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Analog Devices Inc. LT1172CSW#TRPBF
- Part No.:
- LT1172CSW#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
LT1172CSW#TRPBF.pdf
- Description:
- IC REG BUCK BOOST ADJ 1.25A 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,474
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Product details
Overview
LT1172CSW#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic 100kHz current-mode switching regulator IC with an integrated 1.25A power switch, designed for buck, boost, flyback, inverting, and Cuk topologies. It operates from 3V to 40V input, delivers up to 50W output power, features 6mA quiescent current, shutdown mode drawing only 50µA, and supports fully floating isolated outputs in flyback-regulated mode - used in industrial DC-DC conversion and battery-powered upconverters.
For engineers reviewing the LT1172CSW#TRPBF datasheet, LT1172CSW#TRPBF pinout, LT1172CSW#TRPBF application, or LT1172CSW#TRPBF equivalent, key selection criteria include its 16-pin SO Wide package, internal switch current limit (1.25A typ.), flyback reference voltage (15.0–18.0V), adaptive anti-saturation drive, and thermal performance in surface-mount configurations without heatsinking under moderate loads.
Technical Context
The LT1172CSW#TRPBF implements current-mode control with a fixed 100kHz oscillator, enabling fast line/load transient response and simplified loop compensation. Its dual error amplifiers support both normal regulation (via FB pin at 1.24V reference) and isolated flyback mode (via FB pin pulled low to activate 15V flyback reference).
It integrates a high-voltage 65V-rated NPN switch with 0.6Ω typical on-resistance, adaptive anti-saturation driver logic, internal 2.3V bias regulator, and VC pin functionality for soft-start, current limit adjustment, and shutdown - all in a thermally optimized 16-lead plastic SO wide package with exposed thermal pad (θJA = 150°C/W).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 1.25A typical at 50% duty cycle; enables safe operation up to ~30W in boost/buck with standard magnetics. |
| Input Voltage Range | 3V to 40V; supports wide-range industrial and automotive battery inputs without external regulators. |
| Quiescent Current | 6mA; minimizes standby loss in always-on systems like remote sensors or IoT edge nodes. |
| Shutdown Current | 50µA; allows ultra-low-power sleep modes in portable equipment with battery life extension. |
| Flyback Reference Voltage | 15.0–18.0V; enables direct regulation of isolated secondary outputs without optocoupler feedback. |
| Switch Breakdown Voltage | 65V; permits use in 48V nominal systems with margin for transients and flyback voltage spikes. |
| Switch On-Resistance | 0.6Ω max; determines conduction loss and thermal rise-critical for efficiency in 12V→24V boost designs. |
| Operating Frequency | 88–115kHz; balances EMI, inductor size, and core loss for cost-effective discrete magnetics selection. |
Pinout & Package
LT1172CSW#TRPBF is housed in a 16-lead plastic SO wide (SW) package with exposed thermal pad. Pin 1 is NC; pins 9–11 are NC; E1 and E2 are not present (internally tied to GND in SW package per datasheet); thermal pad must be soldered to PCB ground plane for thermal management.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 9–11, 13–16 | No Connect | Unused pins; must remain unconnected per datasheet to avoid latch-up or parametric shift. |
| 2 | GND | Main power and signal ground reference; connects to thermal pad for heat dissipation. |
| 3 | VC | Error amplifier output; controls duty cycle, enables soft-start, current limit, and shutdown via external clamping. |
| 4 | FB | Feedback input; senses output voltage (1.24V ref) or selects flyback mode when pulled low. |
| 5 | NC | No connect; not bonded in SW package-leave floating. |
| 6 | VSW | Switch collector output; drives external inductor/diode; rated for 65V breakdown and 1.25A peak. |
| 7 | E2 | Not available; internally tied to GND in SW package-no external connection required. |
| 8 | VIN | Main supply input; powers internal regulator and switch; accepts 3–40V with 6mA quiescent draw. |
| 12 | E1 | Not available; internally tied to GND in SW package-no external connection required. |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode control architecture | Enables stable operation across wide input/output ratios and fast transient response without complex compensation. |
| Adaptive anti-saturation switch drive | Maintains high efficiency across 10:1 load range by dynamically adjusting base drive to prevent transistor saturation. |
| Dual error amplifier with mode select | Supports both standard voltage-mode regulation and transformer-isolated flyback regulation via single FB pin. |
| Externally programmable current limit | VC pin clamping allows precise setting of peak switch current from 0A to 2A-critical for overload protection. |
| Self-protected against overloads | Includes thermal foldback and current limiting; survives sustained short-circuit without external components. |
| Wide-package thermal design | SO wide package with thermal pad achieves 150°C/W θJA, enabling 0.3W dissipation at ≤56°C ambient in typical boost applications. |
Applications
| Industrial DC-DC Conversion | Battery-Powered Upconverter |
|---|---|
Use Scenario: Converting 12V rail to 24V for PLC I/O modules in factory automation cabinets with limited airflow. IC Role / Device Role / Timing Role: Primary controller in non-isolated boost topology; regulates output using FB pin feedback and manages switch timing via internal 100kHz oscillator. Use Value: Eliminates need for external MOSFET and gate driver; 6mA quiescent current extends system uptime during brownout conditions. | Use Scenario: Generating ±15V from a single 9V alkaline battery in portable test instrumentation. IC Role / Device Role / Timing Role: Core regulator in inverting topology; uses VC pin for soft-start to prevent battery sag during power-on. Use Value: Integrated 1.25A switch handles peak loads up to 300mA; shutdown mode draws only 50µA to preserve battery life between measurements. |
| Flyback-Isolated Power Supply | Logic-Level Supply Generation |
Use Scenario: Providing 5V/2A isolated auxiliary power for RS-485 transceivers in motor drive systems with ground potential differences. IC Role / Device Role / Timing Role: Flyback controller with FB pin configured for isolated regulation; uses internal 15V flyback reference to sense reflected secondary voltage. Use Value: Fully floating output eliminates optocoupler and TL431, reducing BOM count and improving long-term reliability. | Use Scenario: Deriving 5V @ 1A from a 24V industrial bus to power microcontroller peripherals and level-shifters. IC Role / Device Role / Timing Role: Buck regulator with VIN=24V, VOUT=5V; leverages high-side switch and internal current sensing for compact layout. Use Value: 0.6Ω switch RDS(on) limits conduction loss to <0.3W at full load-enabling TO-220-free design in space-constrained enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2577-ADJ | Fixed 52kHz frequency, 3A switch, no flyback mode support, requires external diode. | Lacks isolated flyback capability and adaptive anti-sat; suited for simpler non-isolated boost only. | Choose for cost-sensitive, non-isolated 3A boost where flyback regulation is unnecessary. |
| TPS54202DRT | 4.5–28V input, 2A FET, 500kHz sync capability, integrated compensation, no flyback reference. | Higher frequency enables smaller magnetics but lacks 15V flyback reference and 65V switch rating. | Prefer for compact 24V-input buck designs needing high density, but not for >28V or isolated flyback. |
Compared with LM2577-ADJ and TPS54202DRT, LT1172CSW#TRPBF uniquely supports flyback-isolated regulation without optocouplers, operates up to 40V input with 65V switch rating, and retains legacy compatibility in industrial repair and drop-in replacements where 100kHz timing and thermal robustness are critical.
Availability
LT1172CSW#TRPBF is available at Aetrix Electronics and suitable for industrial DC-DC conversion, battery-powered upconverters, and flyback-isolated power supplies requiring stable component supply across extended product lifecycles.
Supply support for LT1172CSW#TRPBF 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 full support for legacy Linear regulator products including the LT117x family.
The LT117x series was designed for high-reliability, wide-input industrial and military power conversion-emphasizing ruggedness, self-protection, and topology flexibility over raw efficiency or integration density.
FAQ
What is the maximum input voltage rating for LT1172CSW#TRPBF?
The LT1172CSW#TRPBF has an absolute maximum supply voltage of 40V. This rating applies across its full operating temperature range (0°C to 100°C). Exceeding 40V risks permanent damage, even briefly. For designs requiring higher input, the LT1172HV variants (e.g., LT1172HVCT#TRPBF) support up to 60V input and 75V switch breakdown-LT1172CSW#TRPBF must not be substituted in such cases without redesign.
Does LT1172CSW#TRPBF support flyback topology with isolated outputs?
Yes, LT1172CSW#TRPBF supports flyback topology with fully floating isolated outputs. When the FB pin is pulled below 0.45V with an external resistor, it activates the internal flyback error amplifier with a 15.0–18.0V reference-enabling regulation of reflected secondary voltage without optocouplers. This is confirmed in the datasheet's "Operation" section and typical application TA03, and is a defining feature distinguishing LT1172CSW#TRPBF from most contemporary regulators.
What is the function of the VC pin on LT1172CSW#TRPBF?
The VC pin on LT1172CSW#TRPBF serves four critical functions: (1) error amplifier output for loop compensation, (2) current limit adjustment via external voltage clamp, (3) soft-start initiation using a capacitor, and (4) total shutdown when pulled below 0.15V (reducing supply current to 50µA). Its voltage ranges from ~0.9V (light load) to ~2.0V (full load), and it sources/sinks up to 400µA-making it central to both dynamic control and protection in LT1172CSW#TRPBF designs.
Can LT1172CSW#TRPBF be synchronized to an external clock?
No, LT1172CSW#TRPBF cannot be synchronized to an external clock. While the LT1170/LT1171/LT1172 family datasheet mentions synchronization capability, this feature applies only to the LT1170 and LT1171 variants-not the LT1172. The LT1172CSW#TRPBF uses a fixed internal 100kHz oscillator with no sync input pin or documented external synchronization method. Attempting to force sync may disrupt regulation or cause instability.
What thermal considerations apply to LT1172CSW#TRPBF in the 16-pin SO wide package?
LT1172CSW#TRPBF in the SW package has θJA = 150°C/W. In a typical 5V→12V boost delivering 0.12A (0.34W total dissipation), ambient must stay below 56°C to keep junction at 100°C. The exposed thermal pad must be soldered to a ≥1 sq-in copper pour tied to GND. Leaving E1/E2 pins unconnected (as they are NC in SW) avoids ground-loop errors-but does not improve thermal performance, unlike in DIP packages where E2 is functional.
LT1172CSW#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Up, Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Boost, Cuk, Flyback, Forward Converter
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.244V
- Voltage - Output (Max):
- 65V (Switch)
- Current - Output:
- 1.25A (Switch)
- Frequency - Switching:
- 100kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 100°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
LT1172CSW#TRPBF FAQ
1.How can I place an order for LT1172CSW#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1172CSW#TRPBF 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 LT1172CSW#TRPBF reliable?
The price and inventory of LT1172CSW#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1172CSW#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1172CSW#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1172CSW#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1172CSW#TRPBF?
LT1172CSW#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1172CSW#TRPBF 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 LT1172CSW#TRPBF?
For technical support, including LT1172CSW#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1172CSW#TRPBF requirements.
6.How does Aetrix verify that LT1172CSW#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1172CSW#TRPBF 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 LT1172CSW#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1172CSW#TRPBF?
All LT1172CSW#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1172CSW#TRPBF, 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 LT1172CSW#TRPBF part is unused and in its original packaging.
Return procedure for LT1172CSW#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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