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Analog Devices Inc. LT1108CN8-12#PBF
- Part No.:
- LT1108CN8-12#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LT1108CN8-12#PBF.pdf
- Description:
- IC REG BUCK BOOST 12V 1.5A 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,732
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Product details
Overview
LT1108CN8-12#PBF from Analog Devices (formerly Linear Technology) is a micropower, fixed-output 12V DC/DC converter IC operating in step-up, step-down, or inverting topologies. It delivers up to 150mA at 12V from a 2V–12V input in boost mode and supports 30V max input in buck mode, with 110µA quiescent current and internal 1A power switch - ideal for battery-backed LCD bias and portable instrumentation.
For engineers reviewing the LT1108CN8-12#PBF datasheet, LT1108CN8-12#PBF pinout, LT1108CN8-12#PBF application, or LT1108CN8-12#PBF equivalent, key selection criteria include its 12V fixed output accuracy (±2.5%), programmable current limit via ILIM pin, on-chip low-battery comparator, and compatibility with 8-pin PDIP packaging for through-hole prototyping and industrial control power rails.
Technical Context
The LT1108CN8-12#PBF implements a gated-oscillator architecture with a 19kHz typical switching frequency, 70% duty cycle, and internal 1.245V reference. Its dual-mode operation relies on external topology configuration: SW1 and SW2 pins reconfigure as collector/emitter pair for boost (SW2 grounded) or emitter/collector pair for buck (SW1 tied to VIN).
It integrates an auxiliary gain block (A0/SET pins) usable as a low-battery detector or error amplifier, and features user-programmable current limiting via resistor between ILIM and VIN - enabling stable operation across wide input ranges without inductor saturation or switch overcurrent.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 12V ±2.5% (guaranteed over temperature and line/load) |
| Input Voltage Range | 2V–12V (step-up), up to 30V (step-down) - enables single-supply flexibility across AA, 9V, or industrial rails |
| Quiescent Current | 110µA (switch OFF) - extends battery life in always-on sensor nodes and backup systems |
| Switch Current Limit | Programmable up to 1.5A via ILIM resistor - prevents inductor saturation and thermal runaway during input transients |
| Oscillator Frequency | 14–25kHz (typ. 19kHz) - balances EMI, efficiency, and component size for compact designs |
| Operating Temperature | 0°C to 70°C - validated for commercial-grade embedded and portable equipment |
| Package | 8-lead plastic DIP (N8) - supports manual assembly, socketing, and legacy PCB layouts |
Pinout & Package
LT1108CN8-12#PBF uses an 8-lead plastic DIP (N8) package with 0.300" width, lead pitch of 0.100", and through-hole mounting. Pin 1 is ILIM; pin 5 is GND; pin 8 is SENSE (FB) - internally connected to fixed 12V divider network.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ILIM (Pin 1) | Current limit programming input | Resistor to VIN sets peak switch current; open or tied to VIN enables full 1.5A rating |
| VIN (Pin 2) | Main power input | Accepts 2V–30V; supplies internal circuitry and switch driver; must be bypassed with ≥10µF capacitor |
| SW1 (Pin 3) | Power switch collector | In boost: drives inductor/diode; in buck: connects to input rail - defines high-side switching node |
| SW2 (Pin 4) | Power switch emitter | In boost: grounded; in buck: drives inductor - defines low-side switching node; must not drop below –0.5V |
| GND (Pin 5) | Analog and power ground | Common return for feedback, gain block, and oscillator; requires low-impedance connection to input capacitor |
| A0 (Pin 6) | Auxiliary gain block output | Open-collector NPN; sinks 100µA; used for low-battery flag or linear post-regulator drive |
| SET (Pin 7) | Gain block non-inverting input | Connects to resistor divider for trip-point setting; bias current <50nA minimizes divider error |
| SENSE/FB (Pin 8) | Feedback input | Internally tied to 12V divider; no external resistors needed - simplifies layout and improves regulation stability |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 12V output with ±2.5% tolerance | Eliminates external feedback resistors, reducing BOM count and layout sensitivity in space-constrained designs |
| Programmable switch current limit | Enables robust operation across 2V–30V input range without redesigning magnetics or risking switch failure |
| On-chip low-battery comparator | Uses internal 1.245V reference and A0/SET pins to generate system reset or warning at precise voltage thresholds |
| Triple-mode topology support | Single IC replaces separate boost/buck/inverter solutions - reduces inventory and design validation effort |
| 110µA quiescent current | Supports >1-year runtime on two AA cells in standby mode for remote sensors and security peripherals |
Applications
| LCD Bias Generator | Portable Instrument Power |
|---|---|
Use Scenario: Generating stable +12V bias for STN or TFT LCD panels in handheld test meters and medical displays. IC Role / Device Role / Timing Role: Fixed-output DC/DC converter providing regulated 12V rail with minimal ripple and fast load transient response. Use Value: Enables direct use of low-cost 12V LCD modules without external LDO post-regulation or complex feedback networks. | Use Scenario: Powering analog front-ends and microcontrollers in battery-operated multimeters and data loggers. IC Role / Device Role / Timing Role: Micropower step-down converter delivering 12V from 9V alkaline or 12V Li-ion sources with high light-load efficiency. Use Value: Extends battery life by >30% vs. linear regulators while maintaining tight output regulation under varying load conditions. |
| Battery Backup Supply | Cellular Telephone Subsystem |
Use Scenario: Maintaining real-time clock and SRAM retention during main power loss in industrial controllers. IC Role / Device Role / Timing Role: Low-quiescent-current boost converter sourcing 12V from depleted 2xAA cells (down to 2V). Use Value: Guarantees >72-hour backup runtime with 100µF output capacitance and no external supervision circuitry. | Use Scenario: Providing isolated 12V bias for RF power amplifiers or camera flash drivers in early GSM handsets. IC Role / Device Role / Timing Role: Inverting DC/DC converter generating –12V from 3.3V or 5V logic rails for analog signal conditioning. Use Value: Replaces discrete charge-pump ICs with higher efficiency and lower EMI in tightly packed RF modules. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1108CN8-5#PBF | Same package and architecture, but fixed 5V output (±2.5%) and different internal feedback divider | Used where 5V logic rail generation is required instead of 12V; not interchangeable without board revision | Select only when target output voltage matches - pinout and thermal behavior are identical |
| MAX630CPA+ | 5V fixed output, 100µA IQ, 100kHz switching, SO8 package - lacks ILIM programming and inverting capability | Suitable for simpler 5V boost applications with tighter space constraints but no need for current limiting or multi-topology flexibility | Choose for higher-frequency, lower-noise 5V conversion where programmability and topology versatility are secondary |
Compared with LT1108CN8-12#PBF, the LT1108CN8-5#PBF offers identical form-factor and thermal performance but targets 5V systems, while MAX630CPA+ trades topology flexibility and current limit control for higher switching frequency and smaller footprint in dedicated 5V applications.
Availability
LT1108CN8-12#PBF is available at Aetrix Electronics and suitable for LCD bias generators, portable instrument power supplies, and battery backup systems requiring stable component supply, long-lifecycle support, and through-hole manufacturability.
Supply support for LT1108CN8-12#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 full technical and supply chain support for legacy Linear power products.
The LT1108 product line was designed for ultra-low-power, multi-topology DC/DC conversion in portable and battery-critical applications - emphasizing simplicity, reliability, and minimal external component count.
FAQ
What is the output voltage tolerance of the LT1108CN8-12#PBF?
The LT1108CN8-12#PBF provides a fixed 12V output with ±2.5% tolerance over temperature (0°C to 70°C), line (2V–12V input), and load (0–150mA). This specification is guaranteed per the Electrical Characteristics table and applies without external resistors - the internal feedback network ensures consistent regulation across operating conditions. The LT1108CN8-12#PBF achieves this using a precision 1.245V bandgap reference and trimmed on-die resistor divider.
Can the LT1108CN8-12#PBF operate in inverting (positive-to-negative) mode?
Yes, the LT1108CN8-12#PBF supports inverting configuration using standard external components: SW2 drives the inductor, SW1 connects to ground, and the output is referenced to ground with polarity inversion. The datasheet Figure 4 shows a verified +5V-to–5V design delivering 100mA. Output magnitude is limited to ≤6.2V for stability, but higher voltages are achievable with Schottky diode selection and inductor derating. The LT1108CN8-12#PBF's dual-switch architecture and internal 1.245V reference make this topology fully supported.
What is the maximum continuous output current for the LT1108CN8-12#PBF in step-down mode?
In step-down (buck) mode, the LT1108CN8-12#PBF delivers up to 300mA at 12V from a 9V input, as confirmed in the Applications section and Typical Performance Characteristics. This assumes proper thermal management (θJA = 150°C/W for N8 package), 100µH inductor, and 1N5817 Schottky diode. Peak switch current is limited to 1.5A, but continuous output is constrained by power dissipation - exceeding 300mA risks junction temperature rise beyond 90°C. The LT1108CN8-12#PBF's internal current limit and thermal shutdown protect against sustained overload.
How does the ILIM pin function on the LT1108CN8-12#PBF?
The ILIM pin on the LT1108CN8-12#PBF allows user-programmable peak switch current limiting by connecting a resistor between ILIM and VIN. A 220Ω resistor sets ~400mA limit; lower resistance increases current, higher resistance decreases it. This feature prevents inductor saturation and switch overstress when input voltage varies - critical in battery-powered systems where VIN drops from 3V to 2V. The LT1108CN8-12#PBF's current-limit circuitry has ~2µs propagation delay and operates independently of feedback loop dynamics.
Is the LT1108CN8-12#PBF RoHS compliant and lead-free?
Yes, the LT1108CN8-12#PBF carries the #PBF suffix, indicating lead-free (Pb-free) and RoHS-compliant construction per Analog Devices' specifications. The N8 package uses matte tin lead finish, and the device meets JEDEC J-STD-020 moisture sensitivity level (MSL) 1 requirements. No exemptions apply, and full compliance documentation is available in the Analog Devices product change notification (PCN) archive. The LT1108CN8-12#PBF is qualified for reflow soldering per IPC/JEDEC J-STD-020 standards.
LT1108CN8-12#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, Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Boost
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2V
- Voltage - Input (Max):
- 30V
- Voltage - Output (Min/Fixed):
- 12V
- Voltage - Output (Max):
- -
- Current - Output:
- 1.5A (Switch)
- Frequency - Switching:
- 19kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LT1108CN8-12#PBF FAQ
1.How can I place an order for LT1108CN8-12#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1108CN8-12#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 LT1108CN8-12#PBF reliable?
The price and inventory of LT1108CN8-12#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1108CN8-12#PBF is usually 5 days.
3.What payment methods are accepted for LT1108CN8-12#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1108CN8-12#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1108CN8-12#PBF?
LT1108CN8-12#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1108CN8-12#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 LT1108CN8-12#PBF?
For technical support, including LT1108CN8-12#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1108CN8-12#PBF requirements.
6.How does Aetrix verify that LT1108CN8-12#PBF is sourced from the original manufacturer or authorized distributors?
All LT1108CN8-12#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 LT1108CN8-12#PBF meets industry standards.
7.What is the process for return or replacement of LT1108CN8-12#PBF?
All LT1108CN8-12#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1108CN8-12#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 LT1108CN8-12#PBF part is unused and in its original packaging.
Return procedure for LT1108CN8-12#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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