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Analog Devices Inc. LT3502EMS#PBF
- Part No.:
- LT3502EMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LT3502EMS#PBF.pdf
- Description:
- IC REG BUCK ADJ 500MA 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,089
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Product details
Overview
LT3502EMS#PBF from Analog Devices (formerly Linear Technology) is a current-mode PWM step-down DC/DC converter with an integrated 500mA bipolar NPN power switch, designed for industrial and automotive power regulation. It operates from 3V to 40V input, delivers up to 500mA output, switches at 1.1MHz (LT3502 variant), features 0.8V feedback reference, internal boost diode, and thermally enhanced 10-lead MSOP package - enabling compact 3.3V/5V point-of-load conversion in space-constrained systems.
For engineers reviewing the LT3502EMS#PBF datasheet, LT3502EMS#PBF pinout, LT3502EMS#PBF application, or LT3502EMS#PBF equivalent, key selection criteria include input voltage range (3–40V), switching frequency (1.1MHz), output current capability (500mA), thermal performance in MSOP-10, and fault protection mechanisms including cycle-by-cycle current limit and DA-pin-based frequency foldback.
Technical Context
The LT3502EMS#PBF implements constant-frequency current-mode control using an internal oscillator and RS flip-flop to drive its bipolar NPN switch. Its error amplifier regulates the FB pin to 0.8V via external resistor divider, while slope compensation prevents subharmonic oscillation above 50% duty cycle. The VC node is clamped by both the SHDN pin (enabling soft-start) and active current-limit circuitry.
Protection architecture includes dual-stage current limiting: peak switch current limit (~0.9A typical) and DA-pin valley current monitoring (650mA threshold), which triggers frequency foldback during overload or short-circuit conditions. An internal regulator with ~3V undervoltage lockout powers control circuitry, and the BOOST pin - driven via external capacitor and internal Schottky diode - supplies >VIN gate drive to fully saturate the NPN switch.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 40V - supports direct regulation from 24V industrial rails and automotive batteries without pre-regulation. |
| Output Current | 500mA continuous - sufficient for powering microcontrollers, sensors, and interface ICs in embedded systems. |
| Switching Frequency | 1.1MHz - enables use of small 6.8µH inductors and 10µF ceramic output capacitors, minimizing board area. |
| Feedback Reference | 0.8V ±15mV - allows precise output programming (e.g., 3.3V with 10k/32.4k divider) and reduces resistor tolerance sensitivity. |
| Shutdown Current | <2µA - ensures ultra-low system standby power in battery-backed or energy-sensitive applications. |
| Max Duty Cycle | 90% - supports low-VIN operation down to ~3.7V for 3.3V output, extending usable input range in brownout conditions. |
| Thermal Resistance | θJA = 110°C/W - requires minimal copper pour in MSOP-10 layout to maintain safe junction temperature at full load. |
Pinout & Package
LT3502EMS#PBF uses a 10-lead plastic MSOP package (3mm × 3mm × 1.1mm height) with exposed pad thermally connected to GND. Pin 5 is dedicated GND; pins 1 and 10 are VIN and SW respectively; BD (pin 8) and BOOST (pin 2) form the charge-pump network; DA (pin 4) provides valley-current fault sensing; SHDN (pin 6) enables shutdown, soft-start, and frequency foldback control.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 10) | Power input supply | Supplies internal regulator and switch; must be locally bypassed with ≥1µF X7R ceramic capacitor. |
| BD (Pin 8) | Boost diode anode connection | Provides current path to internal Schottky diode; ties to BOOST capacitor's low-side node. |
| FB (Pin 7) | Feedback reference node | Regulated to 0.8V; connects to resistor divider tap for output voltage programming. |
| SHDN (Pin 6) | Shutdown/soft-start control | Pull ≤0.3V to disable; ≥2V to enable; RC ramp here controls start-up inrush and frequency foldback. |
| GND (Pin 5) | Power and signal ground | Common return for internal circuits, exposed pad must be soldered to PCB ground plane. |
| DA (Pin 4) | Diode anode current sense | Monitors catch diode valley current; triggers frequency foldback if >650mA to limit fault energy. |
| BOOST (Pin 2) | Switch driver bootstrap supply | Must be ≥2.2V above SW pin; generated via external capacitor and internal diode for NPN saturation. |
| SW (Pin 1) | Switch node output | Connects to inductor, catch diode cathode, and BOOST capacitor; carries high di/dt switching current. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Boost Diode | Eliminates external Schottky diode in bootstrap path, reducing BOM count and PCB footprint in MSOP-10 layout. |
| Internally Compensated | Requires no external compensation components - simplifies design and improves stability across input/output/load variations. |
| Cycle-by-Cycle Current Limit | Prevents switch destruction during momentary overloads by terminating each switching cycle when peak current exceeds ~0.9A. |
| DA-Pin Frequency Foldback | Reduces switching frequency under sustained overload, lowering power dissipation and enabling robust short-circuit survival without thermal shutdown. |
| Soft-Start via SHDN Pin | External RC on SHDN pin ramps VC node voltage, limiting inrush current and preventing output overshoot during power-up. |
Applications
| Automotive Infotainment Power | Industrial Sensor Node Supply |
|---|---|
Use Scenario: Regulating 12V vehicle battery to stable 3.3V for MCU, CAN transceiver, and display controller in head unit. IC Role / Device Role / Timing Role: Primary buck converter supplying core logic voltage with AM-band–free 1.1MHz switching to avoid radio interference. Use Value: Eliminates need for external boost diode and compensation network, reducing bill-of-materials and layout complexity in EMI-sensitive cabin environments. | Use Scenario: Converting 24V factory bus to 5V for analog sensor front-end, ADC, and wireless SoC in predictive maintenance node. IC Role / Device Role / Timing Role: High-input-voltage step-down regulator with robust short-circuit protection during field wiring faults. Use Value: Withstands 40V transients and maintains regulation down to 3V input, ensuring uptime in unregulated industrial power domains. |
| Portable Medical Device Rail | Distributed Telecom Supply |
Use Scenario: Generating 3.3V from Li-ion battery (3.0–4.2V) or wall adapter (5–24V) for patient monitor processor and memory subsystem. IC Role / Device Role / Timing Role: Wide-input buck converter with <2µA shutdown current to extend battery life during sleep mode. Use Value: Achieves >85% efficiency at 100mA load with 1.1MHz operation, enabling compact inductor selection without sacrificing runtime. | Use Scenario: Local 5V supply for FPGA I/O banks and SerDes interfaces in modular base station card with 48V backplane input. IC Role / Device Role / Timing Role: Point-of-load regulator supporting fast transient response via low-ESR ceramic output capacitance. Use Value: Internal compensation and 0.8V reference simplify loop tuning for stable operation under dynamic FPGA load steps. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3605EMS#PBF | Higher 3MHz switching frequency, 600mA output, requires external compensation, no integrated boost diode. | Better suited for ultra-compact designs needing <1µH inductors; lacks DA-foldback for short-circuit robustness. | Select LTC3605EMS#PBF only when board space is critical and fault tolerance is managed externally. |
| TPS54202DRCT | 2.5V–17V input, 2A output, 500kHz–2.2MHz adjustable frequency, integrated MOSFET, no DA-pin protection. | Higher current capacity but narrower input range; lacks valley-current foldback and 40V absolute max rating. | Choose TPS54202DRCT for cost-sensitive 12V-rail applications where 2A output is required and input stays below 17V. |
Compared with LTC3605EMS#PBF and TPS54202DRCT, the LT3502EMS#PBF offers unique combination of 40V input tolerance, integrated boost diode, DA-pin frequency foldback, and MSOP-10 thermal performance - making it optimal for ruggedized 24V/automotive point-of-load designs where reliability trumps raw current rating or minimum footprint.
Availability
LT3502EMS#PBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial sensor nodes, and portable medical devices requiring stable component supply across extended temperature ranges (–40°C to 125°C).
Supply support for LT3502EMS#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LT3502 series belongs to Linear Technology's monolithic current-mode buck regulator product line, engineered specifically for wide-input industrial and automotive power conversion where reliability, fault resilience, and compact solution size are critical.
FAQ
What is the switching frequency of the LT3502EMS#PBF?
The LT3502EMS#PBF operates at a fixed 1.1MHz switching frequency. This frequency is inherent to the LT3502 variant (as opposed to the LT3502A's 2.2MHz) and is not adjustable. It enables use of small passive components while staying above the AM radio band to prevent electromagnetic interference in automotive and consumer applications. The LT3502EMS#PBF maintains this 1.1MHz frequency across its full operating temperature range (–40°C to 125°C) and input voltage range (3V to 40V).
Does the LT3502EMS#PBF require an external boost diode?
No, the LT3502EMS#PBF integrates a boost Schottky diode internally, connected between the BD and BOOST pins. This eliminates the need for an external diode in the bootstrap circuit, reducing component count and PCB area - especially valuable in the compact 10-lead MSOP package. The internal diode supports efficient NPN switch drive, and its forward drop is characterized at 0.8V to 1.0V at 100mA, as specified in the Electrical Characteristics table.
How does the DA pin function in the LT3502EMS#PBF?
The DA (Diode Anode) pin on the LT3502EMS#PBF monitors valley current through the external catch diode. When this current exceeds 650mA, the LT3502EMS#PBF initiates frequency foldback - reducing switching frequency to limit power dissipation during overload or short-circuit events. This mechanism works in tandem with the peak switch current limit (~0.9A) to provide dual-level fault protection. The DA pin must be connected directly to the anode of the Schottky catch diode to enable this feature.
What is the maximum output current capability of the LT3502EMS#PBF?
The LT3502EMS#PBF is rated for 500mA continuous output current under typical thermal conditions (TA = 25°C, adequate PCB copper). Actual deliverable current depends on input/output voltage, ambient temperature, and PCB layout. At 12VIN → 3.3VOUT, it sustains 500mA with >85% efficiency; derating occurs above 85°C ambient or with poor thermal vias. The internal 500mA bipolar NPN switch and DA-pin foldback ensure robust operation even under sustained overload, unlike controllers requiring external FETs.
Can the LT3502EMS#PBF operate with a 3.3V input supply?
Yes, the LT3502EMS#PBF can operate with a 3.3V input, but only when configured for output voltages significantly lower than input - e.g., 1.8V or 1.2V - due to its minimum on-time of 60ns and maximum duty cycle of 90%. For a 3.3V input, the lowest practical regulated output is approximately 2.8V (accounting for switch and diode drops). Operation near the 3V undervoltage lockout threshold requires careful attention to boost capacitor charging and minimum load requirements during startup.
LT3502EMS#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):
- 36V
- Current - Output:
- 500mA
- Frequency - Switching:
- 1.1MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP
LT3502EMS#PBF FAQ
1.How can I place an order for LT3502EMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3502EMS#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 LT3502EMS#PBF reliable?
The price and inventory of LT3502EMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3502EMS#PBF is usually 5 days.
3.What payment methods are accepted for LT3502EMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3502EMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3502EMS#PBF?
LT3502EMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3502EMS#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 LT3502EMS#PBF?
For technical support, including LT3502EMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3502EMS#PBF requirements.
6.How does Aetrix verify that LT3502EMS#PBF is sourced from the original manufacturer or authorized distributors?
All LT3502EMS#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 LT3502EMS#PBF meets industry standards.
7.What is the process for return or replacement of LT3502EMS#PBF?
All LT3502EMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3502EMS#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 LT3502EMS#PBF part is unused and in its original packaging.
Return procedure for LT3502EMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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