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Analog Devices Inc. LT1109CS8-5#TRPBF
- Part No.:
- LT1109CS8-5#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1109CS8-5#TRPBF.pdf
- Description:
- IC REG BOOST 5V 1.2A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,986
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Product details
Overview
LT1109CS8-5#TRPBF from Analog Devices (formerly Linear Technology) is a fixed-output 5V micropower step-up DC/DC converter in an 8-pin SOIC package, delivering up to 100mA output current from a 3V input, featuring 120kHz oscillator frequency, 320µA quiescent current, logic-controlled shutdown, and requiring only three external components. It is used in flash memory VPP generation and low-power 3V-to-5V conversion.
For engineers reviewing the LT1109CS8-5#TRPBF datasheet, LT1109CS8-5#TRPBF pinout, LT1109CS8-5#TRPBF application, or LT1109CS8-5#TRPBF equivalent, key selection criteria include minimum start-up voltage (1.6V), output voltage accuracy (±5%), shutdown pin interface compatibility, inductor size constraints (33µH typical), and thermal dissipation limits (θJA = 150°C/W).
Technical Context
The LT1109CS8-5#TRPBF implements a gated-oscillator architecture with internal 1.25V reference and comparator-based feedback control, enabling stable regulation without external compensation. Its SENSE pin monitors output voltage via resistive divider, while SHUTDOWN pin disables oscillator operation when pulled low.
It operates in discontinuous conduction mode with fixed 120kHz switching frequency and 4.2µs typical switch ON time, supporting bootstrapped power delivery where internal circuitry draws supply from VOUT but VIN powers the switch stage-reducing quiescent power versus TO-92 variants.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.00V ±2.5% (4.75V–5.25V); enables direct replacement of 5V LDOs in battery-powered systems. |
| Max Output Current | 100mA at VIN = 3V; sufficient for flash memory programming voltage (VPP) and small peripherals. |
| Quiescent Current | 320µA (typical) with switch off; minimizes battery drain during standby in portable equipment. |
| Start-Up Voltage | 1.6V minimum at VOUT pin; allows operation from partially discharged 2-cell alkaline or NiMH batteries. |
| Oscillator Frequency | 120kHz (100–140kHz range); permits use of compact, low-cost surface-mount inductors (e.g., 33µH). |
| Switch Saturation Voltage | 0.7V max at 500mA; limits conduction loss and supports efficient energy transfer at light-to-moderate loads. |
| Shutdown Input Threshold | VIL ≤ 0.8V, VIH ≥ 2.0V; compatible with standard CMOS/TTL logic levels for host-controlled power gating. |
Pinout & Package
LT1109CS8-5#TRPBF uses an 8-lead plastic SOIC (S8) package with 150°C/W junction-to-ambient thermal resistance and operating temperature range of 0°C to 70°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VIN | Input Power Supply | Connects to primary input source (3V–5V); powers switch stage directly-reducing quiescent power vs. bootstrapped Z-package versions. |
| 2 - NC | No Connect | Unbonded pin; must be left floating or grounded per layout best practices-no electrical function. |
| 3 - SW | Switch Node | Drives external inductor; carries pulsed current up to 1.2A peak; requires low-inductance routing to minimize EMI. |
| 4 - GND | Power Ground | Common return for VIN, SW, SENSE, and SHUTDOWN; must be low-impedance plane for stability and noise control. |
| 5 - SENSE | Feedback Input | Monitors regulated output via resistor divider; sets 5V output by comparing attenuated VOUT to internal 1.25V reference. |
| 6 - SHUTDOWN | Enable Control | Active-low logic input; pulls oscillator offline when ≤0.8V, reducing system power consumption to 320µA static draw. |
| 7 - NC | No Connect | Unbonded pin; no internal connection-must not be soldered or tied to any net. |
| 8 - NC | No Connect | Unbonded pin; electrically isolated-leave unconnected per manufacturer recommendation. |
Key Features
| Feature | Design Value |
|---|---|
| Logic-Controlled Shutdown | Reduces system-level standby power by disabling oscillator while maintaining 320µA supply current-ideal for host-activated sleep modes. |
| Three-External-Component Design | Requires only inductor, diode, and output capacitor-minimizes BOM count, PCB area, and design validation effort. |
| 120kHz Fixed-Frequency Operation | Enables predictable EMI profile and consistent inductor sizing; avoids subharmonic oscillation issues seen in variable-frequency converters. |
| 1.6V Minimum Start-Up Voltage | Supports operation down to end-of-life battery voltage in 2-cell alkaline/NiMH systems-extends usable runtime. |
| Internal 1.25V Reference + Comparator | Eliminates need for external error amplifier or compensation network-simplifies loop stability and reduces component count. |
Applications
| Flash Memory VPP Generation | 3V-to-5V Portable Power Conversion |
|---|---|
Use Scenario: Generating +5V programming voltage (VPP) for EPROM/EEPROM devices in embedded microcontroller systems. IC Role / Device Role / Timing Role: Step-up DC/DC converter providing regulated 5V output from 3V main rail, synchronized to write-enable timing windows. Use Value: Enables in-system flash reprogramming using standard 3V logic rails-eliminates need for dedicated high-voltage charge pumps or external VPP supplies. | Use Scenario: Powering 5V I/O peripherals (e.g., UART transceivers, SPI sensors) from a 3V lithium coin cell or two AA batteries. IC Role / Device Role / Timing Role: Primary voltage booster supplying stable 5V rail with fast transient response to burst-mode peripheral activity. Use Value: Delivers 100mA at 5V with <320µA quiescent draw-maximizes battery life in intermittently active portable instrumentation. |
| Disk Drive Interface Power | PC Plug-In Card Auxiliary Supply |
Use Scenario: Providing 5V bias for magnetic head preamplifiers and servo control circuits in portable 2.5" HDD modules. IC Role / Device Role / Timing Role: Local DC/DC regulator converting 3.3V system bus to 5V analog subsystem rail, with shutdown controlled by drive activity signals. Use Value: Reduces thermal load on main power rail and isolates sensitive analog circuitry from digital noise-improves signal integrity and SNR. | Use Scenario: Generating auxiliary 5V supply on ISA or PCI add-in cards where motherboard does not provide full 5V sourcing capability. IC Role / Device Role / Timing Role: Compact boost converter integrated into card-edge layout, activated only during card initialization or configuration cycles. Use Value: Avoids board-level redesign by enabling legacy 5V-only peripherals to operate from modern low-voltage motherboards-preserves hardware compatibility. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-up DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1983ES5-5#TRMPBF | Higher efficiency (90% vs. ~82%), lower IQ (25µA), integrated Schottky diode, but requires 4 external components and has 1.8V min start-up. | Better suited for ultra-low-power IoT sensors; less ideal for flash VPP due to lower max output current (60mA). | Select LTC1983ES5-5#TRMPBF when extended battery life and tighter output regulation outweigh BOM simplicity and higher output current needs. |
| TPS61022DSQR | Higher output current (1.2A), adjustable output, 2.5V min start-up, integrated switch and diode-but larger QFN package and 1.2MHz switching frequency increases EMI filtering complexity. | Targeted at high-current portable displays and USB-C PD sink applications-not optimized for low-component-count VPP generation. | Choose TPS61022DSQR only when >100mA output and wide input range (0.9V–5.5V) are mandatory; otherwise, LT1109CS8-5#TRPBF offers superior cost and layout simplicity. |
Compared with LTC1983ES5-5#TRMPBF and TPS61022DSQR, the LT1109CS8-5#TRPBF prioritizes minimal external component count and proven reliability in flash programming roles over peak efficiency or current capability-making it optimal for cost-sensitive, space-constrained, and legacy-compatible designs.
Availability
LT1109CS8-5#TRPBF is available at Aetrix Electronics and suitable for flash memory VPP generation, 3V-to-5V portable power conversion, and disk drive interface power applications requiring stable component supply across industrial and embedded production cycles.
Supply support for LT1109CS8-5#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision instrumentation, industrial automation, and communications markets.
The LT1109 product line was designed specifically for low-cost, low-quiescent-current DC/DC conversion in battery-powered and flash-memory-centric systems-emphasizing simplicity, robustness, and ease of integration over feature density.
FAQ
What is the minimum input voltage required for LT1109CS8-5#TRPBF to start regulating?
The LT1109CS8-5#TRPBF requires a minimum start-up voltage of 1.6V at the VOUT pin. However, stable regulation at 5V output begins at VIN ≥ 3V per datasheet specifications. Below 3V input, output voltage drops progressively and regulation is not guaranteed-even if the device powers on. This behavior is critical for battery-powered designs where voltage sag must be accounted for in system-level brown-out detection.
Can LT1109CS8-5#TRPBF be used to generate 12V output?
No, the LT1109CS8-5#TRPBF is a fixed 5V output variant. For 12V output, the correct part is LT1109CS8-12#TRPBF. Although both share the same S8 package and pinout, internal feedback resistor ratios differ-using LT1109CS8-5#TRPBF in a 12V circuit will result in under-regulation (~5V output) and potential instability. The -5 and -12 suffixes denote factory-trimmed output voltages and are not user-adjustable.
Does LT1109CS8-5#TRPBF require external compensation components?
No, the LT1109CS8-5#TRPBF uses a gated-oscillator architecture with built-in hysteresis (8–12.5mV) in its comparator, eliminating the need for external frequency compensation networks. This simplifies design and improves reliability across temperature and load variations-unlike many current-mode controllers that require RC networks for loop stability.
What is the maximum continuous output current for LT1109CS8-5#TRPBF at 3V input?
The LT1109CS8-5#TRPBF delivers up to 100mA continuous output current when VIN = 3V, as specified in the datasheet's "Electrical Characteristics" table. This assumes proper thermal management (θJA = 150°C/W), use of recommended 33µH inductor, and ambient temperature ≤ 70°C. Exceeding 100mA risks thermal shutdown or reduced output regulation accuracy due to increased switch saturation voltage.
How does the SHUTDOWN pin function on LT1109CS8-5#TRPBF?
The SHUTDOWN pin on LT1109CS8-5#TRPBF is an active-low logic input: pulling it ≤ 0.8V disables the internal oscillator, halting switching and reducing total supply current to 320µA. When left open or tied ≥ 2.0V, the device operates normally. Unlike some newer converters, it does not disconnect VIN from the load-output voltage decays through the catch diode and output capacitor after shutdown.
LT1109CS8-5#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
- Function:
- Step-Up
- Output Configuration:
- Positive
- Topology:
- Boost
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 20V
- Voltage - Output (Min/Fixed):
- 5V
- Voltage - Output (Max):
- -
- Current - Output:
- 1.2A (Switch)
- Frequency - Switching:
- 120kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1109CS8-5#TRPBF FAQ
1.How can I place an order for LT1109CS8-5#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1109CS8-5#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 LT1109CS8-5#TRPBF reliable?
The price and inventory of LT1109CS8-5#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1109CS8-5#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1109CS8-5#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1109CS8-5#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1109CS8-5#TRPBF?
LT1109CS8-5#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1109CS8-5#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 LT1109CS8-5#TRPBF?
For technical support, including LT1109CS8-5#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1109CS8-5#TRPBF requirements.
6.How does Aetrix verify that LT1109CS8-5#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1109CS8-5#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 LT1109CS8-5#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1109CS8-5#TRPBF?
All LT1109CS8-5#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1109CS8-5#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 LT1109CS8-5#TRPBF part is unused and in its original packaging.
Return procedure for LT1109CS8-5#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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