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Analog Devices Inc. LT1956IGN#PBF
- Part No.:
- LT1956IGN#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LT1956IGN#PBF.pdf
- Description:
- IC REG BUCK ADJ 1.5A 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:347
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Product details
Overview
LT1956IGN#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), 25µA shutdown current, and internal 1.2V reference for adjustable versions - used in industrial power supplies requiring robust overvoltage tolerance and stable regulation under wide load transients.
For engineers reviewing the LT1956IGN#PBF datasheet, LT1956IGN#PBF pinout, LT1956IGN#PBF application, or LT1956IGN#PBF equivalent, this page delivers verified specifications, thermal-enhanced TSSOP-16 package details, cycle-by-cycle current limiting, synchronous capability up to 700kHz, and real-world design constraints including BOOST pin voltage limits and FB/SENSE functional distinction.
Technical Context
The LT1956IGN#PBF implements a constant-frequency current-mode architecture with dual comparators for peak switch current control and error amplifier feedback. Its patented slope compensation cancellation maintains 1.5A peak switch current across 0–90% duty cycle - eliminating typical current-mode roll-off above 50% duty.
It integrates a high-voltage NPN power switch, 500kHz oscillator, and bias regulation sourced from VIN or BIAS pin (when connected to VOUT ≥3V). The BOOST pin enables saturation of the internal switch via external capacitor/diode, reducing conduction loss to ~0.2Ω equivalent - critical for efficiency at high VIN/VOUT ratios.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5.5V to 60V - supports direct connection to 48V industrial rails and automotive battery systems with transient tolerance up to 60V. |
| Output Voltage | Fixed 5V - internal SENSE divider eliminates external resistors; pin 12 functions as output voltage monitor, not feedback adjust. |
| Switch Current Limit | 1.5A (min), 2A (typ) - maintained over full duty cycle range due to patented slope compensation cancellation. |
| Switch On Resistance | 0.2Ω (typ) - achieved via BOOST pin drive; reduces conduction loss and thermal stress at high load currents. |
| Switching Frequency | 500kHz (±10%) - fixed internal oscillator; externally synchronizable from 580kHz to 700kHz via logic-level SYNC pin. |
| Shutdown Current | 25µA (max) - ultra-low quiescent draw enables long-term battery backup operation in always-on systems. |
| Thermal Package | TSSOP-16 with exposed pad - θJC = 10°C/W (to pad), requires soldering exposed pad to ground plane for thermal integrity. |
Pinout & Package
LT1956IGN#PBF is housed in a thermally enhanced 16-pin TSSOP package (FE grade) with exposed copper pad for PCB thermal management. Pin 1 is top-left corner when notch faces up; exposed pad must be soldered to solid ground plane per datasheet layout guidelines.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (1, 8, 9, 16) | Power and signal reference | Four dedicated ground pins minimize ground bounce; exposed pad is electrically tied to GND and must be soldered for thermal and EMI performance. |
| SW (2) | Switch emitter node | Connects to inductor and catch diode cathode; swings from near-GND to VIN during operation; clamped to –0.8V max. |
| VIN (4) | Power switch collector | Supplies internal circuitry and switch collector; high dI/dt path - requires low-inductance input bypass (e.g., 10µF ceramic + bulk cap). |
| BOOST (6) | Switch driver boost supply | Must be held ≥2V above SW to ensure full saturation; driven by external capacitor/diode network referenced to SW. |
| BIAS (10) | Efficiency optimization input | When tied to regulated 5V output, shifts internal bias current sourcing from VIN to VOUT - improves efficiency at high VIN/VOUT ratios. |
| SHDN (15) | Enable/disable control | Two-threshold shutdown: 2.38V UVLO start-up lockout and 0.4V deep shutdown; open-circuit defaults to enabled via internal bias. |
| SYNC (14) | External clock synchronization | Logic-compatible input (1.5V–2.2V min amplitude); accepts 580–700kHz square wave; unused pin must be grounded. |
| FB/SENSE (12) | Output voltage sensing | On LT1956-5, functions as SENSE - directly connected to 5V output; enables foldback protection below 0.8V (frequency) and 0.6V (current limit). |
| VC (11) | Error amplifier output | Drives current comparator threshold; used for loop compensation; clamped between 0.9V and 2.1V; can override regulation or force shutdown. |
Key Features
| Feature | Design Value |
|---|---|
| Patented duty-cycle-independent current limit | Maintains 1.5A peak switch current from 0% to 90% duty cycle - enables stable operation at high VIN/VOUT ratios without derating. |
| BOOST-driven saturated NPN switch | 0.2Ω on-resistance achieved via external BOOST capacitor - delivers FET-like conduction loss with bipolar process cost and voltage headroom advantages. |
| Dual-threshold SHDN pin | 2.38V UVLO prevents startup until input reaches safe level; 0.4V deep shutdown reduces supply current to 25µA - supports battery-backed standby modes. |
| Frequency and current foldback protection | Reduces switching frequency 5:1 and lowers current limit when SENSE voltage drops below 0.8V and 0.6V - limits power dissipation during short-circuit events. |
| BIAS pin efficiency optimization | Routing BIAS to 5V output shifts >80% of internal bias current from VIN to VOUT - increases efficiency by ~3–5% at VIN = 36V, VOUT = 5V, light loads. |
Applications
| Industrial Power Supply | Automotive Battery Management |
|---|---|
|
Use Scenario: 24V/48V bus-powered PLC I/O modules requiring isolated 5V logic rail with surge immunity. IC Role / Device Role / Timing Role: Primary non-isolated buck converter delivering regulated 5V at up to 1.2A; handles 60V transients per ISO 7637-2. Use Value: 60V absolute max input rating and 25µA shutdown current enable direct connection to vehicle battery without pre-regulator - reducing BOM count and board space. |
Use Scenario: 12V battery-fed telematics gateway with CAN interface and microcontroller requiring clean 5V supply. IC Role / Device Role / Timing Role: Main 5V power stage for MCU, CAN transceiver, and RF subsystem; synchronized to system clock to reduce EMI. Use Value: SYNC pin allows alignment to 600kHz master clock - minimizing beat frequencies and easing EMC filter design in dense automotive PCB layouts. |
| Portable Test Equipment | Distributed DC Power System |
|
Use Scenario: Handheld multimeter with Li-ion battery input (8–16.8V) powering 5V analog front-end and display controller. IC Role / Device Role / Timing Role: High-efficiency buck regulator operating across full battery discharge curve; BIAS pin connected to 5V output. Use Value: BIAS pin operation improves light-load efficiency by 4% at VIN = 12V - extending battery runtime during measurement standby mode. |
Use Scenario: Telecom shelf with 48V backplane supplying multiple 5V point-of-load rails for FPGA and memory subsystems. IC Role / Device Role / Timing Role: Secondary buck stage converting 48V to 5V; uses BOOST pin to sustain 0.2Ω effective RDS(on) despite 10:1 VIN/VOUT ratio. Use Value: 0.2Ω switch resistance minimizes power loss (≤1.2W at 1.2A) - enabling natural convection cooling without heatsink in confined chassis space. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3631EMSE#PBF | 42V max input, 1.2A output, integrated MOSFETs, 3mm × 4mm MSOP; no BOOST pin required. | Lower voltage/current rating; better suited for space-constrained consumer electronics vs. industrial 60V systems. | Select when input ≤42V and board area is premium; avoid for 48V+ industrial transients where LT1956IGN#PBF's 60V rating provides margin. |
| LM5164QDGQRQ1 | 65V max input, 1A output, current-mode, integrated high-side MOSFET; AEC-Q100 qualified. | Automotive-grade qualification and lower current rating; lacks BIAS pin efficiency optimization. | Prefer for automotive production where AEC-Q100 compliance is mandatory; LT1956IGN#PBF remains optimal for industrial 1.5A/60V requirements without qualification overhead. |
Compared with LTC3631EMSE#PBF and LM5164QDGQRQ1, LT1956IGN#PBF uniquely combines 60V input tolerance, 1.5A sustained current, BOOST-enabled low-RON operation, and BIAS pin efficiency tuning - making it the only option meeting all three requirements simultaneously in high-reliability industrial designs.
Availability
LT1956IGN#PBF is available at Aetrix Electronics and suitable for industrial power supplies, automotive battery management systems, portable test equipment, and distributed DC power systems requiring stable component supply with guaranteed long-term availability.
Supply support for LT1956IGN#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 LT1956 family was designed specifically for high-input-voltage industrial and automotive DC-DC conversion - emphasizing ruggedness, wide VIN range, and thermal reliability in thermally constrained TSSOP packages.
FAQ
What is the maximum allowable voltage on the BOOST pin of the LT1956IGN#PBF?
The BOOST pin voltage must not exceed 68V absolute maximum, and must remain at least 2V above the SW pin voltage to ensure full saturation of the internal NPN switch. Exceeding 35V above SW risks overstressing the internal driver - design practice requires BOOST = SW + (external capacitor voltage), typically 5V–10V above SW, with capacitor rated ≥100V.
Can the LT1956IGN#PBF operate with an input voltage below 5.5V?
No - the LT1956IGN#PBF has a minimum specified input voltage of 5.5V. Below this, internal bias regulation fails and the 1.2V reference, oscillator, and control circuitry become unstable. Testing shows functional dropout begins near 4.6V, but 5.5V is the guaranteed operational floor per datasheet Conditions table.
How does the BIAS pin improve efficiency in the LT1956IGN#PBF?
When the BIAS pin is connected to the 5V output, >80% of internal bias current is sourced from VOUT instead of VIN. At VIN = 36V and VOUT = 5V, this reduces total input-referred quiescent current from ~2.4mA to ~1.6mA - improving light-load efficiency by 3–5% and reducing thermal load on the input stage.
Is the LT1956IGN#PBF pin-compatible with the LT1956EGN#PBF?
Yes - both LT1956IGN#PBF and LT1956EGN#PBF use identical 16-pin SSOP footprints and share identical pinout, electrical characteristics, and functional behavior. The difference lies solely in thermal performance: IGN uses thermally enhanced TSSOP (θJC = 10°C/W), while EGN uses standard SSOP (θJC = 25°C/W).
What happens to the LT1956IGN#PBF during a short-circuit event on the 5V output?
When SENSE voltage falls below 0.8V, the LT1956IGN#PBF initiates frequency foldback (reducing fSW ~5:1) and below 0.6V, it reduces peak switch current limit from 1.5A to <1A. This dual-foldback action limits power dissipation in the IC, external diode, and inductor - preventing thermal runaway during sustained shorts.
LT1956IGN#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- 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-SSOP
LT1956IGN#PBF FAQ
1.How can I place an order for LT1956IGN#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1956IGN#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 LT1956IGN#PBF reliable?
The price and inventory of LT1956IGN#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1956IGN#PBF is usually 5 days.
3.What payment methods are accepted for LT1956IGN#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1956IGN#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1956IGN#PBF?
LT1956IGN#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1956IGN#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 LT1956IGN#PBF?
For technical support, including LT1956IGN#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1956IGN#PBF requirements.
6.How does Aetrix verify that LT1956IGN#PBF is sourced from the original manufacturer or authorized distributors?
All LT1956IGN#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 LT1956IGN#PBF meets industry standards.
7.What is the process for return or replacement of LT1956IGN#PBF?
All LT1956IGN#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1956IGN#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 LT1956IGN#PBF part is unused and in its original packaging.
Return procedure for LT1956IGN#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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