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Analog Devices Inc. LT1172CQ#TRPBF
- Part No.:
- LT1172CQ#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LT1172CQ#TRPBF.pdf
- Description:
- IC REG BCK BST ADJ 1.25A DDPAK-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,127
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Product details
Overview
LT1172CQ#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic 1.25A current-mode switching regulator IC in 5-lead DD (TO-220 variant) package, operating from 3V to 40V input, delivering up to 50W output power in buck/boost/flyback topologies with 100kHz fixed-frequency switching, 6mA quiescent current, and internal 1.25A switch. It enables compact, high-efficiency DC/DC conversion in battery-powered industrial power supplies.
For engineers reviewing the LT1172CQ#TRPBF datasheet, LT1172CQ#TRPBF pinout, LT1172CQ#TRPBF application, or LT1172CQ#TRPBF equivalent, key selection criteria include its 1.25A integrated switch rating, flyback-regulated floating output capability, shutdown mode drawing only 50µA, adaptive anti-saturation drive for wide load range efficiency, and compatibility with standard 5-pin TO-220 thermal layout practices.
Technical Context
The LT1172CQ#TRPBF implements current-mode control with a 100kHz oscillator, where switch duty cycle is directly set by sensed switch current rather than output voltage feedback alone-enabling fast line transient response and simplified loop compensation. Its dual error amplifier architecture supports both normal regulation (via FB pin at 1.24V reference) and isolated flyback mode (via FB pin pulled low to enable 15V flyback reference).
It integrates a 1.25A/65V DMOS power switch with 1Ω max on-resistance, adaptive anti-saturation driver, internal 2.3V bias regulator, and VC pin that serves as error amplifier output, current limit adjust, soft-start node, and shutdown control input-pulling VC below 0.15V reduces supply current to 50µA while disabling switching.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 1.25A typical at 50% duty cycle; enables reliable 1A continuous output in boost/buck designs without external FET. |
| Input Voltage Range | 3V to 40V; supports wide-range battery inputs (e.g., 4S Li-ion up to 16.8V or 12V lead-acid with headroom). |
| Quiescent Current | 6mA typical; ensures low standby loss in always-on systems like remote sensors or IoT edge nodes. |
| Shutdown Current | 50µA typical; allows ultra-low-power sleep modes in portable equipment with minimal battery drain. |
| Reference Voltage | 1.24V ±20mV at FB pin; provides stable feedback threshold for precise output voltage setting via resistor divider. |
| Switch Breakdown Voltage | 65V; permits safe operation with 48V nominal bus inputs after derating, including flyback transformer leakage spikes. |
| Switch On-Resistance | 1.0Ω max; determines conduction loss-e.g., 1.25A × 1.25A × 1.0Ω = 1.56W dissipation at full switch current. |
| Operating Temperature | 0°C to 100°C junction; validated for commercial-grade embedded power stages without forced cooling. |
Pinout & Package
LT1172CQ#TRPBF uses the Q-package: 5-lead DD (plastic TO-220 variant) with tab connected to GND. Thermal resistance θJA = 75°C/W, enabling moderate-power operation without heatsink under proper PCB copper area.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Power Input | Accepts 3V–40V unregulated DC; must be bypassed with ≥1µF ceramic near pin to suppress switching noise. |
| VSW | Switch Output | Drives external inductor/diode network; connects to drain of internal 1.25A DMOS switch; handles high di/dt. |
| GND | Ground Reference | Power and signal ground; tab is internally connected-must be soldered to ≥1 sq-in copper pour for thermal management. |
| FB | Feedback Input | Senses output voltage divider; 1.24V reference enables regulation; pulled low enables flyback mode (15V ref). |
| VC | Error Amplifier Output | Provides gm-amplifier output; used for compensation, current limit adjustment, soft-start, and shutdown control. |
Key Features
| Feature | Design Value |
|---|---|
| Current-Mode Control | Enables immediate line transient response and inherent pulse-by-pulse overcurrent protection without sensing resistors. |
| Flyback-Regulated Mode | Supports fully floating, transformer-isolated outputs up to breakdown voltage of windings-no optocoupler required. |
| Adaptive Anti-Saturation Drive | Maintains high efficiency across 10:1 load range by dynamically adjusting gate drive to prevent switch saturation. |
| External Synchronization | Accepts 120–160kHz sync pulses on VC pin to eliminate beat frequencies in multi-regulator systems. |
| Thermal Shutdown Protection | Internal thermal limit disables switching during overload or poor heatsinking-prevents catastrophic failure in sealed enclosures. |
| Low Component Count | Requires only inductor, diode, capacitor, and two resistors for basic buck/boost-reduces BOM cost and board space. |
Applications
| Battery-Powered Boost Supply | Isolated Flyback Power Supply |
|---|---|
Use Scenario: Generating 12V from a 3.6V Li-ion cell for MCU peripherals and sensors in portable test equipment. IC Role / Device Role / Timing Role: Primary controller in non-synchronous boost topology; regulates output using internal 1.25A switch and 100kHz oscillator. Use Value: Eliminates need for external MOSFET and gate driver-reducing solution size by >30% and component count by 4 parts versus discrete controllers. | Use Scenario: Providing isolated ±15V rails for op-amps in medical data acquisition front-ends with reinforced insulation requirements. IC Role / Device Role / Timing Role: Flyback controller with floating secondary outputs; uses FB pin pull-down to activate 15V flyback reference and regulate via primary-side sensing. Use Value: Achieves <1% output regulation without optocoupler or TL431, simplifying certification and reducing bill-of-materials cost by $0.42 per unit. |
| Industrial 24V-to-5V Buck Converter | Programmable Logic Controller (PLC) Auxiliary Supply |
Use Scenario: Converting 24V factory bus to regulated 5V for digital I/O modules in harsh industrial environments. IC Role / Device Role / Timing Role: Fixed-frequency buck regulator with internal switch; operates across –40°C to +85°C ambient with 0°C to 100°C junction rating. Use Value: Withstands 40V transients per IEC 61000-4-4; 6mA quiescent current minimizes self-heating during extended idle periods. | Use Scenario: Powering microcontroller and communication interfaces in DIN-rail mounted PLCs requiring long-term reliability and EMI robustness. IC Role / Device Role / Timing Role: Primary-side controller in flyback configuration with synchronous rectification option; supports shutdown via VC pin for firmware-controlled power cycling. Use Value: 50µA shutdown current extends backup battery life to >12 months; integrated current limiting prevents latch-up during field wiring faults. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2574HVS-5.0/NOPB | Fixed 5V output, 0.5A switch, 52V max input, no flyback mode support, 52kHz switching. | Limited to fixed-output non-isolated buck; unsuitable for variable output or isolated topologies. | Select when only 5V buck required and board space allows larger inductor due to lower frequency. |
| TPS54202DRCT | 2A integrated FET, 60V input, 400kHz switching, requires external compensation, no flyback reference mode. | Higher efficiency at light loads but lacks native flyback regulation-requires optocoupler for isolation. | Prefer for higher-power buck/boost where footprint and efficiency outweigh design complexity. |
Compared with LM2574HVS-5.0/NOPB and TPS54202DRCT, the LT1172CQ#TRPBF uniquely combines 1.25A switching, flyback-mode capability without optocoupler, and 100kHz fixed frequency in a thermally optimized TO-220 package-making it optimal for cost-sensitive, isolated, or multi-topology industrial power designs.
Availability
LT1172CQ#TRPBF is available at Aetrix Electronics and suitable for battery upconverters, isolated sensor supplies, and industrial 24V-to-5V buck converters requiring stable component supply, long-lifecycle availability, and RoHS-compliant packaging.
Supply support for LT1172CQ#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 product support, documentation, and manufacturing continuity for legacy Linear parts including the LT117x family.
The LT117x series was designed specifically for high-reliability, low-component-count DC/DC conversion in industrial, automotive, and instrumentation applications-emphasizing ruggedness, wide input range, and topology flexibility over digital programmability.
FAQ
What is the maximum output power achievable with the LT1172CQ#TRPBF in boost configuration?
The LT1172CQ#TRPBF delivers up to 50W in boost mode under optimal thermal conditions (e.g., 12V output from 5V input at 1.25A switch current). Derate by factor of 4 versus LT1170 due to its 1.25A switch rating-actual power depends on input voltage, duty cycle, and PCB thermal design. At 24V input/12V output, expect ~15W continuous with TO-220 copper pour.
Can the LT1172CQ#TRPBF be used in flyback topology without an optocoupler?
Yes-the LT1172CQ#TRPBF supports flyback-regulated mode by pulling the FB pin low, activating an internal 15V flyback reference. This enables primary-side regulation of isolated outputs without optocoupler or secondary-side feedback components, reducing cost and improving reliability in medical and industrial isolation applications.
What is the function of the VC pin on the LT1172CQ#TRPBF beyond error amplification?
The VC pin on the LT1172CQ#TRPBF serves four critical functions: (1) error amplifier output for loop compensation, (2) current limit adjustment via external clamp, (3) soft-start initiation using capacitor coupling, and (4) shutdown control-pulling VC below 0.15V reduces supply current to 50µA and halts switching, enabling ultra-low-power standby states.
Does the LT1172CQ#TRPBF require external components for basic operation?
Yes-LT1172CQ#TRPBF requires at minimum: an inductor (e.g., 50µH for boost), catch diode (e.g., MUR110), output capacitor (e.g., 100µF), input bypass capacitor (≥1µF), and two resistors for FB voltage divider. No external current sense resistor or gate driver is needed due to integrated switch and current-mode architecture.
How does the LT1172CQ#TRPBF handle thermal overload conditions?
The LT1172CQ#TRPBF includes internal thermal shutdown that disables switching when junction temperature exceeds safe limits-protecting the die during sustained overload or inadequate heatsinking. This is not a tested specification but a functional safeguard; for mission-critical applications, external thermal monitoring or reduced current limit via VC pin clamping is recommended.
LT1172CQ#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- 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:
- DDPAK-5
LT1172CQ#TRPBF FAQ
1.How can I place an order for LT1172CQ#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1172CQ#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 LT1172CQ#TRPBF reliable?
The price and inventory of LT1172CQ#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1172CQ#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1172CQ#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1172CQ#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1172CQ#TRPBF?
LT1172CQ#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1172CQ#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 LT1172CQ#TRPBF?
For technical support, including LT1172CQ#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1172CQ#TRPBF requirements.
6.How does Aetrix verify that LT1172CQ#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1172CQ#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 LT1172CQ#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1172CQ#TRPBF?
All LT1172CQ#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1172CQ#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 LT1172CQ#TRPBF part is unused and in its original packaging.
Return procedure for LT1172CQ#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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