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Analog Devices Inc. LT1109CS8-12#PBF
- Part No.:
- LT1109CS8-12#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1109CS8-12#PBF.pdf
- Description:
- IC REG BOOST 12V 1.2A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:111
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Product details
Overview
LT1109CS8-12#PBF from Analog Devices (formerly Linear Technology) is a fixed-output 12V step-up DC/DC converter in an 8-lead SOIC package, featuring logic-controlled shutdown, 120kHz oscillator, 320µA quiescent current, and 1.6V minimum start-up voltage. It delivers up to 80mA output from a 5V input and is used in flash memory VPP generation and peripheral power rails.
For engineers reviewing the LT1109CS8-12#PBF datasheet, LT1109CS8-12#PBF pinout, LT1109CS8-12#PBF application, or LT1109CS8-12#PBF equivalent, key selection criteria include shutdown control capability, fixed 12V output tolerance (±4.2%), 33µH inductor requirement, and compatibility with low-ESR tantalum output capacitors.
Technical Context
The LT1109CS8-12#PBF implements a gated-oscillator topology with internal 1.25V reference and comparator-based feedback, eliminating need for external frequency compensation. Its SENSE pin enables input-referred regulation, decoupling VIN supply from output voltage path.
It integrates a 1.2A switch with 0.7V typical saturation voltage at 500mA, operates in discontinuous conduction mode, and uses bootstrapped gate drive. The SHUTDOWN pin disables oscillator when pulled low, maintaining 320µA quiescent current during disable.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 12.00V ±4.2% (11.52V–12.55V), enabling direct VPP programming for EPROM/Flash devices |
| Oscillator Frequency | 120kHz typical (100–140kHz), permitting use of compact 33µH surface-mount inductors |
| Quiescent Current | 320µA typical at shutdown, minimizing battery drain in standby mode |
| Start-Up Voltage | 1.6V minimum at VOUT pin, supporting single-cell Li-ion or dual-cell NiMH operation |
| Switch Saturation Voltage | 0.7V max at 500mA, limiting conduction loss and thermal rise under load |
| Duty Cycle | 50% typical at full load, balancing efficiency and inductor size constraints |
| SHUTDOWN Threshold | VIL = 0.8V max, VIH = 2.0V min - compatible with 3.3V/5V logic interfaces |
Pinout & Package
LT1109CS8-12#PBF is housed in an 8-lead plastic SOIC (S8) package with standard JEDEC MS-012AC dimensions (3.9mm × 4.9mm × 1.5mm), θJA = 150°C/W, and Pb-free #PBF finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SENSE) | Feedback reference input | Connects to output divider network (fixed version ties internally); sets regulation point at 1.25V threshold |
| 2 (SHUTDOWN) | Logic enable/disable control | Pull low ≤0.8V to halt oscillator; float or pull high ≥2.0V for normal operation |
| 3 (NC) | No connect | Not bonded; must remain unconnected per datasheet |
| 4 (NC) | No connect | Not bonded; must remain unconnected per datasheet |
| 5 (VIN) | Main power input | Accepts 3V–12V DC input; powers internal circuitry directly (not bootstrapped) |
| 6 (NC) | No connect | Not bonded; must remain unconnected per datasheet |
| 7 (SW) | Internal switch collector | Drives external inductor/diode; switches at 120kHz with 4.2µs typical ON time |
| 8 (GND) | Analog and power ground | Common return for feedback, shutdown, and switch paths; requires low-impedance PCB connection |
Key Features
| Feature | Design Value |
|---|---|
| Logic-controlled shutdown | Reduces system-level standby power by disabling switching while retaining 320µA bias current |
| Fixed 12V output | Eliminates external resistor divider, simplifying BOM and improving output accuracy vs adjustable variants |
| Gated-oscillator architecture | Removes need for external compensation components, reducing design cycle time and layout sensitivity |
| Low-startup-voltage operation | Enables use with partially discharged batteries (down to 1.6V), extending usable runtime |
| SOIC-8 surface-mount package | Supports automated assembly and offers better thermal performance than TO-92 or DIP alternatives |
Applications
| Flash Memory VPP Generation | 3V-to-12V Peripheral Power |
|---|---|
Use Scenario: Programming voltage supply for EPROM, EEPROM, and early Flash memory chips requiring +12V VPP. IC Role / Device Role / Timing Role: Step-up regulator providing regulated 12V output from 3V–5V system rail. Use Value: Delivers stable 80mA at 12V with ±4.2% tolerance, meeting JEDEC VPP specification for reliable byte-programming. | Use Scenario: Powering legacy ISA bus peripherals, SCSI terminators, or analog front-end bias rails in embedded systems. IC Role / Device Role / Timing Role: Fixed-output DC/DC converter generating isolated 12V from main 3.3V/5V supply. Use Value: Enables single-supply designs without discrete charge pumps or transformer-based solutions, reducing board area by >40%. |
| Disk Drive Head Actuator Bias | PC Plug-in Card Auxiliary Supply |
Use Scenario: Providing bias voltage for voice coil motor drivers or preamplifier stages in 2.5″/3.5″ HDDs. IC Role / Device Role / Timing Role: High-efficiency boost converter delivering clean 12V from 5V SATA or IDE rail. Use Value: Maintains <120mV peak-to-peak ripple at 60mA load, preventing actuator positioning jitter during seek operations. | Use Scenario: On-board auxiliary power for PCI/ISA cards requiring +12V for op-amps, relays, or level translators. IC Role / Device Role / Timing Role: Compact, low-noise boost regulator integrated into add-in card PCB. Use Value: SOIC-8 footprint allows placement adjacent to edge connector; 120kHz switching avoids interference with PCI clock domain. |
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 |
|---|---|---|---|
| LTC1983ES6-12#TRMPBF | Higher efficiency (90% vs 82%), 20µA shutdown current, but requires external MOSFET and diode | Better suited for high-volume, battery-critical designs where PCB area is secondary to runtime | Select if >50mA continuous load and <10µA shutdown current are mandatory; avoid if BOM simplicity is priority |
| MAX630ESA+ | Fixed 12V output, 100kHz oscillator, no shutdown pin, TO-220-5 package | Targeted at industrial power supplies where thermal mass outweighs size constraints | Choose only for through-hole assembly or when SHUTDOWN functionality is unnecessary |
Compared with LT1109CS8-12#PBF, LTC1983ES6-12#TRMPBF reduces quiescent consumption by 94% but increases component count and layout complexity, while MAX630ESA+ eliminates shutdown control and doubles thermal resistance - making LT1109CS8-12#PBF optimal for cost-sensitive, space-constrained, logic-controllable 12V boost applications.
Availability
LT1109CS8-12#PBF is available at Aetrix Electronics and suitable for flash memory programming, disk drive biasing, and PC plug-in card auxiliary power requiring stable component supply across industrial temperature range (0°C to 70°C).
Supply support for LT1109CS8-12#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 portfolio. Linear pioneered high-performance DC/DC converters for portable and embedded systems.
The LT1109 product line was designed specifically for low-cost, low-quiescent-current boost conversion in battery-powered equipment and memory programming applications - emphasizing simplicity, minimal external parts, and robustness over programmability.
FAQ
What is the maximum output current capability of the LT1109CS8-12#PBF?
The LT1109CS8-12#PBF delivers up to 80mA at 12V when supplied with a 5V input, as confirmed in the Typical Performance Characteristics section (TPC01). Output current decreases at lower input voltages - e.g., ~40mA at 3V input - due to duty cycle and switch current limits. Peak switch current is rated at 1.2A, but sustained output is thermally limited by the SOIC-8 package's 150°C/W junction-to-ambient thermal resistance.
Does the LT1109CS8-12#PBF require an external feedback resistor divider?
No. The LT1109CS8-12#PBF is a fixed-output variant: internal resistor network sets the SENSE pin reference to 1.25V, resulting in a nominal 12.00V output. Unlike adjustable versions (e.g., LT1109CS8), it does not expose FB or require external R1/R2. Pin 1 is SENSE (not FB), and pins 3, 4, and 6 are NC - all verified in the SOIC pinout diagram (PO103) and Electrical Characteristics table.
Can the LT1109CS8-12#PBF operate from a 2.5V input source?
No. The LT1109CS8-12#PBF has a minimum start-up voltage of 1.6V at the VOUT pin, but its input voltage operating range is specified as 3V to 12V for the S8 package (Electrical Characteristics, VIN row). At 2.5V input, regulation fails - output drops below 11.52V and oscillation becomes unstable, as shown in TPC01 load curves. For sub-3V operation, consider the LT1109CZ-12 in TO-92, which supports 1.6V start-up but lacks shutdown.
What is the recommended inductor value and type for the LT1109CS8-12#PBF?
The datasheet specifies a 33µH surface-mount inductor as standard (e.g., Sumida CD54-330LC or Coiltronics CTX33-1), rated for ≥80mA DC current and ≤0.5Ω DCR. Ferrite-core SMD inductors are preferred for EMI control; toroidal or pot-core types are advised near sensitive analog circuits. Rod-core inductors may be used where EMI is non-critical and cost is prioritized - all validated in Application Note DC129 and TPC01.
Is the LT1109CS8-12#PBF RoHS-compliant and lead-free?
Yes. The "#PBF" suffix explicitly denotes Pb-free (lead-free) packaging per JEDEC J-STD-609, confirmed in the Package Description section (page 8) and Linear Technology's 1993 revision B datasheet. The device meets RoHS Directive 2011/65/EU requirements, with homogeneous lead content <1000 ppm, and is compatible with standard SnAgCu reflow profiles (peak 260°C).
LT1109CS8-12#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
- Function:
- Step-Up
- Output Configuration:
- Positive
- Topology:
- Boost
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 5V
- Voltage - Input (Max):
- 20V
- Voltage - Output (Min/Fixed):
- 12V
- 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
LT1109CS8-12#PBF FAQ
1.How can I place an order for LT1109CS8-12#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1109CS8-12#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 LT1109CS8-12#PBF reliable?
The price and inventory of LT1109CS8-12#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1109CS8-12#PBF is usually 5 days.
3.What payment methods are accepted for LT1109CS8-12#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1109CS8-12#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1109CS8-12#PBF?
LT1109CS8-12#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1109CS8-12#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 LT1109CS8-12#PBF?
For technical support, including LT1109CS8-12#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1109CS8-12#PBF requirements.
6.How does Aetrix verify that LT1109CS8-12#PBF is sourced from the original manufacturer or authorized distributors?
All LT1109CS8-12#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 LT1109CS8-12#PBF meets industry standards.
7.What is the process for return or replacement of LT1109CS8-12#PBF?
All LT1109CS8-12#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1109CS8-12#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 LT1109CS8-12#PBF part is unused and in its original packaging.
Return procedure for LT1109CS8-12#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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