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Analog Devices Inc. LT3502AEMS#PBF
- Part No.:
- LT3502AEMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LT3502AEMS#PBF.pdf
- Description:
- IC REG BUCK ADJ 500MA 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:23,924
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Product details
Overview
LT3502AEMS#PBF from Analog Devices (formerly Linear Technology) is a 2.2MHz, 500mA current-mode PWM step-down DC/DC converter with integrated 500mA bipolar NPN power switch, 0.8V feedback reference, internal boost diode, and cycle-by-cycle current limiting-designed for compact 3.3V/5V point-of-load regulation in automotive and industrial systems operating from 3V to 40V input.
For engineers reviewing the LT3502AEMS#PBF datasheet, LT3502AEMS#PBF pinout, LT3502AEMS#PBF application, or LT3502AEMS#PBF equivalent, key selection considerations include its 2.2MHz fixed switching frequency, MS10 package thermal performance (θJA = 110°C/W), DA-pin–based frequency foldback for short-circuit robustness, and compatibility with low-ESR ceramic output capacitors down to 10µF at 3.3V output.
Technical Context
The LT3502AEMS#PBF implements constant-frequency current-mode control using an RS flip-flop–driven oscillator and slope-compensated peak current sensing. Its VC node is servo-controlled by an error amplifier monitoring the FB pin at 0.8V, while soft-start and frequency foldback are implemented via voltage ramping and clamping on the SHDN pin.
Protection architecture combines switch peak current limit (0.75–1.1A), DA-pin valley current detection (650mA threshold), and thermal shutdown. The internal boost circuit-fed via BD pin and capacitor between BOOST and SW-enables full saturation of the bipolar switch by generating a BOOST voltage ≥2.2V above SW, critical for efficiency at high input-to-output ratios.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 2.2MHz - Enables use of ≤6.8µH inductors and 10µF ceramic output capacitors, minimizing solution size and avoiding AM-band interference. |
| Input Voltage Range | 3V to 40V - Supports direct regulation from 24V industrial rails and 12V/24V automotive batteries without pre-regulation. |
| Output Current | 500mA continuous - Rated for sustained load delivery with thermal derating per MS10 package θJA = 110°C/W. |
| Feedback Reference | 0.8V ±13mV - Sets output voltage via external resistor divider (e.g., 3.3V = 0.8V × (1 + R1/R2)); enables precise, stable regulation across temperature. |
| Shutdown Current | <2µA - Minimizes battery drain in always-on automotive modules during ignition-off states. |
| Current Limit Threshold | 0.75–1.1A (peak), 650mA (valley via DA pin) - Provides dual-stage overcurrent protection: fast peak limiting and foldback-based fault current capping. |
| Package | 10-Lead Plastic MSOP - Thermally enhanced surface-mount package with exposed pad tied to GND; requires PCB copper area for heat dissipation. |
Pinout & Package
LT3502AEMS#PBF uses a 10-lead plastic MSOP package (θJA = 110°C/W) with exposed pad soldered to PCB ground for thermal management. Pin numbering follows top-view orientation with Pin 1 at bottom-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 10) | Power Input | Supplies internal regulator and power switch; must be bypassed with ≥1µF X7R/X5R ceramic capacitor near pin. |
| BD (Pin 8) | Boost Drive Supply | Provides current path to internal Schottky diode; connects to external boost capacitor (typically 0.1µF) between BOOST and SW. |
| FB (Pin 7) | Feedback Sense | Regulated to 0.8V; sets output voltage via resistor divider (e.g., R2 = 10kΩ, R1 = 32.4kΩ for 3.3V). |
| SHDN (Pin 6) | Shutdown & Soft-Start Control | Logic-level enable (≥2V = ON); also accepts RC network for controlled start-up ramp and frequency foldback during faults. |
| GND (Pin 5) | Power Ground | Common return for internal circuits and exposed pad; must be low-impedance connection to PCB ground plane. |
| DA (Pin 4) | Diode Anode Monitor | Detects catch diode valley current; triggers frequency foldback when >650mA to limit fault current under short-circuit conditions. |
| BOOST (Pin 2) | Switch Driver Boost | Generates gate drive voltage >VIN for bipolar switch saturation; requires capacitor to SW pin (min. 2.2V above SW). |
| SW (Pin 1) | Switch Node | Drives external inductor and catch diode; high dv/dt node requiring tight layout and minimal trace length. |
Key Features
| Feature | Design Value |
|---|---|
| 2.2MHz Fixed Switching Frequency | Enables ultra-compact designs with 6.8µH inductors and 10µF ceramic output caps-reducing board area by >40% vs. 1.1MHz alternatives. |
| Internal Boost Diode | Eliminates need for external boost diode, reducing BOM count and PCB footprint while maintaining efficient bipolar switch drive. |
| DA-Pin Frequency Foldback | Automatically reduces switching frequency during overload/short-circuit to hold valley current at 650mA-preventing thermal runaway without external circuitry. |
| 0.8V Feedback Reference | Allows precise output programming with standard 1% resistors; low reference tolerance (±13mV) ensures <±1.5% output accuracy over temperature. |
| Thermally Enhanced MS10 Package | Exposed pad design achieves θJA = 110°C/W with 2-in² 2-oz copper; supports 500mA continuous output at 85°C ambient without forced air. |
Applications
| Automotive Infotainment Power | Industrial Sensor Node Regulator |
|---|---|
|
Use Scenario: Powering 3.3V microcontrollers, CAN transceivers, and display drivers in head units and ADAS ECUs where EMI must avoid AM radio band. IC Role / Device Role / Timing Role: Primary 3.3V buck regulator delivering 500mA with 2.2MHz switching to suppress conducted emissions below 1.6MHz. Use Value: Eliminates need for external EMI filters due to AM-band–free operation, reducing cost and board space in space-constrained dash modules. |
Use Scenario: Generating stable 5V supply for 4–20mA loop-powered sensors and isolated ADCs in factory automation PLCs. IC Role / Device Role / Timing Role: Input-flexible buck converter accepting 12–36V field wiring while maintaining regulation during brownouts. Use Value: Wide 3–40V input range avoids external pre-regulators, enabling direct connection to industrial 24V rails with no additional components. |
| Portable Medical Instrumentation | Smart Building Controller Supply |
|
Use Scenario: Providing 3.3V rail for low-power ARM Cortex-M MCUs and BLE radios in handheld diagnostic devices powered by Li-ion batteries. IC Role / Device Role / Timing Role: High-efficiency step-down regulator with <2µA shutdown current preserving battery life during standby. Use Value: Ultra-low quiescent current extends battery runtime in battery-only operation, while 2.2MHz operation minimizes inductor size for portable form factor. |
Use Scenario: Powering 5V logic and PoE-powered peripherals (e.g., door controllers, occupancy sensors) in commercial HVAC systems. IC Role / Device Role / Timing Role: Robust buck converter handling 40V transients from long building wiring runs and inductive load switching. Use Value: Absolute maximum VIN rating of 40V and built-in short-circuit foldback ensure reliable operation despite voltage spikes common in building infrastructure. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3502EMS#PBF | 1.1MHz switching frequency, same 500mA rating and pinout; lower frequency increases inductor size but improves light-load efficiency. | Suitable for noise-sensitive audio subsystems where 2.2MHz EMI may couple into analog paths. | Select LT3502EMS#PBF only if lower frequency is required for EMI compliance; otherwise LT3502AEMS#PBF offers smaller magnetics. |
| MP2307DN-LF-Z | MOSFET-based synchronous buck (no external diode needed); 2A rating but wider 4.5–26V input range and no DA-pin foldback. | Better suited for higher-current, lower-input-voltage applications like 5V USB-C PD adapters. | Use MP2307DN-LF-Z only when >500mA output or synchronous rectification is mandatory; LT3502AEMS#PBF provides superior short-circuit robustness in 24V+ systems. |
Compared with LT3502EMS#PBF and MP2307DN-LF-Z, the LT3502AEMS#PBF uniquely combines 2.2MHz operation, bipolar switch ruggedness for 40V inputs, and DA-pin–enabled foldback-making it optimal for compact, high-reliability 3–40V automotive and industrial buck conversion where fault tolerance is critical.
Availability
LT3502AEMS#PBF is available at Aetrix Electronics and suitable for automotive infotainment, industrial sensor nodes, and portable medical instrumentation requiring stable component supply with guaranteed long-term availability and full traceability.
Supply support for LT3502AEMS#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 ICs, serving aerospace, automotive, industrial, and communications markets.
The LT3502A belongs to Linear Technology's monolithic current-mode buck regulator product line, engineered for high-voltage input-to-lower-voltage conversion in space-constrained, thermally demanding environments such as automotive engine compartments and factory floor controllers.
FAQ
What is the maximum input voltage rating for the LT3502AEMS#PBF?
The LT3502AEMS#PBF has an absolute maximum input voltage rating of 40V on the VIN pin and 50V on the BOOST pin. For continuous fixed-frequency operation, the practical maximum input depends on output voltage and duty cycle limits-e.g., at 3.3V output, VIN(MAX) ≈ 33V for DCMIN = 0.15. Transient excursions up to 40V are tolerated, but sustained operation above VIN(MAX) causes pulse-skipping and increased ripple.
Does the LT3502AEMS#PBF require an external catch diode?
Yes, the LT3502AEMS#PBF requires an external Schottky catch diode (e.g., Diodes Inc. DFLS140 or ON Semi MBRM140) connected between SW and GND. The DA pin monitors this diode's anode current to trigger frequency foldback during overload. The internal boost diode serves only the BOOST circuit-not the power path-so the external diode remains essential for energy recirculation.
How does the SHDN pin function beyond enable/disable control in the LT3502AEMS#PBF?
In the LT3502AEMS#PBF, the SHDN pin provides three functions: (1) logic-level enable/disable (≥2V = ON, ≤0.3V = OFF), (2) soft-start via external RC network that ramps SHDN voltage to control inrush current, and (3) frequency foldback initiation during faults. During startup, SHDN voltage clamps the VC node, slowing error amplifier response and reducing initial switching frequency to prevent current-limit triggering.
What is the purpose of the DA pin on the LT3502AEMS#PBF, and how is it used?
The DA pin on the LT3502AEMS#PBF senses valley current through the external catch diode. When DA current exceeds 650mA, the IC reduces switching frequency to maintain safe inductor valley current-critical for short-circuit protection. It must be connected directly to the anode of the catch diode; floating or misrouting disables foldback and compromises fault robustness.
Can the LT3502AEMS#PBF operate with a 3.3V output from a 40V input source?
Yes, the LT3502AEMS#PBF can regulate 3.3V from 40V input, but not in continuous fixed-frequency mode. At such high VIN/VOUT ratios, the required duty cycle falls below DCMIN = 0.15, forcing pulse-skipping operation. Output ripple increases, but the part remains functional and protected-provided the inductor saturation current exceeds 1.2A and components are rated for 40V stress.
LT3502AEMS#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 32V
- Current - Output:
- 500mA
- Frequency - Switching:
- 2.25MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP
LT3502AEMS#PBF FAQ
1.How can I place an order for LT3502AEMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3502AEMS#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 LT3502AEMS#PBF reliable?
The price and inventory of LT3502AEMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3502AEMS#PBF is usually 5 days.
3.What payment methods are accepted for LT3502AEMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3502AEMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3502AEMS#PBF?
LT3502AEMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3502AEMS#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 LT3502AEMS#PBF?
For technical support, including LT3502AEMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3502AEMS#PBF requirements.
6.How does Aetrix verify that LT3502AEMS#PBF is sourced from the original manufacturer or authorized distributors?
All LT3502AEMS#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 LT3502AEMS#PBF meets industry standards.
7.What is the process for return or replacement of LT3502AEMS#PBF?
All LT3502AEMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3502AEMS#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 LT3502AEMS#PBF part is unused and in its original packaging.
Return procedure for LT3502AEMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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