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Analog Devices Inc. LT1109CN8-5#PBF
- Part No.:
- LT1109CN8-5#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LT1109CN8-5#PBF.pdf
- Description:
- IC REG BOOST 5V 1.2A 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,519
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Product details
Overview
LT1109CN8-5#PBF from Analog Devices (formerly Linear Technology) is a fixed-output 5V step-up DC/DC converter in an 8-pin plastic DIP package, delivering 100mA output from a 3V input with 320µA quiescent current, 120kHz oscillator frequency, and logic-controlled shutdown - used in flash memory VPP generation and low-power 3V-to-5V conversion.
For engineers reviewing the LT1109CN8-5#PBF datasheet, LT1109CN8-5#PBF pinout, LT1109CN8-5#PBF application, or LT1109CN8-5#PBF equivalent, key selection criteria include minimum 1.6V start-up voltage, 4.75–5.25V output regulation tolerance, shutdown pin compatibility, and use of off-the-shelf 33µH inductors in battery-powered peripherals and PC plug-in cards.
Technical Context
The LT1109CN8-5#PBF implements a gated-oscillator architecture with internal 1.25V reference and comparator-based feedback control, enabling stable regulation without external frequency compensation components. Its 120kHz fixed-frequency operation allows compact surface-mount magnetics and capacitors while maintaining discontinuous conduction mode for light-load efficiency.
It features separate VIN and SENSE pins to power internal circuitry from the lower input rail rather than the higher output rail, reducing quiescent power dissipation. The SHUTDOWN pin (Pin 6) disables the oscillator when pulled low, retaining only 320µA supply current during standby.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.00V ±2.5%, tightly regulated across 3V–5V input range for reliable flash programming voltage |
| Oscillator Frequency | 120kHz typical, enables use of small 33µH inductors and avoids audible noise in portable equipment |
| Quiescent Current | 320µA at no load, minimizes battery drain in always-on or infrequently active systems |
| Minimum Start-Up Voltage | 1.6V at VOUT pin, supports operation from single-cell LiFePO₄ or two alkaline cells |
| Switch Saturation Voltage | 0.5–0.8V at 500mA, limits conduction loss and thermal rise in cost-sensitive DIP packages |
| Shutdown Pin Threshold | VIL = 0.8V max, VIH = 2.0V min - compatible with standard TTL/CMOS logic interfaces |
| Duty Cycle Range | 45–60% at full load, balances inductor energy transfer and switch stress in step-up topology |
Pinout & Package
LT1109CN8-5#PBF uses an 8-lead plastic DIP (N8) package with 0.300-inch width, 130°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 unregulated 3V–5V source; powers internal regulator independently of VOUT |
| 2 (NC) | No Connect | Not internally bonded; must be left floating or grounded per layout best practice |
| 3 (SW) | Internal Switch Collector | Drives external inductor; handles peak currents up to 1.2A with 0.5–0.8V saturation drop |
| 4 (GND) | Power and Signal Ground | Common return for input, output, and internal circuitry; requires low-impedance PCB plane |
| 5 (SENSE) | Feedback Input | Monitors regulated output via resistor divider; sets 5V output by comparing to 1.25V internal reference |
| 6 (SHUTDOWN) | Logic-Controlled Enable | Active-low digital input; pulls oscillator offline when ≤0.8V, reducing system standby power |
| 7 (NC) | No Connect | Not internally bonded; must be left floating or grounded per layout best practice |
| 8 (NC) | No Connect | Not internally bonded; must be left floating or grounded per layout best practice |
Key Features
| Feature | Design Value |
|---|---|
| Three-external-component design | Requires only inductor, diode, and output capacitor - reduces BOM count and board space in space-constrained peripherals |
| Logic-controlled shutdown | Enables system-level power gating without external MOSFETs or sequencing ICs in portable devices |
| 1.6V minimum start-up | Allows operation from partially discharged batteries, extending usable runtime in flash memory programmers |
| Gated-oscillator architecture | Eliminates need for external compensation network, simplifying design validation and reducing debug time |
| Fixed 5V output version | Removes external feedback resistors, improving output accuracy and long-term stability over adjustable variants |
Applications
| Flash Memory VPP Generation | 3V-to-5V Portable Conversion |
|---|---|
Use Scenario: Generating +5V programming voltage for EPROM/EEPROM chips in handheld programmers and embedded firmware update tools. IC Role / Device Role / Timing Role: Step-up DC/DC converter providing regulated VPP supply independent of main system rail. Use Value: Enables reliable flash write cycles using only two alkaline cells, eliminating need for dedicated high-voltage charge pumps. | Use Scenario: Powering 5V logic circuits (e.g., UART transceivers, SPI peripherals) from 3V microcontroller rails in battery-operated sensors. IC Role / Device Role / Timing Role: Fixed-output boost converter supplying clean, low-noise 5V rail with minimal external parts. Use Value: Reduces component count versus switching controller + external FET solutions while meeting 100mA load requirement. |
| Disk Drive Interface Power | PC Plug-In Card Auxiliary Rail |
Use Scenario: Providing isolated 5V bias for IDE/ATA interface level shifters and buffer ICs in legacy laptop disk drive modules. IC Role / Device Role / Timing Role: Local DC/DC converter decoupling peripheral power from noisy main system supply. Use Value: Prevents data corruption during read/write operations by rejecting ripple from shared 3.3V/5V motherboard rails. | Use Scenario: Delivering auxiliary 5V rail to ISA or PCI add-in cards requiring separate logic voltage from host bus. IC Role / Device Role / Timing Role: Compact, through-hole mountable boost converter supporting hot-plug-compatible power sequencing. Use Value: Simplifies card-level power architecture with single-chip solution and no layout-sensitive compensation. |
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 |
|---|---|---|---|
| LT1109CS8-5#PBF | Same electrical specs, but in 8-lead SOIC package - smaller footprint, higher thermal resistance (150°C/W) | Better suited for automated SMT assembly and space-constrained PCBs; less suitable for hand-soldered prototyping | Select when board area is constrained and reflow capability exists; verify thermal margin under full load. |
| LT1301CS8-5#PBF | Higher output current (200mA), lower shutdown current (20µA), same 5V fixed output; requires different inductor value | Preferred for longer battery life in always-on monitoring nodes where deep sleep current matters most | Choose when >100mA load or <100µA shutdown current is required; redesign inductor and feedback network. |
Compared with LT1109CN8-5#PBF, LT1109CS8-5#PBF offers identical performance in a surface-mount package ideal for volume production, while LT1301CS8-5#PBF delivers higher current and ultra-low shutdown draw at the cost of increased complexity and cost - making LT1109CN8-5#PBF optimal for cost-sensitive, moderate-current DIP-based designs.
Availability
LT1109CN8-5#PBF is available at Aetrix Electronics and suitable for flash memory programming, 3V-to-5V portable conversion, and PC plug-in card auxiliary power applications requiring stable component supply and long-term industrial availability.
Supply support for LT1109CN8-5#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 acquired Linear Technology in 2017 and maintains its precision analog and power management product lines with full datasheet, reliability, and support continuity.
The LT1109 belongs to Linear's micropower DC/DC converter family, designed specifically for low-cost, low-quiescent-current boost applications in battery-powered and space-constrained systems.
FAQ
What is the maximum output current capability of the LT1109CN8-5#PBF?
The LT1109CN8-5#PBF delivers up to 100mA continuous output current when converting from a 3V input to 5V output, as specified in the datasheet under typical conditions. Peak switch current is rated at 1.2A, but sustained output is limited by thermal dissipation in the 8-pin DIP package and external component selection - particularly inductor saturation current and diode forward voltage.
Does the LT1109CN8-5#PBF require external feedback resistors to set the output voltage?
No, the LT1109CN8-5#PBF is a fixed-output variant with internal resistor divider configured for 5.00V regulation. Unlike adjustable versions (e.g., LT1109CN8), it does not require external R1/R2 on the SENSE pin - simplifying layout and improving output accuracy and temperature stability.
Can the LT1109CN8-5#PBF operate from a single 1.5V alkaline cell?
No - the LT1109CN8-5#PBF has a minimum start-up voltage of 1.6V at the VOUT pin, and its recommended input voltage range is 3V to 5V. A single 1.5V cell falls below this threshold; however, two series alkaline cells (2.0–3.2V) meet the 1.6V start-up requirement and are commonly used in flash programmers with LT1109CN8-5#PBF.
What is the purpose of the NC pins (2, 7, and 8) on the LT1109CN8-5#PBF?
Pins 2, 7, and 8 on the LT1109CN8-5#PBF are no-connect terminals - not bonded to the die and electrically inactive. They must be left floating or tied to ground per PCB layout best practices to avoid parasitic coupling; they do not support any functional role or alternate configurations in this fixed-output DIP variant.
How does the SHUTDOWN pin function on the LT1109CN8-5#PBF?
The SHUTDOWN pin (Pin 6) on the LT1109CN8-5#PBF is an active-low digital control input. When pulled below 0.8V (VIL), it disables the internal oscillator and halts switching, reducing total supply current to 320µA. When left open or pulled above 2.0V (VIH), the device operates normally - enabling simple microcontroller GPIO-based power management.
LT1109CN8-5#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- 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:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LT1109CN8-5#PBF FAQ
1.How can I place an order for LT1109CN8-5#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1109CN8-5#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 LT1109CN8-5#PBF reliable?
The price and inventory of LT1109CN8-5#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1109CN8-5#PBF is usually 5 days.
3.What payment methods are accepted for LT1109CN8-5#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1109CN8-5#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1109CN8-5#PBF?
LT1109CN8-5#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1109CN8-5#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 LT1109CN8-5#PBF?
For technical support, including LT1109CN8-5#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1109CN8-5#PBF requirements.
6.How does Aetrix verify that LT1109CN8-5#PBF is sourced from the original manufacturer or authorized distributors?
All LT1109CN8-5#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 LT1109CN8-5#PBF meets industry standards.
7.What is the process for return or replacement of LT1109CN8-5#PBF?
All LT1109CN8-5#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1109CN8-5#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 LT1109CN8-5#PBF part is unused and in its original packaging.
Return procedure for LT1109CN8-5#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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