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Analog Devices Inc. LTC1147IS8-3.3#TRPBF
- Part No.:
- LTC1147IS8-3.3#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1147IS8-3.3#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,083
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Product details
Overview
LTC1147IS8-3.3#TRPBF from Analog Devices (formerly Linear Technology) is a high-efficiency, constant off-time current-mode step-down switching regulator controller driving an external P-channel MOSFET to deliver a regulated 3.3V output. It operates from 3.5V to 16V input, achieves >95% efficiency at full load, maintains 160µA standby current in Burst Mode, and supports 100% duty cycle for ultra-low dropout operation in portable instrumentation and battery-powered digital systems.
For engineers reviewing the LTC1147IS8-3.3#TRPBF datasheet, LTC1147IS8-3.3#TRPBF pinout, LTC1147IS8-3.3#TRPBF application, or LTC1147IS8-3.3#TRPBF equivalent, key selection criteria include its fixed 3.3V output voltage (±3% over load/temperature), 5µs typical off-time, 125°C junction temperature rating, 8-pin SO package, and compatibility with low-RDS(ON) P-MOSFETs for high-efficiency DC/DC conversion in space-constrained designs.
Technical Context
The LTC1147IS8-3.3#TRPBF implements a constant off-time current-mode architecture where the timing capacitor (CT) at Pin 2 sets switching frequency, and the SENSE+ (Pin 5)/SENSE– (Pin 4) differential pair monitors inductor current via an external sense resistor. Its internal 1.25V reference and fixed resistor divider establish the 3.3V output without external feedback components.
Burst Mode™ operation activates below ~15mA load to reduce quiescent current to 160µA, while shutdown mode draws <20µA when SHDN (Pin 6) is pulled above 0.8V. The PDRIVE (Pin 8) output delivers rail-to-rail drive for P-channel MOSFETs, and GND (Pin 7) requires separate high-current and signal ground routing per layout guidelines.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±3% (3.23V–3.43V) at 700mA load; no external resistors required |
| Input Voltage Range | 3.5V to 16V; enables direct operation from Li-ion, 5V rails, or automotive-derived supplies |
| Efficiency | >95% typical at full load; maintained across three decades of output current (1mA–2A) |
| Quiescent Current | 160µA in Burst Mode; reduces system power draw during light-load sleep states |
| Off-Time | 4–6.5µs (typ. 5µs); determines minimum on-time and dropout behavior |
| Shutdown Current | <22µA at VSHDN > 0.8V; enables deep system-level power gating |
| Current Sense Threshold | 125–185mV differential; sets peak inductor current and maximum output capability |
Pinout & Package
Package: 8-lead plastic SO (SOIC-8), 150°C/W junction-to-ambient thermal resistance, RoHS-compliant, tape-and-reel (TRPBF).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Main supply input | Accepts 3.5V–16V; requires local 100µF + 0.1µF ceramic decoupling |
| CT (Pin 2) | Timing capacitor connection | Sets switching frequency; discharge current scales with VOUT for stable off-time |
| ITH (Pin 3) | Gain amplifier decoupling | Stabilizes current comparator threshold; connect 0.1µF to GND |
| SENSE– (Pin 4) | Current sense negative input | Internal node tied to output voltage divider; forms differential pair with SENSE+ |
| SENSE+ (Pin 5) | Current sense positive input | Connects across RSENSE; 125–185mV threshold sets peak inductor current |
| SHDN/VFB (Pin 6) | Shutdown control / feedback | Logic-level input: <0.5V = active, >0.8V = shutdown; no external divider needed for fixed 3.3V |
| GND (Pin 7) | Power and signal ground | Two independent ground paths required: one to COUT(–), one to diode cathode/CIN(–) |
| PDRIVE (Pin 8) | P-channel MOSFET gate driver | Rail-to-rail output (VIN to GND); drives logic-level or standard-threshold P-MOSFETs |
Key Features
| Feature | Design Value |
|---|---|
| Constant off-time current-mode control | Delivers fast line/load transient response and inherent cycle-by-cycle current limiting |
| Automatic Burst Mode™ operation | Reduces IQ to 160µA at light loads while maintaining regulation and minimizing output ripple |
| 100% duty cycle capability | Enables ultra-low dropout (VOUT ≈ VIN) when input approaches output voltage |
| Short-circuit protection | Extends off-time during overload to limit average short-circuit current to safe levels |
| Logic-controlled micropower shutdown | Draws <22µA in shutdown; compatible with CMOS logic signals (tr/tf < 1µs) |
Applications
| Portable Instrumentation | Battery-Powered Digital Devices |
|---|---|
Use Scenario: Handheld multimeters and data loggers powered by two AA cells (3.0V–3.6V) requiring clean, regulated 3.3V for microcontroller and ADC operation. IC Role / Device Role / Timing Role: Step-down controller managing P-MOSFET switch and external passive components to maintain 3.3V under varying battery voltage and load conditions. Use Value: Enables >90% efficiency down to 1mA load via Burst Mode, extending battery life while supporting 2A peak current for sensor bursts. | Use Scenario: Wireless sensor nodes using Li-ion batteries (3.6V–4.2V) that must sustain 3.3V for BLE SoC and flash memory during intermittent transmission. IC Role / Device Role / Timing Role: Primary DC/DC controller providing regulated 3.3V with 160µA quiescent current and fast wake-up from shutdown. Use Value: Delivers 100% duty cycle operation near end-of-discharge (3.5V input), avoiding brownout resets during critical data uploads. |
| Notebook Subsystem Power | DC Power Distribution Systems |
Use Scenario: Secondary 3.3V rail generation in ultrabooks for USB-C PD companion ICs and display interface logic. IC Role / Device Role / Timing Role: Compact, high-efficiency buck controller interfacing with discrete P-MOSFET and Schottky diode for cost-sensitive, thermally constrained layouts. Use Value: Achieves >95% efficiency at 1.5A with minimal board area-no external feedback resistors required due to fixed 3.3V configuration. | Use Scenario: Distributed 3.3V point-of-load regulation in industrial I/O modules fed from centralized 12V backplane. IC Role / Device Role / Timing Role: Robust step-down controller handling wide input transients (up to 16V) and delivering stable 3.3V to FPGA I/O banks and communication PHYs. Use Value: Maintains regulation during 12V rail sag with 100% duty cycle, while Burst Mode preserves efficiency during idle periods between fieldbus polling cycles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1147IS8-5#TRPBF | Fixed 5V output; identical pinout, package, and architecture; same 3.5V–16V input range and Burst Mode behavior | Requires redesign of output filter and sense resistor for 5V operation; not drop-in for 3.3V systems | Select only if target application requires 5V output and can accommodate revised RSENSE and COUT values |
| LTC1148CS8#TRPBF | Higher-frequency version (up to 1MHz); lower quiescent current (120µA Burst Mode); requires different CT value and smaller inductor | Better suited for compact designs needing higher switching frequency; not pin-compatible due to different CT discharge characteristics | Choose when board space is critical and 1MHz operation is acceptable; verify loop stability with new component values |
Compared with LTC1147IS8-3.3#TRPBF, the LTC1147IS8-5#TRPBF provides identical functionality at 5V output but mandates circuit re-optimization, while the LTC1148CS8#TRPBF offers higher frequency and lower IQ but requires layout and compensation changes-not a direct replacement.
Availability
LTC1147IS8-3.3#TRPBF is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered digital devices, and DC power distribution systems requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for LTC1147IS8-3.3#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LTC1147 series belongs to Linear's legacy high-efficiency DC/DC controller product line, designed specifically for low-quiescent-current, P-channel MOSFET-based buck converters in battery-critical and space-constrained applications.
FAQ
What is the regulated output voltage of the LTC1147IS8-3.3#TRPBF?
The LTC1147IS8-3.3#TRPBF delivers a fixed, factory-trimmed 3.3V output with ±3% tolerance (3.23V–3.43V) across load currents from 5mA to 2A and operating temperatures from –40°C to 85°C. This is achieved via internal resistor divider and 1.25V reference-no external feedback components are required, simplifying design and reducing BOM count.
Does the LTC1147IS8-3.3#TRPBF require an external MOSFET?
Yes, the LTC1147IS8-3.3#TRPBF is a controller-not an integrated power stage-and requires an external P-channel MOSFET connected to PDRIVE (Pin 8). It is optimized for logic-level or standard-threshold P-MOSFETs with RDS(ON) selected based on load current and thermal constraints; the controller itself does not include any power switches.
How does Burst Mode™ operation improve efficiency in the LTC1147IS8-3.3#TRPBF?
Burst Mode™ in the LTC1147IS8-3.3#TRPBF reduces switching activity at light loads, lowering quiescent current to 160µA and cutting standby power to ~2mW at 10V input. This extends battery life in portable applications without sacrificing regulation-output voltage remains within spec while the controller cycles on/off only as needed to maintain 3.3V.
What is the maximum input voltage rating for the LTC1147IS8-3.3#TRPBF?
The absolute maximum input voltage for the LTC1147IS8-3.3#TRPBF is 16V applied to VIN (Pin 1). Continuous operation is specified from 3.5V to 14V, with the 16V limit representing the absolute stress rating beyond which permanent damage may occur. Designs operating near 14V–16V should include input transient suppression per Linear Application Note 54.
Can the LTC1147IS8-3.3#TRPBF operate with 100% duty cycle?
Yes, the LTC1147IS8-3.3#TRPBF supports 100% duty cycle operation when input voltage approaches output voltage, enabling ultra-low dropout regulation (VOUT ≈ VIN). This occurs automatically in constant off-time architecture when the timing capacitor discharge current increases as (VIN – VOUT) falls below 1.5V, maintaining regulation down to 3.5V input for 3.3V output.
LTC1147IS8-3.3#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 3.5V ~ 14V
- Frequency - Switching:
- -
- Duty Cycle (Max):
- 100%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC1147IS8-3.3#TRPBF FAQ
1.How can I place an order for LTC1147IS8-3.3#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1147IS8-3.3#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 LTC1147IS8-3.3#TRPBF reliable?
The price and inventory of LTC1147IS8-3.3#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1147IS8-3.3#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1147IS8-3.3#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1147IS8-3.3#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1147IS8-3.3#TRPBF?
LTC1147IS8-3.3#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1147IS8-3.3#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 LTC1147IS8-3.3#TRPBF?
For technical support, including LTC1147IS8-3.3#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1147IS8-3.3#TRPBF requirements.
6.How does Aetrix verify that LTC1147IS8-3.3#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1147IS8-3.3#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 LTC1147IS8-3.3#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1147IS8-3.3#TRPBF?
All LTC1147IS8-3.3#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1147IS8-3.3#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 LTC1147IS8-3.3#TRPBF part is unused and in its original packaging.
Return procedure for LTC1147IS8-3.3#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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