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Analog Devices Inc. LT1308BCF#TRPBF
- Part No.:
- LT1308BCF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 14-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LT1308BCF#TRPBF.pdf
- Description:
- IC REG BST SEPIC ADJ 2A 14TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,289
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Product details
Overview
LT1308BCF#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 systems. It delivers up to 1A at 5V from 1.1V–10V input, features 2.5mA quiescent current in continuous switching mode, 300mV switch saturation voltage at 2A, and integrated low-battery detection with ±2% 200mV reference - used in digital cameras and handheld computers requiring stable high-current step-up conversion.
For engineers reviewing the LT1308BCF#TRPBF datasheet, LT1308BCF#TRPBF pinout, LT1308BCF#TRPBF application, or LT1308BCF#TRPBF equivalent, key selection criteria include its 600kHz switching frequency, 36V switch voltage rating, TSSOP-14 package thermal performance (θJA = 80°C/W), continuous light-load operation (vs. Burst Mode), and compatibility with SEPIC topologies for wide-input-range bias supplies.
Technical Context
The LT1308BCF#TRPBF implements a current-mode PWM architecture with fixed 600kHz oscillator and ramp compensation to suppress subharmonic oscillation above 50% duty cycle. Its error amplifier drives an internal 0.03Ω N-channel MOSFET switch, regulated via external feedback divider connected to the 1.22V FB pin.
Unlike the LT1308A variant, the LT1308B lacks hysteresis in its control comparator, enforcing continuous switching down to ~100mA inductor current - eliminating low-frequency output ripple but increasing light-load quiescent consumption to 2.5mA. The LBI/LBO pins provide ±2% accurate low-battery monitoring independent of VIN, with open-collector LBO sinking 50μA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 600kHz typical - enables compact magnetics and EMI filtering while maintaining >70% efficiency at 1A load across 1.5V–4.2V input. |
| Input Voltage Range | 1.1V to 10V - supports direct operation from single Li-ion (2.7–4.2V), two/three alkaline (1.8–4.5V), or four NiCd (4.8–6.0V) cells. |
| Output Current Capability | Up to 1A at 5V from 3.6V input - enabled by 2A switch current limit and 300mV VCE(SAT) at 2A, minimizing conduction loss. |
| Quiescent Current | 2.5mA during active switching - ensures predictable light-load behavior without Burst Mode discontinuity, simplifying EMI compliance testing. |
| Low-Battery Reference | 200mV ±2% over temperature - allows precise battery voltage monitoring with <±5mV trip-point error using standard resistor dividers. |
| Shutdown Current | ≤1μA max - guarantees ultra-low system standby power when SHDN is grounded, critical for battery-backed real-time clocks. |
| Switch Voltage Rating | 36V - supports output voltages up to 34V in boost configuration, enabling LCD bias (12–24V) and industrial sensor excitation rails. |
Pinout & Package
LT1308BCF#TRPBF is housed in a 14-lead plastic TSSOP package (JEDEC MO-153) with exposed pad for thermal enhancement. Pin pitch is 0.65mm; body dimensions are 5.0mm × 6.4mm × 1.2mm. Four GND pins (4–7), three SW pins (8–10), and two VIN pins (11–12) must be shorted together at the package per datasheet Note 6.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (Pin 1) | Compensation node for error amplifier | Connects external RC network (e.g., 47kΩ + 100pF) to set loop stability; trace area must be minimized to avoid noise coupling. |
| FB (Pin 2) | Feedback input referenced to 1.22V | Sets output voltage as VOUT = 1.22V × (1 + R1/R2); bias current ≤80nA minimizes divider error. |
| SHDN (Pin 3) | Enable/disable control input | Active-high logic: ≥1V enables converter; floating or 0V disables with ≤1μA shutdown current. |
| GND (Pins 4–7) | Power and signal ground return | All four pins must connect to local ground plane; copper under package acts as heat sink (θJA = 80°C/W). |
| SW (Pins 8–10) | Switch node for inductor/diode connection | Three parallel pins reduce trace inductance and resistive loss; must be routed with minimal area to suppress EMI. |
| VIN (Pins 11–12) | Main power supply input | Dual pins lower impedance path; requires local 47μF tantalum capacitor placed within 5mm of package. |
| LBI (Pin 13) | Low-battery detector analog input | Accepts 0–1V input; 200mV threshold with ±2% accuracy; bias current flows out (33–100nA), affecting divider design. |
| LBO (Pin 14) | Open-collector low-battery output | Sinks 50μA when LBI < 200mV; requires external pull-up (e.g., 220kΩ) to system rail for processor interrupt signaling. |
Key Features
| Feature | Design Value |
|---|---|
| Continuous light-load operation | Eliminates Burst Mode ripple (unlike LT1308A), ensuring clean output for noise-sensitive analog circuits and RF sections. |
| 36V switch voltage rating | Enables 34V boost outputs - sufficient for TFT-LCD gate drivers and industrial 24V auxiliary rails without external FETs. |
| Integrated ±2% low-battery detector | Reduces BOM count by replacing discrete comparator + reference; supports programmable trip points via resistor dividers on LBI. |
| Multi-pin power routing (VIN/SW/GND) | Low-impedance parallel connections cut conduction losses by >15% vs. single-pin packages, improving thermal margin at 1A loads. |
| Start-up into heavy loads | Delivers full 3.5A peak switch current at startup - avoids brownout during cold boot of high-capacitance systems (e.g., camera flash capacitors). |
Applications
| Digital Camera Power Supply | LCD Bias Generation |
|---|---|
Use Scenario: Powers CCD/CMOS image sensor, flash LED driver, and SD card interface from single Li-ion cell (3.0–4.2V). IC Role / Device Role / Timing Role: Primary 5V/1A boost regulator with fast transient response to handle burst-mode sensor readout current spikes. Use Value: 600kHz switching enables small 4.7μH inductor and 220μF low-ESR tantalum output cap; 2.5mA IQ prevents premature battery cutoff during standby. | Use Scenario: Generates +12V and –10V bias rails for TFT-LCD panels in portable medical monitors and industrial HMIs. IC Role / Device Role / Timing Role: High-voltage boost stage (12V @ 150mA) followed by inverting charge pump; leverages 36V switch rating for headroom. Use Value: ±2% LBI threshold ensures accurate end-of-life battery detection before display flicker occurs; TSSOP thermal performance sustains 85°C ambient operation. |
| Handheld Computer System Rail | SEPIC Battery Backup Supply |
Use Scenario: Provides regulated 3.3V/800mA core logic rail from 4-cell NiCd pack (4.8–6.0V), surviving deep discharge to 1.2V/cell. IC Role / Device Role / Timing Role: Main system DC/DC converter with integrated low-battery warning to trigger graceful OS shutdown. Use Value: 1.1V minimum start-up voltage extends usable battery life; continuous switching avoids audio-band ripple in speaker amplifiers. | Use Scenario: Maintains 5V/500mA output during AC failure using 3–10V battery input - e.g., smart meter RTC and memory backup. IC Role / Device Role / Timing Role: SEPIC topology controller supporting input voltage crossing output (3V–10V → 5V), enabled by dual-inductor layout guidance. Use Value: Pin-compatible with LT1308A/B SO-8 variants; LBO output directly interfaces with microcontroller wake-up interrupt pin. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3525EDD#TRMPBF | Higher 2MHz switching frequency; 1.5A switch; integrated soft-start; no LBI/LBO. | Requires smaller inductors/caps but lacks battery monitoring; better for space-constrained apps without low-battery signaling. | Select when board area is critical and battery state monitoring is handled externally. |
| TPS61040DRCT | 5V fixed output; 28V switch rating; 0.95mA IQ; no LBI/LBO; 500kHz switching. | Lower cost for fixed 5V output; insufficient for >24V bias rails; no integrated battery monitor. | Select for cost-sensitive 5V-only systems where external battery sensing is acceptable. |
Compared with LT1308BCF#TRPBF, LTC3525EDD#TRMPBF offers higher frequency and current but removes battery monitoring, while TPS61040DRCT trades versatility for lower cost and fixed output - making LT1308BCF#TRPBF optimal when combined boost regulation, wide input range, and accurate low-battery detection are required.
Availability
LT1308BCF#TRPBF is available at Aetrix Electronics and suitable for digital camera power supplies, LCD bias generation, handheld computer system rails, and SEPIC battery backup supplies requiring stable component supply with guaranteed long-term manufacturability.
Supply support for LT1308BCF#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 its high-performance analog IC portfolio, emphasizing precision power management, signal conditioning, and robust industrial-grade reliability.
The LT1308B belongs to Linear's micropower DC/DC converter product line, designed specifically for battery-powered portable electronics demanding high efficiency across wide input ranges and integrated system monitoring functions.
FAQ
What is the minimum input voltage required for LT1308BCF#TRPBF to start up and regulate?
The LT1308BCF#TRPBF starts up and regulates from a minimum input voltage of 1.1V, as specified in the Electrical Characteristics table. This enables operation directly from deeply discharged single-cell Li-ion batteries or two alkaline cells. Startup into heavy loads is supported, with peak switch current reaching 3.5A during initial capacitor charging - verified in Figure 13 of the datasheet under 1.5V input into a 20Ω load.
Does LT1308BCF#TRPBF support SEPIC topology, and what design considerations apply?
Yes, LT1308BCF#TRPBF supports SEPIC topology, as confirmed in Figure 8 and Application Information section. For reliable operation, use coupled inductors (e.g., Coiltronics CTX10-2) and ensure both L1A and L1B windings share identical turns ratio. Layout must minimize parasitic inductance in the high-di/dt paths - particularly between SW pins (8–10) and the coupled inductor center tap - to prevent ringing and EMI issues observed in discontinuous mode.
How does the low-battery detector in LT1308BCF#TRPBF differ from the original LT1308?
The LT1308BCF#TRPBF low-battery detector improves upon the LT1308 with ±2% accuracy on its 200mV reference (vs. ±3% typical for LT1308) and enhanced drive capability - sinking 50μA on LBO (vs. 20μA). Unlike the LT1308, it does not require VIN connection for operation; LBI accepts inputs from 0–1V independently, and LBO remains functional even when SHDN is active, enabling flexible system-level battery monitoring.
Can LT1308BCF#TRPBF replace LT1308BIS8#TRPBF in a design, and what changes are needed?
LT1308BCF#TRPBF is not a direct replacement for LT1308BIS8#TRPBF due to package and thermal differences: the TSSOP-14 (CF) has θJA = 80°C/W and requires PCB copper under the exposed pad, while the SO-8 (IS8) has θJA = 190°C/W. No schematic changes are needed, but layout must accommodate the larger footprint, additional GND/SW/VIN pins, and thermal pad soldering - verified in Figures 6 and 7 of the datasheet.
What is the purpose of the VC pin on LT1308BCF#TRPBF, and how is it configured?
VC is the error amplifier output compensation pin on LT1308BCF#TRPBF. It requires an external series RC network (e.g., 47kΩ + 100pF) connected to ground to stabilize the control loop. This network sets dominant pole and phase margin - critical because ceramic output capacitors eliminate the ESR zero that aids stability in tantalum-based designs. Minimizing trace area at VC prevents noise injection that could cause erratic regulation or oscillation.
LT1308BCF#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 14-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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:
- 14-TSSOP
LT1308BCF#TRPBF FAQ
1.How can I place an order for LT1308BCF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1308BCF#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 LT1308BCF#TRPBF reliable?
The price and inventory of LT1308BCF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1308BCF#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1308BCF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1308BCF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1308BCF#TRPBF?
LT1308BCF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1308BCF#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 LT1308BCF#TRPBF?
For technical support, including LT1308BCF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1308BCF#TRPBF requirements.
6.How does Aetrix verify that LT1308BCF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1308BCF#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 LT1308BCF#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1308BCF#TRPBF?
All LT1308BCF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1308BCF#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 LT1308BCF#TRPBF part is unused and in its original packaging.
Return procedure for LT1308BCF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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