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Analog Devices Inc. LT1956EFE#PBF
- Part No.:
- LT1956EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT1956EFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 1.5A 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:5,018
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Product details
Overview
LT1956EFE#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 integrates a bipolar NPN power switch, oscillator, error amplifier, and cycle-by-cycle current limiting-designed for industrial power conversion where wide VIN and robust short-circuit protection are required.
For engineers reviewing the LT1956EFE#PBF datasheet, LT1956EFE#PBF pinout, LT1956EFE#PBF application, or LT1956EFE#PBF equivalent, key selection criteria include its fixed 5V output (LT1956-5 variant), thermally enhanced TSSOP-16 package with exposed pad, 25µA shutdown current, and ability to maintain 1.5A peak switch current across full duty cycle-critical for high-VIN battery charger and distributed power designs.
Technical Context
The LT1956EFE#PBF implements a constant-frequency current-mode control architecture with dual comparators for precise peak-current sensing and slope compensation cancellation-enabling stable operation up to 90% duty cycle without current limit roll-off. Its BOOST pin drives an external capacitor-diode network to saturate the internal NPN switch, achieving FET-like 0.2Ω conduction loss despite bipolar construction.
It features three integrated protection functions tied to the FB/SENSE pin: frequency foldback below 0.8V, current limit reduction below 0.6V, and SYNC disable-all active during startup or short-circuit conditions. The SHDN pin provides dual-threshold control: 2.38V UVLO lockout and 0.4V deep shutdown, delivering 25µA quiescent current in micropower mode.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5.5V to 60V - supports 24V/48V industrial rails and automotive transients up to 60V |
| Output Configuration | Fixed 5V output (LT1956-5 variant) - no external feedback divider required; SENSE pin connects directly to VOUT |
| Switch Current Limit | 1.5A (min), maintained over full duty cycle - enables high step-down ratios without current derating |
| Switch On Resistance | 0.2Ω (typ) - achieved via BOOST-driven saturation, reducing conduction loss vs. standard bipolar switches |
| Switching Frequency | 500kHz (±10%) - fixed frequency simplifies EMI filtering; synchronizable from 580kHz to 700kHz |
| Shutdown Current | 25µA (max) - enables ultra-low-power standby in battery-backed systems |
| Thermal Resistance | θJA = 45°C/W, θJC (pad) = 10°C/W - exposed thermal pad requires soldered ground plane for rated 125°C junction operation |
Pinout & Package
LT1956EFE#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 integrity per datasheet layout requirements.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pins 1, 8, 9, 16) | Power and signal reference ground | Four dedicated GND pins minimize ground impedance; exposed pad must be connected to same ground plane for thermal management and load regulation |
| SW (Pin 2) | Switch emitter node | Drives external inductor; swings from near 0V to VIN during operation; negative swing clamped externally |
| VIN (Pin 4) | Switch collector and bias supply input | Supplies internal circuitry when BIAS pin is unconnected; high dI/dt path requires low-inductance input capacitor placement |
| BOOST (Pin 6) | Switch driver voltage boost | Accepts external capacitor-diode charge pump to raise drive voltage above VIN, enabling NPN saturation and 0.2Ω RON |
| BIAS (Pin 10) | Efficiency-optimized bias supply | When connected to VOUT ≥3V, shifts internal bias current from VIN to VOUT, improving efficiency at high VIN/light loads |
| SHDN (Pin 15) | Enable/disable control | Dual-threshold: 2.38V disables switching (UVLO), 0.4V forces 25µA shutdown; open-circuit defaults to enabled via internal bias |
| FB/SENSE (Pin 12) | Output voltage sense (LT1956-5) | 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 clamp | Provides loop compensation node; also serves as current limit override point; clamped at 2.1V max, sinks up to 450µA |
Key Features
| Feature | Design Value |
|---|---|
| Full-duty-cycle current limit maintenance | Patented slope compensation cancellation preserves 1.5A peak switch current up to 90% duty cycle-no derating needed for high-VIN/low-VOUT applications |
| Integrated short-circuit protection | Three-tier FB/SENSE response: frequency foldback (below 0.8V), current limit reduction (below 0.6V), and SYNC disable-limits power dissipation during faults without external circuitry |
| Thermally enhanced TSSOP-16 (FE) | θJC = 10°C/W via exposed pad - enables 1.5A continuous operation at 125°C junction temperature with proper PCB copper area |
| BOOST-assisted NPN saturation | External BOOST capacitor enables 0.2Ω effective switch resistance - achieves MOSFET-level conduction loss while retaining bipolar process advantages |
| Logic-compatible synchronization | SYNC pin accepts 580–700kHz external clock with 10–90% duty cycle - eliminates beat frequencies in multi-regulator systems without additional level-shifting |
Applications
| Industrial Power Supply | Automotive Battery Charger |
|---|---|
Use Scenario: 24V or 48V DC bus powering 5V logic, sensors, and communication modules in factory automation controllers. IC Role / Device Role / Timing Role: Primary non-isolated buck converter delivering regulated 5V at up to 1.5A from wide-input industrial rail. Use Value: Maintains full 1.5A current limit across 90% duty cycle enables reliable operation even at 48V→5V (10.4:1 ratio), avoiding derating seen in conventional current-mode regulators. |
Use Scenario: On-board 12V–60V transient-tolerant charging circuit for auxiliary 5V Li-ion or lead-acid battery banks in commercial vehicles. IC Role / Device Role / Timing Role: High-VIN buck regulator with UVLO and short-circuit foldback protecting against load dumps and battery shorts. Use Value: 60V absolute max VIN rating and 25µA shutdown current support direct connection to vehicle battery; foldback limits fault energy during cranking or jump-start events. |
| Distributed Power System | Portable Medical Equipment |
Use Scenario: Point-of-load conversion in telecom shelf systems where 48V backplane supplies isolated 5V for FPGA I/O banks and interface ICs. IC Role / Device Role / Timing Role: Compact, thermally efficient local regulator replacing larger discrete solutions in space-constrained modules. Use Value: TSSOP-16 FE package with 45°C/W θJA allows 1.5A output in <1 cm² footprint without heatsink-reducing board area vs. TO-220 or D2PAK alternatives. |
Use Scenario: Battery-powered portable ultrasound or patient monitor requiring 5V rail with low-noise, high-reliability power under variable load and temperature. IC Role / Device Role / Timing Role: Main system supply with micropower shutdown and robust thermal performance across –40°C to +85°C ambient. Use Value: Guaranteed –40°C to +125°C junction operation and 25µA shutdown enable long battery life and field reliability; BOOST-assisted low RON reduces thermal stress during peak imaging loads. |
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 VIN, 1.2A output, integrated MOSFETs, 3mm × 4mm MSOP-10 package | Lower voltage/current rating; lacks BOOST-assisted saturation and full-duty-cycle current maintenance | Preferred for compact, lower-VIN designs where 40V/1.2A suffices and PCB area is critical |
| LM5164QPWPRQ1 | 100V max VIN, 0.6A output, integrated MOSFETs, 16-pin HTSSOP with thermal pad | Higher VIN rating but lower current; uses valley-current mode vs. LT1956's current-mode with slope cancellation | Selected for automotive AEC-Q100-compliant 100V systems where 0.6A is adequate and qualification is mandatory |
Compared with LTC3631EMSE#PBF and LM5164QPWPRQ1, LT1956EFE#PBF uniquely delivers 1.5A at 60V with full-duty-cycle current stability and BOOST-enabled 0.2Ω switch-making it optimal for high-ratio industrial buck conversion where both current and voltage headroom are simultaneously constrained.
Availability
LT1956EFE#PBF is available at Aetrix Electronics and suitable for industrial power supplies, automotive battery chargers, and distributed power systems requiring stable component supply, extended temperature operation, and high-VIN reliability.
Supply support for LT1956EFE#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 high-performance analog and power management portfolio. Linear pioneered monolithic high-voltage switching regulators with proprietary process and circuit techniques.
The LT1956 product line was designed specifically for rugged industrial and transportation applications demanding wide input range, high current, and fault resilience-leveraging Linear's high-voltage bipolar process and patented current-mode control innovations.
FAQ
What is the maximum input voltage rating for LT1956EFE#PBF?
The LT1956EFE#PBF has an absolute maximum input voltage rating of 60V, with guaranteed operation from 5.5V to 60V. This enables direct use in 48V industrial systems and automotive applications subject to load dump transients. Exceeding 60V risks permanent damage per Absolute Maximum Ratings.
Does LT1956EFE#PBF require an external feedback resistor divider?
No. LT1956EFE#PBF is the -5 variant with fixed 5V output; its FB pin functions as SENSE and connects directly to the output. Internal precision resistors set the 5V regulation point (4.94V to 5.06V), eliminating external divider components and associated tolerance errors.
How does the BOOST pin function in LT1956EFE#PBF?
The BOOST pin on LT1956EFE#PBF accepts an external capacitor-diode charge pump to generate a voltage ~5V above VIN. This elevated drive voltage saturates the internal NPN power switch, achieving a typical on-resistance of 0.2Ω-significantly lower than standard bipolar switches and critical for high-efficiency high-VIN operation.
What thermal design is required for LT1956EFE#PBF at full 1.5A load?
LT1956EFE#PBF requires the exposed thermal pad to be soldered to a minimum 1 cm² copper ground plane for θJA = 45°C/W. At 1.5A and 60V input, junction temperature must be verified using TJ = TA + (PD × θJA); thermal vias under the pad and multilayer ground planes are strongly recommended for sustained operation at 125°C junction.
Can LT1956EFE#PBF be synchronized to an external clock?
Yes. The SYNC pin on LT1956EFE#PBF accepts logic-level signals from 580kHz to 700kHz with 10–90% duty cycle, enabling noise-sensitive systems to avoid beat frequencies. When unused, SYNC must be tied to GND; floating the pin may cause erratic operation due to noise coupling.
LT1956EFE#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:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT1956EFE#PBF FAQ
1.How can I place an order for LT1956EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1956EFE#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 LT1956EFE#PBF reliable?
The price and inventory of LT1956EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1956EFE#PBF is usually 5 days.
3.What payment methods are accepted for LT1956EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1956EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1956EFE#PBF?
LT1956EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1956EFE#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 LT1956EFE#PBF?
For technical support, including LT1956EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1956EFE#PBF requirements.
6.How does Aetrix verify that LT1956EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT1956EFE#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 LT1956EFE#PBF meets industry standards.
7.What is the process for return or replacement of LT1956EFE#PBF?
All LT1956EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1956EFE#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 LT1956EFE#PBF part is unused and in its original packaging.
Return procedure for LT1956EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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