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Analog Devices Inc. LT1308BCS8#TRPBF
- Part No.:
- LT1308BCS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1308BCS8#TRPBF.pdf
- Description:
- IC REG BOOST SEPIC ADJ 2A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,500
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Product details
Overview
LT1308BCS8#TRPBF 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 integrated low-battery detector with ±2% 200mV reference-designed for compact, high-efficiency portable power rails in digital cameras and GPS receivers.
For engineers reviewing the LT1308BCS8#TRPBF datasheet, LT1308BCS8#TRPBF pinout, LT1308BCS8#TRPBF application, or LT1308BCS8#TRPBF equivalent, key selection criteria include its 600kHz fixed-frequency operation, continuous-mode light-load behavior (vs. Burst Mode in LT1308A), 2.5mA IQ, 36V switch voltage rating, and SO-8 package compatibility with existing LT1308 layouts.
Technical Context
The LT1308BCS8#TRPBF implements a current-mode PWM architecture with a 600kHz oscillator and ramp compensation to suppress subharmonic oscillation above 50% duty cycle. Its error amplifier drives the VC pin for external RC compensation, enabling stable regulation across wide input/output ranges.
Unlike the LT1308A, the LT1308B omits hysteresis in the enable comparator, ensuring continuous switching down to ~100mA inductor current-eliminating low-frequency output ripple but increasing light-load quiescent current to 2.5mA. The low-battery detector uses a precision 200mV reference with ±2% accuracy over temperature and an open-collector LBO output sinking 50μA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 600kHz fixed-enables small external magnetics and filtering components; supports compact PCB layout. |
| Input Voltage Range | 1.1V to 10V-supports single Li-ion (2.7–4.2V), two/three NiCd (1.2V/cell), or four-cell alkaline stacks. |
| Output Voltage Capability | Up to 34V-achieved via 36V-rated internal NPN switch; enables high-ratio boost and SEPIC topologies. |
| Quiescent Current (IQ) | 2.5mA during switching-ensures predictable light-load efficiency without Burst Mode discontinuity. |
| Feedback Reference Voltage | 1.22V ±1.5% (typ)-sets output via resistor divider; enables precise 3.3V, 5V, or 12V regulation. |
| Switch Saturation Voltage | 290mV at 2A (25°C)-minimizes conduction loss; supports ≥1A output at high efficiency. |
| Shutdown Current | 1μA max-reduces system standby drain; compatible with host microcontroller GPIO control. |
Pinout & Package
LT1308BCS8#TRPBF is housed in an 8-lead plastic SOIC (SO-8) package with exposed pad thermal enhancement. Pin 4 is GND; pins 1–3 and 5–8 are functionally assigned as VC, FB, SHDN, SW, VIN, LBI, LBO respectively. All pins are surface-mount compatible with JEDEC MS-012AC standard footprint.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | VC (Compensation) | Error amplifier output; connect series RC (e.g., 47kΩ + 100pF) to GND for loop stability. |
| 2 | FB (Feedback) | Sense node for 1.22V reference; sets VOUT = 1.22V × (1 + R1/R2); minimize trace area to reduce noise coupling. |
| 3 | SHDN (Shutdown) | Active-high enable; ≥1V enables operation; floating or grounded disables IC and reduces IQ to ≤1μA. |
| 4 | GND | Power and signal ground; tie directly to local ground plane; serves as primary heat sink path. |
| 5 | SW (Switch) | Collector of internal NPN switch; connects to inductor/diode; minimize copper area to limit EMI. |
| 6 | VIN | Main supply input; requires local ceramic bypass capacitor (e.g., 47μF tantalum + 100nF ceramic) placed ≤5mm away. |
| 7 | LBI | Low-battery detector input; referenced to 200mV ±2%; voltage <196mV pulls LBO low. |
| 8 | LBO | Open-collector output; sinks 50μA when LBI <200mV; requires external pull-up (e.g., 220kΩ to VOUT). |
Key Features
| Feature | Design Value |
|---|---|
| Continuous light-load operation | Eliminates Burst Mode ripple-critical for noise-sensitive analog/RF circuits in GPS and camera modules. |
| 36V internal switch rating | Enables >30V outputs without external MOSFETs; supports 5V→12V boost and 3V→10V SEPIC designs. |
| ±2% low-battery reference | Reduces false low-battery triggers in handheld devices; improves battery gauge accuracy vs. older LT1308. |
| Pin-for-pin upgrade from LT1308 | Direct replacement in legacy designs-no PCB changes required; improved IQ, accuracy, and transient response. |
| Start-up into heavy loads | Charges output capacitor under full load (e.g., 20Ω) from 1.5V input-avoids bootstrapping failure in cold-start scenarios. |
Applications
| Digital Camera Power Supply | GPS Receiver Bias Rail |
|---|---|
Use Scenario: Powers CCD/CMOS sensor bias and flash LED drivers from single Li-ion cell. IC Role / Device Role / Timing Role: Primary boost regulator generating stable 5V/1A rail with minimal output ripple. Use Value: Continuous switching prevents low-frequency ripple that could interfere with image sensor sampling clocks. |
Use Scenario: Supplies clean 3.3V rail to GPS baseband processor and RF front-end from 2×NiMH cells. IC Role / Device Role / Timing Role: High-efficiency step-up converter with accurate low-battery detection for runtime estimation. Use Value: ±2% 200mV LBI threshold ensures precise battery depletion warning before GPS lock loss. |
| LCD Bias Generation | Handheld Computer Main Rail |
Use Scenario: Generates positive and negative bias voltages (e.g., +12V/–5V) for TFT LCD panels in portable medical displays. IC Role / Device Role / Timing Role: Core boost controller in charge-pump-assisted topology delivering regulated high-voltage outputs. Use Value: 36V switch rating enables direct +12V generation without cascaded stages-reducing component count and board space. |
Use Scenario: Provides main 5V system rail for ARM-based handheld computers powered by 3×alkaline cells. IC Role / Device Role / Timing Role: Primary DC/DC converter supporting dynamic load steps from 10mA (sleep) to 800mA (active). Use Value: 2.5mA quiescent current maintains battery life during idle; start-up into 5Ω load ensures reliable boot at end-of-life battery voltage. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1308ACS8#TRPBF | Burst Mode operation at light loads; 140μA no-load IQ vs. LT1308B's 2.5mA. | Lower noise-sensitive applications where light-load efficiency > ripple performance. | Select LT1308ACS8#TRPBF if minimizing standby current is critical and output ripple is tolerable. |
| MAX77801EWA+T | Integrated 2A synchronous boost; 2.2MHz switching; I²C programmable output; no LBO/LBI pins. | Requires firmware control; lacks dedicated low-battery monitoring; higher BOM cost. | Choose MAX77801EWA+T only when programmability, higher frequency, or synchronous rectification justify added complexity. |
Compared with LT1308ACS8#TRPBF, the LT1308BCS8#TRPBF trades 2.36mA higher light-load IQ for zero low-frequency ripple-making it preferable in imaging and RF systems. Against MAX77801EWA+T, it offers simpler analog control, integrated LBO/LBI, and lower system-level design overhead despite lower peak current capability.
Availability
LT1308BCS8#TRPBF is available at Aetrix Electronics and suitable for digital cameras, GPS receivers, LCD bias supplies, and handheld computers requiring stable component supply with guaranteed long-term availability and consistent parametric performance.
Supply support for LT1308BCS8#TRPBF 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 product support, datasheet documentation, and application engineering resources for legacy Linear parts including the LT1308 family.
The LT1308 series was designed specifically for high-efficiency, micropower DC/DC conversion in space-constrained portable electronics-emphasizing single-cell startup, low-noise regulation, and integrated battery monitoring.
FAQ
What is the maximum output current achievable with LT1308BCS8#TRPBF in a standard 5V boost configuration?
The LT1308BCS8#TRPBF supports up to 1A output current at 5V when supplied from a single Li-ion cell (3.6V nominal), as verified in Figure 1 of the datasheet using a 4.7μH inductor and 220μF output capacitor. This assumes ambient temperature ≤70°C, proper thermal layout, and continuous conduction mode operation-peak switch current remains within the 2A–4.5A specified limit.
Does LT1308BCS8#TRPBF require an external compensation network, and if so, what are typical values?
Yes, LT1308BCS8#TRPBF requires an external RC network from VC (Pin 1) to GND for loop stability. Typical values are 47kΩ in series with 100pF, as stated in the PIN FUNCTIONS section. These values optimize phase margin for standard boost configurations with 4.7μH inductors and 220μF output capacitors-deviations require re-evaluation using the error amplifier transconductance (60μmhos) and gain (100V/V) parameters.
How does the low-battery detector in LT1308BCS8#TRPBF differ from the original LT1308?
The LT1308BCS8#TRPBF features a significantly tighter low-battery detector with ±2% accuracy on its 200mV reference (vs. unspecified tolerance in LT1308), and an LBO output capable of sinking 50μA (vs. weaker drive in LT1308). The LBI input also operates independently of VIN-unlike LT1308, which required SHDN tied to VIN-allowing flexible logic-level enable schemes.
Can LT1308BCS8#TRPBF be used in SEPIC topology, and what are the key layout considerations?
Yes, LT1308BCS8#TRPBF supports SEPIC operation-as demonstrated in Figure 8-and is explicitly listed under APPLICATIONS for "5V at 800mA in SEPIC Mode from Four NiCd Cells." Critical layout requirements include separate, low-inductance paths for both inductor windings, minimized SW node copper area, and grounding the output capacitor's negative terminal directly to the IC's GND pin (Pin 4) to avoid ground bounce in the feedback loop.
What is the recommended minimum input voltage for reliable start-up of LT1308BCS8#TRPBF?
The LT1308BCS8#TRPBF guarantees start-up from 1.1V input, as specified in the ELECTRICAL CHARACTERISTICS table. Real-world validation shows successful start-up into a 20Ω load from 1.5V input (Figure 13), with inductor current peaking at 3.5A. Below 1.1V, regulation is not assured-designs targeting end-of-discharge alkaline or NiCd cells must verify minimum operating voltage against actual load conditions.
LT1308BCS8#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LT1308BCS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1308BCS8#TRPBF 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#TRPBF reliable?
The price and inventory of LT1308BCS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1308BCS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1308BCS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1308BCS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1308BCS8#TRPBF?
LT1308BCS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1308BCS8#TRPBF 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#TRPBF?
For technical support, including LT1308BCS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1308BCS8#TRPBF requirements.
6.How does Aetrix verify that LT1308BCS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1308BCS8#TRPBF 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#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1308BCS8#TRPBF?
All LT1308BCS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1308BCS8#TRPBF, 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#TRPBF part is unused and in its original packaging.
Return procedure for LT1308BCS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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