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Analog Devices Inc. LT1956IFE#PBF
- Part No.:
- LT1956IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT1956IFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 1.5A 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:121
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Product details
Overview
LT1956IFE#PBF from Analog Devices (formerly Linear Technology) is a high-voltage, current-mode 500kHz step-down switching regulator with 5.5V–60V input range, 1.5A peak switch current, and 0.2Ω on-resistance. It features a fixed 5V output (LT1956-5 variant), 1.2V feedback reference (LT1956), and operates in thermally enhanced 16-pin TSSOP package. Used in industrial power supplies requiring stable 5V rail generation from wide-input unregulated sources.
For engineers reviewing the LT1956IFE#PBF datasheet, LT1956IFE#PBF pinout, LT1956IFE#PBF application, or LT1956IFE#PBF equivalent, this page delivers verified electrical parameters, thermal package details, functional pin roles, real-world use cases in battery-powered and automotive systems, and two validated alternative parts with documented technical and application differences.
Technical Context
The LT1956IFE#PBF implements a constant-frequency current-mode control architecture with internal 500kHz oscillator, cycle-by-cycle current limiting, and patented duty-cycle-independent peak switch current maintenance. Its bipolar NPN power switch is driven via BOOST pin to achieve 0.2Ω saturation resistance, enabling high efficiency across 5.5V–60V input range.
It integrates dual shutdown thresholds (0.4V for full micropower shutdown, 2.38V for UVLO), SYNC input supporting 580kHz–700kHz external synchronization, and FB/SENSE pin with foldback protection (frequency reduction below 0.8V, current limit reduction below 0.6V). BIAS pin operation improves light-load efficiency by sourcing bias current from regulated output when VOUT ≥ 3V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5.5V to 60V - supports direct connection to 48V industrial buses, automotive batteries, and unregulated DC rails without pre-regulation. |
| Output Voltage | Fixed 5V - eliminates external feedback divider; SENSE pin connects directly to output for precision regulation. |
| Switch Current Limit | 1.5A (min) - sustains full rated current across entire duty cycle range (0–90%), unlike conventional current-mode controllers. |
| Switch On Resistance | 0.2Ω (typ) - enables low conduction loss at 1.5A, reducing thermal stress and improving efficiency above 12V input. |
| Switching Frequency | 500kHz (±10%) - allows compact magnetics and output filtering; externally synchronizable from 580kHz to 700kHz. |
| Shutdown Current | 25µA (max) - ensures ultra-low standby power in battery-backed systems during sleep mode. |
| Thermal Resistance θJA | 45°C/W - achieved via exposed pad soldered to ground plane; enables 1.5A continuous operation at TJ ≤ 125°C with minimal heatsinking. |
Pinout & Package
LT1956IFE#PBF is housed in a 16-lead plastic TSSOP package with exposed thermal pad (FE package). The exposed pad must be soldered to a PCB ground plane for thermal and electrical performance. Package dimensions: 5.0mm × 6.4mm × 1.2mm (L × W × H).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pins 1, 8, 9, 16) | Power and signal reference ground | Four dedicated ground pins minimize ground bounce; exposed pad must be connected to same ground plane as load return path. |
| SW (Pin 2) | Emitter of internal NPN power switch | Drives external catch diode and inductor; swings from near 0V to VIN during operation; requires low-inductance routing. |
| VIN (Pin 4) | Collector of internal NPN power switch | Primary input supply for switch and internal bias circuitry; high dI/dt node-must be decoupled with low-ESR capacitor adjacent to pin. |
| BOOST (Pin 6) | Switch driver boost voltage input | Accepts voltage ≥ VIN + 2V (up to 68V); enables saturation of NPN switch; requires external boost capacitor and diode. |
| SHDN (Pin 15) | Enable/disable control with dual thresholds | 0.4V threshold forces full shutdown (25µA IQ); 2.38V threshold enables UVLO; open-circuit defaults to enabled state. |
| SYNC (Pin 14) | External oscillator synchronization input | Logic-compatible (1.5V–2.2V min amplitude); accepts 580–700kHz square wave; tied to GND if unused. |
| FB/SENSE (Pin 12) | Output voltage sense input (fixed 5V mode) | Direct connection to 5V output; enables foldback protection: frequency reduction below 0.8V, current limit reduction below 0.6V. |
| VC (Pin 11) | Error amplifier output / current limit setpoint | Provides loop compensation node; clamped between 0.9V and 2.1V; can be overridden for current limiting or shutdown. |
| BIAS (Pin 10) | Efficiency-optimized bias supply input | When connected to VOUT ≥ 3V, shifts internal bias current from VIN to VOUT, improving light-load efficiency at high input voltages. |
Key Features
| Feature | Design Value |
|---|---|
| Duty-cycle-independent current limit | Maintains 1.5A peak switch current up to 90% duty cycle-enables high step-down ratios (e.g., 48V→5V) without current derating. |
| Integrated BOOST drive circuitry | Enables NPN switch saturation with 0.2Ω RON, achieving FET-like conduction loss while retaining bipolar robustness and cost efficiency. |
| Two-stage shutdown with UVLO | 2.38V UVLO prevents startup until input reaches safe level; 0.4V deep-shutdown reduces IQ to 25µA-critical for long-life battery systems. |
| Frequency and current foldback protection | Reduces switching frequency below 0.8V FB and lowers current limit below 0.6V FB-limits power dissipation during short-circuit or start-up faults. |
| Thermally enhanced TSSOP (FE) | θJA = 45°C/W (vs. 85°C/W for SSOP) due to exposed pad soldered to ground plane-supports 1.5A continuous output without heatsink. |
Applications
| Industrial 48V DC Power Distribution | Automotive Body Control Module (BCM) |
|---|---|
|
Use Scenario: Converting 36–60V nominal industrial bus to stable 5V for microcontrollers, sensors, and CAN transceivers. IC Role / Device Role / Timing Role: Primary buck regulator delivering regulated 5V at up to 1.5A with high PSRR and fast transient response to load steps. Use Value: Wide 5.5V–60V input range eliminates need for pre-regulator; 0.2Ω switch minimizes heat rise at 48V input; SYNC pin enables EMI reduction via clock dithering. |
Use Scenario: Powering 5V logic in vehicle body electronics where input may dip to 5.5V during cranking or surge to 60V during load dump. IC Role / Device Role / Timing Role: High-reliability 5V supply with integrated UVLO (2.38V) and overvoltage tolerance (60V VIN, 68V BOOST). Use Value: Dual shutdown thresholds ensure clean power sequencing; thermal-enhanced TSSOP maintains operation at 125°C junction temperature in under-hood environments. |
| Portable Medical Equipment Battery Supply | Telecom Remote Radio Unit (RRU) |
|
Use Scenario: Regulating 12–36V Li-ion stack or lead-acid battery to 5V for embedded processors and display interfaces. IC Role / Device Role / Timing Role: Efficient step-down converter with BIAS pin support-draws bias current from 5V output instead of battery at light loads. Use Value: 25µA shutdown current extends battery life in standby; 500kHz switching enables small 10–22µH inductors and ceramic output capacitors. |
Use Scenario: Generating 5V auxiliary rail from 48V telecom plant supply in outdoor base station equipment. IC Role / Device Role / Timing Role: High-input-voltage buck controller with robust thermal design for sealed, fanless enclosures. Use Value: Exposed-pad TSSOP package achieves 45°C/W θJA; cycle-by-cycle current limiting protects against sustained overload in remote deployments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3631EMSE#PBF | 40V max input, 1.2A output, 3mm × 4mm MSOP; synchronous rectification; no BOOST pin required. | Better suited for space-constrained designs with <40V input; lacks 60V rating and external sync capability. | Select when board area is critical and input never exceeds 40V; avoid for 48V+ industrial or automotive applications. |
| LM5164QPWPRQ1 | 65V max input, 1A output, 1.5MHz switching, integrated high-side MOSFET; AEC-Q100 qualified. | Designed for automotive grade-1 (−40°C to 125°C); higher frequency enables smaller inductors but lower current rating. | Select for automotive production requiring AEC-Q100 qualification; not drop-in-requires layout changes and different compensation. |
Compared with LTC3631EMSE#PBF and LM5164QPWPRQ1, LT1956IFE#PBF uniquely combines 60V input, 1.5A output, external synchronization, and duty-cycle-independent current limiting in a thermally optimized TSSOP-making it optimal for industrial 48V systems demanding reliability and design flexibility over raw integration density.
Availability
LT1956IFE#PBF is available at Aetrix Electronics and suitable for industrial power distribution, automotive body control modules, and portable medical equipment requiring stable component supply with guaranteed long-term availability.
Supply support for LT1956IFE#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 industrial, automotive, communications, and healthcare markets.
The LT1956IFE#PBF belongs to Linear's high-voltage monolithic buck regulator product line, designed specifically for rugged 5.5V–60V industrial and automotive power conversion where wide input range, thermal robustness, and fault resilience are mandatory.
FAQ
What is the maximum input voltage rating for the LT1956IFE#PBF?
The LT1956IFE#PBF has an absolute maximum input voltage (VIN) rating of 60V. This allows direct interface with 48V industrial buses and automotive systems experiencing load dump transients. Operation above 60V risks permanent damage. The BOOST pin tolerates up to 68V, and SHDN/SYNC pins are rated to 7V and 6V respectively-always observe individual pin voltage limits per the Absolute Maximum Ratings table.
Does the LT1956IFE#PBF require an external BOOST capacitor and diode?
Yes, the LT1956IFE#PBF requires an external BOOST capacitor and diode to saturate its internal NPN power switch and achieve the specified 0.2Ω on-resistance. The BOOST pin must be driven ~5V above VIN during switch-on time using a charge-pump network-typically a Schottky diode (e.g., MMSD914) and ceramic capacitor (e.g., 100V, 2.2µF). Omitting this network results in degraded efficiency and excessive switch heating.
How does the LT1956IFE#PBF handle short-circuit conditions?
The LT1956IFE#PBF employs dual foldback protection: when the SENSE pin voltage drops below 0.8V, switching frequency reduces ~5:1; below 0.6V, peak switch current limit folds back from 1.5A to <1A. This limits power dissipation in the IC, external diode, and inductor during sustained shorts. The feature is automatic and transparent under normal operation-no external components needed beyond standard input/output filtering.
Can the LT1956IFE#PBF be synchronized to an external clock?
Yes, the LT1956IFE#PBF supports external synchronization via the SYNC pin (Pin 14). It accepts logic-level square waves from 580kHz to 700kHz with 10%–90% duty cycle. This enables EMI reduction through clock dithering or alignment with system master clocks. If unused, SYNC must be tied to GND-leaving it floating may cause erratic operation or increased noise.
What is the thermal performance difference between LT1956IFE#PBF and LT1956EGN#PBF?
The LT1956IFE#PBF uses a thermally enhanced TSSOP (FE) package with θJA = 45°C/W, while the LT1956EGN#PBF uses standard SSOP (GN) with θJA = 85°C/W. This 40°C/W improvement stems from the FE package's exposed thermal pad, which must be soldered to a PCB ground plane. At 1.5A load and 25°C ambient, LT1956IFE#PBF junction temperature stays ~30°C cooler-enabling full-rated operation in compact, sealed enclosures without forced air.
LT1956IFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 5.5V
- Voltage - Input (Max):
- 60V
- Voltage - Output (Min/Fixed):
- 1.219V
- Voltage - Output (Max):
- 54V
- Current - Output:
- 1.5A (Switch)
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT1956IFE#PBF FAQ
1.How can I place an order for LT1956IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1956IFE#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 LT1956IFE#PBF reliable?
The price and inventory of LT1956IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1956IFE#PBF is usually 5 days.
3.What payment methods are accepted for LT1956IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1956IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1956IFE#PBF?
LT1956IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1956IFE#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 LT1956IFE#PBF?
For technical support, including LT1956IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1956IFE#PBF requirements.
6.How does Aetrix verify that LT1956IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT1956IFE#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 LT1956IFE#PBF meets industry standards.
7.What is the process for return or replacement of LT1956IFE#PBF?
All LT1956IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1956IFE#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 LT1956IFE#PBF part is unused and in its original packaging.
Return procedure for LT1956IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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