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Analog Devices Inc. LT1339ISW#PBF
- Part No.:
- LT1339ISW#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
LT1339ISW#PBF.pdf
- Description:
- IC REG CTLR BST/FWRD CONV 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:496
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Product details
Overview
LT1339ISW#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), 150 kHz synchronizable oscillator, and features a 5V reference output (±2.5% tolerance, 10 mA load capability). It is used in 48V telecom power supplies delivering 20A at 5V.
For engineers reviewing the LT1339ISW#PBF datasheet, LT1339ISW#PBF pinout, LT1339ISW#PBF application, or LT1339ISW#PBF equivalent, key selection considerations include its 20-pin SO Wide package, dual N-FET drive capability (up to 10,000 pF gate capacitance), programmable minimum off-time protection, phase-reversal pin for topology flexibility, and integrated undervoltage lockout with 350 mV hysteresis.
Technical Context
The LT1339ISW#PBF implements a constant-frequency current-mode control architecture with internal transconductance error amplifier (2000 µmho typ), programmable slope compensation via SL/ADJ pin, and adaptive nonoverlapping logic that prevents shoot-through independent of FET size or switching conditions. Its VC pin serves as the error amplifier output and current comparator threshold node, enabling direct integration into the feedback loop.
It features dual independent gate drivers: TG delivers 11.9 V on-voltage with 130 ns rise time, BG matches it with 70 ns rise time; both support bootstrapped operation via VBOOST and TS pins. The IAVG pin enables true average current limiting by integrating the sense amplifier output through an external capacitor, decoupling limit accuracy from duty cycle and ripple current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | –0.3 V to 60 V on SENSE+/-; 12VIN supply: –0.3 V to 20 V - supports wide-input industrial and telecom rails. |
| Switching Frequency | Programmable up to 150 kHz (±5% error) - enables optimization of magnetics size vs. efficiency in high-power designs. |
| Average Current Limit Threshold | 120 mV across RSENSE (typ) - provides precise DC load current regulation independent of inductor ripple. |
| 5V Reference Output | 4.75 V to 5.25 V (line/load/temp), 10 mA DC capable - powers external bias circuitry without auxiliary LDO. |
| Error Amplifier Reference | 1.250 V ±8 mV (VFB pin) - sets output voltage accuracy via resistor divider; low 0.5 µA input bias minimizes divider error. |
| Undervoltage Lockout | Falling threshold 9.00 V, rising 9.95 V, 350 mV hysteresis - ensures stable startup and prevents brownout oscillation. |
| Operating Temperature | –40°C to +85°C (I-grade) - qualified for industrial and automotive under-hood environments. |
Pinout & Package
LT1339ISW#PBF is housed in a 20-lead plastic SO Wide (SW) package with exposed thermal pad, 0.65 mm pitch, and θJA = 85°C/W. Pin 1 is SYNC; pin 20 is VBOOST. All pins are electrically defined per Linear Technology's official pin function table.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SYNC (1) | Oscillator synchronization input | TTL-compatible rising-edge trigger; enables system-level clock alignment without jitter accumulation. |
| 5VREF (2) | Regulated 5V output supply | Powers timing components and external logic; disabled during shutdown - eliminates need for separate bias rail. |
| CT (3) | Oscillator timing node | Connects to RCT–CCT network; defines switching frequency and minimum off-time; discharge current 2.5 mA (typ). |
| IAVG (5) | Average current limit integrator | 50 kΩ internal impedance + external capacitor forms low-pass filter; disables average limit when shorted to SGND. |
| PHASE (14) | Topology configuration control | Floating = buck; grounded = inverting/boost - enables single IC to support multiple converter topologies without redesign. |
| TS (18) | Topside driver reference | Connects to switch-node; establishes bootstrap return path - critical for reliable high-side N-FET gate drive. |
| TG (19) | Top gate driver output | Drives gate of high-side N-MOSFET; 11.9 V on-voltage ensures full enhancement even with VBOOST droop. |
| VBOOST (20) | Bootstrap power supply input | Accepts bootstrapped voltage up to 75 V max - enables efficient high-side drive without isolated supply. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive nonoverlapping gate drive | Prevents shoot-through by dynamically adjusting dead time based on actual TG/BG transitions - eliminates fixed-delay tuning and FET-dependent layout constraints. |
| Programmable average current limiting | 120 mV sense threshold with external RC averaging - delivers accurate DC current regulation unaffected by duty cycle or inductor ripple. |
| Phase reversal pin (PHASE) | Single-pin topology reconfiguration - supports buck, inverting, and negative-output converters using identical PCB layout and BOM. |
| Soft start with UVLO/SHDN gating | 8 µA SS charge current clamped during shutdown and UVLO - ensures graceful recovery from fault or sequencing events without output overshoot. |
| 5V reference with 10 mA drive | Stable 5V rail derived from internal bandgap - powers external comparators, logic, or sensing circuitry without loading main supply. |
Applications
| 48V Telecom Power Supply | Industrial Distributed Power |
|---|---|
Use Scenario: 48V backplane-to-5V/20A conversion in carrier-grade telecom shelf systems. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing dual N-FETs, current limiting, and soft-start sequencing. Use Value: Delivers >90% efficiency at full load while meeting ETSI transient response specs via fast VC-loop compensation and 150 kHz switching. |
Use Scenario: Point-of-load regulation in PLC racks requiring robust 24V-to-5V/15A conversion with input brownout immunity. IC Role / Device Role / Timing Role: High-voltage current-mode controller with UVLO hysteresis and adaptive gate drive for reliability in noisy factory environments. Use Value: Maintains regulation down to 9.0 V input and recovers cleanly after line sag due to gated soft-start and 350 mV UVLO hysteresis. |
| Lead-Acid Battery Backup System | Automotive Heavy Equipment DC/DC |
Use Scenario: 36V battery-to-12V/10A conversion in UPS systems with cold-cranking voltage drop support. IC Role / Device Role / Timing Role: Synchronous controller with programmable average current limit and phase-reversal for flexible output polarity. Use Value: Enables inverting topology to generate negative bias rails for analog sensors while maintaining tight current limit during deep discharge. |
Use Scenario: 24V vehicle battery-to-5V/8A supply for infotainment ECUs operating in –40°C to +85°C ambient. IC Role / Device Role / Timing Role: Industrial-grade controller with I-temp rating, bootstrapped high-side drive, and robust gate drive timing. Use Value: Guarantees reliable startup at –40°C via low-temperature characterized oscillator and gate drivers with <200 ns transition times. |
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 |
|---|---|---|---|
| LTC3779EFE#PBF | Higher integration: includes MOSFET drivers, current-sense amp, and PMBus interface; supports 4–36 V VIN, up to 60 A. | Targeted at digitally controlled, multi-phase, high-current server/industrial supplies - not pin-compatible. | Select LTC3779EFE#PBF when digital monitoring, phase interleaving, or >30 A output is required; LT1339ISW#PBF remains optimal for cost-sensitive, analog-controlled 10–25 A designs. |
| LM5116MH/NOPB | Lower voltage: 6–100 V VIN range; no integrated 5V reference; uses external VREF; peak-current mode only (no average limit). | Suited for high-input-voltage industrial converters where average current limiting is unnecessary. | Choose LM5116MH/NOPB for >60 V input applications or where board space allows external reference; LT1339ISW#PBF is preferred when 5V bias rail and precise DC current limiting are mandatory. |
Compared with LTC3779EFE#PBF and LM5116MH/NOPB, the LT1339ISW#PBF uniquely combines average current limiting, integrated 5V reference, phase-reversal flexibility, and I-grade temperature range in a 20-pin SOIC - making it the most direct solution for analog-controlled, medium-power telecom and industrial buck/inverting converters requiring design simplicity and proven reliability.
Availability
LT1339ISW#PBF is available at Aetrix Electronics and suitable for 48V telecom power supplies, industrial distributed power systems, and lead-acid battery backup systems requiring stable component supply over extended production lifecycles.
Supply support for LT1339ISW#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LT1339 product line was developed specifically for high-efficiency, high-current synchronous DC/DC conversion in telecom, industrial, and transportation infrastructure - emphasizing ruggedness, precision current control, and topology flexibility.
FAQ
What is the maximum input voltage supported by the LT1339ISW#PBF?
The LT1339ISW#PBF supports up to 60 V on its SENSE+ and SENSE– pins, and 20 V on the 12VIN supply pin. Its TS pin tolerates up to 60 V, and VBOOST accepts up to 75 V maximum - enabling safe operation in 48V telecom and 36V battery systems with transient headroom. Absolute maximum ratings must not be exceeded during normal operation or fault conditions.
How does the average current limit function work in the LT1339ISW#PBF?
The LT1339ISW#PBF implements average current limiting via the IAVG pin, which integrates the current sense amplifier output through an external capacitor. When the averaged voltage exceeds 2.5 V (corresponding to ~120 mV across RSENSE), the current comparator threshold is clamped - enforcing precise DC load current regulation independent of duty cycle or inductor ripple. Shorting IAVG to SGND disables this function.
Can the LT1339ISW#PBF be used in inverting or negative-output converter topologies?
Yes - the LT1339ISW#PBF supports inverting and negative-output configurations using the PHASE pin. When PHASE is grounded, the bottom-side driver (BG) becomes the main switch and TG operates the synchronous rectifier. This topology reconfiguration requires no PCB changes and maintains full current-mode control and protection features in the LT1339ISW#PBF.
What is the purpose of the 5VREF pin on the LT1339ISW#PBF?
The 5VREF pin on the LT1339ISW#PBF provides a regulated 5 V output (4.75–5.25 V, ±2.5%) capable of sourcing 10 mA DC. It powers the oscillator timing network (RCT/CCT), external logic, or sensing circuitry - eliminating the need for a separate LDO. The 5VREF output is disabled during shutdown, preventing unintended biasing of downstream circuitry.
Does the LT1339ISW#PBF include undervoltage lockout, and how is it configured?
Yes - the LT1339ISW#PBF includes a precision undervoltage lockout (UVLO) circuit monitoring the 12VIN supply. It disables all internal functions when 12VIN falls below 9.00 V (typical falling threshold) and re-enables at 9.95 V (rising threshold), providing 350 mV hysteresis. This prevents unstable operation during brownout conditions and ensures clean startup in industrial and telecom power systems.
LT1339ISW#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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
LT1339ISW#PBF FAQ
1.How can I place an order for LT1339ISW#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1339ISW#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 LT1339ISW#PBF reliable?
The price and inventory of LT1339ISW#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1339ISW#PBF is usually 5 days.
3.What payment methods are accepted for LT1339ISW#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1339ISW#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1339ISW#PBF?
LT1339ISW#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1339ISW#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 LT1339ISW#PBF?
For technical support, including LT1339ISW#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1339ISW#PBF requirements.
6.How does Aetrix verify that LT1339ISW#PBF is sourced from the original manufacturer or authorized distributors?
All LT1339ISW#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 LT1339ISW#PBF meets industry standards.
7.What is the process for return or replacement of LT1339ISW#PBF?
All LT1339ISW#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1339ISW#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 LT1339ISW#PBF part is unused and in its original packaging.
Return procedure for LT1339ISW#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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