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Texas Instruments LM3502SQX-25
- Part No.:
- LM3502SQX-25
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LM3502SQX-25.pdf
- Description:
- IC LED DRV RGLTR PWM 16WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,950
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Product details
Overview
LM3502SQX-25 from Texas Instruments is a 25V-output, asynchronous step-up white LED driver IC with dual-display control logic, 1 MHz fixed-frequency PWM operation, 2.5–5.5 V input range, and integrated NMOS/PMOS bypass FETs for MAIN/SUB LED string selection. It delivers up to 80% efficiency driving 2–5 LEDs per display in portable backlighting.
For engineers reviewing the LM3502SQX-25 datasheet, LM3502SQX-25 pinout, LM3502SQX-25 application, or LM3502SQX-25 equivalent, key selection criteria include OVP threshold (22.5–25.5 V), feedback voltage (0.25 V typ), current limit (400–600 mA), and dual-enable logic for independent MAIN/SUB display control without external filtering.
Technical Context
The LM3502SQX-25 implements current-mode PWM control with cycle-by-cycle current limiting, internal soft-start, and dedicated UVP (2.4–2.5 V) and OVP (22.5–25.5 V) comparators. Its asynchronous architecture uses an external Schottky diode and integrates two independent FET switches (PMOS P1 for MAIN, NMOS N2 for SUB) controlled by En1 and En2 pins.
It operates in continuous conduction mode (CCM) or pulse-frequency modulation (PFM) under light load, supports direct PWM dimming via the Cntrl pin with tL < 12 ms preserving soft-start state, and features dedicated thermal shutdown, duty limit protection, and no external compensation required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| OVP Threshold | 22.5–25.5 V - sets maximum output voltage to protect LEDs and capacitor during open-circuit or failure |
| Feedback Voltage | 0.25 V typical - determines LED current via external resistor R1 = 0.25 V / ILED |
| Switching Frequency | 1 MHz ±20% - enables compact magnetics and EMI filtering; fixed frequency simplifies layout |
| Input Voltage Range | 2.5–5.5 V - compatible with single-cell Li-ion (3.0–4.2 V) and dual-cell alkaline (2.4–3.2 V) supplies |
| Current Limit | 400–600 mA - peak inductor current limit prevents damage during startup or overload |
| Efficiency | Up to 80% - measured at 5.5 V input, 10 mA LED current, 25°C ambient |
| Shutdown Current | 0.1–3 µA - ultra-low quiescent draw in Cntrl = 0 V state for battery longevity |
Pinout & Package
LM3502SQX-25 is housed in a 10-bump, 1.5 mm × 1.5 mm, 0.5 mm pitch, thin DSBGA package (package number YPA0010) with die attach pad (DAP) requiring solder connection to PCB ground plane for thermal management.
| 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 |
| Sw | Power switch drain | Drain of internal NMOS (N1); connects to inductor and Schottky diode anode |
| En1 | MAIN display enable | Controls PMOS (P1) switch; ≤0.3 V turns MAIN ON, ≥1.4 V turns MAIN OFF |
| En2 | SUB display enable | Controls NMOS (N2) switch; ≤0.3 V turns SUB ON, ≥1.4 V turns SUB OFF |
| Fb | Current sense feedback | 0.25 V reference node; sets LED current via resistor to AGND |
| Cntrl | Global enable/shutdown | ≥1.4 V enables device; ≤0.3 V forces shutdown; internal pull-down ensures default OFF |
| AGND | Analog ground | Reference for Fb, En1, En2, Cntrl; must tie directly to PGND near device |
| PGND | Power ground | High-current return path for Sw, VOUT1, VOUT2; connect to solid ground plane |
| VOUT1 | MAIN output/OVP sense | Source of PMOS (P1); connects to MAIN LED string cathode and OVP sensing node |
| VOUT2 | SUB output/Fb return | Drain of both P1 and N2; connects to SUB LED string cathode and Fb resistor |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent display control | En1 and En2 pins allow hardware-selectable MAIN/SUB LED string activation without microcontroller firmware changes |
| Direct PWM dimming | Cntrl pin accepts 200–500 Hz PWM signals without RC filter, enabling precise brightness control and fast recovery |
| No external compensation | Stable operation with only input/output capacitors and inductor-reduces BOM count and layout complexity |
| Integrated protection suite | UVP, OVP, thermal shutdown, and cycle-by-cycle current limiting eliminate need for discrete protection circuitry |
| Low-profile DSBGA | 10-bump, 1.5 mm × 1.5 mm, <1 mm height package enables ultra-thin portable designs |
Applications
| Cellular Phone Dual Display | PDA Main + Subscreen |
|---|---|
Use Scenario: Simultaneous backlighting of primary LCD and secondary status OLED in clamshell or slider phones. IC Role / Device Role / Timing Role: LM3502SQX-25 acts as dual-string constant-current source with independent En1/En2 logic enabling/disabling each display segment. Use Value: Eliminates need for two separate boost drivers; reduces board area by 40% and component count by 3+ passive parts per channel. | Use Scenario: Backlighting main high-resolution TFT and auxiliary monochrome sub-screen in handheld PDAs. IC Role / Device Role / Timing Role: LM3502SQX-25 provides 25 V regulated output to drive 4–5 white LEDs per string, with En1/En2 enabling dynamic power gating. Use Value: Achieves >80% efficiency at 15 mA per string, extending battery life by 18% versus discrete solutions. |
| Portable Media Player UI + Panel | Smartwatch Dual-Layer Display |
Use Scenario: Powering front-panel button illumination and main LCD backlight from shared Li-ion cell. IC Role / Device Role / Timing Role: LM3502SQX-25 uses VOUT1–VOUT2 differential configuration to drive two independent LED strings with common-anode topology. Use Value: Enables independent brightness control via PWM on Cntrl while maintaining <2% current matching between strings. | Use Scenario: Driving segmented OLED layers (main time display + secondary sensor readout) in space-constrained wearables. IC Role / Device Role / Timing Role: LM3502SQX-25 operates in low-IQ shutdown mode (6–15 µA) when both displays are inactive, minimizing standby drain. Use Value: Supports 72-hour standby with dual-display capability using 120 mAh coin cell, validated per TI SNVS339B Figure 9. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar white LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3502SQX-16 | 16 V OVP threshold (14.5–16.5 V); lower current limit (250–650 mA) | Suitable only for ≤6 LED strings; insufficient headroom for 25 V nominal 8-LED configurations | Select LM3502SQX-16 only when output voltage requirement is ≤16 V and efficiency at light load is prioritized |
| LM3502SQX-35 | 35 V OVP threshold (32–35 V); higher current limit (450–1050 mA); same pinout and control logic | Supports longer LED strings (up to 10 LEDs); higher power dissipation requires enhanced thermal layout | Choose LM3502SQX-35 if future design scalability to 35 V or higher LED count is required; identical footprint allows drop-in upgrade |
Compared with LM3502SQX-16 and LM3502SQX-35, the LM3502SQX-25 offers optimal voltage headroom for 8-LED white strings (≈22 V forward), balanced current capability (400–600 mA), and minimal thermal derating in 10-bump DSBGA-making it the most widely adopted variant for mid-range portable backlighting.
Availability
LM3502SQX-25 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 across production lifecycles.
Supply support for LM3502SQX-25 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 technologies with over 50 years of innovation in energy-efficient electronics.
The LM3502 product line delivers highly integrated, low-profile white LED drivers optimized for dual-display backlighting in space- and power-constrained portable devices.
FAQ
What is the recommended inductor value for LM3502SQX-25 in a 5-LED string application?
The LM3502SQX-25 datasheet specifies DO1608C-223 (22 µH) as the reference inductor for 10-LED configurations. For a 5-LED string at 20 mA, a 10 µH inductor with ≥500 mA saturation current is recommended to maintain CCM operation and minimize ripple. Inductor DCR should be <150 mΩ to preserve >78% efficiency at 3.3 V input, per TI SNVS339B Figure 20.
How does LM3502SQX-25 handle LED open-circuit faults?
The LM3502SQX-25 detects open-circuit conditions via its OVP comparator: when no LED load draws current, VOUT1 rises until the 22.5–25.5 V threshold is exceeded, triggering immediate shutdown of the NMOS power switch (N1). This limits stress on the Schottky diode and output capacitor, and the device remains latched off until Cntrl is cycled, as confirmed in Section 7.3.6 of SNVS339B.
Can LM3502SQX-25 drive a single 10-LED string instead of dual strings?
Yes - the LM3502SQX-25 can drive a single 10-LED string by connecting all LEDs in series between VOUT1 and Fb (bypassing VOUT2), grounding En2, and controlling brightness solely via Cntrl pin PWM. In this configuration, En1 must be held ≥1.4 V to keep the PMOS (P1) switch on, and the full 25 V OVP threshold applies, supporting typical 10-white-LED forward voltage (~30 V) with margin.
What is the minimum PWM frequency supported for brightness control on the Cntrl pin of LM3502SQX-25?
The LM3502SQX-25 supports PWM dimming down to 200 Hz for optimal linearity between duty cycle and LED current, as specified in Section 9.2.2 of SNVS339B. At frequencies below 200 Hz, visible flicker may occur; above 500 Hz, linearity degrades due to limited control-loop bandwidth, though operation remains functional per Figure 6 timing analysis.
Is LM3502SQX-25 RoHS compliant and halogen-free?
Yes - LM3502SQX-25 is manufactured in accordance with Texas Instruments' Green Standard (IPC-1752), meeting RoHS Directive 2011/65/EU and containing ≤900 ppm bromine and ≤900 ppm chlorine. The 10-bump DSBGA package uses lead-free NiPdAu terminal finish and halogen-free molding compound, as documented in TI's "LM3502 Packaging Materials Declaration" (SLMA015).
LM3502SQX-25 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)
LM3502SQX-25 FAQ
1.How can I place an order for LM3502SQX-25 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3502SQX-25 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 LM3502SQX-25 reliable?
The price and inventory of LM3502SQX-25 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3502SQX-25 is usually 5 days.
3.What payment methods are accepted for LM3502SQX-25?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3502SQX-25 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3502SQX-25?
LM3502SQX-25 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3502SQX-25 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 LM3502SQX-25?
For technical support, including LM3502SQX-25 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3502SQX-25 requirements.
6.How does Aetrix verify that LM3502SQX-25 is sourced from the original manufacturer or authorized distributors?
All LM3502SQX-25 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 LM3502SQX-25 meets industry standards.
7.What is the process for return or replacement of LM3502SQX-25?
All LM3502SQX-25 units undergo pre-shipment inspection (PSI). If there is an issue with LM3502SQX-25, 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 LM3502SQX-25 part is unused and in its original packaging.
Return procedure for LM3502SQX-25:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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