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Texas Instruments LM3502SQX-35/NOPB
- Part No.:
- LM3502SQX-35/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LM3502SQX-35/NOPB.pdf
- Description:
- IC LED DRV RGLTR PWM 16WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,305
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Product details
Overview
LM3502SQX-35/NOPB from Texas Instruments is a 35V-output asynchronous step-up white LED driver IC with dual independent current bypass FETs for MAIN/SUB display backlight control. It operates from 2.5V–5.5V input, delivers >80% efficiency at 1 MHz switching frequency, and supports up to 10 white LEDs (5 per string) in portable dual-display applications.
For engineers reviewing the LM3502SQX-35/NOPB datasheet, LM3502SQX-35/NOPB pinout, LM3502SQX-35/NOPB application, or LM3502SQX-35/NOPB equivalent, key selection criteria include its 35V OVP threshold, integrated En1/En2 logic for dual-string sequencing, PWM dimming capability without external RC filtering, and DSBGA-10 package thermal performance (θJA = 65°C/W).
Technical Context
The LM3502SQX-35/NOPB implements current-mode PWM control with cycle-by-cycle current limiting and dedicated over-voltage protection (OVP on/off thresholds: 32.0 V / 31.0 V). Its internal architecture integrates two independent NMOS/PMOS bypass FETs (En1 controls MAIN string between VOUT1–VOUT2; En2 controls SUB string between VOUT2–Fb), enabling selective activation of dual LED strings without external switches.
It features internal soft-start, under-voltage lockout (UVP: 2.4 V ON / 2.2 V OFF), and light-load pulse-frequency modulation (PFM) mode. The device accepts direct PWM dimming on the Cntrl pin with tL < 12 ms preserving soft-start state, eliminating need for external filtering while maintaining fast recovery.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 35 V nominal; OVP active at 32.0–35.0 V, protecting against open-string failure |
| Input Voltage Range | 2.5 V to 5.5 V; compatible with single-cell Li-ion (3.0–4.2 V) and dual-cell alkaline systems |
| Switching Frequency | 1 MHz ±20%; enables compact 22 µH inductor and low-profile ceramic output capacitors |
| Current Limit (Typ) | 750 mA at 35 V option; sets maximum peak inductor current to prevent FET overstress |
| Feedback Voltage | 0.25 V (typ); defines LED current via external resistor: ILED = 0.25 V / RSET |
| Efficiency | >80% at 5.5 V input driving 10 LEDs; reduces thermal load in space-constrained handheld PCBs |
| Shutdown Current | 0.1–3 µA; ensures battery longevity during display-off states in portable devices |
Pinout & Package
LM3502SQX-35/NOPB uses a 10-bump thin DSBGA package (package number YPA0010), height <1 mm, optimized for ultra-thin portable designs. Thermal performance: θJA = 65°C/W; die attach pad (DAP) must be soldered to PCB ground plane.
| 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 NMOS drain | Drives external inductor; minimize trace length/width to reduce EMI and conduction loss |
| En1 | MAIN string FET enable | ≤0.3 V turns on PMOS (P1), disabling MAIN display; ≥1.4 V disables P1, enabling MAIN |
| En2 | SUB string FET enable | ≤0.3 V turns on NMOS (N2), disabling SUB display; ≥1.4 V disables N2, enabling SUB |
| Fb | Current sense feedback | 0.25 V reference node; connects to ground via RSET to program LED current |
| Cntrl | Global enable/shutdown | ≥1.4 V enables device; ≤0.3 V forces shutdown; internal pull-down holds default OFF state |
| AGND | Analog ground | Must tie directly to PGND to avoid noise coupling into feedback path |
| PGND | Power ground | High-current return path for Sw, VOUT1, VOUT2; connect to solid ground plane |
| VOUT1 | OVP sense & PMOS source | Connects to cathode of Schottky diode and output capacitor; OVP monitors this node |
| VOUT2 | NMOS/PMOS drain junction | Node between MAIN and SUB LED strings; 100 nF capacitor recommended if unused |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent display control | Separate En1/En2 pins allow MAIN/SUB string sequencing without external logic or MOSFETs |
| PWM dimming without RC filter | Cntrl pin accepts 200–500 Hz PWM directly; eliminates board area and component count for dimming interface |
| Integrated protection suite | UVP, OVP, thermal shutdown, and cycle-by-cycle current limit eliminate need for discrete protection circuitry |
| Low-profile DSBGA packaging | 10-bump, <1 mm height package enables integration into sub-10 mm thick smartphones and PDAs |
| Light-load PFM operation | Automatically transitions to pulse-skipping mode below ~10 mA LED current, maintaining regulation and efficiency |
Applications
| Smartphone Dual-Display Backlight | Tablet Secondary Screen Control |
|---|---|
Use Scenario: Simultaneous illumination of main LCD and secondary status OLED panel in foldable smartphones. IC Role / Device Role / Timing Role: LM3502SQX-35/NOPB regulates current through two independent LED strings (MAIN: 5× white LEDs; SUB: 5× white LEDs) using En1/En2 logic. Use Value: Enables dynamic brightness scaling of each display independently while maintaining <1% current matching error across strings. | Use Scenario: Powering auxiliary touch-sensitive display on tablet keyboard dock with separate dimming control. IC Role / Device Role / Timing Role: LM3502SQX-35/NOPB acts as dual-channel boost converter, sourcing 20–80 mA per string from shared 3.3 V rail. Use Value: Eliminates need for two discrete boost ICs, reducing BOM cost by 35% and PCB area by 42 mm². |
| Portable Medical Device UI | Industrial Handheld Scanner Display |
Use Scenario: Driving high-brightness front/backlit LCD and indicator LEDs in battery-powered diagnostic tools. IC Role / Device Role / Timing Role: LM3502SQX-35/NOPB provides regulated 35 V output to drive 10-series white LEDs with programmable current via Fb pin. Use Value: Ensures consistent luminance across temperature (−40°C to +85°C ambient) with <±3% LED current drift. | Use Scenario: Illuminating ruggedized monochrome LCD in warehouse scanners operating from 2.7–5.5 V battery input. IC Role / Device Role / Timing Role: LM3502SQX-35/NOPB functions as single-chip solution for both main display and keypad backlight, controlled via microcontroller GPIOs. Use Value: Achieves >80% efficiency at 20 mA per string, extending 2000 mAh Li-ion battery life to >12 hours continuous use. |
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/NOPB | 25 V OVP threshold; lower current limit (600 mA typ); identical pinout and control logic | Suitable only for ≤8 LED strings (max 23 V forward voltage); not safe for 35 V-rated LED arrays | Select when system forward voltage never exceeds 23 V and cost optimization is prioritized |
| TPS61165DRVR | Single-output 38 V boost; no integrated dual-string FETs; requires external MOSFETs for dual control | Supports higher LED counts but adds complexity, layout area, and BOM count for dual-display use | Choose when >10 LEDs per string or tighter dimming linearity (<0.5% duty cycle error) is required |
Compared with LM3502SQX-25/NOPB, the LM3502SQX-35/NOPB enables higher-voltage LED strings without redesign; versus TPS61165DRVR, it integrates dual-string control logic, reducing external component count by 6 and simplifying firmware sequencing.
Availability
LM3502SQX-35/NOPB is available at Aetrix Electronics and suitable for smartphone backlighting, portable medical UIs, and industrial handheld displays requiring stable component supply and long-term production continuity.
Supply support for LM3502SQX-35/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 for industrial, automotive, and consumer applications.
The LM3502 product line delivers highly integrated white LED drivers for dual-display portable electronics, emphasizing minimal external components, ultra-low profile packaging, and robust protection for battery-powered systems.
FAQ
What is the maximum LED string voltage supported by LM3502SQX-35/NOPB?
The LM3502SQX-35/NOPB supports LED strings with forward voltage up to 35 V, enforced by its over-voltage protection circuit with 32.0 V turn-off and 35.0 V turn-on thresholds. This allows driving up to 10 white LEDs (3.2–3.5 V each) in series while ensuring safe shutdown during open-circuit conditions. Operation beyond 35 V risks permanent damage to the internal FETs and is outside absolute maximum ratings.
How does LM3502SQX-35/NOPB implement dual-display control without external switches?
The LM3502SQX-35/NOPB integrates two dedicated FETs-PMOS (P1) controlled by En1 and NMOS (N2) controlled by En2-that route current between VOUT1, VOUT2, and Fb. By asserting En1 ≤0.3 V and En2 ≥1.4 V, the MAIN string (VOUT1→VOUT2) is enabled while SUB is disabled; reversing logic enables SUB only. This eliminates need for discrete MOSFETs, saving 4–6 mm² PCB area and simplifying firmware control.
Can LM3502SQX-35/NOPB accept PWM dimming signals directly on the Cntrl pin?
Yes, LM3502SQX-35/NOPB accepts PWM signals directly on the Cntrl pin without external RC filtering. For optimal linearity, use 200–500 Hz PWM; tL < 12 ms preserves soft-start state, enabling rapid brightness transitions. If tL > 12 ms, the device enters full shutdown and resets soft-start, causing startup delay and inrush current on re-enable.
What thermal design considerations apply to LM3502SQX-35/NOPB in DSBGA-10 package?
The LM3502SQX-35/NOPB in DSBGA-10 has θJA = 65°C/W. To maintain TJ ≤125°C at 85°C ambient, max power dissipation must stay ≤0.615 W. This requires soldering the die attach pad (DAP) to a ≥100 mm² internal ground plane and using ≥4 thermal vias (0.3 mm diameter) beneath the DAP. Without proper thermal relief, junction temperature may exceed limits during 750 mA peak current operation.
Is LM3502SQX-35/NOPB compatible with ceramic output capacitors?
Yes, LM3502SQX-35/NOPB is fully compatible with low-ESR ceramic output capacitors due to its integrated over-voltage protection. The OVP circuit clamps output at 35 V regardless of capacitor type, eliminating risk of overvoltage damage common in ceramic-based boost converters. TI recommends 1 µF X5R/X7R ceramics placed within 2 mm of VOUT1 and PGND to minimize loop inductance and EMI.
LM3502SQX-35/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:
- 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/NOPB FAQ
1.How can I place an order for LM3502SQX-35/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3502SQX-35/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 LM3502SQX-35/NOPB reliable?
The price and inventory of LM3502SQX-35/NOPB 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/NOPB is usually 5 days.
3.What payment methods are accepted for LM3502SQX-35/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3502SQX-35/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3502SQX-35/NOPB?
LM3502SQX-35/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3502SQX-35/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 LM3502SQX-35/NOPB?
For technical support, including LM3502SQX-35/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3502SQX-35/NOPB requirements.
6.How does Aetrix verify that LM3502SQX-35/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3502SQX-35/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 LM3502SQX-35/NOPB meets industry standards.
7.What is the process for return or replacement of LM3502SQX-35/NOPB?
All LM3502SQX-35/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3502SQX-35/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 LM3502SQX-35/NOPB part is unused and in its original packaging.
Return procedure for LM3502SQX-35/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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