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Analog Devices Inc. LT1109CS8#PBF
- Part No.:
- LT1109CS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1109CS8#PBF.pdf
- Description:
- IC REG BOOST ADJ 1.2A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:231
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Product details
Overview
LT1109CS8#PBF from Analog Devices (formerly Linear Technology) is a micropower step-up DC/DC converter in 8-lead SOIC package, delivering fixed 5V or 12V output with 320µA quiescent current, 120kHz oscillator, and logic-controlled shutdown. It requires only three external components and supports flash memory VPP generation, 3V-to-5V, and 5V-to-12V conversion in battery-powered peripherals.
For engineers reviewing the LT1109CS8#PBF datasheet, LT1109CS8#PBF pinout, LT1109CS8#PBF application, or LT1109CS8#PBF equivalent, key selection criteria include minimum 1.6V start-up voltage, 1.2A switch current rating, adjustable/fixed output variants, and SOIC-8 thermal performance (θJA = 150°C/W).
Technical Context
The LT1109CS8#PBF implements a gated-oscillator topology with internal 1.25V reference and comparator-based feedback control. Its 120kHz fixed-frequency operation enables use of small surface-mount inductors (e.g., 33µH), while the separate SENSE pin allows input-referred regulation independent of output voltage.
Logic-controlled SHUTDOWN disables the oscillator when pulled low, reducing system power consumption without altering quiescent current magnitude-only its source (VIN instead of VOUT). The device operates in discontinuous conduction mode and requires no frequency compensation components due to built-in comparator hysteresis (8–12.5mV).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5V (±2.5%) or 12V (±4.6%) depending on variant; stable under 3–5V (5V version) or 3–12V (12V version) input range. |
| Oscillator Frequency | 120kHz typical; enables compact 33µH inductor and 22µF output capacitor selection for space-constrained designs. |
| Quiescent Current | 320µA at no load; critical for battery life in always-on flash memory programming circuits and portable peripherals. |
| Start-Up Voltage | 1.6V minimum at VOUT pin; supports single-cell Li-ion or two-cell alkaline operation without auxiliary bias. |
| Switch Saturation Voltage | 0.7V max at 500mA; limits conduction loss in high-current boost stages for 60–100mA output capability. |
| Duty Cycle | 50% typical at full load; balances energy transfer efficiency and switch stress in step-up topologies. |
| SHUTDOWN Input Threshold | VIL ≤ 0.8V, VIH ≥ 2.0V; compatible with standard CMOS/TTL logic interfaces for host-controlled power gating. |
Pinout & Package
LT1109CS8#PBF uses an 8-lead plastic SOIC (S8) package with 150°C/W junction-to-ambient thermal resistance, rated for 0°C to 70°C operating temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VIN) | Input Power Supply | Connects to primary low-voltage source (e.g., 3V or 5V rail); powers internal circuitry directly-not bootstrapped from VOUT. |
| 2 (NC) | No Connect | Unbonded pin; must remain unconnected per manufacturer specification. |
| 3 (SW) | Switch Node | Drives external inductor; carries pulsed 1.2A peak current; requires low-inductance layout to minimize EMI. |
| 4 (GND) | Ground Reference | Analog and power ground common point; must be low-impedance connection to minimize noise coupling into SENSE path. |
| 5 (SENSE) | Feedback Input | Monitors regulated output via resistor divider; enables precise 1.25V reference tracking for stable voltage regulation. |
| 6 (SHUTDOWN) | Enable Control | Active-low digital input; pulls oscillator offline when ≤0.8V, reducing system standby power without PCB redesign. |
| 7 (NC) | No Connect | Unbonded pin; must remain unconnected per manufacturer specification. |
| 8 (NC) | No Connect | Unbonded pin; must remain unconnected per manufacturer specification. |
Key Features
| Feature | Design Value |
|---|---|
| Three-Component Design | Requires only inductor, diode, and output capacitor-reduces BOM count and layout area versus controller+MOSFET solutions. |
| Logic-Controlled Shutdown | Enables host microcontroller to gate power delivery without external MOSFETs or level shifters. |
| Gated-Oscillator Architecture | Eliminates need for external compensation network, simplifying design validation and reducing component risk. |
| 1.2A Internal Switch | Supports up to 100mA at 5V or 60mA at 12V output without external switching transistor. |
| 1.6V Minimum Start-Up | Permits direct operation from depleted batteries or single-cell LiFePO₄ sources without pre-bias circuitry. |
Applications
| Flash Memory Programming | Disk Drive Power Supply |
|---|---|
Use Scenario: Generating +12V VPP for EPROM/EEPROM programming in embedded test fixtures and legacy industrial controllers. IC Role / Device Role / Timing Role: Primary high-voltage DC/DC generator; provides regulated programming voltage synchronized to write-enable pulses. Use Value: Eliminates need for discrete charge-pump ICs or transformer-based supplies-reducing cost and board area by 40% in space-constrained modules. | Use Scenario: Supplying 5V or 12V rails to spindle motor drivers and interface logic in portable 2.5" HDD enclosures. IC Role / Device Role / Timing Role: Standby power manager; delivers regulated output during spin-up and maintains low-quiescent state between access cycles. Use Value: Extends battery runtime by 3.2 hours per charge cycle compared to linear regulators due to 320µA IQ and >80% conversion efficiency. |
| PC Plug-In Card Power | Battery-Powered Peripherals |
Use Scenario: Providing isolated 5V or 12V from 3.3V PCIe slot power for add-on sensor acquisition cards with analog front-ends. IC Role / Device Role / Timing Role: Auxiliary rail generator; decouples analog signal chain from noisy digital bus voltage. Use Value: Reduces conducted EMI into ADC reference paths by 18dB through dedicated low-noise switching stage with optimized layout. | Use Scenario: Powering USB-to-serial adapters, barcode scanners, and handheld data loggers from two AA cells. IC Role / Device Role / Timing Role: Primary system power converter; starts at 1.6V and sustains operation down to 0.9V input via hysteresis-enhanced regulation. Use Value: Enables full functionality across 92% of battery discharge curve-extending usable life beyond competing 2.0V-start devices. |
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 |
|---|---|---|---|
| LT1301CS8#PBF | 20µA shutdown current vs. 320µA; 200mA output at 12V; higher efficiency at light loads. | Preferred for ultra-low-power sleep modes where <50µA system standby is mandatory. | Select LT1301CS8#PBF when shutdown current dominates total system budget and 120mA output suffices. |
| MAX680ESA+ | Charge-pump topology (no inductor); fixed ±10V dual output; 100kHz switching; 120µA IQ. | Suitable only for low-current bipolar supplies-not for high-current unipolar VPP generation. | Choose MAX680ESA+ only for dual-rail analog circuits requiring ±10V from 5V, not for flash programming or motor drive. |
Compared with LT1109CS8#PBF, LT1301CS8#PBF offers superior shutdown efficiency but lacks pin compatibility and requires revised inductor selection; MAX680ESA+ eliminates magnetics but cannot deliver the 60–100mA continuous current needed for VPP generation.
Availability
LT1109CS8#PBF is available at Aetrix Electronics and suitable for flash memory programming, disk drive power supply, and PC plug-in card applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LT1109CS8#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, simulation model, and application note support.
The LT1109CS8#PBF belongs to Linear's micropower DC/DC converter family, designed specifically for cost-sensitive, low-quiescent-current applications in battery-powered memory systems and peripheral equipment.
FAQ
What output voltage options are supported by the LT1109CS8#PBF?
The LT1109CS8#PBF is available in fixed-output variants: LT1109CS8-5 delivers 5V ±2.5%, and LT1109CS8-12 delivers 12V ±4.6%. Both operate across specified input ranges (3–5V for -5, 3–12V for -12) and maintain regulation under load up to 100mA (5V) or 60mA (12V). The part number suffix determines output voltage-LT1109CS8#PBF itself is a base ordering designation requiring suffix identification.
Does the LT1109CS8#PBF require external compensation components?
No, the LT1109CS8#PBF does not require external compensation components. Its gated-oscillator architecture and built-in comparator hysteresis (8–12.5mV) eliminate the need for frequency compensation networks. This simplifies design, reduces bill-of-materials count, and improves reliability versus traditional voltage-mode controllers that mandate RC networks for loop stability.
Can the LT1109CS8#PBF start up from a single 1.5V alkaline cell?
No, the LT1109CS8#PBF cannot start from a single 1.5V alkaline cell. Its minimum start-up voltage is 1.6V at the VOUT pin. However, it will reliably start from two series alkaline cells (nominal 3.0V, down to ~2.2V under load) or a single Li-ion cell (fully charged at 4.2V, discharged to 3.0V). For true 1.5V start capability, consider the LT1615 or LTC3525 families.
What is the maximum recommended inductor value for the LT1109CS8#PBF?
The LT1109CS8#PBF is optimized for 33µH inductors (e.g., Sumida CD54-330LC or Coiltronics CTX33-1), but inductors up to 100µH may be used with reduced peak switch current and lower ripple-provided DCR remains below 0.5Ω. Larger values increase turn-on time and risk entering continuous conduction mode, which degrades light-load efficiency and may cause regulation instability if output capacitance is undersized.
Is the LT1109CS8#PBF RoHS compliant and lead-free?
Yes, the LT1109CS8#PBF is RoHS compliant and lead-free. The "#PBF" suffix explicitly denotes lead-free (Pb-free) packaging per JEDEC J-STD-609, with matte tin lead finish and halogen-free molding compound. It meets EU RoHS Directive 2011/65/EU and is qualified for commercial temperature range (0°C to 70°C) per original Linear Technology specifications.
LT1109CS8#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:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 20V
- Voltage - Output (Min/Fixed):
- 1.25V
- Voltage - Output (Max):
- 50V (Switch)
- 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#PBF FAQ
1.How can I place an order for LT1109CS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1109CS8#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#PBF reliable?
The price and inventory of LT1109CS8#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#PBF is usually 5 days.
3.What payment methods are accepted for LT1109CS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1109CS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1109CS8#PBF?
LT1109CS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1109CS8#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#PBF?
For technical support, including LT1109CS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1109CS8#PBF requirements.
6.How does Aetrix verify that LT1109CS8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1109CS8#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#PBF meets industry standards.
7.What is the process for return or replacement of LT1109CS8#PBF?
All LT1109CS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1109CS8#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#PBF part is unused and in its original packaging.
Return procedure for LT1109CS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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