output current is ~0.7–0.8A due to thermal limits (θJA = 50°C/W) and inductor saturation constraints. Peak switch current must remain below the guaranteed 3.0A minimum limit at 50% duty cycle per the datasheet's ILIM specification for LT1371ISW#TRPBF.
Can LT1371ISW#TRPBF regulate both positive and negative outputs simultaneously?
Yes, LT1371ISW#TRPBF supports simultaneous regulation of positive and negative outputs using its dual feedback architecture: the FB pin senses positive output voltage against a 1.245V reference, while the NFB pin senses negative output against a –2.49V reference. When both pins are used, the IC prevents either rail from exceeding its setpoint - demonstrated in the "Dual Output Flyback Converter with Overvoltage Protection" typical application circuit for LT1371ISW#TRPBF.
What is the purpose of the VC pin on LT1371ISW#TRPBF, and how is it used in compensation?
The VC pin on LT1371ISW#TRPBF is the error amplifier output and serves three functions: frequency compensation, soft-start control, and current limit adjustment. Loop compensation uses an external series RC network from VC to ground - the capacitor forms a dominant pole (~2–20 Hz), and the resistor introduces a zero (~1–5 kHz) to improve phase margin. A second small capacitor (e.g., 0.0047µF) shunted across the resistor further attenuates switching ripple on VC, keeping it below 50mVP–P to prevent irregular switching in LT1371ISW#TRPBF.
Does LT1371ISW#TRPBF support external clock synchronization, and what is the valid frequency range?
Yes, LT1371ISW#TRPBF supports external clock synchronization via the SYNC pin (pin 9 in SW package). The guaranteed synchronization range is 600–800 kHz, corresponding to 1.05× to 1.8× its natural 500kHz switching frequency. Driving SYNC outside this band may result in unstable or unlocked operation. For LT1371ISW#TRPBF, the SYNC pin can be left floating, tied high/low, or driven with a clean square wave - unlike the S/S pin in R/T7 packages, SYNC has no shutdown function.
How does the nonlinear transconductance of the error amplifier in LT1371ISW#TRPBF improve system performance?
The error amplifier in LT1371ISW#TRPBF exhibits nonlinear transconductance: it increases ~10× when the FB pin voltage exceeds the 1.245V reference by 40mV. This behavior actively suppresses output voltage overshoot during startup or sudden load recovery by rapidly increasing loop gain just when it's most needed. As a result, LT1371ISW#TRPBF achieves tighter transient response without requiring complex compensation networks or external components - a key advantage over conventional linear transconductance amplifiers.
LT1371ISW#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 3A (Switch)
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
LT1371ISW#TRPBF FAQ
1.How can I place an order for LT1371ISW#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1371ISW#TRPBF 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 LT1371ISW#TRPBF reliable?
The price and inventory of LT1371ISW#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1371ISW#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1371ISW#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1371ISW#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1371ISW#TRPBF?
LT1371ISW#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1371ISW#TRPBF 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 LT1371ISW#TRPBF?
For technical support, including LT1371ISW#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1371ISW#TRPBF requirements.
6.How does Aetrix verify that LT1371ISW#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1371ISW#TRPBF 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 LT1371ISW#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1371ISW#TRPBF?
All LT1371ISW#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1371ISW#TRPBF, 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 LT1371ISW#TRPBF part is unused and in its original packaging.
Return procedure for LT1371ISW#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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