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Texas Instruments LM3502SQ-25/NOPB
- Part No.:
- LM3502SQ-25/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LM3502SQ-25/NOPB.pdf
- Description:
- IC LED DRV RGLTR PWM 16WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,179
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Product details
Overview
LM3502SQ-25/NOPB from Texas Instruments is a 25 V-output, asynchronous current-mode step-up white LED driver IC with dual independent display control logic, 1 MHz fixed switching frequency, 2.5–5.5 V input range, and integrated PMOS/NMOS bypass FETs for MAIN/SUB backlight segmentation in portable devices.
For engineers reviewing the LM3502SQ-25/NOPB datasheet, LM3502SQ-25/NOPB pinout, LM3502SQ-25/NOPB application, or LM3502SQ-25/NOPB equivalent, this page delivers verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternative options, and supply-ready availability details - all specific to the LM3502SQ-25/NOPB variant.
Technical Context
The LM3502SQ-25/NOPB implements an asynchronous current-mode PWM control architecture with cycle-by-cycle current limiting, dedicated over-voltage protection (OVP) set at 22.5–25.5 V (on-threshold), and under-voltage lockout (UVP) at 2.4–2.5 V. It integrates two independent FET switches - a 5–10 Ω PMOS (P1) for MAIN display control and a 2.5–5 Ω NMOS (N2) for SUB display control - enabling dynamic segmentation of a single LED string.
Its feedback loop regulates LED current via a 0.18–0.30 V reference at the Fb pin, supporting direct PWM dimming on the Cntrl pin without external RC filtering. The device operates in continuous conduction mode (CCM) or pulse-frequency modulation (PFM) under light loads, with soft-start eliminating inrush current and thermal shutdown protecting junction temperatures up to +150°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 25 V nominal; OVP on-threshold 22.5–25.5 V ensures safe operation when LEDs open or disconnect. |
| Input Voltage Range | 2.5 V to 5.5 V; supports single-cell Li-ion (3.0–4.2 V) and dual-cell alkaline (2.5–3.2 V) battery inputs. |
| Switching Frequency | 1 MHz ±20%; enables compact magnetics (e.g., 2.2 µH inductor) and reduces EMI susceptibility. |
| Feedback Reference | 0.25 V typical at Fb pin; sets LED current via external resistor: ILED = 0.25 V / RSET. |
| Current Limit | 400–800 mA (typical 600 mA); protects internal NMOS switch (N1) during startup or short-circuit events. |
| Quiescent Current | 1.9–3 mA (switching), 0.1–3 µA (shutdown); extends battery life in always-on portable displays. |
| Efficiency | >80% typical at 5 mA–90 mA LED load; peaks near 85–90% for 4–10 LED strings at 5.5 V input. |
Pinout & Package
LM3502SQ-25/NOPB uses a 10-bump thin DSBGA package (package code YPA0010), height <1 mm, suitable for ultra-thin portable designs. Thermal performance optimized via die attach pad (DAP) soldered to PCB ground plane (θJA = 65°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Supply input | Connects to 2.5–5.5 V source; requires local 4.7 µF ceramic capacitor to PGND for stability. |
| Sw | Power NMOS drain | Drives external inductor; minimize trace length/width to reduce EMI and conduction loss. |
| En1 | MAIN display FET control | ≤0.3 V enables MAIN segment (P1 ON); ≥1.4 V disables MAIN (P1 OFF); internal pull-down defaults to OFF. |
| En2 | SUB display FET control | ≤0.3 V enables SUB segment (N2 ON); ≥1.4 V disables SUB (N2 OFF); internal pull-down defaults to OFF. |
| Fb | Current-sense feedback | 0.25 V reference node; connect current-setting resistor to AGND to program LED current. |
| Cntrl | Global enable/shutdown | ≥1.4 V enables device; ≤0.3 V forces shutdown; supports direct PWM dimming without RC filter. |
| AGND | Analog ground | Must be tied directly to PGND to avoid noise coupling into feedback path. |
| PGND | Power ground | High-current return path for Sw, VOUT1, VOUT2; connect to low-impedance PCB ground plane. |
| VOUT1 | OVP sense & P1 source | Connects to cathode of Schottky diode and output capacitor; OVP monitors this node for 25 V threshold. |
| VOUT2 | N2/P1 drain junction | Used only when splitting LED string between MAIN and SUB; otherwise tie to GND or leave unconnected per datasheet. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent display control | Separate En1/En2 pins allow hardware-selectable MAIN/SUB backlight activation without MCU intervention. |
| Direct PWM dimming | Cntrl pin accepts 200–500 Hz PWM signals for linear brightness control-no external RC network required. |
| Integrated OVP/UVP protection | OVP (25 V) prevents capacitor overvoltage during LED open-circuit; UVP (2.5 V) disables operation below battery cutoff. |
| Low-profile DSBGA package | 10-bump, <1 mm height package enables integration into space-constrained handheld displays. |
| No external compensation | Stable operation with only input/output capacitors and inductor-reduces BOM count and layout complexity. |
Applications
| Cellular Phone Dual Display | PDA Main/Sub Backlight |
|---|---|
Use Scenario: Simultaneous illumination of main LCD and secondary status OLED in clamshell or slider phones. IC Role / Device Role / Timing Role: LM3502SQ-25/NOPB acts as dual-string boost controller, regulating current through two physically separate LED segments using En1/En2 logic. Use Value: Enables independent brightness control and power gating of each display-reducing total system current by up to 50% when only one display is active. | Use Scenario: Powering primary touchscreen backlight and auxiliary keypad or notification LED array in PDAs. IC Role / Device Role / Timing Role: LM3502SQ-25/NOPB serves as segmented LED driver, sourcing up to 90 mA per string with matched current accuracy across both outputs. Use Value: Eliminates need for two discrete boost converters-saving PCB area and reducing component count by 30% versus dual-IC solution. |
| Portable Media Player UI | Handheld GPS Navigation |
Use Scenario: Driving high-brightness main screen and low-power menu indicator bar in MP3/video players. IC Role / Device Role / Timing Role: LM3502SQ-25/NOPB functions as adaptive backlight manager, using Cntrl PWM for global dimming and En1/En2 for UI context-aware segment enable. Use Value: Achieves >80% efficiency at 20 mA per string-extending playback time by 12% compared to linear drivers at same brightness. | Use Scenario: Illuminating outdoor-readable main map display and indoor-optimized compass/status panel in GPS units. IC Role / Device Role / Timing Role: LM3502SQ-25/NOPB operates as dual-rail LED driver, delivering 25 V to 8-white-LED main string and 16 V (via VOUT2 tap) to 4-LED sub-string. Use Value: Maintains consistent luminance across temperature (−40°C to +85°C ambient) due to stable 0.25 V reference and thermal shutdown protection. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar white LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3502SQ-16/NOPB | 16 V OVP threshold; lower current limit (250–650 mA); identical pinout and control logic. | Optimized for 4–6 LED strings; insufficient headroom for 8–10 LED configurations requiring ≥22 V. | Select when driving shorter LED strings with tighter voltage margin and lower power dissipation. |
| LM3502SQ-35/NOPB | 35 V OVP threshold; higher current limit (450–1050 mA); same DSBGA-10 package and interface. | Supports longer LED strings (up to 10 LEDs at 3.2 V each); higher quiescent current in shutdown (0.1–3 µA vs. 0.1–3 µA, same). | Choose for high-brightness industrial or automotive displays needing extended output voltage range. |
Compared with LM3502SQ-16/NOPB, the LM3502SQ-25/NOPB provides 9 V more OVP headroom for reliable 8-LED operation; versus LM3502SQ-35/NOPB, it reduces peak switch stress and improves light-load efficiency in mid-range portable displays.
Availability
LM3502SQ-25/NOPB is available at Aetrix Electronics and suitable for cellular phone backlighting, PDA dual-display systems, and portable media player UI illumination requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LM3502SQ-25/NOPB 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
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management ICs, with decades of expertise in portable power conversion and display interface solutions.
The LM3502 product line was designed specifically for dual-display white LED backlighting in battery-powered handheld devices, emphasizing low IQ, small footprint, and robust protection for consumer-grade reliability.
FAQ
What is the maximum LED string voltage supported by LM3502SQ-25/NOPB?
The LM3502SQ-25/NOPB supports up to 25 V output with over-voltage protection triggered at 22.5–25.5 V. This allows driving up to 8 standard white LEDs (3.2 V forward voltage each) or 10 lower-Vf LEDs in series while maintaining safety margin. Exceeding 25 V risks OVP activation and shutdown.
How does LM3502SQ-25/NOPB implement dual-display control without external logic?
The LM3502SQ-25/NOPB uses dedicated En1 and En2 pins to independently gate its internal PMOS (P1) and NMOS (N2) FETs. When En1 ≤0.3 V, MAIN display activates; when En2 ≤0.3 V, SUB display activates. Both can be controlled directly by GPIOs-no external transistors or level shifters needed.
Can LM3502SQ-25/NOPB be used with a single LED string split into MAIN and SUB sections?
Yes. LM3502SQ-25/NOPB is explicitly designed for this topology: VOUT1 connects to the anode of the first LED segment (MAIN), VOUT2 taps between MAIN and SUB, and Fb connects to the cathode of the final LED. En1 and En2 control current flow through each segment independently.
What is the recommended inductor value for LM3502SQ-25/NOPB in a 5.5 V input, 8-LED application?
For 5.5 V input driving eight 3.2 V white LEDs (25.6 V total), a 2.2 µH shielded inductor with ≥800 mA saturation current is recommended. This value balances ripple current (<30% of LED current), efficiency (>85%), and physical size-matching TI's reference design DO1608C-223.
Does LM3502SQ-25/NOPB require external compensation components?
No. LM3502SQ-25/NOPB is internally compensated and operates stably with only the required external components: input capacitor (4.7 µF), output capacitor (1 µF), inductor (2.2 µH), and current-set resistor. No RC networks, op-amps, or additional feedback elements are needed.
LM3502SQ-25/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- DC DC Regulator
- Topology:
- Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 2
- Voltage - Supply (Min):
- 2.5V
- Voltage - Supply (Max):
- 5.5V
- Voltage - Output:
- 25V
- Current - Output / Channel:
- 600mA (Switch)
- Frequency:
- 1MHz
- Dimming:
- PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-WQFN (4x4)
LM3502SQ-25/NOPB FAQ
1.How can I place an order for LM3502SQ-25/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3502SQ-25/NOPB 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 LM3502SQ-25/NOPB reliable?
The price and inventory of LM3502SQ-25/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3502SQ-25/NOPB is usually 5 days.
3.What payment methods are accepted for LM3502SQ-25/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3502SQ-25/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3502SQ-25/NOPB?
LM3502SQ-25/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3502SQ-25/NOPB 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 LM3502SQ-25/NOPB?
For technical support, including LM3502SQ-25/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3502SQ-25/NOPB requirements.
6.How does Aetrix verify that LM3502SQ-25/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3502SQ-25/NOPB 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 LM3502SQ-25/NOPB meets industry standards.
7.What is the process for return or replacement of LM3502SQ-25/NOPB?
All LM3502SQ-25/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3502SQ-25/NOPB, 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 LM3502SQ-25/NOPB part is unused and in its original packaging.
Return procedure for LM3502SQ-25/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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