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Analog Devices Inc. LT1373IS8#PBF
- Part No.:
- LT1373IS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1373IS8#PBF.pdf
- Description:
- IC REG BUCK BOOST ADJ 1.5A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:125
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Product details
Overview
LT1373IS8#PBF from Analog Devices (formerly Linear Technology) is a 250kHz constant-frequency current-mode switching regulator IC with integrated 1.5A power switch, designed for boost, buck, flyback, inverting, and Cuk topologies. It operates from 2.7V to 25V input, delivers up to 1.5A switch current, regulates both positive and negative outputs, and achieves typical 1mA quiescent current. It is used in laptop computer supplies, CCFL backlight drivers, and multiple-output flyback converters.
For engineers reviewing the LT1373IS8#PBF datasheet, LT1373IS8#PBF pinout, LT1373IS8#PBF application, or LT1373IS8#PBF equivalent, key selection considerations include its 250kHz switching frequency, ±2.45V dual-reference architecture (1.245V FB / –2.45V NFB), 12µA shutdown current, 8-pin SO package thermal resistance (120°C/W), and compatibility with small 15µH inductors for space-constrained designs.
Technical Context
The LT1373IS8#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 feedback. Its error amplifier features nonlinear transconductance (250–600 µmho) that increases tenfold above 40mV FB overdrive to suppress startup/overload overshoot.
It integrates a 2.3V low-dropout internal regulator for biasing, adaptive anti-saturation logic for rapid switch turn-off, and oscillator frequency shifting (5:1 reduction below 0.6V FB) for overload protection. The VC pin serves triple function: error amplifier output, compensation node, and soft-start/current-limit control point.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 250 kHz typical; enables use of compact 15 µH inductors and reduces EMI filtering burden. |
| Supply Current (IQ) | 1 mA typical at 250 kHz; minimizes no-load power loss in battery-powered systems. |
| Shutdown Current | 12 µA typical; supports ultra-low-power standby modes in portable electronics. |
| Output Switch Current Limit | 1.5 A minimum at 50% duty cycle; defines maximum deliverable load current before foldback. |
| Reference Voltage (FB) | 1.245 V ±15 mV; sets positive output voltage via resistor divider with <150 nA input bias. |
| Negative Reference (NFB) | –2.45 V ±60 mV; enables direct regulation of negative outputs without external op-amps. |
| Min Input Voltage | 2.7 V; supports single-cell Li-ion (3.0 V nominal) and two-cell alkaline operation. |
| Package Thermal Resistance | 120 °C/W (θJA, SO-8); requires moderate copper area for 125°C junction limit at full load. |
Pinout & Package
LT1373IS8#PBF is housed in an 8-lead plastic SO (SO-8) surface-mount package with exposed pad thermal enhancement (JEDEC MS-012AC). Pin 6 (GND S) is the clean reference ground for analog circuitry; Pin 7 (GND) carries high-current switch return; Pin 8 (VSW) connects directly to the collector of the internal 1.5A NPN switch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (Pin 1) | Error amplifier output & compensation node | External RC network sets loop stability; clamping controls soft-start and current limit. |
| FB (Pin 2) | Positive output voltage sense input | Connects to resistor divider; referenced to 1.245 V internal bandgap; <150 nA bias current. |
| NFB (Pin 3) | Negative output voltage sense input | Referenced to –2.45 V; includes 400 kΩ series source resistor for direct negative regulation. |
| S/S (Pin 4) | Shutdown & synchronization input | Logic-low (<1.3 V) enables 12 µA shutdown; 300–340 kHz AC signal synchronizes switching. |
| VIN (Pin 5) | Main input supply | Bypass with ≥10 µF capacitor; UVLO activates below 2.5 V to prevent erratic operation. |
| GND S (Pin 6) | Analog ground reference | Reference point for FB, NFB, and internal regulators; must be isolated from high-current GND paths. |
| GND (Pin 7) | Power switch emitter return | Carries full switch current; connect directly to low-impedance ground plane. |
| VSW (Pin 8) | Internal switch collector | High di/dt node; requires shortest possible trace to output diode and capacitor to minimize EMI. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-reference regulation | Simultaneous +1.245 V (FB) and –2.45 V (NFB) references enable single-chip positive/negative output control without external amplifiers. |
| Nonlinear error amplifier | Transconductance jumps 10× when FB exceeds VREF by 40 mV, actively suppressing output overshoot during startup and load recovery. |
| Oscillator frequency shifting | Reduces switching frequency 5:1 when FB drops below 0.6 V, lowering peak switch current and protecting components during overload. |
| Adaptive anti-saturation logic | Dynamically adjusts driver current to minimize switch saturation time, reducing conduction loss and enabling fast turn-off. |
| External synchronization | Accepts 300–340 kHz logic-level signal on S/S pin to align switching with system clocks or reduce beat frequencies. |
| Low minimum input voltage | Operates down to 2.7 V, supporting single-cell Li-ion and wide-input industrial supplies without pre-regulation. |
Applications
| Laptop Computer Supplies | CCFL Backlight Drivers |
|---|---|
Use Scenario: Generating regulated 12 V or 19 V rails from 3.3 V or 5 V system buses in ultraportable notebooks. IC Role / Device Role / Timing Role: Primary DC-DC boost controller managing power conversion, current limiting, and thermal safety. Use Value: 1 mA IQ extends battery runtime; 250 kHz switching allows <0.6 in² board area using 15 µH inductors and surface-mount passives. | Use Scenario: Driving cold-cathode fluorescent lamps requiring high-voltage AC (600–1000 V) from low-voltage DC inputs. IC Role / Device Role / Timing Role: High-efficiency flyback controller providing precise current regulation and lamp ignition sequencing. Use Value: Integrated 1.5 A switch eliminates external MOSFET; frequency shifting protects transformer and diodes during lamp strike and fault conditions. |
| Inverting Supplies | Multiple-Output Flyback Supplies |
Use Scenario: Generating –5 V or –15 V rails for analog front-ends, op-amp biasing, or RS-232 interfaces from 5 V or 12 V sources. IC Role / Device Role / Timing Role: Inverting topology controller using NFB pin for direct negative output sensing and regulation. Use Value: Eliminates need for external inverting op-amp; –2.45 V NFB reference ensures stable regulation across temperature (±0.05 %/°C line regulation). | Use Scenario: Providing isolated +15 V and –15 V outputs from a single 12 V input in industrial PLC I/O modules. IC Role / Device Role / Timing Role: Dual-polarity flyback controller regulating both outputs independently via FB and NFB pins. Use Value: Prevents unregulated overvoltage on either rail under mismatched loading; maintains ≤±3 % cross-regulation without optocouplers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3873EMS#PBF | Higher 500 kHz switching frequency; 3.5 A switch; requires external MOSFET gate drive; no integrated NFB path. | Targets higher-power (>3 A) applications; lacks native negative output regulation capability. | Select when higher efficiency at light loads or >2 A output is required; redesign needed for negative rail support. |
| TPS61088RHLR | 5.5 V max input; 12 A switch; fixed 500 kHz frequency; no NFB pin; only positive output regulation. | Optimized for USB PD and display power; incompatible with inverting/flyback topologies requiring NFB. | Choose for high-current boost-only designs with 2.7–5.5 V input; not suitable for dual-polarity or wide-input applications. |
Compared with LTC3873EMS#PBF and TPS61088RHLR, the LT1373IS8#PBF uniquely combines 2.7–25 V input range, integrated 1.5 A switch, and dual-reference (FB/NFB) architecture - enabling compact, low-IQ, dual-polarity regulation in a single SO-8 package without external op-amps or gate drivers.
Availability
LT1373IS8#PBF is available at Aetrix Electronics and suitable for laptop computer supplies, CCFL backlight drivers, and industrial inverting power supplies requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT1373IS8#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 military-grade screening options.
The LT1373 product line was designed specifically for space-constrained, multi-topology DC-DC conversion in portable and industrial equipment, emphasizing low quiescent current, dual-polarity regulation, and robust overload protection without external complexity.
FAQ
What is the maximum input voltage rating for the LT1373IS8#PBF?
The LT1373IS8#PBF has an absolute maximum supply voltage rating of 30 V on the VIN pin. Its internal switch breakdown voltage is rated at 35 V for the standard LT1373 variant. Operation above 25 V is not recommended for reliable long-term performance, as electrical characteristics are specified only up to 25 V per the datasheet's test conditions.
Can the LT1373IS8#PBF regulate both positive and negative outputs simultaneously?
Yes, the LT1373IS8#PBF can regulate both polarities simultaneously using its FB and NFB pins. In dual-output flyback configurations, it 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 remain below 100 µA when NFB is active to maintain accuracy.
What inductor value is recommended for a 5 V to 12 V boost converter using the LT1373IS8#PBF?
The LT1373IS8#PBF datasheet recommends a 15 µH inductor (e.g., Coilcraft D03316-153) for 5 V-to-12 V boost operation. This value balances size, peak current (≤1.5 A), and efficiency. For higher output current or lower ripple, a 22 µH inductor (e.g., Sumida CD75-220KC) may be used, but peak inductor current must be verified against the 1.5 A switch limit.
How does the LT1373IS8#PBF achieve low output overshoot during startup?
The LT1373IS8#PBF uses nonlinear error amplifier transconductance: when FB voltage exceeds the 1.245 V reference by 40 mV, gm increases tenfold (from ~375 µmho to ~3750 µmho), sharply increasing correction speed. This active response suppresses overshoot without requiring complex external compensation networks.
Is the LT1373IS8#PBF pin-compatible with other members of the LT137x family?
Yes, the LT1373IS8#PBF shares identical pinout and footprint with LT1372, LT1373HV, and LT1375 variants in the SO-8 (S8) package. However, switching frequency (250 kHz vs. 500 kHz), quiescent current (1 mA vs. 4 mA), and switch voltage rating (35 V vs. 42 V) differ - requiring verification of loop stability and stress margins when substituting.
LT1373IS8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm 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:
- 1.5A (Switch)
- Frequency - Switching:
- 250kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1373IS8#PBF FAQ
1.How can I place an order for LT1373IS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1373IS8#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 LT1373IS8#PBF reliable?
The price and inventory of LT1373IS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1373IS8#PBF is usually 5 days.
3.What payment methods are accepted for LT1373IS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1373IS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1373IS8#PBF?
LT1373IS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1373IS8#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 LT1373IS8#PBF?
For technical support, including LT1373IS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1373IS8#PBF requirements.
6.How does Aetrix verify that LT1373IS8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1373IS8#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 LT1373IS8#PBF meets industry standards.
7.What is the process for return or replacement of LT1373IS8#PBF?
All LT1373IS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1373IS8#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 LT1373IS8#PBF part is unused and in its original packaging.
Return procedure for LT1373IS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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