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Analog Devices Inc. LTC1147CS8-5#TRPBF
- Part No.:
- LTC1147CS8-5#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1147CS8-5#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,021
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Product details
Overview
LTC1147CS8-5#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 regulated 5 V output. It operates from 3.5 V to 16 V input, achieves >95% efficiency at full load, maintains regulation down to 160 µA quiescent current in Burst Mode, and supports up to 2 A output current with user-programmable current sense resistor. It is used in portable battery-powered systems requiring low-noise, high-efficiency DC/DC conversion.
For engineers reviewing the LTC1147CS8-5#TRPBF datasheet, LTC1147CS8-5#TRPBF pinout, LTC1147CS8-5#TRPBF application, or LTC1147CS8-5#TRPBF equivalent, key selection criteria include its fixed 5 V output, 8-pin SOIC package, 160 µA sleep-mode supply current, 130–170 mV current sense threshold, and compatibility with external P-channel MOSFETs for low-dropout operation.
Technical Context
The LTC1147CS8-5#TRPBF implements a constant off-time current-mode architecture that sets switching frequency via external CT capacitor and regulates output by comparing sensed voltage across RSENSE (pins 4–5) against a 125 mV internal reference. Its gain block and voltage comparator jointly manage transition between continuous conduction mode and Burst Mode based on output voltage deviation.
Burst Mode reduces quiescent current to 160 µA by disabling switching until output droop exceeds hysteresis; shutdown draws <20 µA. The device supports 100% duty cycle for low-dropout operation and includes short-circuit protection via extended off-time during overload.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.05 V (typical), ±2% over load/line/temp - ensures stable rail for logic and analog circuitry without external feedback resistors. |
| Input Voltage Range | 3.5 V to 16 V - supports wide-range battery inputs (e.g., 2S Li-ion, 12 V automotive) and industrial supplies. |
| Quiescent Current | 160 µA (sleep mode), <20 µA (shutdown) - enables multi-day battery life in always-on portable devices. |
| Current Sense Threshold | 130–170 mV (typical) - sets peak inductor current; allows precise IMAX control via RSENSE = 100 mV / IMAX. |
| Off-Time | 3.8–6.5 µs (CT = 390 pF, ILOAD = 700 mA) - determines minimum on-time and dropout behavior; scales inversely with VOUT. |
| Efficiency | >95% at 1 A, VIN = 10 V - minimizes thermal stress and extends runtime in space-constrained designs. |
| Shutdown Threshold | 0.5–2.0 V on SHDN pin - compatible with standard CMOS logic; enables clean system-level power sequencing. |
Pinout & Package
Package: 8-lead plastic SOIC (S8), 150°C/W junction-to-ambient thermal resistance, RoHS-compliant, tape-and-reel packaging (#TRPBF).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Main power input | Accepts 3.5–16 V supply; requires local 100 µF + 1 µF ceramic decoupling to minimize noise and transient voltage spikes. |
| CT (Pin 2) | Timing capacitor connection | Sets operating frequency via external capacitor; discharge current scales with VOUT to stabilize frequency near dropout. |
| ITH (Pin 3) | Gain amplifier decoupling | Adjusts current comparator threshold; connects to RC network for loop compensation and stability tuning. |
| SENSE– (Pin 4) | Current sense reference | Internal resistive divider node; forms differential pair with SENSE+ to detect RSENSE voltage drop and trigger MOSFET turn-off. |
| SENSE+ (Pin 5) | Current sense input | (+) input of current comparator; offset of 25–150 mV vs SENSE– defines trip point for inductor peak current limiting. |
| SHDN/VFB (Pin 6) | Shutdown control / feedback | Logic-level shutdown input (0.5–2 V threshold); grounded for normal operation; floating prohibited. |
| GND (Pin 7) | Analog/digital ground | Two independent ground paths required: one to COUT (–) and one to diode cathode/CIN (–) to prevent noise coupling. |
| PDRIVE (Pin 8) | MOSFET gate driver output | High-current source/sink (VIN to GND swing); drives P-channel gate directly; requires low-inductance layout for fast transitions. |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Burst Mode operation | Maintains >90% efficiency down to 0 mA load by disabling switching and reducing IQ to 160 µA - critical for IoT sensor nodes and standby power budgets. |
| Constant off-time current-mode control | Provides inherent line/load transient immunity and eliminates need for external compensation components in most applications. |
| 100% duty cycle capability | Enables ultra-low dropout regulation (VOUT ≈ VIN) using only RDS(ON) and inductor DCR - ideal for battery end-of-discharge operation. |
| Short-circuit protection | Extends off-time during overload to limit average short-circuit current to ~IMAX - prevents thermal runaway without external sensing. |
| Logic-compatible shutdown | CMOS-level SHDN pin (tr/tf < 1 µs) allows direct interface with microcontrollers and PMICs for coordinated power sequencing. |
Applications
| Portable Medical Monitors | Industrial Handheld Scanners |
|---|---|
Use Scenario: Battery-powered ECG or pulse oximeter requiring stable 5 V rail during intermittent wireless transmission and long idle periods. IC Role / Device Role / Timing Role: Step-down controller managing power delivery from 2S Li-ion (6–8.4 V) to 5 V microcontroller, ADC, and BLE radio subsystems. Use Value: Burst Mode extends battery life beyond 72 hours per charge; 160 µA sleep current avoids parasitic drain during patient monitoring intervals. | Use Scenario: Ruggedized barcode scanner operating from 9–16 V vehicle power with frequent wake/sleep cycles. IC Role / Device Role / Timing Role: Primary DC/DC controller converting unregulated vehicle supply to clean 5 V for imaging sensor, decoder ASIC, and display backlight drivers. Use Value: Wide 3.5–16 V input range accommodates cold-crank transients; 100% duty cycle sustains operation below 6 V during engine start. |
| GPS Tracking Modules | Wireless Sensor Nodes |
Use Scenario: Asset tracker powered by primary lithium thionyl chloride cell (3.6 V nominal) with boost converter feeding LTC1147CS8-5#TRPBF input. IC Role / Device Role / Timing Role: Secondary regulator generating precise 5 V for GPS receiver IC and cellular modem under variable load (10 mA–1.5 A bursts). Use Value: >95% efficiency at 1 A preserves limited energy budget; low 25 mV minimum sense threshold enables accurate current limiting with small RSENSE. | Use Scenario: LoRaWAN environmental sensor node powered by two AA alkaline cells (1.8–3.2 V), using boost stage to feed LTC1147CS8-5#TRPBF. IC Role / Device Role / Timing Role: Load-regulated 5 V source for microcontroller, temperature/humidity sensor, and RF transceiver during brief active intervals. Use Value: Shutdown current <20 µA prevents measurable battery depletion during multi-week sleep intervals; fast Burst Mode recovery ensures sub-100 µs wake-up latency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1148CS8-5#TRPBF | Higher efficiency (>96%), lower 120 µA sleep current, integrated soft-start, same pinout and function. | Preferred for new designs where lowest possible quiescent power and tighter output tolerance (±1%) are required. | Select LTC1148CS8-5#TRPBF when upgrading for improved light-load efficiency and tighter regulation; drop-in replacement with no layout change. |
| TPS54202DRCT | Integrated 28 V/2 A N-channel MOSFET, 500 kHz fixed frequency, no external RSENSE needed, but higher 19 µA shutdown current. | Better suited for compact, cost-sensitive designs where board area is constrained and external MOSFET layout is undesirable. | Choose TPS54202DRCT if integrating power stage simplifies design; not pin-compatible - requires new PCB layout and different compensation. |
Compared with LTC1147CS8-5#TRPBF, LTC1148CS8-5#TRPBF offers measurable efficiency gains at light loads and tighter output accuracy, while TPS54202DRCT trades external component flexibility for integration and smaller footprint - selection depends on whether priority lies in optimization of quiescent power, layout simplicity, or thermal management.
Availability
LTC1147CS8-5#TRPBF is available at Aetrix Electronics and suitable for portable medical monitors, industrial handheld scanners, GPS tracking modules, and wireless sensor nodes requiring stable component supply with guaranteed long-term availability.
Supply support for LTC1147CS8-5#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 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 battery-powered portable electronics, emphasizing Burst Mode operation, wide input range, and external P-MOSFET flexibility.
FAQ
What is the regulated output voltage of the LTC1147CS8-5#TRPBF?
The LTC1147CS8-5#TRPBF provides a fixed 5.05 V (typical) regulated output voltage with ±2% tolerance over temperature, line, and load conditions. This value is factory-trimmed and does not require external feedback resistors - unlike the adjustable LTC1147L variants. The output remains stable across 5 mA to 2 A load current and input voltages from 3.5 V to 16 V, making LTC1147CS8-5#TRPBF suitable for powering 5 V logic, sensors, and communication ICs in portable systems.
How does the LTC1147CS8-5#TRPBF achieve high efficiency at light loads?
The LTC1147CS8-5#TRPBF achieves high efficiency at light loads through automatic Burst Mode operation, which disables switching and reduces quiescent current to 160 µA when output current drops below ~300 mA. During Burst Mode, the device wakes periodically to recharge the output capacitor, minimizing switching losses while maintaining regulation. This behavior is intrinsic to the constant off-time architecture and requires no external enable signal - a key advantage of LTC1147CS8-5#TRPBF in battery-powered applications where standby power dominates total energy consumption.
Which external components are mandatory for basic operation of the LTC1147CS8-5#TRPBF?
Four external components are mandatory for basic operation of the LTC1147CS8-5#TRPBF: (1) an external P-channel MOSFET (e.g., Si4431DY), (2) a current sense resistor (RSENSE) sized per desired IMAX, (3) a timing capacitor (CT) on Pin 2 to set operating frequency, and (4) an output Schottky diode (e.g., MBRD330). Additionally, input (CIN) and output (COUT) capacitors are required for stability and ripple suppression - COUT ESR must be <2×RSENSE per LTC1147CS8-5#TRPBF specifications to avoid false Burst Mode triggering.
Can the LTC1147CS8-5#TRPBF operate in 100% duty cycle mode, and what is its significance?
Yes, the LTC1147CS8-5#TRPBF supports 100% duty cycle operation, meaning the external P-channel MOSFET remains continuously on when VIN approaches VOUT. This enables ultra-low dropout regulation where VOUT ≈ VIN – ILOAD × RDS(ON), critical for sustaining operation during battery end-of-discharge (e.g., 5.2 V input delivering 5 V output). Unlike PWM controllers limited by minimum off-time, LTC1147CS8-5#TRPBF's constant off-time architecture inherently permits this mode - a defining feature for portable equipment relying on diminishing battery voltage.
What is the function of the SHDN pin on the LTC1147CS8-5#TRPBF, and what voltage levels activate it?
The SHDN pin (Pin 6) on the LTC1147CS8-5#TRPBF provides logic-controlled micropower shutdown: grounding the pin enables normal operation, while pulling it to >0.8 V (up to 2.0 V max) places the device in shutdown mode drawing <20 µA. The pin accepts standard CMOS logic signals with rise/fall times <1 µs and must never be left floating. This feature allows system-level power sequencing - for example, a microcontroller GPIO can assert SHDN to disable LTC1147CS8-5#TRPBF during deep sleep, ensuring zero-load battery drain in always-on edge devices.
LTC1147CS8-5#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
LTC1147CS8-5#TRPBF FAQ
1.How can I place an order for LTC1147CS8-5#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1147CS8-5#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 LTC1147CS8-5#TRPBF reliable?
The price and inventory of LTC1147CS8-5#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1147CS8-5#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1147CS8-5#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1147CS8-5#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1147CS8-5#TRPBF?
LTC1147CS8-5#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1147CS8-5#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 LTC1147CS8-5#TRPBF?
For technical support, including LTC1147CS8-5#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1147CS8-5#TRPBF requirements.
6.How does Aetrix verify that LTC1147CS8-5#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1147CS8-5#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 LTC1147CS8-5#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1147CS8-5#TRPBF?
All LTC1147CS8-5#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1147CS8-5#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 LTC1147CS8-5#TRPBF part is unused and in its original packaging.
Return procedure for LTC1147CS8-5#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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