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Analog Devices Inc. LT1111CS8-5#PBF
- Part No.:
- LT1111CS8-5#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1111CS8-5#PBF.pdf
- Description:
- IC REG BUCK BOOST 5V 1.5A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:4,428
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Product details
Overview
LT1111CS8-5#PBF from Analog Devices (formerly Linear Technology) is a micropower, fixed-output 5V step-up/step-down DC/DC converter IC with integrated 1A NPN power switch, 72kHz gated oscillator, and on-chip low-battery detector comparator. It operates from 2V to 30V input, delivers up to 100mA at 5V from 3V input (step-up), or 200mA at 5V from 12V input (step-down), and targets battery-powered portable instrumentation and flash memory VPP generation.
For engineers reviewing the LT1111CS8-5#PBF datasheet, LT1111CS8-5#PBF pinout, LT1111CS8-5#PBF application, or LT1111CS8-5#PBF equivalent, key selection criteria include its fixed 5V output tolerance (±5%), programmable current limit via ILIM pin, 300µA quiescent current in shutdown, and compatibility with surface-mount inductors in SO-8 package for space-constrained designs.
Technical Context
The LT1111CS8-5#PBF implements a gated-oscillator architecture where the 72kHz oscillator activates only when feedback voltage falls below the 1.25V internal reference, enabling ultra-low quiescent current. Its dual-mode operation-step-up (boost) or step-down (buck)-is determined by external component topology, not internal configuration.
Pin 8 (FB/SENSE) connects directly to output in fixed-5V versions, eliminating external resistive dividers; the on-chip voltage-setting resistor network ensures 4.75V–5.25V output regulation over temperature and line. The auxiliary gain block (A0/SET pins) supports configurable functions including low-battery detection with 1.20V–1.30V trip point and hysteresis of 8–12.5mV.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5V ±5% (4.75V–5.25V); eliminates need for external feedback resistors in standard boost/buck designs. |
| Oscillator Frequency | 72kHz typical; optimized for use with off-the-shelf surface-mount inductors and minimizes EMI vs higher-frequency alternatives. |
| Quiescent Current | 300µA max (switch OFF); enables multi-year battery life in always-on low-power sensor nodes and remote controls. |
| Switch Current Limit | Programmable up to 1.5A via ILIM-to-VIN resistor; prevents inductor saturation and switch overstress across wide input voltage ranges. |
| Operating Input Range | 2V–12V (step-up), 2V–30V (step-down); supports single-cell Li-ion (2.7–4.2V), 9V alkaline, and 12V industrial rails without redesign. |
| Package | SO-8 (S8); 8-pin plastic small-outline package with 1.27mm pitch, compatible with automated SMT assembly and IPC-7351B land patterns. |
| Temperature Range | 0°C to 70°C (Commercial grade C-temp); validated for consumer electronics, peripherals, and non-automotive embedded systems. |
Pinout & Package
LT1111CS8-5#PBF uses an 8-lead plastic SO (S8) package with standard SOIC footprint and gull-wing leads. Thermal resistance θJA = 150°C/W enables operation at full load without forced air in ambient temperatures ≤50°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ILIM (Pin 1) | Current limit programming input | Resistor from ILIM to VIN sets peak switch current; 220Ω yields ~400mA limit; open or tied to VIN disables limit. |
| VIN (Pin 2) | Main power supply input | Accepts 2V–30V; powers internal circuitry and switch driver; must be bypassed with ≥10µF ceramic capacitor near pin. |
| SW1 (Pin 3) | Power switch collector | In step-up: connects to inductor/diode node; in step-down: connects to VIN rail; rated to 50V max. |
| SW2 (Pin 4) | Power switch emitter | In step-up: connects to GND; in step-down: connects to inductor/diode node; must not fall below –0.5V. |
| GND (Pin 5) | Analog and power ground reference | Common return for feedback, gain block, and switch; requires low-impedance connection to PCB ground plane. |
| A0 (Pin 6) | Auxiliary gain block output | Open-collector output sinking up to 300µA; used for low-battery detect, post-regulation, or error amplification. |
| SET (Pin 7) | Auxiliary gain block inverting input | Connects to resistor divider from VIN for programmable comparator trip point; bias current 70–300nA. |
| FB/SENSE (Pin 8) | Feedback input / fixed-output sense | Internally connected to 5V divider in LT1111CS8-5#PBF; must connect directly to regulated 5V output for closed-loop control. |
Key Features
| Feature | Design Value |
|---|---|
| Micropower operation | 300µA quiescent current extends battery life in intermittent-use devices like remote controls and handheld test tools. |
| Dual-mode topology support | Single IC replaces separate boost and buck converters in designs requiring both 3V→5V and 12V→5V conversion paths. |
| On-chip low-battery detector | Comparator with 1.25V reference and 12.5mV hysteresis enables reliable brown-out warning without external comparators. |
| Programmable current limiting | External resistor on ILIM pin provides precise, temperature-stable switch current control to prevent inductor saturation. |
| Fixed-output simplicity | LT1111CS8-5#PBF integrates internal feedback resistors-no external components needed for stable 5V output. |
Applications
| Remote Controls | Flash Memory VPP Generators |
|---|---|
Use Scenario: IR remote with alkaline batteries powering microcontroller and IR LED driver. IC Role / Device Role / Timing Role: Step-up converter generating stable 5V from decaying 1.2–3.0V battery input. Use Value: Maintains logic-level compliance and LED drive strength down to 1.8V battery voltage, extending usable battery life by >30%. | Use Scenario: Embedded system programming NAND/NOR flash requiring +12V VPP during write/erase cycles. IC Role / Device Role / Timing Role: Step-up converter delivering 12V at 10mA from 3.3V system rail, activated only during programming windows. Use Value: Eliminates need for dedicated high-voltage charge pump IC; reduces BOM count and PCB area by 40% vs discrete solutions. |
| Laptop/Palmtop Peripherals | Battery Backup Supplies |
Use Scenario: USB-powered add-on card (e.g., CAN interface) requiring isolated 5V rail from 5V USB bus. IC Role / Device Role / Timing Role: Step-down regulator converting 5V USB input to clean 5V output with <50mV ripple under dynamic load. Use Value: Achieves >85% efficiency at 100mA load while meeting USB power budget constraints and EMI limits. | Use Scenario: Real-time clock (RTC) backup circuit maintaining SRAM state during main power failure. IC Role / Device Role / Timing Role: Low-quiescent-current step-up converter charging supercapacitor from 3V coin cell to 5V storage rail. Use Value: 300µA IQ enables >10-year backup runtime on BR2032; programmable current limit prevents capacitor overcharge. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX630CPA+ | Fixed 5V output, 100kHz oscillator, 200µA IQ, but no ILIM pin or auxiliary gain block; DIP-8 only. | Lacks programmable current limit and low-battery detection; limited to simple boost-only topologies. | Choose for cost-sensitive, low-complexity boost-only designs where ILIM and A0 functionality are unnecessary. |
| TPS61040DRVR | 500kHz switching, 0.4A switch, 20µA IQ, but requires external feedback resistors even for fixed 5V; WSON-6 package. | Higher frequency enables smaller magnetics but increases EMI sensitivity; no integrated comparator or gain block. | Prefer for ultra-low-power applications needing <50µA IQ and minimal solution size, accepting added design complexity. |
Compared with MAX630CPA+ and TPS61040DRVR, the LT1111CS8-5#PBF uniquely combines fixed 5V output, programmable current limiting, and an auxiliary gain block in SO-8 - enabling robust, feature-rich DC/DC conversion without external compensation or additional ICs.
Availability
LT1111CS8-5#PBF is available at Aetrix Electronics and suitable for remote controls, flash memory VPP generation, and battery backup supplies requiring stable component supply, long-term lifecycle support, and commercial-grade temperature performance.
Supply support for LT1111CS8-5#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 full support for legacy Linear products including the LT1111 family. ADI specializes in high-performance analog, mixed-signal, and power management ICs.
The LT1111 product line was designed for micropower, multi-topology DC/DC conversion in portable and battery-operated systems - emphasizing simplicity (3 external components), wide input range, and integrated protection features.
FAQ
What is the output voltage tolerance of the LT1111CS8-5#PBF?
The LT1111CS8-5#PBF provides a fixed 5V output with guaranteed regulation of 4.75V to 5.25V (±5%) over the full 0°C to 70°C operating temperature range and input voltages from 2V to 12V in step-up mode. This tolerance is achieved using factory-trimmed internal resistive dividers, eliminating external component variation.
Can the LT1111CS8-5#PBF operate in step-down (buck) mode?
Yes, the LT1111CS8-5#PBF supports step-down operation with input voltages up to 30V and delivers up to 200mA at 5V from a 12V input. In buck mode, SW1 connects to VIN and SW2 drives the inductor; the device maintains regulation via the same internal 1.25V reference and FB/SENSE pin monitoring.
How do I configure the low-battery detector using the LT1111CS8-5#PBF?
Connect a resistor divider from VIN to GND with the midpoint to the SET pin, and pull A0 to VOUT via a 22kΩ resistor. The comparator trips when VIN × (R2/(R1+R2)) falls below 1.25V; hysteresis of 8–12.5mV prevents chatter. For example, R1=1MΩ, R2=100kΩ sets trip at ~1.14V.
What is the purpose of the ILIM pin on the LT1111CS8-5#PBF?
The ILIM pin allows programming of the peak switch current limit by connecting a resistor between ILIM and VIN. A 220Ω resistor limits current to ~400mA; higher resistance lowers the limit. This prevents inductor saturation and switch overstress when input voltage varies widely - critical in battery-powered applications.
Is the LT1111CS8-5#PBF pin-compatible with other LT1111 variants?
Yes, all LT1111 variants (including LT1111CS8, LT1111CS8-12, LT1111IS8) share identical SO-8 pinouts and electrical characteristics except for output voltage setting. The LT1111CS8-5#PBF's FB/SENSE pin is internally connected to the 5V divider, so it must connect directly to the 5V output - unlike adjustable versions requiring external resistors.
LT1111CS8-5#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, 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):
- 5V
- Voltage - Output (Max):
- -
- Current - Output:
- 1.5A (Switch)
- Frequency - Switching:
- 72kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1111CS8-5#PBF FAQ
1.How can I place an order for LT1111CS8-5#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1111CS8-5#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 LT1111CS8-5#PBF reliable?
The price and inventory of LT1111CS8-5#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1111CS8-5#PBF is usually 5 days.
3.What payment methods are accepted for LT1111CS8-5#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1111CS8-5#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1111CS8-5#PBF?
LT1111CS8-5#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1111CS8-5#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 LT1111CS8-5#PBF?
For technical support, including LT1111CS8-5#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1111CS8-5#PBF requirements.
6.How does Aetrix verify that LT1111CS8-5#PBF is sourced from the original manufacturer or authorized distributors?
All LT1111CS8-5#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 LT1111CS8-5#PBF meets industry standards.
7.What is the process for return or replacement of LT1111CS8-5#PBF?
All LT1111CS8-5#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1111CS8-5#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 LT1111CS8-5#PBF part is unused and in its original packaging.
Return procedure for LT1111CS8-5#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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