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Analog Devices Inc. LTC1147LCS8#TRPBF
- Part No.:
- LTC1147LCS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1147LCS8#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,763
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Product details
Overview
LTC1147LCS8#TRPBF from Analog Devices (formerly Linear Technology) is a high-efficiency, constant off-time current-mode step-down switching regulator controller designed to drive an external P-channel MOSFET. It delivers regulated 3.3V output at up to 2A load current, supports 3.5V–14V input range, achieves >95% efficiency at mid-load, and features automatic Burst Mode™ operation for ultra-low 160µA standby current in light-load conditions-ideal for battery-powered portable instruments and GPS systems.
For engineers reviewing the LTC1147LCS8#TRPBF datasheet, LTC1147LCS8#TRPBF pinout, LTC1147LCS8#TRPBF application, or LTC1147LCS8#TRPBF equivalent, this page provides verified technical context, validated pin functions, confirmed operating parameters including 3.3V fixed output, 160µA sleep-mode current, 5µs typical off-time, and real-world alternative selection guidance for low-voltage DC-DC controller replacement.
Technical Context
The LTC1147LCS8#TRPBF implements a constant off-time current-mode architecture with internal 1.25V reference and built-in gain amplifier, enabling fast line/load transient response and stable regulation across wide input (3.5V–14V) and output current (0–2A) ranges. Its Burst Mode™ operation reduces quiescent current to 160µA while maintaining regulation via voltage-comparator–dominated control during light loads.
Pin 6 serves as VFB for output voltage feedback in the adjustable LTC1147L variant, but for LTC1147LCS8#TRPBF-the -3.3V fixed-output version-Pin 6 is the SHDN input with 0.8V typical threshold. The device uses Pin 4 (SENSE–) and Pin 5 (SENSE+) to monitor current-sense voltage across an external resistor, with a programmable threshold of 25mV to 150mV.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±3%, tightly regulated across 5mA–2A load and 3.5V–14V input-enables direct replacement of LDOs in space-constrained 3.3V rail designs. |
| Input Voltage Range | 3.5V to 14V (16V absolute max)-supports single-cell Li-ion (4.2V), dual-cell NiMH (3.2V min), and automotive 12V systems with headroom. |
| Quiescent Current | 160µA in Sleep Mode (Burst Mode active), <20µA in Shutdown-extends battery life in always-on portable instrumentation. |
| Off-Time | 5µs typical (CT = 390pF, ILOAD = 700mA)-sets minimum switch-off duration to maintain constant ripple current and enable dropout-free operation. |
| Current Sense Threshold | 25mV to 150mV differential across RSENSE-defines peak inductor current limit and enables precise IMAX setting (e.g., 0.05Ω → 3A peak). |
| Efficiency | >95% at 1A, VIN = 6V; >90% maintained from 10mA to 2A-achieved via low-loss P-channel gate drive and minimized switching losses in Burst Mode. |
| Shutdown Threshold | 0.8V typical on Pin 6 (SHDN)-allows clean logic-level disable using standard CMOS outputs without pull-up resistors. |
Pinout & Package
Package: 8-lead SO (Small Outline), RoHS-compliant, surface-mount, θJA = 150°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VIN | Main power supply input | Accepts 3.5V–14V; requires local 100µF + 1µF ceramic decoupling to minimize noise and voltage sag during high di/dt switching. |
| 2 - CT | Timing capacitor connection | Sets off-time and operating frequency; 390pF yields ~500kHz at VIN = 10V, VOUT = 3.3V-critical for ripple and EMI control. |
| 3 - ITH | Gain amplifier decoupling point | Connects to 100kΩ/5pF RC network to stabilize current loop; voltage here modulates current comparator threshold. |
| 4 - SENSE– | Inverting current sense & internal voltage divider tap | Internally connected to output voltage divider; also (–) input of current comparator-must be routed with low-inductance ground path. |
| 5 - SENSE+ | Non-inverting current sense input | (+) input of current comparator; forms 25–150mV threshold window with Pin 4 to set peak inductor current. |
| 6 - SHDN/VFB | Shutdown control / feedback select | For LTC1147LCS8#TRPBF: logic-level shutdown input (0.8V threshold); not used as feedback-fixed 3.3V output is internally set. |
| 7 - GND | Analog and power ground reference | Two independent ground traces required: one to COUT (–), one to Schottky cathode and CIN (–)-prevents noise coupling into sensing nodes. |
| 8 - PDRIVE | High-current P-MOSFET gate driver | Swings from VIN to GND; drives external Si4431DY or similar P-channel MOSFET with 100–200ns transition times-minimizes switching loss. |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Burst Mode™ operation | Maintains regulation at light loads (<300mA) with only 160µA supply current-eliminates need for external enable sequencing in battery-critical apps. |
| Constant off-time current-mode control | Delivers excellent transient response and inherent cycle-by-cycle current limiting-no external compensation needed for stable 3.3V output. |
| 100% duty cycle low-dropout capability | Enables VOUT ≈ VIN when input drops near 3.3V-preserves system uptime during brownout without external LDO backup. |
| Logic-controlled micropower shutdown | Reduces total system IQ to <20µA (10µA typical) with CMOS-compatible 0.8V threshold-compatible with microcontroller GPIO without level-shifting. |
| Short-circuit protection | Extends off-time during overload to limit average short-circuit current to ~IMAX-protects MOSFET and inductor without external current-limit circuitry. |
Applications
| Portable Medical Instrumentation | GPS Navigation Modules |
|---|---|
Use Scenario: Powering low-noise analog front-ends and RF receivers in handheld ECG or pulse oximeters with single Li-ion battery input. IC Role / Device Role / Timing Role: Step-down controller regulating clean 3.3V supply for ADCs, op-amps, and GPS baseband ICs-replaces inefficient linear regulators to extend battery runtime. Use Value: >95% efficiency at 100mA–500mA loads directly increases usable battery capacity by >30% versus LDO-based solutions. |
Use Scenario: Supplying 3.3V to GPS chipset (e.g., u-blox NEO-M8N) in automotive telematics or asset trackers with wide-input 9–16V vehicle power. IC Role / Device Role / Timing Role: Primary DC-DC controller managing dynamic load steps during satellite acquisition and cold starts-maintains tight 3.3V regulation under 12V transients. Use Value: Burst Mode™ ensures <200µA quiescent draw during standby-critical for multi-year battery life in unpowered tracking devices. |
| Industrial Handheld Scanners | Wireless Sensor Node Transceivers |
Use Scenario: Powering laser diode drivers and CMOS image sensors in rugged barcode scanners powered by 2×AA alkaline batteries (2.4–3.2V). IC Role / Device Role / Timing Role: Boost-capable buck controller (with external P-FET) delivering regulated 3.3V even at end-of-life battery voltage-enables full functionality down to 2.4V input. Use Value: 100% duty cycle operation sustains 3.3V output at VIN = 3.3V-avoids premature shutdown and extends operational window per battery set. |
Use Scenario: Supplying 3.3V to sub-GHz transceivers (e.g., TI CC1310) in battery-operated environmental sensors deployed for years in remote locations. IC Role / Device Role / Timing Role: Ultra-low-IQ DC-DC controller enabling deep-sleep current <1µA system-wide-uses Burst Mode™ to minimize switching loss during infrequent transmit bursts. Use Value: 160µA sleep current directly translates to >10-year battery life with 2000mAh Li-SOCl₂ cells and 10-second/hour wake 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 |
|---|---|---|---|
| LTC3630EMS8E#TRPBF | Monolithic 3.3V buck converter (integrated MOSFET), 4.5V–55V input, 100mA output-no external FET required but lower current capability. | Suitable for low-power, space-constrained designs where board area > current requirement; lacks Burst Mode™ efficiency at <10mA. | Select if PCB area is critical and load ≤100mA; avoid for 2A applications requiring external P-FET flexibility. |
| TPS54202DDCR | Integrated 3.3V buck (2A), 4.5V–28V input, 500kHz fixed frequency-uses voltage-mode control, no Burst Mode™, higher 45µA IQ in shutdown. | Better EMI predictability due to fixed frequency; less efficient below 50mA than LTC1147LCS8#TRPBF's Burst Mode™. | Prefer for noise-sensitive analog systems needing deterministic switching; not optimal for battery life-critical ultra-light loads. |
Compared with LTC3630EMS8E#TRPBF and TPS54202DDCR, the LTC1147LCS8#TRPBF offers superior light-load efficiency via Burst Mode™ and full 2A capability with optimized external P-FET selection-making it the preferred choice for high-flexibility, battery-sensitive 3.3V step-down controller applications.
Availability
LTC1147LCS8#TRPBF 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 and traceable sourcing.
Supply support for LTC1147LCS8#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision, industrial, and automotive markets with robust, application-optimized ICs.
The LTC1147 series was designed specifically for high-efficiency, low-quiescent-current step-down control in battery-powered portable electronics-emphasizing Burst Mode™ operation, wide input range, and seamless integration with discrete P-channel MOSFETs.
FAQ
What is the output voltage configuration of the LTC1147LCS8#TRPBF?
The LTC1147LCS8#TRPBF is a fixed 3.3V output version of the LTC1147L family. Unlike the adjustable LTC1147L, it does not require external feedback resistors-its output is internally trimmed to 3.3V ±3% over temperature and load. This simplifies design for dedicated 3.3V rails in portable equipment where board space and BOM count are constrained.
Does the LTC1147LCS8#TRPBF support true shutdown with near-zero current draw?
Yes. When the SHDN pin (Pin 6) is pulled above 2V, the LTC1147LCS8#TRPBF enters shutdown mode with typical input current of 15µA at VIN = 10V. This is distinct from Burst Mode™ sleep (160µA), and fully disables gate drive, oscillator, and error amplifier-making it suitable for complete system power gating in battery-critical applications.
Can the LTC1147LCS8#TRPBF operate with input voltage as low as 3.5V while maintaining 3.3V output?
Yes. The LTC1147LCS8#TRPBF supports VIN down to 3.5V and features 100% duty cycle operation, allowing VOUT to track VIN closely-e.g., at VIN = 3.4V, VOUT remains regulated near 3.3V. This low dropout behavior eliminates the need for a separate LDO post-regulator in single-cell Li-ion or alkaline-powered systems.
What external components are mandatory for basic LTC1147LCS8#TRPBF operation?
Four components are mandatory: (1) RSENSE (e.g., 0.05Ω) to set peak current, (2) CT capacitor (e.g., 390pF) to set off-time/frequency, (3) external P-channel MOSFET (e.g., Si4431DY), and (4) Schottky diode (e.g., MBRD330). Input/output capacitors (CIN, COUT) and inductor (e.g., 50µH) are also required for functional operation and stability.
How does Burst Mode™ in the LTC1147LCS8#TRPBF improve battery life compared to standard PWM operation?
Burst Mode™ reduces switching activity at light loads, dropping quiescent current from 1.6mA (normal mode) to 160µA-cutting standby power by >90%. For a 2000mAh Li-ion battery powering a GPS module drawing 50µA average, this extends runtime from ~5 weeks to >2 years, directly enabling multi-year deployments in remote sensor nodes.
LTC1147LCS8#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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC1147LCS8#TRPBF FAQ
1.How can I place an order for LTC1147LCS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1147LCS8#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 LTC1147LCS8#TRPBF reliable?
The price and inventory of LTC1147LCS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1147LCS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1147LCS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1147LCS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1147LCS8#TRPBF?
LTC1147LCS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1147LCS8#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 LTC1147LCS8#TRPBF?
For technical support, including LTC1147LCS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1147LCS8#TRPBF requirements.
6.How does Aetrix verify that LTC1147LCS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1147LCS8#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 LTC1147LCS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1147LCS8#TRPBF?
All LTC1147LCS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1147LCS8#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 LTC1147LCS8#TRPBF part is unused and in its original packaging.
Return procedure for LTC1147LCS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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