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Analog Devices Inc. LTC1147LCS8-3.3#PBF
- Part No.:
- LTC1147LCS8-3.3#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1147LCS8-3.3#PBF.pdf
- Description:
- IC REG CTRLR BUCK 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,431
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Product details
Overview
LTC1147LCS8-3.3#PBF 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 fixed 3.3V output. It operates from 3.5V to 16V input, achieves >95% efficiency at full load, maintains regulation down to 160µA quiescent current in Burst Mode, and supports 100% duty cycle for ultra-low dropout operation - ideal for battery-powered portable instrumentation and GPS systems.
For engineers reviewing the LTC1147LCS8-3.3#PBF datasheet, LTC1147LCS8-3.3#PBF pinout, LTC1147LCS8-3.3#PBF application, or LTC1147LCS8-3.3#PBF equivalent, key selection criteria include its 3.3V fixed output voltage tolerance (±2.0%), programmable current sense threshold (125–185mV), 3.8–6.5µs off-time range, micropower shutdown (<20µA), and SO-8 package compatibility with ground-referenced RSENSE layouts.
Technical Context
The LTC1147LCS8-3.3#PBF implements a constant off-time current-mode architecture with internal 1.25V reference and built-in 25mV–150mV current sense comparator offset. Its CT pin controls switching frequency via external capacitor, while ITH pin enables dynamic current threshold adjustment for load transient optimization.
Burst Mode operation activates below ~15mV/RSENSE load current, reducing IQ to 160µA and enabling <2mW standby power at VIN = 10V. Short-circuit protection extends tOFF to limit peak inductor current, and 100% duty cycle operation ensures regulation even when VIN approaches VOUT + 0.3V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±2.0% (3.23–3.43V) at 700mA load - ensures stable logic supply for 3.3V microcontrollers and RF ICs |
| Input Voltage Range | 3.5V to 16V - supports single-cell Li-ion (4.2V), dual-cell NiMH (3.6V), and automotive 12V rail with headroom |
| Current Sense Threshold | 125–185mV - sets peak inductor current; determines max output current with RSENSE = 100mV/IMAX |
| Off-Time | 3.8–6.5µs (CT = 390pF, ILOAD = 700mA) - defines minimum switch-off duration and regulates frequency vs. VIN–VOUT |
| Quiescent Current | 160–260µA in Sleep Mode - enables multi-week battery life in always-on sensor nodes |
| Shutdown Current | 10–22µA - allows deep system sleep with logic-level SHDN control |
| Feedback Reference | 1.25V internal - used with internal divider for fixed 3.3V output; no external resistors required |
Pinout & Package
Package: 8-lead plastic SO (SO-8), RoHS-compliant, θJA = 150°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Main power input | Accepts 3.5–16V; requires local 0.1µF ceramic + bulk decoupling; absolute max 16V |
| CT (Pin 2) | Timing capacitor node | Connects to ground via CT (e.g., 390pF); sets off-time and operating frequency |
| ITH (Pin 3) | Current threshold adjust | Voltage applied here scales current comparator threshold linearly for adaptive loop tuning |
| SENSE– (Pin 4) | Current sense negative input | Internal connection to output voltage divider; also (–) input of current comparator |
| SENSE+ (Pin 5) | Current sense positive input | (+) input of current comparator; forms 25–150mV offset with Pin 4 across RSENSE |
| SHDN/VFB (Pin 6) | Shutdown control / feedback | Logic-level input: <0.8V = normal, >2V = shutdown; not used as VFB in fixed-output LTC1147LCS8-3.3#PBF |
| GND (Pin 7) | Analog and power ground | Two independent ground paths required: one to COUT (–), one to diode cathode and CIN (–) |
| PDRIVE (Pin 8) | P-channel MOSFET gate driver | High-current output (VIN to GND swing); drives Si4431DY-class P-MOSFETs with 100–200ns transition times |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Burst Mode™ operation | Maintains >85% efficiency down to 0mA load by reducing switching losses and dropping IQ to 160µA |
| Constant off-time current-mode control | Delivers excellent line/load transient response and inherent cycle-by-cycle current limiting without slope compensation |
| 100% duty cycle low-dropout capability | Regulates with VIN as low as VOUT + 0.3V (e.g., 3.6V → 3.3V), eliminating need for LDO post-regulation |
| Logic-controlled micropower shutdown | Reduces total system standby current to <22µA - critical for energy-harvesting and battery-backed applications |
| Short-circuit protected operation | Extends off-time during overload to limit ISC(PK) ≈ 150mV/RSENSE and prevent thermal runaway |
Applications
| Portable Medical Sensors | GPS Navigation Modules |
|---|---|
Use Scenario: Compact wearable ECG patch powered by coin cell or small Li-ion battery requiring regulated 3.3V for ADC, BLE radio, and MCU. IC Role / Device Role / Timing Role: Primary DC-DC controller managing power conversion from variable battery voltage to stable 3.3V rail. Use Value: Burst Mode extends battery life to >6 months; 160µA sleep current minimizes self-discharge; 3.5V min VIN supports discharge down to 3.6V. |
Use Scenario: Automotive-grade GPS receiver board needing clean 3.3V supply under wide-input 9–16V automotive rail with cold-crank immunity. IC Role / Device Role / Timing Role: High-efficiency buck controller delivering low-noise 3.3V to GNSS RF front-end and baseband processor. Use Value: >95% efficiency at 1A reduces thermal stress; 100% duty cycle sustains operation during 6V cold-crank; SO-8 footprint simplifies layout. |
| Industrial Handheld Scanners | IoT Edge Node Gateways |
Use Scenario: Rugged barcode scanner using 2xAA alkaline batteries (up to 3.2V fresh, down to 1.8V per cell) powering 3.3V logic and laser driver. IC Role / Device Role / Timing Role: Input-wide step-down controller enabling direct battery-to-3.3V conversion without intermediate boost stage. Use Value: 3.5V min VIN accommodates two fresh AA cells (3.2V); Burst Mode preserves runtime during idle scanning intervals. |
Use Scenario: LoRaWAN gateway with cellular modem, MCU, and multiple sensors requiring reliable 3.3V rail from 12V PoE or solar input. IC Role / Device Role / Timing Role: Primary power controller for main system rail, interfacing with external P-MOSFET and Schottky diode. Use Value: Wide 3.5–16V input handles PoE transients and solar MPPT variations; short-circuit protection safeguards against field wiring faults. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3502AEDD-3.3#PBF | Fixed 3.3V output, integrated 1.5A P-MOSFET, 3mm × 3mm DFN package, no external RSENSE required | Lower BOM count and smaller footprint; limited to ≤1.5A; less flexible current limit tuning | Select LT3502AEDD-3.3#PBF for space-constrained designs needing ≤1.5A with simplified layout |
| TPS54202DDCR | Integrated 2A FET, adjustable output (0.6–6V), 2.5V min VIN, 500kHz fixed frequency, no Burst Mode | Higher integration but lower light-load efficiency; requires external feedback resistors; unsuitable for <2.5V inputs | Select TPS54202DDCR where higher current and adjustable output outweigh efficiency loss below 100mA |
Compared with LTC1147LCS8-3.3#PBF, LT3502AEDD-3.3#PBF trades external component flexibility for compactness and ease of use, while TPS54202DDCR offers higher current and adjustable output at the cost of reduced micropower performance and wider input limitations.
Availability
LTC1147LCS8-3.3#PBF is available at Aetrix Electronics and suitable for portable instrumentation, GPS navigation modules, and industrial handheld scanners requiring stable component supply with long-term lifecycle support.
Supply support for LTC1147LCS8-3.3#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 full product support, datasheets, and application engineering for legacy Linear parts including the LTC1147 family.
The LTC1147 series was designed as a high-efficiency, micropower step-down controller targeting battery-operated portable electronics where extended runtime and ultra-low dropout are critical design requirements.
FAQ
What is the minimum input voltage supported by the LTC1147LCS8-3.3#PBF?
The LTC1147LCS8-3.3#PBF supports a minimum input voltage of 3.5V, as specified for the LTC1147L series. This enables operation directly from two alkaline AA cells (3.2V fresh) or single-cell LiFePO₄ batteries. Operation below 3.5V is not guaranteed and may result in loss of regulation or Burst Mode instability. The device remains functional down to 3.5V across the full temperature range.
Does the LTC1147LCS8-3.3#PBF require external feedback resistors to set the 3.3V output?
No, the LTC1147LCS8-3.3#PBF does not require external feedback resistors. It integrates an internal resistive divider and 1.25V reference to deliver a factory-trimmed fixed 3.3V output. Pin 6 (SHDN/VFB) functions solely as a logic shutdown input in this variant - unlike the adjustable LTC1147L, which uses Pin 6 as the feedback node.
How does Burst Mode operation improve efficiency at light loads in the LTC1147LCS8-3.3#PBF?
Burst Mode in the LTC1147LCS8-3.3#PBF disables switching cycles when output voltage exceeds regulation, reducing average switching losses and lowering quiescent current to 160–260µA. This maintains >85% efficiency down to zero load, enabling multi-month battery life in always-on sensor applications - a key advantage over fixed-frequency controllers that waste energy pulsing at low current.
What is the purpose of the ITH pin on the LTC1147LCS8-3.3#PBF?
The ITH (Current Threshold) pin on the LTC1147LCS8-3.3#PBF allows dynamic adjustment of the current comparator threshold voltage. Applying a voltage to ITH scales the 25–150mV sense window linearly, enabling adaptive current limiting during load transients or temperature drift compensation - critical for maintaining stability in high-precision portable power systems.
Can the LTC1147LCS8-3.3#PBF drive a logic-level P-channel MOSFET?
Yes, the LTC1147LCS8-3.3#PBF can drive logic-level P-channel MOSFETs, but only when VIN remains above the MOSFET's absolute maximum VGS rating. For example, with a –12V VGS(max) MOSFET, VIN must stay ≤12V. Standard-threshold P-MOSFETs (VGS(TH) < –4V) are preferred for VIN > 8V applications to avoid gate overstress and ensure robust turn-on margin.
LTC1147LCS8-3.3#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC1147LCS8-3.3#PBF FAQ
1.How can I place an order for LTC1147LCS8-3.3#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1147LCS8-3.3#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 LTC1147LCS8-3.3#PBF reliable?
The price and inventory of LTC1147LCS8-3.3#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1147LCS8-3.3#PBF is usually 5 days.
3.What payment methods are accepted for LTC1147LCS8-3.3#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1147LCS8-3.3#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1147LCS8-3.3#PBF?
LTC1147LCS8-3.3#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1147LCS8-3.3#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 LTC1147LCS8-3.3#PBF?
For technical support, including LTC1147LCS8-3.3#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1147LCS8-3.3#PBF requirements.
6.How does Aetrix verify that LTC1147LCS8-3.3#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1147LCS8-3.3#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 LTC1147LCS8-3.3#PBF meets industry standards.
7.What is the process for return or replacement of LTC1147LCS8-3.3#PBF?
All LTC1147LCS8-3.3#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1147LCS8-3.3#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 LTC1147LCS8-3.3#PBF part is unused and in its original packaging.
Return procedure for LTC1147LCS8-3.3#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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