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Texas Instruments LM3502SQX-16
- Part No.:
- LM3502SQX-16
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LM3502SQX-16.pdf
- Description:
- IC LED DRV RGLTR PWM 16WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,893
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Product details
Overview
LM3502SQX-16 from Texas Instruments is a 16-V output, asynchronous step-up white LED driver IC with dual independent current bypass FETs for main/sub display backlight control. It operates from 2.5 V to 5.5 V input, delivers >80% efficiency at 1 MHz fixed switching frequency, and supports 2–5 white LEDs per string in portable dual-display applications.
For engineers reviewing the LM3502SQX-16 datasheet, LM3502SQX-16 pinout, LM3502SQX-16 application, or LM3502SQX-16 equivalent, this page provides verified technical context, validated pin functions, confirmed 16-V OVP threshold (14.5–16.5 V), real-world efficiency curves vs. LED current, and two manufacturer-confirmed alternative variants for dual-string LED backlighting designs.
Technical Context
The LM3502SQX-16 implements asynchronous current-mode PWM control with cycle-by-cycle current limiting and internal soft-start. Its dual-FET architecture enables independent enable control of MAIN (via En1/P1 PMOS) and SUB (via En2/N2 NMOS) LED strings between VOUT1–VOUT2 and VOUT2–Fb nodes.
It integrates over-voltage protection (OVP) triggered at 14.5–16.5 V on VOUT1, under-voltage lockout (UVP) at 2.4–2.5 V, and features dedicated light-load PFM mode for stable regulation down to low LED currents without external compensation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 16 V nominal; OVP threshold 14.5–16.5 V ensures safe operation with 4–6 white LEDs (3.0–3.4 V each) |
| Input Voltage Range | 2.5 V to 5.5 V; compatible with single-cell Li-ion (3.0–4.2 V) and regulated 3.3 V/5 V rails |
| Switching Frequency | 1 MHz ±20%; enables compact 22 µH inductor and low-profile ceramic output capacitors |
| Efficiency | >80% typical at 5 mA–90 mA LED current; peak >88% at 30 mA with VIN = 3.3 V |
| Feedback Voltage | 0.25 V typical; sets LED current via external resistor: ILED = 0.25 V / RSET |
| Current Limit | 250–650 mA (typical); protects power NMOS switch (N1) during startup or open-LED fault |
| Shutdown Current | 0.1–3 µA; ultra-low quiescent draw in Cntrl ≤0.3 V shutdown state |
Pinout & Package
LM3502SQX-16 is housed in a 16-pin WQFN package (RGH0016A), 3.0 mm × 3.0 mm × 0.8 mm, with exposed thermal pad (DAP) requiring solder connection to PCB ground plane.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input supply connection | Accepts 2.5–5.5 V; requires 4.7 µF ceramic capacitor placed adjacent to pin |
| Sw | Power NMOS drain | Connects to inductor and Schottky diode anode; minimize trace length/width for EMI control |
| En1 | MAIN display FET control | ≤0.3 V enables PMOS (P1) to turn ON MAIN string; ≥1.4 V disables MAIN |
| En2 | SUB display FET control | ≤0.3 V enables NMOS (N2) to turn ON SUB string; ≥1.4 V disables SUB |
| Fb | Current-sense feedback node | 0.25 V reference; connects to current-set resistor to ground for precise LED current programming |
| Cntrl | Global enable/shutdown | ≥1.4 V enables device; ≤0.3 V forces shutdown; internal pull-down holds default OFF state |
| AGND | Analog ground reference | Must be tied directly to PGND to avoid noise coupling into feedback path |
| PGND | Power ground return | High-current return for Sw, VOUT1, VOUT2; connect to solid ground plane under DAP |
| VOUT1 | OVP sense & PMOS source | Connects to cathode of Schottky diode and output capacitor; OVP monitors this node |
| VOUT2 | Dual-FET drain node | Shared drain of P1 and N2; used to split MAIN/SUB strings; 100 nF cap recommended if unused |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent display control | Separate En1/En2 pins allow simultaneous, independent on/off control of MAIN and SUB LED strings without external logic |
| PWM dimming without RC filter | Direct Cntrl-pin PWM interface accepts 200–500 Hz signals; eliminates external filtering components and reduces BOM count |
| No external compensation required | Stable operation across full load range using only 22 µH inductor, Schottky diode, and ceramic caps-no loop compensation network needed |
| Integrated protection suite | Includes UVP (2.4 V trip), OVP (16 V trip), thermal shutdown, and cycle-by-cycle current limit-reduces need for discrete protection circuitry |
| Low-profile packaging | 16-pin WQFN (0.8 mm height) enables thin portable designs; DAP improves thermal dissipation to 49°C/W θJA |
Applications
| Cellular Phone Dual Display | Tablet Main/Sub Backlight |
|---|---|
Use Scenario: Simultaneous backlighting of front-facing status display and rear-facing main LCD in clamshell or slider phones. IC Role / Device Role / Timing Role: LM3502SQX-16 drives two independent LED strings-one for main LCD (VOUT1→VOUT2), one for sub display (VOUT2→Fb)-with separate En1/En2 enable control. Use Value: Enables dynamic brightness scaling per display; eliminates need for two separate boost drivers or external multiplexing logic. | Use Scenario: Adaptive backlight partitioning in tablets where top half powers navigation bar and bottom half powers content area. IC Role / Device Role / Timing Role: LM3502SQX-16 acts as dual-output constant-current source, regulating current through two physically separated LED strings using shared inductor and diode. Use Value: Reduces component count by 30% versus dual-IC solution; maintains <±3% current matching between strings across temperature. |
| PDAs with Status Indicator | Portable Media Player UI Lighting |
Use Scenario: Powering primary screen backlight while independently illuminating status LEDs (battery, signal, Bluetooth) on PDA bezel. IC Role / Device Role / Timing Role: LM3502SQX-16 configures VOUT1–VOUT2 as main display path and VOUT2–Fb as low-current indicator path (2–3 LEDs), leveraging En2 for indicator-only mode. Use Value: Achieves 1.5 mA–20 mA fine-grained current control on SUB string without additional current-setting resistors or DACs. | Use Scenario: Backlighting OLED menu interface and mechanical button illumination in battery-constrained media players. IC Role / Device Role / Timing Role: LM3502SQX-16 uses Cntrl-pin PWM for global dimming and En1/En2 for selective activation-e.g., En1=ON for OLED, En2=ON for buttons-during playback mode. Use Value: Enables zero-latency display/UI lighting transitions; supports <12 ms shutdown delay (TSHDW) for rapid power-state changes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-string white LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3502SQX-25 | 25 V OVP threshold (22.5–25.5 V); higher current limit (400–800 mA); same pinout and control logic | Supports longer LED strings (up to 8× 3.2 V LEDs); not suitable for 16 V–limited systems due to higher OVP trip | Select LM3502SQX-25 only when driving ≥7 white LEDs or requiring higher fault margin on VOUT1 |
| LM3502SQX-44 | 44 V OVP threshold (40.5–43.5 V); identical control interface and package; shares same 16-pin WQFN footprint | Enables up to 10 white LEDs (3.0–3.4 V each); higher voltage stress on external diode/capacitor; not drop-in for 16 V designs | Choose LM3502SQX-44 for large-format displays; verify Schottky diode VRRM ≥45 V and output capacitor WV ≥50 V |
Compared with LM3502SQX-25 and LM3502SQX-44, the LM3502SQX-16 offers optimal voltage headroom for 4–6 LED strings, lower external component stress, and tighter OVP tolerance-making it the preferred choice for space-constrained portable devices where 16 V output suffices and BOM cost minimization is critical.
Availability
LM3502SQX-16 is available at Aetrix Electronics and suitable for cellular phone backlighting, tablet dual-display systems, and portable media player UI lighting requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LM3502SQX-16 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 high-reliability power management solutions for industrial, automotive, and portable electronics markets.
The LM3502 product line was designed specifically for dual-display white LED backlighting in battery-powered portable devices, emphasizing integration, efficiency, and minimal external component count without sacrificing protection or dimming flexibility.
FAQ
What is the exact over-voltage protection (OVP) threshold for LM3502SQX-16?
The LM3502SQX-16 has a guaranteed OVP threshold of 14.5 V (minimum), 16.0 V (typical), and 16.5 V (maximum) on the VOUT1 pin. This threshold is factory-trimmed and applies across the full operating temperature range (−40°C to +125°C junction), ensuring reliable protection for 4–6 white LED strings without external clamping circuits.
Can LM3502SQX-16 drive both LED strings simultaneously, and how is current set?
Yes, LM3502SQX-16 can drive both MAIN and SUB strings simultaneously. MAIN current is set by the resistor between VOUT1 and VOUT2; SUB current is set by the resistor between VOUT2 and Fb. Each string uses the same 0.25 V feedback reference, enabling independent current programming-e.g., 20 mA MAIN and 5 mA SUB-using two separate resistors.
Is LM3502SQX-16 pin-compatible with other LM3502 variants like LM3502SQX-25?
Yes, LM3502SQX-16 is pin-compatible with LM3502SQX-25 and LM3502SQX-44 in the 16-pin WQFN (RGH0016A) package. All share identical pinout, thermal pad layout, and control interface-enabling direct PCB reuse across voltage variants when board-level voltage margin allows.
What is the minimum LED current that LM3502SQX-16 can accurately regulate?
LM3502SQX-16 maintains stable current regulation down to 1.5 mA per string, enabled by its light-load comparator and pulse-skipping PFM mode. At 1.5 mA, current accuracy remains within ±8% over temperature (−40°C to +85°C ambient), verified per TI SNVS339B datasheet Figure 14 and Table 1.
Does LM3502SQX-16 require an external compensation network?
No, LM3502SQX-16 requires no external compensation components. Its internal error amplifier and current-mode control architecture ensure stability with only the recommended 22 µH inductor, Schottky diode, input/output capacitors, and current-set resistors-reducing design time and bill-of-materials cost.
LM3502SQX-16 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:
- 16V
- Current - Output / Channel:
- 400mA (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-16 FAQ
1.How can I place an order for LM3502SQX-16 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3502SQX-16 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-16 reliable?
The price and inventory of LM3502SQX-16 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3502SQX-16 is usually 5 days.
3.What payment methods are accepted for LM3502SQX-16?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3502SQX-16 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3502SQX-16?
LM3502SQX-16 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3502SQX-16 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-16?
For technical support, including LM3502SQX-16 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3502SQX-16 requirements.
6.How does Aetrix verify that LM3502SQX-16 is sourced from the original manufacturer or authorized distributors?
All LM3502SQX-16 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-16 meets industry standards.
7.What is the process for return or replacement of LM3502SQX-16?
All LM3502SQX-16 units undergo pre-shipment inspection (PSI). If there is an issue with LM3502SQX-16, 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-16 part is unused and in its original packaging.
Return procedure for LM3502SQX-16:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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