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Texas Instruments LM3502SQX-35
- Part No.:
- LM3502SQX-35
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LM3502SQX-35.pdf
- Description:
- IC LED DRV RGLTR PWM 16WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,069
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Product details
Overview
LM3502SQX-35 from Texas Instruments is a 35V-output, asynchronous step-up white LED driver IC with dual independent FET switches for main/sub display backlight control. It operates from 2.5V–5.5V input, delivers >80% efficiency at 1 MHz fixed switching frequency, and supports PWM dimming without external RC filtering - used in portable dual-display backlight systems requiring precise current regulation across two LED strings.
For engineers reviewing the LM3502SQX-35 datasheet, LM3502SQX-35 pinout, LM3502SQX-35 application, or LM3502SQX-35 equivalent, key selection criteria include its 35V OVP threshold (32–35 V), 750 mA typical current limit (Fb = 0 V), dual enable logic for MAIN/SUB segment control, and compatibility with low-profile 10-bump DSBGA packaging.
Technical Context
The LM3502SQX-35 implements asynchronous current-mode PWM control with cycle-by-cycle current limiting and dedicated over-voltage protection (OVP) set to 32–35 V. Its internal architecture integrates two independent MOSFET switches - a PMOS (P1) controlled by En1 and an NMOS (N2) controlled by En2 - enabling selective activation of MAIN (VOUT1–VOUT2) and SUB (VOUT2–Fb) LED segments.
It features built-in soft-start, under-voltage lockout (UVP at 2.4–2.5 V), thermal shutdown, and light-load pulse-frequency modulation (PFM) mode. The feedback pin (Fb) regulates LED current via external resistor, with a precise 0.25 V typical reference voltage and <500 nA bias current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 35 V nominal OVP threshold; enables driving up to 8–10 white LEDs in series per string. |
| Input Voltage Range | 2.5 V to 5.5 V; compatible with single-cell Li-ion or 3.3 V/5 V system rails. |
| Switching Frequency | 1 MHz ±20%; enables compact magnetics and reduces EMI filter size. |
| Current Limit | 750 mA typical (Fb = 0 V); protects power switch N1 during startup or overload. |
| Feedback Reference | 0.25 V typical (0.18–0.30 V); sets LED current via RSET = 0.25 V / ILED. |
| Efficiency | >80% typical at full load; achieved via low RDS(ON) (0.55 Ω NMOS, 5 Ω PMOS) and synchronous-free topology. |
| Shutdown Current | 0.1–3 µA; ensures ultra-low quiescent draw when Cntrl ≤0.3 V. |
Pinout & Package
LM3502SQX-35 uses a 10-bump thin DSBGA package (package number YPA0010), height <1 mm, suitable for space-constrained portable PCBs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input supply connection | Accepts 2.5–5.5 V; requires local 4.7 µF ceramic capacitor to PGND. |
| Sw | Power NMOS drain | Connects to inductor and Schottky diode anode; high dv/dt node requiring short, wide trace. |
| En1 | PMOS (P1) enable control | ≤0.3 V enables MAIN display (VOUT1–VOUT2); ≥1.4 V disables it; internal pull-down. |
| En2 | NMOS (N2) enable control | ≤0.3 V enables SUB display (VOUT2–Fb); ≥1.4 V disables it; internal pull-down. |
| Fb | Current-sense feedback input | 0.25 V reference; connects to ground via RSET to program LED current. |
| Cntrl | Global enable/shutdown | ≥1.4 V enables device; ≤0.3 V forces shutdown; supports PWM dimming directly. |
| AGND | Analog ground reference | Must be tied directly to PGND to minimize noise coupling into Fb and control loops. |
| PGND | Power ground return | High-current return path for Sw, VOUT1, VOUT2; requires low-impedance connection to PCB ground plane. |
| VOUT1 | OVP sense & PMOS source | Connects to cathode of output Schottky and high-side LED string; OVP triggers at 32–35 V. |
| VOUT2 | Internal FET drain junction | Node between MAIN and SUB LED segments; unused in single-string configs (must be bypassed with 100 nF). |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent display control | Separate En1/En2 pins allow hardware-selectable MAIN/SUB backlight activation without MCU intervention. |
| PWM dimming without RC filter | Internal circuitry accepts direct 200–500 Hz PWM on Cntrl pin; eliminates external filter components and startup delay. |
| Integrated OVP with 35 V threshold | Prevents damage during open-circuit LED failure or string disconnect; allows use of low-voltage-rated output capacitors. |
| Low IQ shutdown mode | 6–15 µA current draw when Cntrl ≥1.4 V and both En1/En2 ≤0.3 V - maintains system-level power budget. |
| Thermal and cycle-by-cycle protection | Combines junction temperature shutdown, UVP (2.4 V), and per-cycle current limiting to ensure robust operation. |
Applications
| Cellular Phone Dual Display | Portable Media Player Backlight |
|---|---|
Use Scenario: Simultaneous illumination of main LCD and secondary status OLED in clamshell or slider phones. IC Role / Device Role / Timing Role: LM3502SQX-35 acts as dual-channel constant-current LED driver, regulating MAIN and SUB strings independently via En1/En2 logic. Use Value: Enables dynamic brightness scaling per display using only two GPIOs; eliminates need for separate drivers or complex sequencing. | Use Scenario: Powering high-brightness white LED arrays behind TFT-LCDs in handheld video players. IC Role / Device Role / Timing Role: LM3502SQX-35 serves as primary boost converter with integrated current regulation, delivering stable 35 V output to 8–10 LED series string. Use Value: Achieves >80% efficiency at 1 MHz, reducing heat and extending battery life without compromising brightness uniformity. |
| Smartphone Status Indicator Panel | Industrial Handheld Terminal Display |
Use Scenario: Driving segmented LED indicators (e.g., signal strength, battery, connectivity) alongside main screen backlight. IC Role / Device Role / Timing Role: LM3502SQX-35 repurposes VOUT2/Fb path as low-current SUB channel for indicator LEDs while MAIN powers display. Use Value: Reduces BOM count by consolidating two lighting functions into one IC; simplifies layout with shared inductor and diode. | Use Scenario: Reliable backlighting for ruggedized LCDs in warehouse scanners or field service terminals operating across −40°C to +85°C. IC Role / Device Role / Timing Role: LM3502SQX-35 provides regulated current with guaranteed operation from −40°C to +125°C junction temperature. Use Value: Maintains consistent luminance across temperature extremes via stable 0.25 V Fb 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 |
|---|---|---|---|
| LM3502SQX-25 | 25 V OVP threshold; lower current limit (600 mA typ); identical pinout and control logic. | Suitable for 4–6 LED strings; insufficient headroom for 8–10 LED configurations requiring 35 V. | Select LM3502SQX-25 only if total forward voltage remains below 23 V - avoids unnecessary overdesign. |
| TPS61165DRVR | Single-output 38 V boost LED driver; no dual-segment control; higher 1.2 MHz switching frequency. | Lacks En1/En2 logic; requires external PWM controller or MCU for multi-string sequencing. | Choose TPS61165DRVR when only one LED string is needed and maximum output voltage margin is critical. |
Compared with LM3502SQX-25 and TPS61165DRVR, the LM3502SQX-35 uniquely balances 35 V OVP headroom with hardware-based dual-display control - enabling simpler, more reliable backlight management in space- and power-constrained portable designs.
Availability
LM3502SQX-35 is available at Aetrix Electronics and suitable for cellular phone backlighting, portable media player displays, and industrial handheld terminal lighting requiring stable component supply and long-term manufacturability.
Supply support for LM3502SQX-35 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 broad industrial and consumer design support.
The LM3502 product line targets portable backlight applications, delivering integrated dual-channel LED drivers with programmable OVP thresholds and minimal external component count.
FAQ
What is the exact over-voltage protection (OVP) threshold for LM3502SQX-35?
The LM3502SQX-35 has a nominal OVP threshold of 35 V, with specified on-threshold range of 32.0–35.0 V and off-threshold of 31.0–34.0 V. This setting is factory-trimmed and applies specifically to the -35 variant; other versions (e.g., -16, -25, -44) have different thresholds. The OVP circuit disables switching when VOUT1 exceeds the threshold, protecting LEDs and external components during open-circuit conditions.
Can LM3502SQX-35 drive both MAIN and SUB LED strings simultaneously?
Yes - LM3502SQX-35 can drive both MAIN and SUB strings concurrently when En1 ≥1.4 V and En2 ≥1.4 V, enabling full dual-display illumination. In this state, the PMOS (P1) and NMOS (N2) switches are both off, allowing current to flow through the complete string from VOUT1 → VOUT2 → Fb. The configuration is confirmed in Figure 5 of the datasheet and supported by the device's dual-FET architecture.
What is the recommended current-setting resistor value for 20 mA LED current with LM3502SQX-35?
Using the standard formula RSET = VFb / ILED, and the typical feedback voltage of 0.25 V, the resistor for 20 mA is 12.5 Ω. A standard 12.4 Ω (1% tolerance) surface-mount resistor is recommended. This value is validated across temperature (−40°C to +125°C) and matches the LM3502SQX-35's 0.18–0.30 V Fb specification range.
Does LM3502SQX-35 require external compensation components?
No - LM3502SQX-35 operates with no external compensation required. Its current-mode control architecture and internal error amplifier are fully stabilized for standard boost configurations using the recommended 22 µH inductor and 1 µF output capacitor. This eliminates tuning effort and improves design reproducibility across production batches.
What package type is used for LM3502SQX-35, and what are its thermal characteristics?
LM3502SQX-35 uses a 10-bump thin DSBGA package (YPA0010) with <1 mm height. Its junction-to-ambient thermal resistance (θJA) is 65°C/W under standard JEDEC conditions. The die attach pad (DAP) must be soldered to the PCB ground plane to achieve this rating; omitting DAP connection degrades thermal performance significantly.
LM3502SQX-35 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:
- 35V
- Current - Output / Channel:
- 750mA (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-35 FAQ
1.How can I place an order for LM3502SQX-35 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3502SQX-35 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-35 reliable?
The price and inventory of LM3502SQX-35 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3502SQX-35 is usually 5 days.
3.What payment methods are accepted for LM3502SQX-35?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3502SQX-35 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3502SQX-35?
LM3502SQX-35 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3502SQX-35 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-35?
For technical support, including LM3502SQX-35 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3502SQX-35 requirements.
6.How does Aetrix verify that LM3502SQX-35 is sourced from the original manufacturer or authorized distributors?
All LM3502SQX-35 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-35 meets industry standards.
7.What is the process for return or replacement of LM3502SQX-35?
All LM3502SQX-35 units undergo pre-shipment inspection (PSI). If there is an issue with LM3502SQX-35, 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-35 part is unused and in its original packaging.
Return procedure for LM3502SQX-35:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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