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Analog Devices Inc. LTC1147LCS8#PBF
- Part No.:
- LTC1147LCS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1147LCS8#PBF.pdf
- Description:
- IC REG CTRLR BUCK 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:909
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Product details
Overview
LTC1147LCS8#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. It operates from 3.5V to 16V input, delivers up to 2A output current, maintains >95% efficiency across three decades of load, and features automatic Burst Mode™ operation for micropower light-load performance. It is used in battery-powered portable instruments requiring stable 3.3V or adjustable regulation.
For engineers reviewing the LTC1147LCS8#PBF datasheet, LTC1147LCS8#PBF pinout, LTC1147LCS8#PBF application, or LTC1147LCS8#PBF equivalent, key selection criteria include its 160µA sleep-mode quiescent current, 125–150mV current-sense threshold, 3.8–6.5µs programmable off-time, 8-pin SOIC package, and compatibility with external feedback networks for adjustable output voltage.
Technical Context
The LTC1147LCS8#PBF implements a constant off-time current-mode architecture where the timing capacitor (CT) at Pin 2 sets switching frequency, and the off-time discharge current scales with VOUT to model inductor current decay. Its internal gain block and voltage comparator jointly manage continuous and Burst Mode operation based on output voltage deviation from the 1.25V reference.
Pin 6 serves as VFB for the LTC1147L variant, enabling adjustable output via external resistor divider; SENSE+ (Pin 5) and SENSE– (Pin 4) form a differential current-sense interface with built-in 25–150mV threshold range; PDRIVE (Pin 8) delivers high-current gate drive to the external P-MOSFET with rail-to-rail swing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5V to 16V - supports wide battery and DC distribution rails including single-cell Li-ion to 12V systems |
| Output Voltage | Adjustable via external resistive divider - enables precise setting of any VOUT ≥ 2.5V using 1.25V internal reference |
| Quiescent Current (Sleep Mode) | 160–260µA - enables multi-day battery life in standby without compromising startup responsiveness |
| Current Sense Threshold | 125–150mV (typ) - defines peak inductor current limit and sets maximum output current with RSENSE |
| Off-Time | 3.8–6.5µs - determines minimum on-time and dropout behavior; programmable via CT capacitor |
| Shutdown Current | 10–22µA - ensures near-zero power draw when SHDN (Pin 6) is pulled high to >0.8V |
| Package | 8-lead SOIC (S8) - industry-standard surface-mount footprint with θJA = 150°C/W for thermal management |
Pinout & Package
Package: 8-lead plastic SOIC (S8), RoHS-compliant, JEDEC MS-012AC, body size 4.9mm × 6.0mm, 1.27mm pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Main power supply input | Accepts 3.5V–16V; requires local 0.1–1µF ceramic decoupling to GND (Pin 7) |
| CT (Pin 2) | Timing capacitor connection | Sets operating frequency via external capacitor; discharge current scales with VOUT |
| ITH (Pin 3) | Gain amplifier decoupling node | Adjusts current comparator threshold; connects to RC network for loop compensation |
| SENSE– (Pin 4) | Inverting current sense input | Connects to low-side of RSENSE; also forms internal resistive divider for VOUT sensing |
| SENSE+ (Pin 5) | Non-inverting current sense input | Connects to high-side of RSENSE; 25–150mV offset vs Pin 4 sets current trip point |
| SHDN/VFB (Pin 6) | Shutdown control / feedback input | Logic-level shutdown input (0.5–2V threshold); for LTC1147L, functions as VFB for adjustable output |
| GND (Pin 7) | Analog and power ground | Two independent ground paths required: one to COUT (–) and one to diode cathode/CIN (–) |
| PDRIVE (Pin 8) | P-channel MOSFET gate driver | High-current output swinging from VIN to GND; drives external P-MOSFET gate directly |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Burst Mode™ operation | Maintains >90% efficiency down to ~0mA load by disabling switching and reducing IQ to 160µA |
| Constant off-time current-mode control | Provides inherent line/load transient immunity and eliminates need for external compensation |
| 100% duty cycle capability | Enables ultra-low dropout operation (VOUT ≈ VIN) when input approaches output voltage |
| Programmable current limit | Set via RSENSE value; peak current threshold determined by 25–150mV differential across pins 4/5 |
| Logic-controlled micropower shutdown | Reduces total supply current to <22µA; compatible with CMOS logic signals (tr/tf < 1µs) |
Applications
| Portable Medical Instrumentation | Battery-Powered Data Acquisition |
|---|---|
Use Scenario: Handheld ECG or pulse oximeter powered by two AA alkaline cells (2.4–3.2V) requiring clean, regulated 3.3V for ADC and microcontroller. IC Role / Device Role / Timing Role: Step-down controller managing dynamic load from 10µA (sleep) to 150mA (active acquisition), maintaining regulation during battery sag. Use Value: Burst Mode™ extends battery life beyond 100 hours; low 160µA sleep current prevents premature cutoff; adjustable VFB allows precise 3.3V tolerance matching sensor requirements. |
Use Scenario: Industrial field logger using Li-ion (3.0–4.2V) with 500mA peak sensor burst loads and 10µA deep-sleep intervals. IC Role / Device Role / Timing Role: Primary DC-DC controller regulating 3.3V rail for precision SAR ADC, low-noise LDO bias, and BLE radio subsystem. Use Value: Constant off-time architecture ensures fast transient response to sensor activation; 125–150mV current-sense threshold enables accurate 500mA overcurrent protection with 0.05Ω RSENSE. |
| GPS Navigation Module | Low-Power IoT Edge Node |
Use Scenario: Automotive-grade GPS receiver operating from 5–16V vehicle supply, requiring stable 3.3V for RF front-end and baseband processor. IC Role / Device Role / Timing Role: High-input-range buck controller delivering 3.3V/1A with tight line regulation (<±40mV from 7–12V VIN). Use Value: Wide 3.5–16V input range accommodates cold-crank transients; 1.25V internal reference + external divider ensures ±1% VOUT accuracy across temperature. |
Use Scenario: Wireless sensor node powered by coin cell (2.0–3.0V) or energy harvester, needing regulated 2.8V for ultra-low-power MCU and sub-GHz transceiver. IC Role / Device Role / Timing Role: Adjustable-output buck controller supporting 2.5–5V outputs via external feedback, optimized for intermittent 10ms active bursts. Use Value: Adjustable VFB (Pin 6) enables custom 2.8V output; 10–22µA shutdown current preserves harvester-stored energy; SOIC package allows compact 2-layer PCB layout. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3975EDD#PBF | Integrated 40V/3.3A synchronous buck regulator (not controller); includes MOSFETs; fixed 3.3V or adjustable output | Eliminates external MOSFET/diode but lacks P-channel flexibility and 100% duty cycle; higher IQ (2.8µA shutdown) | Choose LT3975EDD#PBF for space-constrained designs where integration outweighs efficiency trade-offs at light loads |
| TPS54202DDCR | 4.5–28V input, integrated 2A synchronous buck; uses voltage-mode control; 25µA shutdown current; no Burst Mode™ | Higher input range but lower light-load efficiency due to absence of true micropower discontinuous mode | Choose TPS54202DDCR for industrial 24V bus applications where input voltage exceeds 16V and Burst Mode™ is not critical |
Compared with LTC1147LCS8#PBF, LT3975EDD#PBF offers higher integration but sacrifices adjustable P-MOSFET selection and 100% duty cycle; TPS54202DDCR supports wider VIN but cannot match the 160µA sleep current or Burst Mode™ efficiency below 10mA - making LTC1147LCS8#PBF optimal for long-life battery systems.
Availability
LTC1147LCS8#PBF is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered data loggers, GPS modules, and low-power IoT edge nodes requiring stable component supply with guaranteed long-term availability.
Supply support for LTC1147LCS8#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 LTC series.
The LTC1147 family was designed specifically for high-efficiency, low-quiescent-current step-down regulation in portable and battery-critical applications, emphasizing Burst Mode™ operation and P-channel MOSFET flexibility.
FAQ
What is the function of Pin 6 (SHDN/VFB) on the LTC1147LCS8#PBF?
On the LTC1147LCS8#PBF, Pin 6 serves as the feedback (VFB) input for the adjustable-output LTC1147L variant. It connects to the center tap of an external resistive divider from VOUT to GND, allowing precise setting of output voltage using the internal 1.25V reference. Unlike fixed-output versions, it does not function as a shutdown pin on this part number.
Can the LTC1147LCS8#PBF operate with input voltages below 3.5V?
No - the LTC1147LCS8#PBF has a specified minimum input voltage of 3.5V per the Absolute Maximum Ratings table and Electrical Characteristics. Operation below 3.5V is not guaranteed and may result in loss of regulation, failure to start, or undefined behavior. For sub-3.5V applications, consider alternative controllers such as the LTC3642.
What is the maximum recommended output current for the LTC1147LCS8#PBF?
The LTC1147LCS8#PBF supports up to 2A continuous output current when paired with an appropriately rated external P-channel MOSFET, inductor, and output capacitor. This assumes proper thermal design, ≤0.05Ω RSENSE, and adherence to the 125–150mV current-sense threshold range specified in the datasheet for LTC1147L variants.
How does Burst Mode™ operation improve efficiency in the LTC1147LCS8#PBF?
Burst Mode™ in the LTC1147LCS8#PBF reduces switching activity during light loads, lowering quiescent current from 1.6mA (normal mode) to 160µA (sleep mode). This cuts standby power to ~2mW at VIN = 10V, extending battery life significantly while maintaining regulation - especially critical for portable devices with long idle periods between active cycles.
Is the LTC1147LCS8#PBF pin-compatible with other members of the LTC1147 family?
Yes - the LTC1147LCS8#PBF shares the same 8-pin SOIC (S8) package and pinout as all LTC1147 variants, including LTC1147CS8-3.3, LTC1147IS8-5, and LTC1147LIS8. However, functional differences exist: only LTC1147L variants use Pin 6 as VFB, while fixed-output versions use it as SHDN. External circuitry must match the specific variant's configuration.
LTC1147LCS8#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#PBF FAQ
1.How can I place an order for LTC1147LCS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1147LCS8#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#PBF reliable?
The price and inventory of LTC1147LCS8#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#PBF is usually 5 days.
3.What payment methods are accepted for LTC1147LCS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1147LCS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1147LCS8#PBF?
LTC1147LCS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1147LCS8#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#PBF?
For technical support, including LTC1147LCS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1147LCS8#PBF requirements.
6.How does Aetrix verify that LTC1147LCS8#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1147LCS8#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#PBF meets industry standards.
7.What is the process for return or replacement of LTC1147LCS8#PBF?
All LTC1147LCS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1147LCS8#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#PBF part is unused and in its original packaging.
Return procedure for LTC1147LCS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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