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Analog Devices Inc. LTC1504IS8-3.3#PBF
- Part No.:
- LTC1504IS8-3.3#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1504IS8-3.3#PBF.pdf
- Description:
- IC REG BUCK 3.3V 500MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,176
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Product details
Overview
LTC1504IS8-3.3#PBF from Analog Devices (formerly Linear Technology) is a fixed-output 3.3V, 500mA synchronous step-down DC/DC regulator in an SO-8 package. It integrates dual on-chip 1.5Ω MOSFETs, operates from 4V–10V input, delivers up to 92% peak efficiency, and features internal current limiting, soft-start, and ±3% output voltage regulation via SENSE pin feedback. It is used in portable digital systems requiring compact, low-part-count 3.3V power rails.
For engineers reviewing the LTC1504IS8-3.3#PBF datasheet, LTC1504IS8-3.3#PBF pinout, LTC1504IS8-3.3#PBF application, or LTC1504IS8-3.3#PBF equivalent, key selection criteria include its fixed 3.3V output, SO-8 thermal performance (θJA = 90°C/W), 200kHz switching frequency with synchronization capability up to 500kHz, IMAX-settable current limit, and shutdown-controlled active pull-down of SW pin.
Technical Context
The LTC1504IS8-3.3#PBF implements a synchronous buck topology using integrated P-channel high-side and N-channel low-side MOSFETs. Its feedback loop uses direct SENSE-pin monitoring referenced to a trimmed 1% internal 3.3V threshold, bypassing external resistor dividers. Transient response is enhanced by dedicated MIN/MAX comparators that force full or zero duty cycle when output deviates >±3% from nominal.
Current limiting is implemented via ILIM amplifier comparing SW-node voltage during Q1 conduction against IMAX-set reference voltage; overload triggers controlled discharge of SS capacitor to reduce COMP voltage and duty cycle. Soft-start and current-limit loops share the same SS node and are compensated by a single 0.1µF ceramic capacitor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±3% (SENSE pin regulated directly - no external divider required) |
| Max Output Current | 500mA continuous (limited by SO-8 thermal dissipation at typical 5V→3.3V operation) |
| Input Voltage Range | 4V to 10V (guaranteed operation; factory contact required for 2.7V support) |
| Peak Efficiency | 92% (minimizes heat generation and extends battery life in portable applications) |
| Switching Frequency | 200kHz typical, synchronizable up to 500kHz (enables EMI control and inductor size optimization) |
| Internal Switch RDS(on) | 1.5Ω (typical) per FET - defines conduction loss and thermal budget at full load) |
| Shutdown Current | <1µA (SW pulled low during SHDN assertion - prevents backfeed from other supplies) |
Pinout & Package
Package: 8-lead plastic SO-8 (S8), exposed pad not present; θJA = 90°C/W; recommended copper pour on Pin 4 (GND) for thermal relief.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (IMAX) | Current Limit Threshold Input | Voltage set by resistor from VCC determines peak current limit; floating disables limit |
| 2 (VCC) | Main Power Supply Input | 4V–10V supply; requires local low-ESR ceramic bypass capacitor |
| 3 (SW) | Switch Node Output | Drives external inductor; high dv/dt node - routing critical for EMI and stability |
| 4 (GND) | Power and Signal Ground | Primary thermal path; all bypass caps and feedback components must tie here |
| 5 (SENSE) | Fixed-Output Voltage Sense | Direct connection to 3.3V output; internal 3.3V reference - no external resistors needed |
| 6 (SHDN) | Active-Low Shutdown Control | Logic-low <0.8V halts switching and drops ICC to <1µA; SW actively pulled low |
| 7 (SS) | Soft-Start / Current-Limit Compensation | 0.1µF cap to GND sets ramp rate; shared node for both soft-start and current-limit recovery |
| 8 (COMP) | Error Amplifier Output | High-impedance node for external RC compensation network - stabilizes feedback loop |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous Buck Architecture | Integrated P- and N-channel MOSFETs eliminate external switches and reduce BOM count by ≥2 components |
| Fixed 3.3V Output with SENSE Pin | Eliminates feedback resistor divider - improves accuracy, reduces layout sensitivity, and saves board space |
| Dual-Comparator Transient Enhancement | MIN/MAX comparators override main error amplifier within ±3% window - cuts load-step recovery time vs standard compensation |
| Shared SS Node for Soft-Start & Current Limit | Single 0.1µF capacitor enables coordinated startup and overload recovery without additional passive components |
| Active SW Pull-Down in Shutdown | Prevents back-powering of output rail from downstream sources - essential for multi-rail system sequencing |
Applications
| Portable Digital Systems | Active Termination |
|---|---|
Use Scenario: Powering 3.3V logic in handheld test equipment with tight PCB area constraints and battery runtime targets. IC Role / Device Role / Timing Role: Primary 3.3V point-of-load regulator delivering up to 500mA with minimal external parts (4-component solution). Use Value: 92% peak efficiency extends battery life; SO-8 footprint allows placement near processor/FPGA without thermal interference. | Use Scenario: Providing stable 3.3V termination voltage for high-speed data buses (e.g., SCSI, PCI-X stubs) where dynamic current demand varies rapidly. IC Role / Device Role / Timing Role: Low-noise, fast-transient 3.3V source maintaining bus signal integrity under pulsed load conditions. Use Value: MIN/MAX comparator-assisted transient response holds output within ±3% during 100mA–500mA load steps - avoids bus timing violations. |
| Auxiliary Output Voltage Supplies | Minimum Part Count/Size Switchers |
Use Scenario: Generating isolated 3.3V bias for analog front-end circuitry in industrial sensor nodes powered from 5V or 9V rails. IC Role / Device Role / Timing Role: Secondary regulated supply decoupled from main system rail - supports noise-sensitive ADCs and references. Use Value: Internal 1% reference and direct SENSE feedback yield <±1% DC accuracy over line/load/temperature - meets precision analog requirements. | Use Scenario: Replacing linear regulators (e.g., LM1117-3.3) in space-constrained IoT modules where heat dissipation and efficiency are critical. IC Role / Device Role / Timing Role: Drop-in upgrade path offering 3× higher efficiency and 50% smaller solution size than LDO-based designs. Use Value: Four-component implementation (CIN, COUT, L, CSS) fits within footprint of legacy TO-220 LDO - enables retrofit without PCB redesign. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62231DRVR | 3MHz fixed-frequency operation; 3.3V output; 300mA max; smaller 2mm × 2mm WSON package | Higher switching frequency enables smaller inductors/caps but lower max current and tighter layout tolerances | Select for ultra-compact designs with ≤300mA loads and aggressive EMI filtering needs |
| MP2307DN-LF-Z | 40V max input; 3.3V adjustable via FB resistor; 3A max output; SO-8 package with thermal pad | Wider VIN range and higher current capability - suited for industrial 12V/24V input systems | Select when input exceeds 10V or output current >500mA is required; requires external feedback divider |
Compared with LTC1504IS8-3.3#PBF, TPS62231DRVR trades current capacity and SO-8 familiarity for miniaturization and high-frequency operation, while MP2307DN-LF-Z expands input range and output headroom at the cost of added external components and less precise fixed-voltage accuracy.
Availability
LTC1504IS8-3.3#PBF is available at Aetrix Electronics and suitable for portable digital systems, active termination circuits, auxiliary voltage supplies, and minimum-part-count switcher designs requiring stable component supply, long-term manufacturability, and guaranteed SO-8 sourcing.
Supply support for LTC1504IS8-3.3#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 technical and manufacturing continuity for the LTC portfolio. Linear's legacy design ethos emphasizes robustness, precision, and ease of use in power management ICs.
The LTC1504 product line was engineered for space-constrained, battery-powered digital systems needing high-efficiency, fixed-output DC/DC conversion with minimal external components - targeting portable instrumentation, telecom line cards, and embedded controllers.
FAQ
What is the maximum input voltage rating for the LTC1504IS8-3.3#PBF?
The absolute maximum input voltage applied to the VCC pin of the LTC1504IS8-3.3#PBF is 10V. Operation is specified and guaranteed across 4V to 10V. While the device may function at 2.7V, Linear Technology (now Analog Devices) explicitly states that guaranteed specifications at this level require factory consultation - do not assume full parameter compliance below 4V without validation.
Does the LTC1504IS8-3.3#PBF require external feedback resistors to set its output voltage?
No. The LTC1504IS8-3.3#PBF uses an internal resistor divider and direct SENSE pin connection to regulate precisely to 3.3V. Unlike the adjustable LTC1504CS8 variant, it does not require external FB resistors - simplifying layout, improving accuracy, and eliminating resistor tolerance errors. This fixed architecture is confirmed in the PIN FUNCTIONS section and Typical Application schematics.
How does the current limit function work on the LTC1504IS8-3.3#PBF?
The LTC1504IS8-3.3#PBF implements current limiting by comparing the voltage drop across its internal high-side P-MOSFET (Q1) during conduction to a reference voltage set at the IMAX pin. When the sensed IR drop exceeds the IMAX threshold, the ILIM amplifier pulls current from the SS pin, lowering COMP voltage and reducing duty cycle. Recovery occurs as SS recharges through its external capacitor - making the 0.1µF SS capacitor critical for both soft-start timing and current-limit response.
Can the LTC1504IS8-3.3#PBF be synchronized to an external clock?
Yes. The LTC1504IS8-3.3#PBF's internal oscillator can be synchronized to an external clock signal up to 500kHz. This is achieved by injecting a clean square wave into the COMP pin, overriding the internal 200kHz sawtooth generator. Synchronization helps reduce beat frequencies and EMI in multi-regulator systems - a capability documented in the "FEATURES" and "ELECTRICAL CHARACTERISTICS" sections of the datasheet.
What thermal considerations apply to the LTC1504IS8-3.3#PBF in SO-8 package?
The LTC1504IS8-3.3#PBF has a junction-to-ambient thermal resistance (θJA) of 90°C/W in standard SO-8 layout. Pin 4 (GND) serves as the primary thermal path - it must connect to a large copper pour to dissipate heat effectively. At 500mA output with 5V input, power dissipation reaches ~0.85W; without adequate copper area, junction temperature can exceed the 115°C maximum (TJMAX), triggering thermal shutdown or reliability degradation.
LTC1504IS8-3.3#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-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 10V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 500mA
- Frequency - Switching:
- 200kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC1504IS8-3.3#PBF FAQ
1.How can I place an order for LTC1504IS8-3.3#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1504IS8-3.3#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 LTC1504IS8-3.3#PBF reliable?
The price and inventory of LTC1504IS8-3.3#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1504IS8-3.3#PBF is usually 5 days.
3.What payment methods are accepted for LTC1504IS8-3.3#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1504IS8-3.3#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1504IS8-3.3#PBF?
LTC1504IS8-3.3#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1504IS8-3.3#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 LTC1504IS8-3.3#PBF?
For technical support, including LTC1504IS8-3.3#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1504IS8-3.3#PBF requirements.
6.How does Aetrix verify that LTC1504IS8-3.3#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1504IS8-3.3#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 LTC1504IS8-3.3#PBF meets industry standards.
7.What is the process for return or replacement of LTC1504IS8-3.3#PBF?
All LTC1504IS8-3.3#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1504IS8-3.3#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 LTC1504IS8-3.3#PBF part is unused and in its original packaging.
Return procedure for LTC1504IS8-3.3#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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