My Inquiry
My Account
Analog Devices Inc. LT1371ISW#PBF
- Part No.:
- LT1371ISW#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
LT1371ISW#PBF.pdf
- Description:
- IC REG BUCK BOOST ADJ 3A 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,810
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT1371ISW#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, features 1.245V reference voltage, 4mA typical quiescent current, and operates down to 2.7V input voltage - used in laptop computer supplies and multiple-output flyback converters.
For engineers reviewing the LT1371ISW#PBF datasheet, LT1371ISW#PBF pinout, LT1371ISW#PBF application, or LT1371ISW#PBF equivalent, key selection considerations include its 20-pin SO Wide package, dual feedback capability (FB/NFB), external synchronization support (600–800kHz), shutdown current of 12µA, and thermal design implications given θJA = 50°C/W.
Technical Context
The LT1371ISW#PBF implements current-mode control with adaptive anti-saturation driver circuitry, enabling fast switch turn-off and precise pulse-by-pulse current limiting up to 3.8A. 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; VC pin serves triple function - compensation node, soft-start control, and current limit adjustment - while NFB pin enables direct regulation of negative outputs at –2.49V reference.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 450–550 kHz (typ. 500 kHz); enables use of small 4.7µH inductors and reduces filter size. |
| Integrated Switch Current Limit | 3.0–5.4 A (duty-cycle dependent); provides robust short-circuit protection without external sensing. |
| Reference Voltage (FB) | 1.245 V ±15 mV; sets output voltage via resistor divider with minimal bias current error (≤550 nA). |
| Negative Reference (NFB) | –2.490 V ±50 mV; allows direct negative output regulation without additional amplifiers. |
| Quiescent Supply Current | 4 mA typ.; supports high-efficiency operation in battery-powered systems like laptops. |
| Shutdown Current | 12 µA typ.; enables ultra-low-power standby mode for portable applications. |
| Minimum Input Voltage | 2.7 V; permits operation from single-cell Li-ion or two-cell alkaline inputs. |
| Error Amplifier Transconductance | 1100–1900 µmho; delivers fast transient response and stable loop compensation with RC network on VC pin. |
Pinout & Package
LT1371ISW#PBF is housed in a 20-lead plastic SO Wide (SW) package with exposed ground pins for thermal dissipation. Thermal resistance is θJA = 50°C/W (dependent on PCB copper area), and θJC = 4°C/W. Ground pins (4, 5, 6, 7, 14, 15, 16, 17) are internally tied to die substrate and must be connected to a low-impedance ground plane.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC | Compensation / Error Amplifier Output | External RC network sets loop stability; clamping controls soft-start and current limit; voltage range 1.0–1.9V reflects load condition. |
| FB | Positive Feedback Input | Inverting input of main error amp; referenced to 1.245V internal bandgap; bias current ≤550 nA minimizes divider error. |
| NFB | Negative Feedback Input | Inverting input of dedicated negative-feedback amp; referenced to –2.49V; bias current –30 µA requires divider compensation. |
| VIN | Input Supply | Bypass with ≥10 µF low-ESR capacitor; UVLO activates below 2.5V; supports 2.7–25V input range. |
| VSW | Switch Node | Collector of integrated 3A NPN switch; carries high di/dt current; trace length must be minimized to reduce EMI and voltage spikes. |
| SHDN | Active-Low Shutdown | Pull low to reduce supply current to 12 µA; threshold 0.6–2.0 V; 5–25 µs delay prevents false triggering. |
| SYNC | External Synchronization Input | Accepts 600–800 kHz logic-level square wave; allows system-level clock alignment and EMI reduction. |
| GND (Pins 4,5,6,7,14,15,16,17) | Power & Signal Ground | All eight GND pins connect to common substrate; must be tied directly to solid ground plane for thermal and noise performance. |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode topology with adaptive anti-saturation driver | Enables <100 ns switch turn-off, reduces conduction loss, and eliminates need for external current-sense resistor. |
| Dual feedback architecture (FB + NFB) | Supports independent regulation of positive and negative outputs in same design, e.g., dual-rail flyback supplies. |
| Nonlinear error amplifier transconductance | 10× gain increase above VREF +40 mV suppresses overshoot during startup and load transients without complex compensation. |
| Oscillator frequency shifting | Reduces switching frequency 5:1 when FB < 0.6 V, limiting peak switch current and protecting inductor/diode during overload. |
| Logic-compatible SHDN and SYNC pins | Eliminates need for level-shifting circuitry; SYNC accepts standard CMOS/TTL signals; SHDN achieves 12 µA standby current. |
| Low dropout internal 2.3V bias regulator | Maintains stable internal operation across full 2.7–25V VIN range, ensuring consistent performance regardless of input variation. |
Applications
| Laptop Computer Power Supply | Dual-Output Flyback Converter |
|---|---|
|
Use Scenario: Generating isolated 12V and –5V rails from a 5V USB-C or battery source in ultraportable computing platforms. IC Role / Device Role / Timing Role: LT1371ISW#PBF acts as primary-side controller in flyback topology, regulating both outputs via FB and NFB pins with shared oscillator and current-sense path. Use Value: Eliminates need for secondary-side optocoupler feedback or separate regulators, reducing BOM count and board space while maintaining ±1% output accuracy. |
Use Scenario: Providing tightly regulated +15V and –15V analog supply for precision op-amp and ADC circuits in industrial data acquisition modules. IC Role / Device Role / Timing Role: LT1371ISW#PBF configures as inverting Cuk converter, using NFB for negative rail regulation and FB for positive rail, with synchronized switching to minimize inter-rail coupling. Use Value: Achieves cross-regulation better than 3% between rails without post-regulation LDOs, leveraging shared current-mode control and matched thermal tracking. |
| High-Efficiency Boost Converter | Inverting DC/DC Supply |
|
Use Scenario: Stepping up 3.3V system rail to 12V for USB peripheral powering in embedded edge devices with strict thermal limits. IC Role / Device Role / Timing Role: LT1371ISW#PBF operates in boost configuration with 4.7µH inductor, delivering up to 0.8A at 90% efficiency while maintaining 4mA quiescent draw. Use Value: Enables compact, fanless design using surface-mount magnetics and tantalum output capacitors (TPSD226M025R0200), meeting IEC 62368-1 creepage requirements. |
Use Scenario: Generating –5V from 5V rail for RS-232 interface ICs in IoT gateway hardware where space and component count are constrained. IC Role / Device Role / Timing Role: LT1371ISW#PBF configured as inverting regulator, using NFB pin to sense negative output and VC pin for soft-start ramp control. Use Value: Delivers –5.0V ±2% at 300mA with no external op-amp or charge pump, reducing solution size by 40% versus discrete inverter designs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3872EMS#TRPBF | Fixed 300kHz frequency, no NFB pin, requires external MOSFET; higher efficiency (94%) but lacks negative output capability. | Suitable only for positive-output boost/buck applications; no native inverting or dual-rail support. | Select when higher efficiency and lower EMI at fixed frequency are prioritized over dual-polarity regulation. |
| LM5122MMX/NOPB | Wide-input (3–65V), adjustable frequency (50–750kHz), integrated high-side MOSFET driver; no internal switch or NFB functionality. | Requires external N-channel MOSFET and separate negative regulator; better for high-VIN industrial supplies. | Choose for >25V input systems or when programmable frequency and external FET control outweigh integration benefits. |
Compared with LTC3872EMS#TRPBF and LM5122MMX/NOPB, LT1371ISW#PBF uniquely integrates both positive and negative feedback paths, an internal 3A switch, and oscillator frequency shifting - making it the only option among the three capable of single-chip dual-polarity regulation with overload self-protection.
Availability
LT1371ISW#PBF is available at Aetrix Electronics and suitable for laptop computer supplies, dual-output flyback converters, and inverting DC/DC supplies requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LT1371ISW#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 emphasis on precision, reliability, and application-specific integration.
The LT1371 product line was designed for high-frequency, multi-topology DC/DC conversion in space-constrained and thermally sensitive applications - especially portable computing, test equipment, and industrial instrumentation requiring dual-polarity outputs.
FAQ
What is the maximum output current achievable with LT1371ISW#PBF in boost configuration?
The LT1371ISW#PBF supports up to 0.8A output current in a 5V-to-12V boost configuration using a 4.7µH inductor, as verified in the Typical Application circuit (TA02). Peak switch current is limited to 3.0–5.4A depending on duty cycle, and thermal limits (θJA = 50°C/W) constrain continuous output to ~0.7A at ambient 70°C with 0.75 in² copper. Derating is required above 60°C ambient.
Can LT1371ISW#PBF regulate both positive and negative outputs simultaneously?
Yes, LT1371ISW#PBF can regulate both polarities simultaneously using its dual feedback architecture: FB pin for positive output (referenced to +1.245V) and NFB pin for negative output (referenced to –2.49V). In the "Dual Output Flyback Converter" reference design, both pins are active, and the IC prevents either rail from exceeding its setpoint - enabling true cross-regulated dual-rail supplies without optocouplers.
What is the purpose of the VC pin on LT1371ISW#PBF, and how is it used in layout?
The VC pin on LT1371ISW#PBF serves three critical functions: loop compensation node (via RC network), soft-start control point, and current limit adjustment interface. During layout, VC must be decoupled with a 0.0047µF capacitor to suppress switching ripple (<50mV p-p), and the series RC network should be placed close to the pin with short traces - any noise or inductance here directly destabilizes regulation and increases output overshoot.
Does LT1371ISW#PBF support external clock synchronization, and what is the valid frequency range?
Yes, LT1371ISW#PBF supports external synchronization via the SYNC pin (pin 9), accepting logic-level square waves from 600kHz to 800kHz - a 1.05× to 1.8× multiple of its nominal 500kHz switching frequency. Operation outside this range is not guaranteed; synchronization above 700kHz requires larger inductors to avoid subharmonic oscillation when duty cycle exceeds 50%.
What thermal considerations apply to LT1371ISW#PBF in the SO Wide package?
LT1371ISW#PBF in the 20-lead SO Wide package has θJA = 50°C/W (measured over 0.75 in² 1 oz copper), but actual thermal resistance varies significantly with PCB layout. All eight GND pins (4,5,6,7,14,15,16,17) must connect directly to an internal or backside ground plane; insufficient copper area raises junction temperature rapidly - exceeding 125°C derates switch current and risks thermal shutdown. Surface-mount heat sinks (e.g., Wakefield SW20) can reduce θJA by 2–3×.
LT1371ISW#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- 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:
- 20-SO
LT1371ISW#PBF FAQ
1.How can I place an order for LT1371ISW#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1371ISW#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 LT1371ISW#PBF reliable?
The price and inventory of LT1371ISW#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1371ISW#PBF is usually 5 days.
3.What payment methods are accepted for LT1371ISW#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1371ISW#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1371ISW#PBF?
LT1371ISW#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1371ISW#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 LT1371ISW#PBF?
For technical support, including LT1371ISW#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1371ISW#PBF requirements.
6.How does Aetrix verify that LT1371ISW#PBF is sourced from the original manufacturer or authorized distributors?
All LT1371ISW#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 LT1371ISW#PBF meets industry standards.
7.What is the process for return or replacement of LT1371ISW#PBF?
All LT1371ISW#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1371ISW#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 LT1371ISW#PBF part is unused and in its original packaging.
Return procedure for LT1371ISW#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT1371ISW#PBF Tags
-
TPS562201DDCR
Texas Instruments
-
MC34063ABD-TR
STMicroelectronics
-
TPS561201DDCR
Texas Instruments
-
MC33063ADR
Texas Instruments
-
MC34063ADR
Texas Instruments
-
TPS560200DBVR
Texas Instruments
-
AP3012KTR-G1
Diodes Incorporated
-
TLV61048DBVR
Texas Instruments
-
AZ34063UMTR-G1
Diodes Incorporated
-
TPS562200DDCR
Texas Instruments
-
AP62300TWU-7
Diodes Incorporated
-
MC34063EBD-TR
STMicroelectronics
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
