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Analog Devices Inc. LTC1504ACS8#PBF
- Part No.:
- LTC1504ACS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1504ACS8#PBF.pdf
- Description:
- IC REG BUCK ADJ 500MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,964
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Product details
Overview
LTC1504ACS8#PBF from Analog Devices (formerly Linear Technology) is a 500mA synchronous step-down DC/DC regulator in SO-8 package, featuring integrated 1.3Ω P- and N-channel MOSFETs, 100% duty cycle operation for low dropout, internal 1.265V reference trimmed to ±1%, and 200kHz fixed-frequency PWM control. It delivers regulated 3.3V output from 4V–10V input in portable digital systems requiring compact, high-efficiency power conversion.
For engineers reviewing the LTC1504ACS8#PBF datasheet, LTC1504ACS8#PBF pinout, LTC1504ACS8#PBF application, or LTC1504ACS8#PBF equivalent, key selection criteria include its fixed 3.3V output version, adjustable current limit via IMAX pin, soft-start control via external capacitor on SS, COMP-based loop compensation, and thermal performance in SO-8 with GND pad acting as heat sink.
Technical Context
The LTC1504ACS8#PBF implements a synchronous buck topology with on-chip P-channel high-side and N-channel low-side switches, enabling bidirectional output current (source/sink) for tight regulation during load transients. Its internal 200kHz sawtooth oscillator drives nonoverlapping gate logic, while the error amplifier (gmV = 350–1100 µmho, AV = 40–48 dB) compares FB/SENSE voltage to a precision 1.265V reference.
Current limiting is implemented via an ILIM amplifier that monitors SW node voltage during Q1 conduction and compares it to IMAX-set threshold; overload detection pulls current from SS pin to reduce COMP voltage and throttle duty cycle. Soft-start timing and current-limit response are jointly governed by the same external SS-to-GND capacitor (typically 0.1µF).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 500mA continuous at 3.3V - supports mid-power digital loads without external MOSFETs |
| Input Voltage Range | 4V to 10V - compatible with 5V rail and higher intermediate supplies, not rated for 2.7V |
| Output Voltage | Fixed 3.3V (±3% over temp) - SENSE pin servoed to 3.30V, eliminating feedback resistor divider |
| Peak Efficiency | 92% at 5V→3.3V/500mA - minimizes thermal stress and extends battery life in portable systems |
| Switching Frequency | 200kHz typical (150–250kHz commercial range) - enables use of small, low-cost inductors (e.g., 47–100µH) |
| Internal Switch RDS(on) | 1.3Ω (typ) high-side, 1.3Ω (typ) low-side - defines conduction loss and thermal limits in SO-8 package |
| Reference Accuracy | 1.265V ±1% (25°C), ±1.6% PSRR - ensures stable regulation despite VCC ripple up to 10V |
| Max Duty Cycle | 100% - supports ultra-low dropout operation (e.g., 3.5V→3.3V), critical for brownout resilience |
Pinout & Package
Package: 8-lead plastic SO-8 with exposed GND pad (θJA = 90°C/W); GND pin (Pin 4) serves as primary thermal path and must connect to large copper area.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IMAX (Pin 1) | Current limit threshold set | 12µA internal sink current sets voltage drop across external RIMAX; determines peak switch current before foldback |
| VCC (Pin 2) | Main power supply input | 4V–10V input; requires local low-ESR ceramic bypass (≥1µF) and bulk reservoir capacitor |
| SW (Pin 3) | Switching node | Drives external inductor; carries full AC ripple current; must avoid routing near sensitive analog traces |
| GND (Pin 4) | Power and signal ground | Low-impedance return for input/output caps and feedback; thermal sink for SO-8 package |
| SENSE (Pin 5) | Output voltage feedback | Direct connection to 3.3V output node; internal 3.3V reference eliminates need for external resistors |
| SHDN (Pin 6) | Active-low shutdown control | Pull ≤0.8V to disable regulator; draws <1µA quiescent current; forces SW low to prevent backfeeding |
| SS (Pin 7) | Soft-start timing & current limit response | 0.1µF cap to GND sets ramp time and governs both startup slew rate and overload recovery speed |
| COMP (Pin 8) | Error amplifier output | High-impedance node for external RC compensation network; stability depends on output capacitor ESR |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous buck architecture | Enables bidirectional output current (source/sink), improving transient response and eliminating external diode |
| Integrated 1.3Ω MOSFETs | Reduces BOM count to ≤4 components for basic 5V→3.3V design; eliminates gate drive complexity |
| 100% duty cycle capability | Supports operation down to VIN – VOUT ≈ 200mV, essential for low-dropout scenarios near input rail minimum |
| Adjustable current limit | Single resistor from VCC to IMAX sets threshold (e.g., 47kΩ → ~350mA), protecting IC and inductor during faults |
| Internal 1.265V reference (±1%) | Ensures 3.3V output accuracy within ±3% over temperature and line, without trimming or calibration |
| SO-8 thermal design | GND pin doubles as thermal pad; requires PCB copper pour ≥100 mm² for 500mA continuous operation at 70°C ambient |
Applications
| Portable Digital Systems | Active Termination |
|---|---|
Use Scenario: Powering FPGA I/O banks or microcontroller peripherals in handheld test equipment with 5V battery input. IC Role / Device Role / Timing Role: Primary 3.3V point-of-load regulator delivering 500mA with fast load-step response and minimal footprint. Use Value: Eliminates need for external MOSFETs and feedback resistors, reducing layout area by >30% vs discrete buck controllers. | Use Scenario: Providing bias voltage for SCSI or DDR termination networks where precise 3.3V tracking and low noise are required. IC Role / Device Role / Timing Role: Low-noise, tightly regulated auxiliary supply referenced directly to system VDDQ rail. Use Value: Internal 1% reference and PSRR >1.1% ensure <10mV output deviation under 100mV VCC ripple, maintaining signal integrity. |
| Auxiliary Output Supplies | Minimum Part Count Switchers |
Use Scenario: Generating isolated 3.3V for USB PHY or sensor interface in space-constrained IoT edge nodes. IC Role / Device Role / Timing Role: Standalone fixed-output regulator with SHDN control for dynamic power gating. Use Value: <1µA shutdown current and 100% duty cycle enable operation during brownout conditions without system reset. | Use Scenario: Replacing linear regulators (e.g., LM1117) in cost-sensitive consumer electronics where efficiency >85% is mandated. IC Role / Device Role / Timing Role: Drop-in replacement for LDOs using same input/output capacitors and inductor footprint. Use Value: 92% peak efficiency reduces thermal dissipation by >70% vs LDO at 500mA, eliminating heatsinks and enabling smaller enclosures. |
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 switching frequency, 600mA output, requires external feedback resistors for 3.3V | Better transient response and smaller inductors, but higher EMI and no 100% duty cycle | Select when board space is constrained and input voltage >4.5V; avoid if dropout <200mV is required |
| MP2108DQ-LF-Z | 2.5V–6V input, 600mA, integrated compensation, no IMAX current limit pin | Simpler layout (no SS/COMP/IMAX external components), but fixed current limit (~750mA) and no shutdown control | Select for cost-driven designs needing plug-and-play operation; avoid when programmable fault protection is mandatory |
Compared with TPS62231DRVR and MP2108DQ-LF-Z, the LTC1504ACS8#PBF offers unique 100% duty cycle operation and adjustable current limiting via IMAX-critical for brownout resilience and custom fault thresholds-but requires manual loop compensation and operates at lower frequency, trading size for EMI robustness and thermal margin.
Availability
LTC1504ACS8#PBF is available at Aetrix Electronics and suitable for portable digital systems, active termination networks, and auxiliary output voltage supplies requiring stable component supply, long-term industrial availability, and guaranteed parametric performance over 0°C to 70°C.
Supply support for LTC1504ACS8#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision instrumentation, communications, and industrial markets.
The LTC1504A product line was designed specifically for compact, efficient DC/DC conversion in battery-powered and space-constrained applications, emphasizing integration, thermal manageability in SO-8, and robustness under transient and overload conditions.
FAQ
What is the maximum continuous output current of the LTC1504ACS8#PBF?
The LTC1504ACS8#PBF delivers 500mA continuous output current at 3.3V with 5V input under typical PCB thermal conditions (≥100 mm² GND copper). Derating is required above 70°C ambient or with inadequate copper pour; peak switch current exceeds ±1A, but thermal limits govern sustained output.
Does the LTC1504ACS8#PBF require external feedback resistors to set the 3.3V output?
No. The LTC1504ACS8#PBF is the fixed 3.3V version: Pin 5 is labeled SENSE and internally connected to a precision resistor divider calibrated to servo the output to 3.30V. External resistors are unnecessary-only required for adjustable versions like LTC1504ACS8.
How does the current limit function on the LTC1504ACS8#PBF?
The LTC1504ACS8#PBF uses an IMAX pin with an internal 12µA current sink. A resistor from VCC to IMAX sets the voltage threshold; the ILIM amplifier compares this to the voltage drop across the high-side switch during conduction. Exceeding the threshold pulls current from the SS pin, reducing COMP voltage and throttling duty cycle.
Can the LTC1504ACS8#PBF operate with a 3.6V input supply?
No. The absolute minimum input voltage for the LTC1504ACS8#PBF is 4V per datasheet specifications. Operation below 4V is not characterized or guaranteed; contact Analog Devices for factory-supported 2.7V variants (not available in ACS8 grade).
What is the purpose of the COMP pin on the LTC1504ACS8#PBF?
The COMP pin is the output of the internal error amplifier and serves as the control node for loop compensation. An external RC network connected from COMP to GND stabilizes the feedback loop; network values depend on output capacitor ESR-low-ESR ceramics require a series RC, while higher-ESR tantalums need only a single capacitor.
LTC1504ACS8#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:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 10V
- Voltage - Output (Min/Fixed):
- 1.265V
- Voltage - Output (Max):
- 10V
- 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
LTC1504ACS8#PBF FAQ
1.How can I place an order for LTC1504ACS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1504ACS8#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 LTC1504ACS8#PBF reliable?
The price and inventory of LTC1504ACS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1504ACS8#PBF is usually 5 days.
3.What payment methods are accepted for LTC1504ACS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1504ACS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1504ACS8#PBF?
LTC1504ACS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1504ACS8#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 LTC1504ACS8#PBF?
For technical support, including LTC1504ACS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1504ACS8#PBF requirements.
6.How does Aetrix verify that LTC1504ACS8#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1504ACS8#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 LTC1504ACS8#PBF meets industry standards.
7.What is the process for return or replacement of LTC1504ACS8#PBF?
All LTC1504ACS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1504ACS8#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 LTC1504ACS8#PBF part is unused and in its original packaging.
Return procedure for LTC1504ACS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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