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Analog Devices Inc. LTC1147CS8-5#PBF
- Part No.:
- LTC1147CS8-5#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1147CS8-5#PBF.pdf
- Description:
- IC REG CTRLR BUCK 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:105
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Product details
Overview
LTC1147CS8-5#PBF from Analog Devices (formerly Linear Technology) is a high-efficiency, constant off-time current-mode step-down switching regulator controller that drives an external P-channel MOSFET to deliver up to 2A output current at 5V with input range 3.5V–16V, 95% peak efficiency, and 160µA light-load quiescent current. It enables compact, high-efficiency DC/DC conversion in battery-powered portable systems.
For engineers reviewing the LTC1147CS8-5#PBF datasheet, LTC1147CS8-5#PBF pinout, LTC1147CS8-5#PBF application, or LTC1147CS8-5#PBF equivalent, key selection considerations include its 5V fixed output, 8-pin SO package, Burst Mode™ operation for micropower efficiency, 130–170mV current sense threshold, and compatibility with external P-channel MOSFETs and Schottky diodes in non-synchronous buck topologies.
Technical Context
The LTC1147CS8-5#PBF implements a constant off-time (COT) current-mode architecture where the off-time is set by an external capacitor on CT (Pin 2) and dynamically adjusted based on VOUT to maintain stable frequency across input voltage changes. Its internal voltage comparator controls Burst Mode™ entry/exit using output voltage hysteresis, while a dedicated current comparator monitors SENSE+ and SENSE− (Pins 5 and 4) to regulate peak inductor current via external RSENSE.
It features logic-controlled micropower shutdown (IQ < 20µA), 100% duty cycle low-dropout operation, short-circuit protection via extended tOFF, and built-in offset in the gain stage to prevent current-loop interference during Burst Mode™. The SHDN/VFB pin (Pin 6) serves as shutdown control for fixed-output variants like LTC1147CS8-5#PBF.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.05V nominal (4.90–5.20V over load/temp), enabling direct regulation for 5V logic rails without feedback resistors. |
| Input Voltage Range | 3.5V to 16V - supports wide-input industrial and automotive battery systems including 5V, 9V, and 12V supplies. |
| Max Output Current | 2A continuous - determined by external RSENSE (e.g., 0.05Ω) and MOSFET capability, not limited by IC itself. |
| Quiescent Current | 160–260µA in Sleep Mode - sustains >95% efficiency down to ~1mA load via automatic Burst Mode™ activation. |
| Current Sense Threshold | 125–185mV (typ. 150mV) between SENSE+ and SENSE− - sets peak inductor current and defines IMAX = 150mV/RSENSE. |
| Off-Time | 3.8–6.5µs (CT = 390pF, ILOAD = 700mA) - determines minimum switching frequency and dropout behavior. |
| Shutdown Current | 10–22µA - enables ultra-low-power system sleep states with externally controlled CMOS-level SHDN signal. |
| Operating Temp Range | 0°C to 70°C (Commercial grade) - validated for use in notebook, GPS, and portable instrumentation environments. |
Pinout & Package
Package: 8-lead plastic SO (SOIC-8), 150°C/W junction-to-ambient thermal resistance, surface-mount compatible.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Main power supply input | Accepts 3.5V–16V; requires local 100µF + 1µF ceramic decoupling to GND (Pin 7) to suppress switching noise. |
| CT (Pin 2) | Timing capacitor connection | Sets off-time and operating frequency; value (e.g., 390pF) scales inversely with fSW and tracks VOUT for stability. |
| ITH (Pin 3) | Gain amplifier decoupling | Stabilizes current comparator threshold; connect 100nF ceramic to GND to reduce noise sensitivity. |
| SENSE− (Pin 4) | Current comparator (−) input & internal voltage divider tap | Connects to output rail via internal resistor; forms differential pair with SENSE+ to detect RSENSE voltage drop. |
| SENSE+ (Pin 5) | Current comparator (+) input | Connected across external RSENSE; 25–185mV offset vs. SENSE− sets current trip point for MOSFET turn-off. |
| SHDN/VFB (Pin 6) | Shutdown control / feedback reference | Grounded for normal operation; pulled high (>0.8V) to enter micropower shutdown (IQ < 22µA); not used as feedback in fixed-5V variant. |
| GND (Pin 7) | Analog and power ground return | Must be split: one path to COUT (–) and another to diode cathode/CIN (–) to avoid ground bounce in high di/dt paths. |
| PDRIVE (Pin 8) | High-current P-MOSFET gate driver | Swings from VIN to GND; delivers >1A peak current to drive external P-channel MOSFET with fast 100–200ns transitions. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode™ operation | Reduces IQ to 160µA and maintains >90% efficiency at loads below 300mA by disabling switching until output droops beyond hysteresis band. |
| Constant off-time current mode | Provides inherent line/load transient immunity and stable operation without loop compensation components; frequency varies <±20% over VIN range. |
| Logic-compatible shutdown | CMOS-level SHDN input (0.5–2V threshold) enables seamless integration with microcontroller GPIOs for system-level power sequencing. |
| 100% duty cycle low-dropout | Supports VOUT ≈ VIN operation when (VIN – VOUT) < 1.5V - eliminates need for LDO post-regulation in near-dropout conditions. |
| Short-circuit protection | Extends off-time during overload to limit average short-circuit current to ~IMAX, preventing thermal runaway without external circuitry. |
Applications
| Portable Medical Monitors | Notebook Computer Core Power |
|---|---|
Use Scenario: Battery-powered ECG and pulse oximeter units requiring long runtime and stable 5V analog/digital rails. IC Role / Device Role / Timing Role: Primary step-down controller regulating 5V from single-cell Li-ion (3.0–4.2V) or dual-cell (6–8.4V) battery inputs. Use Value: Burst Mode™ extends battery life by reducing no-load power to 2mW at VIN = 10V; 160µA IQ enables >100-hour standby without recharge. | Use Scenario: Secondary 5V rail generation for USB peripherals, display backlight drivers, and I/O controllers in ultraportable notebooks. IC Role / Device Role / Timing Role: Non-synchronous buck controller driving Si4431DY P-MOSFET to convert 12V main rail to regulated 5V/2A output. Use Value: 95% peak efficiency and 50µH/0.05Ω design minimizes heat rise in confined chassis; SO-8 package eases layout in space-constrained PCBs. |
| GPS Navigation Systems | Industrial Handheld Scanners |
Use Scenario: Compact GPS receivers operating from 9V alkaline or 7.4V Li-Po batteries, demanding clean 5V supply for RF front-end and baseband ICs. IC Role / Device Role / Timing Role: High-efficiency DC/DC controller maintaining tight 5V regulation despite battery voltage sag under pulsed GPS acquisition loads. Use Value: Current-mode control ensures <1% output deviation during 1A load transients; low 130mV sense threshold allows precise current limiting with minimal RSENSE loss. | Use Scenario: Rugged barcode scanners powered by replaceable AA/AAA packs, requiring reliable 5V operation across 3.5–9V input range and shock/vibration tolerance. IC Role / Device Role / Timing Role: Input-flexible buck controller supporting both fresh alkaline (9V) and depleted (4.5V) sources while delivering consistent 5V to imaging sensor and decode ASIC. Use Value: 3.5V minimum VIN and 100% duty cycle enable full functionality even at end-of-battery; SO-8 package withstands reflow and mechanical stress per IPC-A-610 Class 2. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1170CN8-5 | Fixed 5V output, 100kHz fixed-frequency voltage-mode control, higher IQ (6mA), no Burst Mode™ | Less efficient at light loads; suitable only where simplicity outweighs efficiency needs | Choose LT1170CN8-5 only if board space allows larger inductor and thermal budget permits higher idle dissipation. |
| TPS54202DDAR | Integrated 2A synchronous buck converter (no external MOSFET), 4.5–28V input, 500kHz PWM, 25µA IQ in Eco-mode | Higher integration reduces BOM count but eliminates P-MOSFET flexibility and 100% duty cycle capability | Select TPS54202DDAR when minimizing external components is critical and input voltage exceeds 4.5V; avoid if <3.5V start-up or true dropout operation required. |
Compared with LT1170CN8-5, LTC1147CS8-5#PBF delivers >30% lower light-load power and superior transient response via current-mode control; versus TPS54202DDAR, it offers wider VIN range, 100% duty cycle, and design flexibility at the cost of two external power devices.
Availability
LTC1147CS8-5#PBF is available at Aetrix Electronics and suitable for portable medical monitors, notebook computer core power, GPS navigation systems, and industrial handheld scanners requiring stable component supply with guaranteed long-term manufacturability.
Supply support for LTC1147CS8-5#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LTC1147 series was designed specifically for high-efficiency, low-quiescent-current step-down regulation in portable and battery-critical applications - emphasizing Burst Mode™ operation, wide input range, and external P-MOSFET flexibility.
FAQ
What is the function of Pin 6 (SHDN/VFB) on the LTC1147CS8-5#PBF?
On the LTC1147CS8-5#PBF, Pin 6 functions exclusively as the shutdown (SHDN) control input. Grounding this pin enables normal operation; applying a logic-high voltage (>0.8V) places the LTC1147CS8-5#PBF into micropower shutdown mode with IQ < 22µA. Unlike adjustable variants (e.g., LTC1147L), this pin is not used for feedback in the fixed-5V LTC1147CS8-5#PBF.
Does the LTC1147CS8-5#PBF require an external P-channel MOSFET?
Yes, the LTC1147CS8-5#PBF is a controller-not a converter-and requires an external P-channel MOSFET (e.g., Si4431DY) connected to PDRIVE (Pin 8). It does not integrate power switches. This architecture allows optimization of RDS(ON), voltage rating, and thermal performance based on specific application requirements such as input voltage and output current.
What is the recommended value for RSENSE with the LTC1147CS8-5#PBF for a 2A output?
For a 2A maximum output current, RSENSE should be 0.05Ω - derived from ISC(PK) = 150mV / RSENSE and IBURST ≈ 15mV / RSENSE. This value ensures peak current limiting at ~3A and Burst Mode™ initiation near 300mA, aligning with typical application circuits shown in the LTC1147CS8-5#PBF datasheet Figure 1 and matching the 0.05Ω value used in the 5V/2A reference design.
Can the LTC1147CS8-5#PBF operate with input voltages below 3.5V?
No - the absolute minimum input voltage for the LTC1147CS8-5#PBF is 3.5V, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. Operation below 3.5V is not guaranteed and may result in failure to regulate or erratic Burst Mode™ behavior. For sub-3.5V applications, consider the LTC1147L series or alternative controllers rated for lower VIN.
How does the LTC1147CS8-5#PBF achieve high efficiency at light loads?
The LTC1147CS8-5#PBF achieves high light-load efficiency through automatic Burst Mode™ operation: when output current drops below ~300mA, it disables switching cycles entirely, reducing IQ to 160–260µA and cutting total input power to ~2mW at VIN = 10V. Regulation is maintained by discharging COUT until VOUT drops beyond hysteresis, then resuming a single switching cycle - minimizing switching and gate-drive losses.
LTC1147CS8-5#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
LTC1147CS8-5#PBF FAQ
1.How can I place an order for LTC1147CS8-5#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1147CS8-5#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 LTC1147CS8-5#PBF reliable?
The price and inventory of LTC1147CS8-5#PBF 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#PBF is usually 5 days.
3.What payment methods are accepted for LTC1147CS8-5#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1147CS8-5#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1147CS8-5#PBF?
LTC1147CS8-5#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1147CS8-5#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 LTC1147CS8-5#PBF?
For technical support, including LTC1147CS8-5#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1147CS8-5#PBF requirements.
6.How does Aetrix verify that LTC1147CS8-5#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1147CS8-5#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 LTC1147CS8-5#PBF meets industry standards.
7.What is the process for return or replacement of LTC1147CS8-5#PBF?
All LTC1147CS8-5#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1147CS8-5#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 LTC1147CS8-5#PBF part is unused and in its original packaging.
Return procedure for LTC1147CS8-5#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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