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Analog Devices Inc. LT1371IR#PBF
- Part No.:
- LT1371IR#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LT1371IR#PBF.pdf
- Description:
- IC REG BUCK BOOST ADJ 3A DDPAK-7
- Quantity:
- Payment:
- Shipping:
Inventory:2,364
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Product details
Overview
LT1371IR#PBF 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, operates down to 2.7V input, delivers up to 0.8A at 12V in boost configuration, and features 4mA typical quiescent current and 12µA shutdown current.
For engineers reviewing the LT1371IR#PBF datasheet, LT1371IR#PBF pinout, LT1371IR#PBF application, or LT1371IR#PBF equivalent, key selection considerations include its 7-lead DD package thermal performance (θJA = 30°C/W), dual feedback architecture (FB/NFB), external synchronization capability (600–800kHz), and nonlinear error amplifier transconductance for reduced startup overshoot.
Technical Context
The LT1371IR#PBF implements current-mode control with pulse-by-pulse switch current limiting, where duty cycle is directly set by sensed switch current rather than output voltage. Its internal 1.245V bandgap reference feeds the FB pin for positive regulation, while the NFB pin provides –2.49V reference for negative output sensing via an external 100kΩ source resistor.
Switching is governed by a 500kHz oscillator (±50kHz over temperature), with adaptive anti-saturation driver circuitry minimizing switch turn-off time and dissipation. The VC pin serves as error amplifier output, enabling frequency compensation, soft-start, and current limit adjustment through external RC networks.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 500kHz nominal; enables use of compact 4.7µH inductors and reduces EMI filter size. |
| Integrated Switch Current Limit | 3.0A typical; supports up to 0.8A output in 5V-to-12V boost with 4.7µH inductor per typical application. |
| Reference Voltage (FB) | 1.245V ±15mV; sets output voltage via resistor divider; low drift ensures stable regulation across temperature. |
| Negative Reference (NFB) | –2.490V ±50mV; enables direct negative output regulation without external op-amps or level shifters. |
| Quiescent Current | 4mA typical; minimizes standby power loss in battery-powered systems like laptop supplies. |
| Shutdown Current | 12µA typical; allows deep sleep mode with negligible battery drain during system idle. |
| Minimum Input Voltage | 2.7V; supports single-cell Li-ion (3.0V nominal) and two-cell alkaline (3.2V fresh) input sources. |
| Error Amplifier gm | 1500µmho typical; high transconductance enables fast transient response and tight load regulation. |
Pinout & Package
The LT1371IR#PBF is housed in a 7-lead plastic DD (R) package with exposed tab for thermal conduction to PCB ground plane. θJA = 30°C/W when soldered to 0.5 in² copper area.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - GND | Power Ground | Primary return path for switch current and internal bias; must connect directly to ground plane under tab. |
| 2 - VIN | Input Supply | Bypass with ≥10µF low-ESR capacitor; UVLO activates below 2.5V to prevent erratic operation. |
| 3 - S/S | Shutdown/Sync | Logic-level input: low = shutdown (12µA IQ); AC-coupled >600kHz signal = synchronization. |
| 4 - VSW | Switch Collector | High-current node (3A peak); trace length must be minimized to reduce EMI and voltage spikes. |
| 5 - GND | Power Ground | Second ground pin; ties to same ground plane as Pin 1 to reduce ground loop impedance. |
| 6 - NFB | Negative Feedback Input | Senses negative output via resistor divider; internal –2.49V reference enables direct regulation. |
| 7 - FB | Positive Feedback Input | Senses positive output; internal 1.245V reference; max loading 250µA when NFB is active. |
| Tab | Thermal Pad / GND | Exposed metal tab is electrically connected to GND and serves as primary heat path to PCB. |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode control architecture | Enables inherent pulse-by-pulse current limiting, fast line transient response, and simplified loop compensation. |
| Nonlinear error amplifier transconductance | Doubles gm when FB exceeds VREF by 40mV, reducing output overshoot during startup and overload recovery. |
| Oscillator frequency shifting | Reduces switching frequency 5:1 when FB drops below 0.6V, protecting components during overload or short-circuit events. |
| Dual feedback capability (FB + NFB) | Allows single IC to regulate both positive and negative outputs simultaneously in dual-flyback designs without extra amplifiers. |
| External synchronization range | Accepts 600–800kHz logic-level sync signals, enabling noise-sensitive systems to avoid critical EMI bands. |
| Soft-start via VC pin | Capacitor coupling to VC pin provides controlled ramp-up of output voltage, eliminating inrush current stress. |
Applications
| Laptop Computer Supplies | Multiple Output Flyback Supplies |
|---|---|
|
Use Scenario: Generating 12V rail from 5V USB-C PD or 3.3V/5V system bus in portable computing devices. IC Role / Device Role / Timing Role: Primary DC-DC controller implementing boost topology with integrated 3A switch and current-mode regulation. Use Value: Eliminates need for external MOSFET and gate driver; 4mA quiescent current extends battery runtime between charges. |
Use Scenario: Isolated dual-output (±12V) supply for analog front-ends in industrial data acquisition modules. IC Role / Device Role / Timing Role: Regulates both polarities using FB and NFB pins simultaneously, with shared oscillator and current sense. Use Value: Reduces component count vs. dual-controller solution; maintains cross-regulation via common current-mode loop. |
| Inverting Supplies | Boost Regulators for Low-Voltage Sensors |
|
Use Scenario: Generating –5V bias for op-amp rails or ADC reference buffers from a 3.3V microcontroller supply. IC Role / Device Role / Timing Role: Configured in inverting topology with NFB pin regulating negative output referenced to system ground. Use Value: Avoids discrete inverter ICs or charge pumps; achieves <1% output accuracy with simple resistor divider. |
Use Scenario: Powering 5V MEMS sensors from coin-cell batteries (2.0–3.0V) in wireless IoT edge nodes. IC Role / Device Role / Timing Role: High-efficiency boost controller operating down to 2.7V VIN with 500kHz switching for minimal inductor size. Use Value: Enables use of 2.0mm-height 4.7µH shielded inductors; 90% peak efficiency at 100mA load preserves battery life. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1372IS8#PBF | 8-pin SOIC package; higher θJA (50°C/W); no NFB pin; fixed 500kHz frequency only. | Lacks dual-polarity regulation; suited for single-rail boost/buck where space permits larger package. | Select when negative output regulation is unnecessary and board layout favors SOIC over DD. |
| LM2577-ADJ | Fixed 52kHz frequency; 3A switch; no NFB pin; requires external compensation; higher IQ (10mA). | Lower switching frequency demands larger magnetics; not suitable for compact or noise-sensitive designs. | Choose for cost-sensitive industrial supplies where EMI filtering is less critical and thermal budget is宽松. |
Compared with LT1372IS8#PBF and LM2577-ADJ, the LT1371IR#PBF uniquely supports simultaneous positive/negative regulation in a thermally optimized DD package, offers 500kHz operation for miniaturization, and delivers lower quiescent current-making it optimal for space-constrained, battery-powered dual-rail systems.
Availability
LT1371IR#PBF is available at Aetrix Electronics and suitable for laptop computer supplies, multiple-output flyback converters, inverting supplies, and low-voltage boost regulators requiring stable component supply and long-term industrial availability.
Supply support for LT1371IR#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 expertise for legacy Linear parts including the LT1371 family.
The LT1371IR#PBF belongs to Linear's high-frequency current-mode switching regulator product line, engineered for compact, efficient DC-DC conversion in portable and multi-rail power systems where thermal performance and dual-polarity capability are critical.
FAQ
What is the maximum output current achievable with the LT1371IR#PBF in a 5V-to-12V boost configuration?
The LT1371IR#PBF supports up to 0.8A output current in a standard 5V-to-12V boost converter using a 4.7µH inductor (Coilcraft DO3316P-472), as verified in the Typical Application diagram TA02. This assumes 25°C ambient, proper thermal layout (0.5 in² copper), and continuous conduction mode. Peak switch current remains within the 3A limit, and efficiency exceeds 90% at this load point.
Can the LT1371IR#PBF regulate both positive and negative outputs simultaneously?
Yes, the LT1371IR#PBF can regulate both polarities simultaneously using its dedicated FB and NFB pins. In dual-output flyback configurations, the IC prevents either rail from exceeding its setpoint-e.g., if the positive output is heavily loaded, the negative output remains regulated while the positive sags slightly. Load on the FB pin must not exceed 250µA when NFB is active, per datasheet Figure 2 and Applications Information section.
What is the purpose of the VC pin on the LT1371IR#PBF, and how is it used in design?
The VC pin on the LT1371IR#PBF is the error amplifier output and serves three functions: frequency compensation (via RC network to ground), current limit adjustment (by clamping VC voltage), and soft-start (via capacitor coupling). During normal operation, VC sits between 1.0V and 1.9V. Pulling VC below 0.8V forces zero duty cycle, placing the IC in idle mode-enabling precise current limiting and controlled startup without external circuitry.
Does the LT1371IR#PBF require external components for synchronization, and what is the valid frequency range?
The LT1371IR#PBF accepts external synchronization on its S/S pin without additional components: a logic-level square wave (0–5V) between 600kHz and 800kHz synchronizes switching. Frequencies outside this range are not guaranteed. The S/S pin is compatible with standard CMOS/TTL drivers; no pull-up or level-shifting is needed, and the pin may be left floating for free-running operation.
How does the LT1371IR#PBF handle overload or short-circuit conditions?
The LT1371IR#PBF employs multiple protection mechanisms: pulse-by-pulse current limiting (3.0A typical switch limit), oscillator frequency shifting (5:1 reduction when FB < 0.6V), and thermal shutdown (junction limit 125°C). During sustained overload, frequency reduction lowers average power dissipation, while the current limit prevents switch destruction. No external foldback or hiccup circuitry is required for basic protection.
LT1371IR#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
LT1371IR#PBF FAQ
1.How can I place an order for LT1371IR#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1371IR#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 LT1371IR#PBF reliable?
The price and inventory of LT1371IR#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1371IR#PBF is usually 5 days.
3.What payment methods are accepted for LT1371IR#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1371IR#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1371IR#PBF?
LT1371IR#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1371IR#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 LT1371IR#PBF?
For technical support, including LT1371IR#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1371IR#PBF requirements.
6.How does Aetrix verify that LT1371IR#PBF is sourced from the original manufacturer or authorized distributors?
All LT1371IR#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 LT1371IR#PBF meets industry standards.
7.What is the process for return or replacement of LT1371IR#PBF?
All LT1371IR#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1371IR#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 LT1371IR#PBF part is unused and in its original packaging.
Return procedure for LT1371IR#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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