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Analog Devices Inc. LT1308BCS8#PBF
- Part No.:
- LT1308BCS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1308BCS8#PBF.pdf
- Description:
- IC REG BOOST SEPIC ADJ 2A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,079
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Product details
Overview
LT1308BCS8#PBF from Analog Devices (formerly Linear Technology) is a micropower, fixed-frequency 600kHz boost DC/DC converter optimized for single-cell Li-ion and multi-cell NiCd/NiMH battery inputs. It delivers up to 1A at 5V from 1.1V–10V input, features continuous switching at light loads (2.5mA quiescent current), 36V switch rating, and ±2% 200mV low-battery reference - enabling reliable power conversion in portable digital cameras and GPS receivers.
For engineers reviewing the LT1308BCS8#PBF datasheet, LT1308BCS8#PBF pinout, LT1308BCS8#PBF application, or LT1308BCS8#PBF equivalent, key selection criteria include its 600kHz switching frequency, 2.5mA light-load IQ, 36V switch voltage rating, continuous-mode operation (vs. Burst Mode in LT1308A), and SO-8 package compatibility with standard PCB layouts for space-constrained handheld devices.
Technical Context
The LT1308BCS8#PBF implements a current-mode PWM architecture with a 600kHz oscillator and ramp compensation to prevent subharmonic oscillation above 50% duty cycle. Its error amplifier uses external VC-pin compensation (47kΩ + 100pF typical) for loop stability across wide load and input ranges.
Unlike the LT1308A, the LT1308B omits hysteresis in its control comparator, eliminating Burst Mode operation and ensuring constant-frequency switching down to ~100mA inductor current - reducing output ripple but increasing light-load power consumption versus the A variant.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 600kHz (±100kHz over temp); enables compact magnetics and EMI filtering with minimal board area. |
| Input Voltage Range | 1.1V to 10V; supports direct operation from single Li-ion (2.7–4.2V), 1–4 NiCd/NiMH cells, or backup batteries. |
| Output Voltage Range | Up to 34V; achieved via external resistor divider on FB pin (1.22V reference), supporting LCD bias and LED drivers. |
| Quiescent Current | 2.5mA during switching (light load); ensures predictable efficiency curve without low-frequency ripple artifacts. |
| Switch VCE(SAT) | 330mV at 2A (25°C); minimizes conduction loss in high-current boost stages, critical for >800mA output capability. |
| Low-Battery Reference | 200mV ±2% (room temp); provides accurate battery monitoring with <10mV trip uncertainty for system-level shutdown decisions. |
| Shutdown Current | 1μA max; enables true zero-power standby when SHDN is grounded, preserving battery life in sleep modes. |
Pinout & Package
LT1308BCS8#PBF is housed in an 8-lead plastic SOIC (SO-8) package with exposed pad thermal performance (θJA = 190°C/W). Pin 4 serves as the primary ground connection, and layout requires direct low-inductance routing to local ground plane.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VC) | Compensation node | Output of internal error amplifier; connects to RC network (e.g., 47kΩ + 100pF) for loop stability and transient response tuning. |
| 2 (FB) | Feedback input | Senses output voltage via resistive divider; 1.22V reference sets regulation point (VOUT = 1.22V × (1 + R1/R2)). |
| 3 (SHDN) | Enable control | Active-high logic input; ≥1V enables operation (no VIN tie required); floating or grounded disables IC with 1μA shutdown current. |
| 4 (GND) | Power ground | Main return path for switch, error amp, and bias currents; must connect directly to low-impedance ground plane. |
| 5 (SW) | Power switch node | Drives external inductor/diode; handles peak currents up to 4.5A; requires minimized trace area to reduce EMI. |
| 6 (VIN) | Input supply | Accepts 1.1V–10V input; requires local 47μF bypass capacitor placed ≤5mm from pin to suppress input ripple. |
| 7 (LBI) | Low-battery detector input | High-impedance analog input referenced to 200mV; monitors battery voltage via external resistor divider. |
| 8 (LBO) | Low-battery output | Open-collector NPN output sinking up to 50μA; pulls low when LBI < 200mV ±2%, compatible with microcontroller interrupt lines. |
Key Features
| Feature | Design Value |
|---|---|
| Continuous switching at light loads | Eliminates Burst Mode ripple (unlike LT1308A), delivering clean 600kHz output even at 50mA load - critical for noise-sensitive RF sections. |
| 36V integrated switch rating | Supports >30V output applications (e.g., 12V LCD bias, white LED strings) without external MOSFET, reducing BOM count and layout complexity. |
| ±2% low-battery reference accuracy | Enables precise battery state-of-charge detection with <10mV margin, improving runtime estimation and preventing premature system shutdown. |
| Start-up into heavy loads | Delivers full 3.5A peak inductor current at startup (e.g., charging 220μF output cap), avoiding brown-out during cold boot from weak alkaline or depleted NiCd cells. |
| External VC compensation | Allows optimization of phase margin and transient response for diverse output capacitors (tantalum, ceramic, or hybrid), unlike fixed-compensation converters. |
Applications
| Digital Cameras | GPS Receivers |
|---|---|
|
Use Scenario: Powering CCD/CMOS image sensors and flash LEDs from single Li-ion cell (3.0–4.2V). IC Role / Device Role / Timing Role: Boost converter generating stable 5V rail for sensor interface and 12V for flash driver circuitry. Use Value: 600kHz switching allows small 4.7μH inductor and 220μF tantalum output cap; 2.5mA light-load IQ extends capture time between charges. |
Use Scenario: Providing regulated 3.3V and 5V supplies for GPS baseband ICs and RF front-end from dual NiMH cells (2.4V). IC Role / Device Role / Timing Role: Primary DC/DC converter delivering 5V@800mA with tight line/load regulation for sensitive GNSS timing circuits. Use Value: ±2% low-battery detection prevents navigation failure by triggering graceful shutdown before battery sag disrupts 1PPS timing accuracy. |
| LCD Bias Supplies | Battery Backup Supplies |
|
Use Scenario: Generating +12V and –10V rails for TFT-LCD panel gate drivers in handheld medical displays. IC Role / Device Role / Timing Role: High-voltage boost stage (up to 34V) paired with inverting charge pump to create dual-polarity bias voltages. Use Value: 36V switch rating enables single-stage 12V generation without cascaded converters; SO-8 footprint simplifies integration into compact display modules. |
Use Scenario: Maintaining real-time clock (RTC) and SRAM backup during main power loss in industrial data loggers using coin-cell batteries. IC Role / Device Role / Timing Role: Ultra-low-quiescent boost converter sustaining 3.3V from 1.2V lithium-thionyl chloride cell during extended storage. Use Value: 1μA shutdown current preserves 10-year coin-cell lifetime; 1.1V minimum start-up ensures operation even after long-term self-discharge. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1308ACS8#PBF | Features Burst Mode™ operation (140μA no-load IQ) vs. LT1308BCS8#PBF's continuous 2.5mA IQ; identical pinout and package. | Preferred where ultra-low standby power is critical (e.g., pager memory retention), accepting low-frequency output ripple at light loads. | Select LT1308ACS8#PBF only if system can tolerate 100–500Hz ripple; otherwise LT1308BCS8#PBF ensures clean spectral profile for analog/RF sections. |
| TPS61040DRVR | 500kHz fixed frequency, 28V switch rating, 0.55mA typical IQ; uses different compensation scheme (no VC pin) and lacks low-battery detector. | Suitable for cost-sensitive consumer electronics without battery monitoring, but cannot replace LT1308BCS8#PBF in systems requiring 200mV ±2% LBI/LBO functionality. | Choose TPS61040DRVR only when low-battery detection is handled externally; LT1308BCS8#PBF remains optimal for integrated power + monitoring in portable instrumentation. |
Compared with LT1308ACS8#PBF, the LT1308BCS8#PBF trades 2.4mA higher light-load current for ripple-free 600kHz operation and identical protection features; versus TPS61040DRVR, it adds precision low-battery monitoring and higher 36V switch rating at the cost of slightly larger solution size.
Availability
LT1308BCS8#PBF is available at Aetrix Electronics and suitable for digital cameras, GPS receivers, LCD bias supplies, and battery backup supplies requiring stable component supply with guaranteed long-term availability and full traceability.
Supply support for LT1308BCS8#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 legacy of high-performance analog and power management ICs with rigorous testing and automotive-grade reliability standards.
The LT1308B belongs to Linear's micropower DC/DC converter family, designed specifically for battery-powered portable equipment demanding high efficiency across wide input ranges and integrated system monitoring functions.
FAQ
What is the minimum input voltage required for LT1308BCS8#PBF to start switching?
The LT1308BCS8#PBF has a specified minimum input voltage of 1.1V and can start up into heavy loads (e.g., 20Ω) from 1.5V input, delivering full 5V output in under 1ms. This enables reliable operation from partially discharged alkaline or NiCd cells where other boost converters fail to bootstrap.
Does LT1308BCS8#PBF support SEPIC topology, and what design changes are needed?
Yes, the LT1308BCS8#PBF supports SEPIC configuration, as confirmed in Figure 8 of its datasheet. To implement SEPIC, replace the standard boost diode with a second inductor (L1A/L1B), retain the same 4.7μH value, and adjust feedback resistors for desired output. Layout must isolate coupled inductors to avoid magnetic interference.
How does the low-battery detector in LT1308BCS8#PBF differ from the original LT1308?
The LT1308BCS8#PBF improves low-battery detection with ±2% accuracy at room temperature (vs. unspecified tolerance in LT1308) and a dedicated open-collector LBO output capable of sinking 50μA. Its 200mV reference is internally trimmed and stable over temperature, enabling precise battery state-of-charge thresholds without external calibration.
Can LT1308BCS8#PBF be used with ceramic output capacitors, and what compensation adjustments are required?
Yes, LT1308BCS8#PBF supports ceramic output capacitors via its external VC pin. Because ceramics lack ESR (removing a natural loop zero), increase the VC capacitor value (e.g., from 100pF to 470pF) or add a series RC lead network to restore phase margin and prevent instability - verified in Figure 16's soft-start application circuit.
What is the maximum output current achievable with LT1308BCS8#PBF in a standard SO-8 layout?
In a properly laid out SO-8 PCB with 2oz copper, thermal vias under Pin 4 (GND), and 4.7μH inductor, the LT1308BCS8#PBF delivers 1A at 5V from 3.6V input (≥85% efficiency). Peak switch current is limited to 4.5A, but sustained >800mA requires careful thermal management due to θJA = 190°C/W.
LT1308BCS8#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-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Boost, SEPIC
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1V
- Voltage - Input (Max):
- 10V
- Voltage - Output (Min/Fixed):
- 1.22V
- Voltage - Output (Max):
- 34V
- Current - Output:
- 2A (Switch)
- Frequency - Switching:
- 600kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1308BCS8#PBF FAQ
1.How can I place an order for LT1308BCS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1308BCS8#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 LT1308BCS8#PBF reliable?
The price and inventory of LT1308BCS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1308BCS8#PBF is usually 5 days.
3.What payment methods are accepted for LT1308BCS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1308BCS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1308BCS8#PBF?
LT1308BCS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1308BCS8#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 LT1308BCS8#PBF?
For technical support, including LT1308BCS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1308BCS8#PBF requirements.
6.How does Aetrix verify that LT1308BCS8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1308BCS8#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 LT1308BCS8#PBF meets industry standards.
7.What is the process for return or replacement of LT1308BCS8#PBF?
All LT1308BCS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1308BCS8#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 LT1308BCS8#PBF part is unused and in its original packaging.
Return procedure for LT1308BCS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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