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Analog Devices Inc. LT1371CR#PBF
- Part No.:
- LT1371CR#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LT1371CR#PBF.pdf
- Description:
- IC REG BUCK BOOST ADJ 3A DDPAK-7
- Quantity:
- Payment:
- Shipping:
Inventory:434
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Product details
Overview
LT1371CR#PBF from Analog Devices (formerly Linear Technology) is a monolithic 500kHz current-mode switching regulator IC with an integrated 3A power switch, designed for boost, buck, flyback, forward, inverting, and Cuk topologies. It delivers up to 0.8A output current in a 5V-to-12V boost configuration, operates down to 2.7V input, and achieves >90% efficiency at 5VIN/12VOUT. It is used in laptop computer supplies and multiple-output flyback converters.
For engineers reviewing the LT1371CR#PBF datasheet, LT1371CR#PBF pinout, LT1371CR#PBF application, or LT1371CR#PBF equivalent, key selection considerations include its 3A internal switch, ±2.49V dual-polarity feedback architecture, 12µA shutdown current, 500kHz fixed-frequency operation, and R-package thermal performance (θJA = 30°C/W with 0.5 in² copper).
Technical Context
The LT1371CR#PBF implements current-mode control with pulse-by-pulse switch current limiting, enabling fast line transient response and simplified loop compensation. Its error amplifier features nonlinear transconductance (1100–1900 µmho) that increases 10× when FB exceeds VREF by 40mV, reducing output overshoot during startup or overload recovery.
Oscillator frequency shifting (5:1 reduction below 0.6V FB) protects external components under overload; adaptive anti-saturation circuitry minimizes switch turn-off time and driver dissipation. The VC pin serves triple duty: error amplifier output, soft-start node, and current-limit adjustment point - all enabled by a gm-type amplifier with 500 V/V voltage gain and clamp voltages of 0.25–2.30V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 450–550 kHz typical; enables use of 4.7 µH inductors and reduces magnetic component size. |
| Integrated Switch Current Limit | 3.0–5.4 A; provides pulse-by-pulse overcurrent protection without external sensing. |
| Reference Voltage (FB) | 1.245 V ±15 mV; sets positive output voltage via resistor divider with <550 nA input bias. |
| Negative Feedback Reference (NFB) | –2.490 V ±50 mV; enables direct negative output regulation without auxiliary amplifiers. |
| Quiescent Supply Current | 4 mA typical; supports high-efficiency operation in battery-powered systems. |
| Shutdown Supply Current | 12 µA typical; allows ultra-low-power standby in portable applications. |
| Minimum Input Voltage | 2.7 V; permits operation from single-cell Li-ion or two-cell alkaline inputs. |
| Output Switch Breakdown Voltage | 35 V; supports boost outputs up to ~30 V with margin for transients. |
Pinout & Package
The LT1371CR#PBF is housed in a 7-lead plastic DD (R) package with exposed tab connected to GND for thermal conduction. Thermal resistance is θJA = 30°C/W when soldered to 0.5 in² copper area over ground plane.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1: VC | Compensation / Error Amplifier Output | Carries gm-amplifier output; used for RC frequency compensation, soft-start, and current limit adjustment. |
| 2: FB | Positive Feedback Input | Inverting input of main error amp; referenced to 1.245 V; max 250 nA bias current. |
| 3: NFB | Negative Feedback Input | Inverting input of negative-feedback amp; referenced to –2.49 V; –30 µA bias current. |
| 4: GND | Power Ground | Main ground return for switch, logic, and error amplifier; connects to exposed tab. |
| 5: VIN | Input Supply | Bypass with ≥10 µF low-ESR capacitor; UVLO triggers below 2.5 V. |
| 6: S/S | Shutdown & Sync | Logic-level active-low shutdown (1.3 V threshold); also accepts 600–800 kHz sync signal. |
| 7: VSW | Switch Collector | High-current node for internal 3A NPN switch; requires shortest possible PCB trace routing. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-polarity regulation | Single IC regulates both positive (via FB) and negative (via NFB) outputs using shared error amplifier core. |
| Nonlinear error amplifier transconductance | Transconductance jumps 10× above 40 mV FB overdrive, suppressing startup/overload overshoot. |
| Oscillator frequency shifting | Reduces switching frequency 5:1 when FB < 0.6 V, limiting peak switch current during overload. |
| Adaptive anti-saturation drive | Dynamically adjusts base drive to minimize switch saturation voltage and enable rapid turn-off. |
| External synchronization | S/S pin accepts 600–800 kHz logic-level clock, enabling noise-sensitive system timing alignment. |
| Low minimum supply voltage | Operates from 2.7 V input, supporting single-cell Li-ion and multi-cell alkaline battery systems. |
Applications
| Laptop Computer Supplies | Multiple-Output Flyback Supplies |
|---|---|
Use Scenario: Generating 12 V and –5 V rails from a 5 V bus in ultraportable notebooks with strict space and efficiency constraints. IC Role / Device Role / Timing Role: Primary controller regulating both polarities simultaneously via FB and NFB pins in flyback topology. Use Value: Eliminates need for separate positive/negative regulators, reducing BOM count and PCB area while maintaining ±1% output accuracy. |
Use Scenario: Isolated dual-output DC/DC converter powering analog sensor front-end (+3.3 V) and digital interface (–3.3 V) in industrial I/O modules. IC Role / Device Role / Timing Role: Current-mode flyback controller with synchronized switching to minimize EMI coupling between outputs. Use Value: Achieves cross-regulation better than ±3% across load steps using single transformer winding and shared feedback architecture. |
| Inverting Supplies | Boost Regulators |
Use Scenario: Generating –12 V from 5 V USB power for op-amp biasing in portable test equipment. IC Role / Device Role / Timing Role: Inverting topology controller using NFB pin as primary feedback reference at –2.49 V. Use Value: Delivers 0.5 A at –12 V with <150 mV ripple, avoiding discrete inverter ICs or charge pumps with poor PSRR. |
Use Scenario: Step-up converter boosting 5 V system rail to 12 V for SSD power management in embedded storage controllers. IC Role / Device Role / Timing Role: High-efficiency boost controller with 3A internal switch and 4.7 µH inductor. Use Value: Maintains >88% efficiency at full 0.7 A load while fitting within 10 mm × 10 mm board area. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3573EDD#PBF | Higher 3.5 MHz switching frequency; 2.5 A switch; no NFB pin; requires external compensation. | Targets space-constrained apps needing smaller magnetics; lacks native negative output capability. | Select when board area is critical and only positive regulation is required. |
| TPS55340RTER | 4 A switch; 1.2 MHz fixed frequency; integrated soft-start; no negative feedback support. | Optimized for high-current boost with lower EMI via spread-spectrum option; no dual-polarity function. | Choose for higher output current (up to 2 A) where negative rail generation is handled separately. |
Compared with LT1371CR#PBF, LT3573EDD#PBF offers higher frequency and smaller passives but sacrifices dual-polarity regulation; TPS55340RTER delivers greater current and built-in soft-start but requires external circuitry for negative outputs - making LT1371CR#PBF uniquely suited for compact dual-rail designs.
Availability
LT1371CR#PBF is available at Aetrix Electronics and suitable for laptop computer supplies, multiple-output flyback supplies, and inverting supplies requiring stable component supply across industrial temperature ranges and long production lifecycles.
Supply support for LT1371CR#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 its legacy of high-performance analog and power management ICs with rigorous reliability testing and automotive-grade qualification paths.
The LT1371CR#PBF belongs to Linear's legacy current-mode switching regulator family, engineered for flexible topology support (boost/buck/flyback/inverting), minimal external component count, and robust operation in portable and industrial power systems.
FAQ
What is the maximum output current achievable with the LT1371CR#PBF in a boost configuration?
The LT1371CR#PBF supports up to 0.8 A output current in a standard 5V-to-12V boost application, as verified in the Typical Application diagram (TA02). This limit arises from thermal constraints of the R-package (θJA = 30°C/W) and the 3A switch current limit derated by duty cycle and inductor selection. Higher currents require forced air cooling or larger copper areas.
Can the LT1371CR#PBF regulate both positive and negative outputs simultaneously?
Yes, the LT1371CR#PBF can regulate both polarities simultaneously using its dual feedback architecture: the FB pin references +1.245 V for positive outputs, and the NFB pin references –2.49 V for negative outputs. When both pins are active, the IC prevents either rail from exceeding its setpoint - a feature demonstrated in the "Dual Output Flyback Converter" application circuit.
What is the purpose of the VC pin on the LT1371CR#PBF, and how is it used in design?
The VC pin on the LT1371CR#PBF is the output of the gm-type error amplifier and serves three critical functions: (1) frequency compensation via RC network, (2) soft-start control via capacitor-coupled clamping, and (3) current limit adjustment by externally clamping its voltage. During normal operation, VC sits between 1.0 V (light load) and 1.9 V (heavy load), directly modulating switch duty cycle.
Does the LT1371CR#PBF support external clock synchronization, and what is the valid frequency range?
Yes, the LT1371CR#PBF supports external synchronization via the S/S pin (R-package), which accepts logic-level signals from 600 kHz to 800 kHz. This range is guaranteed per the Electrical Characteristics table; operation outside this band may cause erratic switching or loss of regulation. The S/S pin also serves as active-low shutdown input with 1.3 V threshold.
What thermal management guidance applies to the LT1371CR#PBF in the R-package?
The LT1371CR#PBF in the R-package has θJA = 30°C/W when mounted on 0.5 in² copper over a ground plane. To avoid exceeding the 125°C junction limit, total power dissipation must stay below 2.5 W at 70°C ambient. Layout best practices include direct tab-to-ground soldering, short high-current traces (especially VSW), and minimizing thermal resistance through copper fill and vias beneath the GND pins.
LT1371CR#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- 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:
- 3A (Switch)
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DDPAK-7
LT1371CR#PBF FAQ
1.How can I place an order for LT1371CR#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1371CR#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 LT1371CR#PBF reliable?
The price and inventory of LT1371CR#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1371CR#PBF is usually 5 days.
3.What payment methods are accepted for LT1371CR#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1371CR#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1371CR#PBF?
LT1371CR#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1371CR#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 LT1371CR#PBF?
For technical support, including LT1371CR#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1371CR#PBF requirements.
6.How does Aetrix verify that LT1371CR#PBF is sourced from the original manufacturer or authorized distributors?
All LT1371CR#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 LT1371CR#PBF meets industry standards.
7.What is the process for return or replacement of LT1371CR#PBF?
All LT1371CR#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1371CR#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 LT1371CR#PBF part is unused and in its original packaging.
Return procedure for LT1371CR#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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