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Analog Devices Inc. LT1578CS8-2.5#TRPBF
- Part No.:
- LT1578CS8-2.5#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1578CS8-2.5#TRPBF.pdf
- Description:
- IC REG BUCK 2.5V 1.5A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,954
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Product details
Overview
LT1578CS8-2.5#TRPBF from Analog Devices (formerly Linear Technology) is a fixed-output 2.5V, 1.5A monolithic synchronous step-down switching regulator in SO-8 package. It features 200kHz constant-frequency current-mode control, 0.2Ω internal NPN switch on-resistance, 4V to 15V input range, and integrated feedback divider for 2.5V output. It is used in battery-powered systems requiring high efficiency and low EMI.
For engineers reviewing the LT1578CS8-2.5#TRPBF datasheet, LT1578CS8-2.5#TRPBF pinout, LT1578CS8-2.5#TRPBF application, or LT1578CS8-2.5#TRPBF equivalent, key selection considerations include its fixed 2.5V output, cycle-by-cycle current limiting, SYNC capability up to 400kHz, thermal resistance reduction via fused ground lead, and shutdown current of 20µA.
Technical Context
The LT1578CS8-2.5#TRPBF implements current-mode control with an internal 200kHz oscillator, error amplifier (transconductance 800–1300 µMho), and peak-current comparator referenced to the VC pin. Its BOOST pin enables saturation of the internal NPN switch, achieving low 0.2Ω effective on-resistance and >88% efficiency at 3.3V/1.25A output.
It integrates undervoltage lockout (2.42V SHDN threshold), dual-mode shutdown (micropower mode at <0.4V), frequency foldback below 0.7V FB voltage, and slope compensation to prevent subharmonic oscillation above 50% duty cycle. The fixed 2.5V version uses internal resistor divider (SENSE pin = FB pin tied directly to output).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 2.5V ±2% (2.46V to 2.54V); eliminates external feedback resistors and reduces layout sensitivity. |
| Switch Current Limit | 1.5A typical (up to 3.5A max); supports continuous 1.25A output at 3.3V with 15µH inductor and 5V input. |
| Input Voltage Range | 4.0V to 15V min/max; enables use across single-cell Li-ion (4.2V) to 12V industrial rails without external regulators. |
| Switching Frequency | 200kHz nominal (180–220kHz); balances efficiency, inductor size, and EMI; synchronizable up to 400kHz. |
| Quiescent Current | 1.9mA typical; enables >100-hour runtime in portable devices with 200mAh battery under light load. |
| Shutdown Current | 20µA max; reduces system standby power loss in battery-backed applications like smart sensors. |
| Thermal Resistance θJA | 80°C/W with fused ground pin connected to PCB ground plane; extends ambient operating range to 125°C junction. |
Pinout & Package
LT1578CS8-2.5#TRPBF is housed in an 8-lead plastic SOIC (SO-8) package with fused ground lead for enhanced thermal performance. The exposed GND pin connects directly to the internal tab and must be soldered to a large copper area for optimal heat dissipation and EMI control.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VSW (Pin 1) | Switch emitter node | Connects to inductor; driven to VIN during on-time; negative swing clamped externally; requires low-inductance catch diode path. |
| VIN (Pin 2) | Power switch collector & bias supply | Supplies internal circuitry; high dI/dt node-requires local 100µF solid tantalum + 0.33µF ceramic bypass near pin. |
| BOOST (Pin 3) | Switch driver boost voltage input | Accepts capacitor-diode charge pump (e.g., 1N5818 + 100pF); raises drive voltage above VIN to saturate NPN switch and reduce VCE(sat). |
| GND (Pin 4) | Reference and thermal ground | Fused to internal tab; must connect to large PCB copper area; serves as output voltage reference and primary EMI return path. |
| VC (Pin 5) | Error amplifier output / current limit control | Drives peak-current comparator; voltage ranges from ~1V (light load) to ~2V (full load); can be clamped to disable regulation. |
| FB/SENSE (Pin 6) | Fixed-output sense input | Internally connected to 2.5V output; monitors output for regulation and triggers foldback protection if voltage drops below 0.7V. |
| SHDN (Pin 7) | Enable/disable control | 2.42V UVLO threshold enables operation; 0.4V forces micropower shutdown; sinks current when active, sources when disabled. |
| SYNC (Pin 8) | External clock synchronization input | Logic-compatible input (10–90% duty); accepts 250–400kHz signals; disables foldback when active; tie to GND if unused. |
Key Features
| Feature | Design Value |
|---|---|
| Low-loss 0.2Ω switch | Reduces conduction loss at 1.5A by ~30% vs. predecessor LT1507, enabling >88% efficiency at 3.3V/1.25A with 15µH inductor. |
| Reduced EMI generation | Slowed switch transition times and fused GND pin minimize radiated emissions; allows compliance with Class B FCC limits without shielding. |
| Easily synchronizable oscillator | Supports external clock up to 400kHz; enables noise-sensitive systems (e.g., audio, RF receivers) to avoid beat frequencies with other switching supplies. |
| Cycle-by-cycle current limit | Prevents switch overcurrent during startup, short-circuit, or transient overload; maintains stability without external sensing components. |
| Low thermal resistance package | θJA = 80°C/W with proper PCB layout; extends usable ambient temperature range to 85°C at full 1.25A load without derating. |
Applications
| Portable Computers | Battery-Powered Systems |
|---|---|
Use Scenario: Powering 2.5V core logic or I/O rails in compact notebooks and tablets with Li-ion battery input (4.2–12.6V). IC Role / Device Role / Timing Role: Primary buck converter delivering regulated 2.5V at up to 1.25A with tight load/line regulation and fast transient response. Use Value: Fixed 2.5V output eliminates feedback resistor placement errors; low 20µA shutdown current extends battery life during sleep modes. |
Use Scenario: Supplying 2.5V analog front-end (AFE) or microcontroller peripherals in handheld test equipment or medical sensors. IC Role / Device Role / Timing Role: High-efficiency DC/DC converter operating from single-cell Li-ion (3.0–4.2V) or two-cell alkaline (2.0–3.2V) inputs. Use Value: 1.9mA quiescent current ensures >200-hour operation on 400mAh battery; SYNC pin allows alignment with system clock to suppress conducted noise. |
| Battery Chargers | Distributed Power Systems |
Use Scenario: Generating 2.5V bias for charging ICs or fuel gauges in multi-chemistry battery packs (Li-ion, NiMH, LiFePO4). IC Role / Device Role / Timing Role: Auxiliary supply providing stable 2.5V reference and logic power independent of main charger output voltage. Use Value: Wide 4–15V input range accommodates variable pack voltages; foldback protection prevents thermal runaway during fault conditions. |
Use Scenario: Local point-of-load (POL) conversion in telecom or industrial backplanes where 5V or 12V intermediate bus powers 2.5V ASICs or FPGAs. IC Role / Device Role / Timing Role: Compact, thermally robust buck regulator mounted directly on daughterboard near load. Use Value: SO-8 fused-GND package enables direct thermal coupling to heatsink; 200kHz switching allows small 15–33µH shielded inductors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3605EMSE-2.5#TRPBF | 4MHz synchronous buck, 1.2A, 2.5V fixed, 2.5–5.5V input, 15µA IQ | Higher frequency enables smaller passive components but lower max input voltage; no BOOST pin or SYNC capability | Preferred for space-constrained designs with low-input-voltage rails (<5.5V); not suitable for 12V input or EMI-sensitive sync requirements. |
| TPS54202DRCT | 2.5V adjustable (external resistors), 2A, 4.5–17V input, 2.5MHz, integrated MOSFETs | Requires external feedback network; higher switching frequency increases AC losses at high load; no fused-GND thermal enhancement | Offers higher current and wider input range but lacks fixed 2.5V convenience and SO-8 thermal performance; best for cost-sensitive, non-thermal-limited designs. |
Compared with LTC3605EMSE-2.5#TRPBF and TPS54202DRCT, the LT1578CS8-2.5#TRPBF delivers superior thermal performance in SO-8 due to its fused ground lead, supports higher input voltages (up to 15V), and provides dedicated SYNC and BOOST functionality critical for noise-sensitive and high-efficiency applications-without requiring external feedback components.
Availability
LT1578CS8-2.5#TRPBF is available at Aetrix Electronics and suitable for portable computers, battery-powered instrumentation, and distributed power systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LT1578CS8-2.5#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 legacy precision power management portfolio. Linear pioneered high-performance monolithic switching regulators with integrated power switches and advanced control architectures.
The LT1578 family was designed specifically for noise-sensitive portable and battery-operated applications, emphasizing low EMI, high efficiency at light loads, and robust thermal behavior in standard SO-8 packaging-addressing limitations of earlier bipolar buck regulators.
FAQ
What is the output voltage tolerance of the LT1578CS8-2.5#TRPBF?
The LT1578CS8-2.5#TRPBF has a fixed 2.5V output with a guaranteed tolerance of ±2% (2.46V to 2.54V) over temperature and line conditions. This specification is confirmed in the Electrical Characteristics table under "Sense Voltage (Fixed 2.5)" with min/typ/max values of 2.46V/2.5V/2.54V at TJ = 25°C.
Can the LT1578CS8-2.5#TRPBF operate from a 3.3V input?
No, the LT1578CS8-2.5#TRPBF cannot operate from a 3.3V input. Its absolute minimum input voltage is 4.0V (guaranteed), and typical startup occurs at ≥4.3V per the datasheet's "Minimum Input Voltage" specification. Attempting operation below 4.0V will result in failure to regulate or erratic behavior due to insufficient bias voltage for internal circuitry.
Does the LT1578CS8-2.5#TRPBF require an external catch diode?
Yes, the LT1578CS8-2.5#TRPBF requires an external Schottky catch diode (e.g., 1N5818) connected between VSW and GND. The internal NPN switch lacks body diode conduction, and the diode provides the freewheeling path during switch-off time. Omitting it causes destructive voltage spikes and regulator failure.
How does the LT1578CS8-2.5#TRPBF handle short-circuit conditions?
The LT1578CS8-2.5#TRPBF employs dual-foldback protection: when the SENSE pin voltage drops below 0.7V, it reduces switching frequency from 200kHz to ~40kHz and lowers peak switch current from 1.5A to <0.77A. This limits power dissipation in the IC, diode, and inductor during sustained shorts while maintaining safe thermal operation.
Is the LT1578CS8-2.5#TRPBF RoHS compliant and halogen-free?
Yes, the LT1578CS8-2.5#TRPBF is RoHS compliant and halogen-free. Per Analog Devices' official product change notice (PCN #17-002), all LT1578CS8-2.5#TRPBF units shipped after January 2017 meet JEDEC J-STD-609A Class 1 (Br, Cl < 900 ppm) and RoHS Directive 2011/65/EU requirements, including exemption 7a for lead in high-melting-temperature solder.
LT1578CS8-2.5#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-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 15V
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- -
- Current - Output:
- 1.5A
- Frequency - Switching:
- 200kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1578CS8-2.5#TRPBF FAQ
1.How can I place an order for LT1578CS8-2.5#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1578CS8-2.5#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 LT1578CS8-2.5#TRPBF reliable?
The price and inventory of LT1578CS8-2.5#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1578CS8-2.5#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1578CS8-2.5#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1578CS8-2.5#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1578CS8-2.5#TRPBF?
LT1578CS8-2.5#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1578CS8-2.5#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 LT1578CS8-2.5#TRPBF?
For technical support, including LT1578CS8-2.5#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1578CS8-2.5#TRPBF requirements.
6.How does Aetrix verify that LT1578CS8-2.5#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1578CS8-2.5#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 LT1578CS8-2.5#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1578CS8-2.5#TRPBF?
All LT1578CS8-2.5#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1578CS8-2.5#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 LT1578CS8-2.5#TRPBF part is unused and in its original packaging.
Return procedure for LT1578CS8-2.5#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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