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Analog Devices Inc. LT1309CS8
- Part No.:
- LT1309CS8
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1309CS8.pdf
- Description:
- IC REG BOOST 12V 60MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,660
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Product details
Overview
LT1309CS8 from Analog Devices (formerly Linear Technology) is a micropower 500kHz step-up DC/DC converter optimized for 12V Flash memory VPP programming. It delivers 60mA output from 3.3V or 5V input, features a 300mV saturation switch at 0.5A, 85% peak efficiency, and integrated VPP VALID comparator with logic-level output. It is used in PCMCIA Type II/III cards and cellular phone memory subsystems.
For engineers reviewing the LT1309CS8 datasheet, LT1309CS8 pinout, LT1309CS8 application, or LT1309CS8 equivalent, key selection criteria include fixed 12V output accuracy (±4.2%), shutdown current (9µA), Burst Mode™ operation for light-load efficiency, soft-start control via external RC, and SO-8 package compatibility with space-constrained portable designs.
Technical Context
The LT1309CS8 implements a current-mode, Burst Mode™ switching architecture with gated oscillator control to maintain high efficiency across load range. Its internal 1.24V reference and error amplifier regulate output by sensing voltage at the SENSE pin through an external resistor divider.
It integrates a 0.5A NPN power switch with 300mV typical VCE(SAT), a dedicated VPP VALID comparator with 200mV hysteresis and internal 200kΩ pull-up, and ON/OFF shutdown logic with 1.5V threshold. Soft-start is externally programmable via Pin 1 using a 0.1µF capacitor and 1MΩ resistor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 12V ±4.2% (11.5V–12.6V) - ensures reliable Flash memory programming margin |
| Switching Frequency | 500kHz typical - enables use of compact 10µH surface-mount inductors |
| Peak Efficiency | 85% at 60mA - minimizes thermal stress and extends battery life in portable systems |
| Quiescent Current | 650µA operating / 9µA shutdown - supports ultra-low-power standby modes |
| Switch VCE(SAT) | 300mV at 0.5A - reduces conduction loss and improves light-load regulation |
| VPP VALID Threshold | VSENSE – 200mV rising edge - provides precise, hysteresis-stabilized ready signal for Flash control logic |
| Input Voltage Range | 2V to 6V - compatible with 3.3V and 5V system rails without level-shifting |
Pinout & Package
LT1309CS8 is housed in an 8-lead plastic SOIC (SO-8, narrow 0.150") package with standard JEDEC outline and 150°C/W junction-to-ambient thermal resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - SOFT START | Soft-start timing node | Accepts external RC (0.1µF + 1MΩ) to limit inrush current during turn-on |
| 2 - VCC | Main supply input | 3.3V/5V input rail; requires ≥1µF local bypass capacitance |
| 3 - PGND | Power ground return | Low-impedance path for switch current; must connect directly to ground plane |
| 4 - VSW | Switch collector node | High dV/dt node driving external inductor; layout critical for EMI control |
| 5 - GND | Signal ground reference | Reference for internal comparators and bias circuitry; separate from PGND in layout |
| 6 - VPP VALID | Logic-ready output | Active-low open-collector output with internal 200kΩ pull-up; asserts when VOUT ≥ 11.8V |
| 7 - SENSE | Output voltage feedback | Connects to resistive divider; senses regulated 12V output; <1µA leakage in shutdown |
| 8 - ON/OFF | Shutdown control input | Logic-compatible enable/disable; <1.5V = shutdown (9µA IQ); >1.5V = active |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode™ operation | Maintains >80% efficiency down to 1mA load, enabling micropower standby in Flash programming sequences |
| Integrated VPP VALID comparator | Eliminates need for external supervisor IC; provides deterministic, hysteresis-stabilized Flash-ready signal |
| Externally programmable soft start | Prevents input supply transients and inductor saturation during power-up, improving system reliability |
| Low VCE(SAT) switch | Reduces conduction loss and thermal rise in compact layouts where heatsinking is impractical |
| SO-8 footprint | Enables drop-in integration into PCMCIA card PCBs and handheld device modules with minimal board area impact |
Applications
| PCMCIA Type II/III Card Power Supply | Cellular Phone Flash Memory Programming |
|---|---|
Use Scenario: Generating 12V VPP for erasing/writing NAND/NOR Flash in hot-pluggable PCMCIA cards. IC Role / Device Role / Timing Role: Primary step-up regulator with integrated Flash-ready signaling and low-quiescent-current shutdown. Use Value: Enables compact, single-chip VPP generation meeting PCMCIA mechanical and thermal constraints while eliminating discrete supervisor components. | Use Scenario: Providing controlled 12V programming voltage to embedded Flash in GSM/CDMA handsets during firmware update. IC Role / Device Role / Timing Role: Micropower DC/DC converter with precise VPP VALID assertion timing synchronized to Flash command execution. Use Value: Reduces BOM count and PCB area vs. discrete boost + comparator solutions; supports battery-powered operation with 9µA shutdown current. |
| Portable Instrument Flash Configuration | Industrial Data Logger Memory Interface |
Use Scenario: Supplying 12V VPP for configuration Flash in handheld test equipment requiring field-upgradable firmware. IC Role / Device Role / Timing Role: Fixed-output boost converter with soft-start and logic-ready output for sequenced memory access. Use Value: Ensures robust startup under varying battery voltage (3.3V–5V) and prevents false Flash programming due to undershoot on VPP ramp. | Use Scenario: Driving 12V Flash in remote data loggers powered by Li-ion or coin cells with multi-year battery life targets. IC Role / Device Role / Timing Role: Low-IQ DC/DC converter enabling periodic Flash writes while maintaining µA-level system sleep current. Use Value: Achieves 85% efficiency at 60mA and 9µA shutdown, extending operational lifetime without compromising programming reliability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Flash memory VPP generator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1109-12CS8 | Adjustable output (via external resistors); same 12V nominal, but ±1.5% initial accuracy vs. LT1309CS8's ±4.2% | Supports non-12V Flash variants; requires two external resistors; lacks VPP VALID comparator | Select when output flexibility or tighter initial tolerance is required, and external logic can monitor output directly |
| LT1303CS8 | Fixed 5V output; includes low-battery detector; higher 200mA output capability; no VPP VALID or 12V option | Designed for general-purpose 5V supply, not Flash VPP; incompatible for 12V programming use cases | Not suitable as direct alternative for 12V Flash programming; consider only for auxiliary 5V rail generation in same system |
Compared with LT1109-12CS8, the LT1309CS8 offers integrated VPP VALID signaling and simpler 12V-only design, reducing component count; compared with LT1303CS8, it provides the exact 12V output and Flash-specific features required-neither alternative matches its combination of fixed 12V, low-IQ, and ready-signal integration.
Availability
LT1309CS8 is available at Aetrix Electronics and suitable for PCMCIA card power supplies, cellular phone Flash programming circuits, and portable instrument memory interfaces requiring stable component supply and long-term obsolescence management.
Supply support for LT1309CS8 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.
The LT1309CS8 belongs to Linear's micropower DC/DC converter family, designed specifically for Flash memory VPP generation in space- and power-constrained portable electronics.
FAQ
What is the primary function of the LT1309CS8?
The LT1309CS8 is a fixed 12V, 60mA step-up DC/DC converter optimized for Flash memory VPP programming. It integrates a 500kHz switching regulator, low-VCE(SAT) power switch, and a dedicated VPP VALID comparator that signals when output reaches programming threshold. The LT1309CS8 operates from 3.3V or 5V inputs and delivers up to 85% efficiency in a compact SO-8 package.
Does the LT1309CS8 require external components to operate?
Yes, the LT1309CS8 requires external components for full functionality: an inductor (typically 10µH), Schottky diode (e.g., MBR0520), input/output capacitors (≥1µF output), and optional RC network on SOFT START (Pin 1). The SENSE (Pin 7) connects to a resistor divider only if output adjustment is needed-but the LT1309CS8 is factory-trimmed for fixed 12V, so no divider is required for standard use.
What does the VPP VALID pin do on the LT1309CS8?
The VPP VALID pin (Pin 6) is an active-low, open-collector logic output that asserts low when the regulated output reaches ≥11.8V (VSENSE – 200mV), indicating readiness for Flash memory programming. It includes an internal 200kΩ pull-up resistor. This eliminates the need for external supervision circuitry and synchronizes host controller actions with valid VPP establishment in the LT1309CS8.
Can the LT1309CS8 be used with a 3V input supply?
No-the LT1309CS8 specifies a minimum input voltage of 2V but is characterized and recommended for operation from 3.3V or 5V supplies. At 3V input, output current capability drops significantly due to reduced duty cycle headroom and increased conduction losses; the datasheet confirms performance only down to 3.3V for 60mA 12V output. Using 3V risks failure to regulate under load and is outside validated operating conditions for the LT1309CS8.
Is the LT1309CS8 pin-compatible with other Linear DC/DC converters like the LT1109-12?
No-the LT1309CS8 is not pin-compatible with the LT1109-12CS8. Although both are 8-lead SO packages, their pin functions differ: LT1309CS8 uses Pin 1 for SOFT START and Pin 6 for VPP VALID, whereas LT1109-12 assigns Pin 1 to GND and Pin 6 to FB. Substituting either part without PCB redesign will result in functional failure. The LT1309CS8 pinout is unique to its feature set and must be laid out accordingly.
LT1309CS8 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- *
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- -
- Output Configuration:
- -
- Topology:
- -
- Output Type:
- -
- Number of Outputs:
- -
- Voltage - Input (Min):
- -
- Voltage - Input (Max):
- -
- Voltage - Output (Min/Fixed):
- -
- Voltage - Output (Max):
- -
- Current - Output:
- -
- Frequency - Switching:
- -
- Synchronous Rectifier:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1309CS8 FAQ
1.How can I place an order for LT1309CS8 through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1309CS8 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 LT1309CS8 reliable?
The price and inventory of LT1309CS8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1309CS8 is usually 5 days.
3.What payment methods are accepted for LT1309CS8?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1309CS8 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1309CS8?
LT1309CS8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1309CS8 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 LT1309CS8?
For technical support, including LT1309CS8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1309CS8 requirements.
6.How does Aetrix verify that LT1309CS8 is sourced from the original manufacturer or authorized distributors?
All LT1309CS8 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 LT1309CS8 meets industry standards.
7.What is the process for return or replacement of LT1309CS8?
All LT1309CS8 units undergo pre-shipment inspection (PSI). If there is an issue with LT1309CS8, 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 LT1309CS8 part is unused and in its original packaging.
Return procedure for LT1309CS8:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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