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Analog Devices Inc. LTC1147LIS8#PBF
- Part No.:
- LTC1147LIS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1147LIS8#PBF.pdf
- Description:
- IC REG CTRLR BUCK 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:129
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Product details
Overview
LTC1147LIS8#PBF 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% peak efficiency, maintains 160µA standby current in Burst Mode, and operates in an 8-pin SOIC package for compact DC/DC conversion in battery-powered systems.
For engineers reviewing the LTC1147LIS8#PBF datasheet, LTC1147LIS8#PBF pinout, LTC1147LIS8#PBF application, or LTC1147LIS8#PBF equivalent, key selection considerations include its adjustable feedback architecture (via external resistor divider), 1.25V reference voltage, 25–150mV current sense threshold, 3.8–6.5µs programmable off-time, and compatibility with low-RDS(ON) logic-level P-MOSFETs for low-input-voltage operation.
Technical Context
The LTC1147LIS8#PBF implements a constant off-time current-mode control architecture with automatic Burst Mode™ operation to sustain high efficiency across three decades of output current (0mA–2A). Its internal 1.25V reference and feedback pin (Pin 6) enable precise output voltage setting via external resistive dividers, supporting configurable outputs beyond fixed 3.3V/5V variants.
It features dual-mode regulation: continuous conduction mode above ~300mA load, and Burst Mode below that threshold-reducing quiescent current to 160µA and standby power to 2mW at VIN = 10V. The CT pin (Pin 2) sets switching frequency via external capacitor, while SENSE+ (Pin 5) and SENSE– (Pin 4) form a precision current-sense interface with built-in offset for stable ripple-current detection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Adjustable via external resistor divider; nominal 3.3V with ±3% tolerance over line/load/temperature |
| Input Voltage Range | 3.5V to 14V (16V absolute max); enables direct operation from single Li-ion or multi-cell alkaline supplies |
| Feedback Reference | 1.25V ±1% internal reference; determines output as VOUT = 1.25 × (1 + R2/R1) |
| Current Sense Threshold | 25mV to 150mV differential; sets peak inductor current and maximum output capability |
| Off-Time | 3.8–6.5µs (CT = 390pF); defines minimum switch-off duration and enables dropout-free 100% duty cycle |
| Quiescent Current | 160–260µA in Sleep Mode; reduces light-load power loss in portable instrumentation |
| Shutdown Current | 10–22µA; enables ultra-low-power system sleep states with logic-controlled SHDN pin |
Pinout & Package
Package: 8-lead plastic SOIC (S8), 150°C/W junction-to-ambient thermal resistance, RoHS-compliant, lead-free (PBF).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VIN | Main power supply input | Accepts 3.5–14V; requires local 100µF + 0.1µF ceramic decoupling to GND (Pin 7) |
| 2 CT | Timing capacitor connection | Sets off-time and operating frequency; discharge current scales with VOUT for input-voltage compensation |
| 3 ITH | Gain amplifier decoupling | Adjusts current comparator threshold; used to track load-dependent ripple requirements |
| 4 SENSE– | Inverting current sense & output voltage sense node | Connects to internal resistive divider; also (–) input of current comparator |
| 5 SENSE+ | Non-inverting current sense input | (+) input of current comparator; 25–150mV offset vs. Pin 4 sets trip point across RSENSE |
| 6 SHDN/VFB | Shutdown control / feedback input | Logic-level shutdown when >0.8V; functions as VFB for adjustable output configuration |
| 7 GND | Analog and power ground | Two independent ground paths required: one to COUT(–), one to diode cathode/CIN(–) |
| 8 PDRIVE | P-channel MOSFET gate driver | High-current output (VIN to GND swing); drives external Si4431DY or similar logic-level P-MOSFET |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode™ operation | Reduces IQ to 160µA and standby power to 2mW at zero load while maintaining regulation |
| Constant off-time architecture | Enables 100% duty cycle for ultra-low dropout; eliminates need for external compensation |
| Programmable current limit | Set via RSENSE; supports IMAX from 0.5A to 2A with 25mV–150mV threshold range |
| Logic-compatible shutdown | CMOS-level SHDN pin (0.5–2V threshold); allows microcontroller-controlled power gating |
| Internal 1.25V reference | Stable, temperature-compensated reference enabling accurate adjustable output design |
Applications
| Portable Medical Sensors | Industrial Handheld Terminals |
|---|---|
Use Scenario: Battery-powered pulse oximeter with real-time analog front-end and BLE radio. IC Role / Device Role / Timing Role: Primary DC/DC controller regulating 3.3V rail for ADC, MCU, and RF transceiver from single Li-ion cell (3.0–4.2V). Use Value: Burst Mode extends battery life by minimizing no-load current; 3.5V minimum input enables full utilization of cell discharge curve. |
Use Scenario: Ruggedized barcode scanner operating on 4xAA alkaline batteries (6–9V range). IC Role / Device Role / Timing Role: Step-down controller powering 3.3V FPGA core and 1.8V I/O rails via cascaded regulators. Use Value: Wide 3.5–14V input range accommodates battery aging and cold-temperature voltage sag without brownout. |
| GPS Tracking Modules | Low-Power IoT Edge Nodes |
Use Scenario: Solar-charged asset tracker with GPS/GNSS receiver and cellular modem. IC Role / Device Role / Timing Role: High-efficiency buck controller supplying 3.3V to GNSS chip and LDOs feeding modem baseband. Use Value: >95% peak efficiency minimizes thermal rise in sealed enclosure; 160µA sleep current preserves supercapacitor energy between location pings. |
Use Scenario: Wireless environmental sensor node powered by coin-cell battery (3V) with 10-year target lifetime. IC Role / Device Role / Timing Role: Adjustable-output controller configured for 2.5V rail to optimize ultra-low-power MCU and sensor biasing. Use Value: External feedback divider enables precise 2.5V output; 1.25V reference ensures <±1% accuracy over –40°C to 85°C. |
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#PBF | Fixed 3.3V output; integrated 1.5A N-MOSFET; no external P-MOSFET required | Lower BOM count but limited to 3.3V; cannot adjust output or scale beyond 1.5A | Select if fixed 3.3V/≤1.5A suffices and board space is constrained |
| TPS54202DDCR | Integrated 2A N-MOSFET; 4.5–28V input; requires external bootstrap capacitor | Higher input voltage support; lacks Burst Mode - 26µA shutdown vs. 160µA sleep | Select for wider VIN range and higher integration where light-load efficiency is secondary |
Compared with LT3502AEDD#PBF and TPS54202DDCR, the LTC1147LIS8#PBF offers superior light-load efficiency via Burst Mode, full output adjustability, and P-MOSFET drive optimized for low-VIN operation - making it ideal for long-life battery systems requiring flexible voltage rails.
Availability
LTC1147LIS8#PBF is available at Aetrix Electronics and suitable for portable medical sensors, industrial handheld terminals, GPS tracking modules, and low-power IoT edge nodes requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for LTC1147LIS8#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC1147 series belongs to ADI's legacy high-efficiency power management portfolio, specifically engineered for battery-critical applications demanding micropower operation, wide input range, and robust transient response in minimal PCB area.
FAQ
What output voltage does the LTC1147LIS8#PBF regulate?
The LTC1147LIS8#PBF is the adjustable version of the LTC1147 family and does not have a fixed output voltage. It uses an internal 1.25V reference and feedback pin (Pin 6) to support user-configured outputs via external resistor dividers. Typical configurations include 3.3V, 5V, or custom values such as 2.5V - all with ±3% regulation accuracy over line, load, and temperature. The LTC1147LIS8#PBF datasheet specifies VOUT = 1.25 × (1 + R2/R1), where R1 connects from VFB to GND and R2 from VOUT to VFB.
How does the LTC1147LIS8#PBF achieve high efficiency at light loads?
The LTC1147LIS8#PBF achieves high light-load efficiency through automatic Burst Mode™ operation, which disables switching and places most internal circuitry into sleep state when output current drops below ~300mA. In this mode, quiescent current falls to 160–260µA and standby power drops to just 2mW at VIN = 10V. The LTC1147LIS8#PBF resumes normal switching only when output voltage droops beyond hysteresis, ensuring regulation is maintained without sacrificing efficiency during idle or intermittent-use periods.
Which external components are mandatory for basic LTC1147LIS8#PBF operation?
Four external components are mandatory for functional LTC1147LIS8#PBF operation: (1) RSENSE (current sense resistor, typically 0.02–0.05Ω) to set peak inductor current; (2) CT capacitor (e.g., 390pF) on Pin 2 to define off-time and frequency; (3) feedback resistor divider (R1/R2) connecting VOUT to Pin 6 and Pin 6 to GND to set output voltage; and (4) a P-channel MOSFET (e.g., Si4431DY) driven by Pin 8. Additional required passives include input/output capacitors (CIN, COUT) and an output Schottky diode (D1).
Can the LTC1147LIS8#PBF operate with input voltages below 3.5V?
No - the LTC1147LIS8#PBF has a specified minimum input voltage of 3.5V, as confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables. Operation below 3.5V is not guaranteed and may result in failure to start, loss of regulation, or undefined behavior. For sub-3.5V applications, alternative controllers such as the LTC3642 or ADP2370 should be evaluated. The LTC1147LIS8#PBF's 3.5V lower limit is a hard specification tied to internal biasing and reference stability, not a recommended operating condition.
What is the function of Pin 3 (ITH) on the LTC1147LIS8#PBF?
Pin 3 (ITH) on the LTC1147LIS8#PBF serves as the gain amplifier decoupling point and directly modulates the current comparator threshold voltage. By applying a voltage to ITH, the user can dynamically adjust the current trip point - enabling adaptive current limiting or load-tracking functionality. In standard applications, ITH is bypassed to GND with a small capacitor (e.g., 100pF) to stabilize the gain stage. The LTC1147LIS8#PBF datasheet confirms that increasing the ITH voltage raises the current comparator threshold, thereby scaling peak inductor current proportionally to load demand.
LTC1147LIS8#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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC1147LIS8#PBF FAQ
1.How can I place an order for LTC1147LIS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1147LIS8#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 LTC1147LIS8#PBF reliable?
The price and inventory of LTC1147LIS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1147LIS8#PBF is usually 5 days.
3.What payment methods are accepted for LTC1147LIS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1147LIS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1147LIS8#PBF?
LTC1147LIS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1147LIS8#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 LTC1147LIS8#PBF?
For technical support, including LTC1147LIS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1147LIS8#PBF requirements.
6.How does Aetrix verify that LTC1147LIS8#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1147LIS8#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 LTC1147LIS8#PBF meets industry standards.
7.What is the process for return or replacement of LTC1147LIS8#PBF?
All LTC1147LIS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1147LIS8#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 LTC1147LIS8#PBF part is unused and in its original packaging.
Return procedure for LTC1147LIS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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