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Analog Devices Inc. LT1339CSW#PBF
- Part No.:
- LT1339CSW#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
LT1339CSW#PBF.pdf
- Description:
- IC REG CTLR BST/FWRD CONV 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,699
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Product details
Overview
LT1339CSW#PBF from Analog Devices (formerly Linear Technology) is a high-power synchronous current-mode DC/DC controller IC designed for buck, inverting, and negative-output converters up to 60V input. It drives dual N-channel MOSFETs with adaptive nonoverlapping gate logic, supports programmable average current limiting (120 mV threshold), 5 V reference output (±2.5% tolerance, 10 mA load), and synchronizable oscillator up to 150 kHz. Used in telecom power supplies and industrial DC/DC conversion.
For engineers reviewing the LT1339CSW#PBF datasheet, LT1339CSW#PBF pinout, LT1339CSW#PBF application, or LT1339CSW#PBF equivalent, key selection considerations include its 20-pin SO Wide package, dual N-FET drive capability (10,000 pF gate capacitance support), 1.25 V error amplifier reference, undervoltage lockout (9.0–9.75 V falling threshold), and phase-reversal pin for topology flexibility.
Technical Context
The LT1339CSW#PBF implements constant-frequency current-mode control with internal transconductance error amplifier (gm = 1200–3200 µmho), programmable slope compensation via SL/ADJ pin, and minimum off-time protection (~1 µs). Its oscillator uses CT pin timing with RCT/CCT programming and supports external synchronization up to 150 kHz.
It integrates dual gate drivers with adaptive dead-time control, 5 V reference (4.75–5.25 V, ±2.5%), and precision RUN/SHDN shutdown (1.15–1.35 V rising threshold, 25 mV hysteresis). Average current limit is set by IAVG pin integration (50 kΩ internal impedance), independent of inductor ripple.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Operating Input Voltage | Up to 60 V on SENSE+/SENSE−; 12VIN supply range: –0.3 V to 20 V - enables direct interface with high-voltage bus rails. |
| Switching Frequency | Programmable 150 kHz max, synchronized - supports EMI reduction and predictable thermal design in high-power converters. |
| Average Current Limit Threshold | 110–130 mV across sense resistor - provides accurate DC load current regulation independent of duty cycle or ripple. |
| Error Amplifier Reference | 1.242–1.258 V at VFB pin - sets output voltage accuracy for feedback networks (e.g., 5 V out = 1.25 × (1 + R2/R1)). |
| 5 V Reference Output | 4.75–5.25 V, ±2.5% over line/load/temp - powers external bias circuitry (e.g., gate drivers, logic) with 10 mA DC capability. |
| Undervoltage Lockout | Falling threshold 8.20–9.75 V, hysteresis 200–350 mV - prevents erratic startup during brownout conditions in telecom or battery-backed systems. |
| Gate Drive Capability | Drives up to 10,000 pF total gate capacitance with 11–12 V on TG/BG pins - supports high-current discrete N-MOSFETs without external buffers. |
Pinout & Package
LT1339CSW#PBF is housed in a 20-lead plastic SO Wide (SW) package with exposed pad (θJA = 85°C/W), suitable for high-power thermal dissipation in industrial and telecom applications.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SYNC (1) | Oscillator synchronization input | TTL-compatible rising-edge trigger; enables multi-phase or noise-synchronized operation up to 150 kHz. |
| 5VREF (2) | 5 V regulated output | Powers external components (e.g., RCT, logic); disabled in shutdown; requires 1 µF bypass to SGND. |
| CT (3) | Oscillator timing node | Connects to CCT capacitor and RCT resistor to ground/5VREF - sets free-run frequency and sync window. |
| SL/ADJ (4) | Slope compensation adjustment | Resistive divider from 5VREF tailors added ramp for >50% duty cycles; floating = default internal compensation. |
| IAVG (5) | Average current limit integrator | 50 kΩ internal impedance + external CAVG forms low-pass filter - disables average limit if shorted to SGND. |
| SS (6) | Soft start timing | 8 µA current source charges external CSS capacitor - controls ramp rate of VC clamp for controlled startup. |
| VC (7) | Error amplifier output | Transconductance amplifier output; RC network here sets loop compensation and transient response. |
| SGND (8) | Small-signal ground | Reference for VFB, VREF, SL/ADJ, SS, IAVG - must be star-connected to minimize noise coupling. |
| VFB (9) | Error amplifier inverting input | Receives feedback voltage; 0.5 µA bias current - requires Thevenin resistance <5 kΩ for accuracy. |
| VREF (10) | Bandgap reference decoupling | 0.1 µF capacitor stabilizes internal 1.25 V reference - critical for VFB accuracy and loop stability. |
| SENSE+ (11) | Current sense inverting input | Connects to high-side of sense resistor - common-mode range: –0.3 V to 60 V. |
| SENSE– (12) | Current sense noninverting input | Connects to low-side of sense resistor - differential input rejects common-mode noise. |
| RUN/SHDN (13) | Shutdown control / UVLO monitor | 1.25 V bandgap threshold with 25 mV hysteresis - enables sequencing or analog undervoltage detection. |
| PHASE (14) | Topology configuration | Floating = buck; grounded = inverting/boost - reverses TG/BG driver roles without PCB change. |
| PGND (15) | Power ground | Return path for BG driver and internal power circuits - connect directly to VIN decoupling cap negative terminal. |
| BG (16) | Bottom gate driver output | Drives gate of low-side N-MOSFET; clamped to 0.4–0.7 V when 12VIN ≤ 8 V - prevents shoot-through. |
| 12VIN (17) | Main supply input | Powers internal circuitry; bypass with ≥1 µF to PGND - not the main converter input rail. |
| TS (18) | Boost driver reference | Connects to switch node (SW) - defines return for VBOOST and TG driver; withstands up to 60 V. |
| TG (19) | Top gate driver output | Drives gate of high-side N-MOSFET; 11–12 V swing - requires bootstrap capacitor (CBST = 1 µF) from VBOOST to TS. |
| VBOOST (20) | Bootstrap supply input | Charged via Schottky diode from 12VIN to TS - sustains TG drive during high-side conduction. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive nonoverlapping gate drive | Prevents shoot-through by dynamically adjusting dead time based on actual TG/BG switching transitions - eliminates need for fixed external delay networks. |
| Programmable average current limit | 120 mV sense threshold with external CAVG integration - delivers stable DC current regulation unaffected by duty cycle or inductor ripple. |
| Phase reversal pin (PHASE) | Single-pin topology reconfiguration - enables buck, inverting, and negative-output converters without redesigning gate drive layout. |
| Soft start with UVLO/SHDN gating | SS capacitor charging halted during shutdown or UVLO - ensures graceful recovery after fault or power interruption. |
| 5 V reference with 10 mA drive | Stable local supply for timing resistors (RCT), gate driver bias, or monitoring circuitry - reduces need for external LDOs. |
Applications
| 48V Telecom Power Supply | Industrial DC/DC Converter |
|---|---|
Use Scenario: Converting –48 V or +48 V telecom rectified input to isolated 5 V/12 V intermediate bus in central office equipment. IC Role / Device Role / Timing Role: Primary controller for synchronous buck or inverting topology; manages gate timing, current limiting, and soft-start sequencing. Use Value: Enables high-efficiency (>90% at 20 A) conversion with precise average current limit (120 mV) and robust UVLO (9.0 V falling threshold) for brownout resilience. |
Use Scenario: Generating regulated 5 V, 12 V, or 24 V outputs from wide-range industrial inputs (e.g., 18–60 V DC) in PLCs or motor drives. IC Role / Device Role / Timing Role: High-voltage synchronous controller driving discrete N-MOSFETs; handles up to 60 V common-mode sense voltage. Use Value: Supports ruggedized designs with 60 V-rated sense inputs, adaptive gate drive for varying FET sizes, and programmable slope compensation for >50% duty cycles. |
| Lead-Acid Battery Backup System | Automotive Heavy Equipment Power |
Use Scenario: Regulating 12 V or 24 V battery backup to stable 5 V for critical control electronics during grid failure. IC Role / Device Role / Timing Role: Buck controller with precise RUN/SHDN threshold (1.25 V) used for battery voltage monitoring and automatic enable/disable. Use Value: Provides reliable sequencing via analog UVLO function and soft-start recovery - avoids inrush damage during battery switchover. |
Use Scenario: Powering infotainment or ADAS subsystems from 12 V/24 V vehicle batteries subject to load dump and cold-crank transients. IC Role / Device Role / Timing Role: Controller with 60 V sense input rating and 12VIN supply tolerance (–0.3 V to 20 V) - survives automotive voltage extremes. Use Value: Delivers stable operation under harsh conditions using integrated 5 V reference, hysteresis-enabled shutdown, and minimum off-time protection. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-power synchronous DC/DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3775 | Higher max frequency (600 kHz), integrated MOSFET drivers with adjustable dead time, no PHASE pin - requires external level-shifting for inverting topologies. | Optimized for compact, high-density designs; lacks native phase-reversal for inverting configurations without added components. | Choose LTC3775 for higher switching frequencies and tighter layout control; retain LT1339CSW#PBF when topology flexibility (buck/inverting/boost) and 60 V sense rating are critical. |
| LM5116 | Supports up to 100 V VIN, includes integrated bootstrap diode, fixed 1.25 V reference only - no 5 VREF output or average current limit. | Targeted at high-input-voltage industrial converters; lacks dual-reference architecture and programmable average current limiting. | Choose LM5116 for >60 V input applications; select LT1339CSW#PBF when 5 VREF bias, average current limit accuracy, and PHASE-based topology agility are required. |
Compared with LTC3775 and LM5116, the LT1339CSW#PBF uniquely combines 60 V sense capability, dedicated 5 V reference output, average current limit with external CAVG tuning, and single-pin PHASE topology selection - making it optimal for flexible, high-reliability 48 V telecom and industrial DC/DC systems where design reuse across topologies matters.
Availability
LT1339CSW#PBF is available at Aetrix Electronics and suitable for 48V telecom power supplies, industrial DC/DC converters, and lead-acid battery backup systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LT1339CSW#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision instrumentation, industrial, automotive, and communications markets.
The LT1339 product line was developed by Linear Technology specifically for high-efficiency, high-power synchronous DC/DC controllers operating up to 60 V - targeting telecom infrastructure, industrial power, and battery-backed systems needing robust current-mode control and topology flexibility.
FAQ
What is the maximum input voltage supported by the LT1339CSW#PBF for current sensing?
The LT1339CSW#PBF supports a current sense input common-mode voltage range of –0.3 V to 60 V on SENSE+ and SENSE– pins. This allows direct interfacing with high-side or low-side sense resistors in 48 V telecom or industrial bus applications without level-shifting circuitry. The device maintains specified accuracy across this full range, as confirmed in the Electrical Characteristics table under "Sense Amplifier Input Common Mode."
Does the LT1339CSW#PBF provide both peak and average current limiting?
Yes, the LT1339CSW#PBF implements dual current limiting: a fixed peak current limit (170–190 mV threshold) and a programmable average current limit (110–130 mV threshold, set via IAVG pin integration). The average limit is independent of inductor ripple and duty cycle, while the peak limit provides fast overcurrent protection. Both functions are active simultaneously in the LT1339CSW#PBF control architecture.
Can the LT1339CSW#PBF be used in an inverting (negative-output) converter?
Yes, the LT1339CSW#PBF supports inverting topologies via its PHASE pin (Pin 14). When PHASE is shorted to ground, the TG and BG driver roles reverse - enabling use in inverting or boost configurations. This is explicitly documented in the Pin Functions section and verified in the Typical Application schematic (1339 TA03), where PHASE grounding configures the 28 V to –5 V converter.
What is the purpose of the 5VREF pin on the LT1339CSW#PBF, and what load can it drive?
The 5VREF pin on the LT1339CSW#PBF provides a regulated 4.75–5.25 V output derived from the internal bandgap reference. It is rated for up to 10 mA DC load (20 mA pulsed), and is commonly used to power the RCT timing resistor, external logic, or gate driver bias. The pin is disabled during shutdown, and requires a 1 µF bypass capacitor to SGND for stability - all confirmed in the Electrical Characteristics and Pin Functions sections.
How does the LT1339CSW#PBF handle undervoltage lockout and shutdown sequencing?
The LT1339CSW#PBF integrates a precision bandgap-based RUN/SHDN pin with 1.15–1.35 V rising threshold and 25 mV hysteresis. It supports both digital shutdown (logic-low assertion) and analog UVLO monitoring - e.g., a resistor divider from VIN to RUN/SHDN enables power sequencing. During shutdown, all internal functions halt and soft start is gated, ensuring clean entry/exit from low-power state - per Applications Information Section.
LT1339CSW#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
- Output Type:
- Transistor Driver
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Boost, Forward Converter
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- Up to 20V
- Frequency - Switching:
- -
- Duty Cycle (Max):
- 90%
- Synchronous Rectifier:
- No
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Phase Control, Soft Start
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
LT1339CSW#PBF FAQ
1.How can I place an order for LT1339CSW#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1339CSW#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 LT1339CSW#PBF reliable?
The price and inventory of LT1339CSW#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1339CSW#PBF is usually 5 days.
3.What payment methods are accepted for LT1339CSW#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1339CSW#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1339CSW#PBF?
LT1339CSW#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1339CSW#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 LT1339CSW#PBF?
For technical support, including LT1339CSW#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1339CSW#PBF requirements.
6.How does Aetrix verify that LT1339CSW#PBF is sourced from the original manufacturer or authorized distributors?
All LT1339CSW#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 LT1339CSW#PBF meets industry standards.
7.What is the process for return or replacement of LT1339CSW#PBF?
All LT1339CSW#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1339CSW#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 LT1339CSW#PBF part is unused and in its original packaging.
Return procedure for LT1339CSW#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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