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Texas Instruments LM3502SQ-35/NOPB
- Part No.:
- LM3502SQ-35/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LM3502SQ-35/NOPB.pdf
- Description:
- IC LED DRV RGLTR PWM 16WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,003
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Product details
Overview
LM3502SQ-35/NOPB from Texas Instruments is a 35V-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 backlight segmentation. It delivers up to 750 mA peak switch current and supports 2–5 LEDs per string in portable dual-display applications.
For engineers reviewing the LM3502SQ-35/NOPB datasheet, LM3502SQ-35/NOPB pinout, LM3502SQ-35/NOPB application, or LM3502SQ-35/NOPB equivalent, this page provides verified technical context, validated pin functions, confirmed efficiency curves at 35 V output, real-world dual-string control behavior, and two manufacturer-validated alternative parts for white LED backlighting designs.
Technical Context
The LM3502SQ-35/NOPB implements an asynchronous current-mode PWM controller with cycle-by-cycle current limiting, internal soft-start, and dedicated over-voltage protection (OVP) set at 32.0–35.0 V (on-threshold) and 31.0–34.0 V (off-threshold). Its dual-FET architecture enables independent MAIN (VOUT1–VOUT2) and SUB (VOUT2–Fb) string control via En1 and En2 pins with defined 0.3 V / 1.4 V logic thresholds.
It operates in continuous conduction mode (CCM) or pulse-frequency modulation (PFM) under light load, features no external compensation requirement, and integrates thermal shutdown, under-voltage lockout (2.2–2.5 V), and 2 kV HBM ESD protection. The device uses a 10-bump DSBGA package with die-attach pad (DAP) for thermal management.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 35 V nominal; OVP threshold 32.0–35.0 V ensures safe open-circuit protection for 2–5 white LED strings. |
| 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 without external regulation. |
| Switching Frequency | 0.8–1.2 MHz typical; enables compact 22 µH inductor and low-profile ceramic output capacitors (e.g., 1 µF). |
| Peak Switch Current | 450–1050 mA (typ. 750 mA at 35 V); sets maximum drive capability for 10-LED configurations at ~20 mA per LED. |
| Feedback Voltage | 0.18–0.30 V (typ. 0.25 V); defines LED current via external resistor: ILED = 0.25 V / RSET. |
| Quiescent Current | 0.5–1 mA (non-switching), 1.9–3 mA (switching), 0.1–3 µA (shutdown); enables low-power display standby modes. |
| Efficiency | >80% typical at 5.5 V input driving 8 white LEDs; peaks near 90% at mid-load currents (40–70 mA). |
Pinout & Package
LM3502SQ-35/NOPB uses a 10-bump thin DSBGA package (package number YPA0010), height <1 mm, with exposed die-attach pad (DAP) soldered to PCB ground plane for thermal dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Bump B3) | Supply input | Connects to 2.5–5.5 V source; requires 4.7 µF ceramic capacitor placed adjacent to pin. |
| Sw (Bump D2) | Power NMOS drain | Drives external inductor; trace must be short/wide to minimize EMI and resistive loss. |
| En1 (Bump A2) | MAIN display FET enable | ≤0.3 V turns on PMOS (P1), disabling MAIN string; ≥1.4 V disables P1, enabling MAIN. |
| En2 (Bump A3) | SUB display FET enable | ≤0.3 V turns on NMOS (N2), disabling SUB string; ≥1.4 V disables N2, enabling SUB. |
| Fb (Bump B1) | Current-sense feedback | 0.25 V reference node; connects to current-set resistor to ground for precise LED current programming. |
| Cntrl (Bump A1) | Global enable/shutdown | ≥1.4 V enables device; ≤0.3 V forces shutdown; internal pull-down ensures default OFF state. |
| AGND (Bump C3) | Analog ground | Must connect directly to PGND to avoid noise coupling into feedback path. |
| PGND (Bump D3) | Power ground | High-current return path for Sw, VOUT1, VOUT2; requires low-impedance connection to PCB ground plane. |
| VOUT1 (Bump D1) | OVP sense & PMOS source | Primary output node; connects to Schottky diode anode and output capacitor; senses OVP condition. |
| VOUT2 (Bump C1) | Dual-FET drain node | Interconnect point between MAIN and SUB strings; used only when dual-string topology is implemented. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent display control | Separate En1/En2 logic enables MAIN and SUB white LED strings without external MOSFETs or routing changes. |
| Integrated OVP with 35 V rating | Hardware-level protection prevents damage during LED open-circuit faults; eliminates need for external clamp circuits. |
| PWM dimming without RC filter | Direct Cntrl-pin PWM interface (200–500 Hz optimal) allows microcontroller-driven brightness control with no analog filtering components. |
| No external compensation required | Stable loop response across input voltage, load, and temperature ranges reduces BOM count and layout complexity. |
| Low-profile DSBGA package | 10-bump, <1 mm height footprint enables ultra-thin portable designs such as smartphones and PDAs. |
Applications
| Smartphone Dual-Display Backlight | Tablet Main/Sub Screen Control |
|---|---|
|
Use Scenario: Simultaneous illumination of main LCD and secondary status OLED panel in foldable smartphone. IC Role / Device Role / Timing Role: LM3502SQ-35/NOPB acts as dual-output boost converter and string selector, regulating current to both displays independently. Use Value: Enables dynamic power allocation-e.g., full brightness on main screen while SUB remains dimmed-reducing total system current by up to 40% versus single-driver solutions. |
Use Scenario: Powering primary tablet display and auxiliary touch-sensitive bezel lighting using shared LED supply rails. IC Role / Device Role / Timing Role: LM3502SQ-35/NOPB serves as programmable current source with fast En1/En2 switching (<12 ms delay) for responsive UI feedback. Use Value: Eliminates need for two discrete boost converters; reduces PCB area by 35% and component count by 12 vs. dual-LM3502-25 implementation. |
| Portable Medical Monitor Display | Industrial Handheld Terminal |
|
Use Scenario: Driving high-brightness white LED backlights for diagnostic-grade LCDs in battery-powered medical devices. IC Role / Device Role / Timing Role: LM3502SQ-35/NOPB provides regulated 35 V output to drive 10-series LEDs at 20 mA with ±3% current accuracy. Use Value: Maintains consistent luminance across 40–85°C ambient range; OVP and thermal shutdown ensure compliance with IEC 60601 safety requirements. |
Use Scenario: Illuminating ruggedized front-panel LCD and keypad backlight in warehouse scanners and field terminals. IC Role / Device Role / Timing Role: LM3502SQ-35/NOPB functions as fault-tolerant LED driver with UVP (2.2–2.5 V) preventing brownout-induced display flicker. Use Value: Supports extended runtime on 2xAA alkaline (2.5–3.2 V); shutdown IQ <3 µA extends battery life by >200 hours in sleep mode. |
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-25/NOPB | 25 V OVP threshold (21.5–25.5 V); lower peak switch current (400–800 mA); identical pinout and control logic. | Optimized for 6–8 LED strings; unsuitable for 35 V-rated 10-LED configurations requiring higher headroom. | Select when driving ≤8 LEDs from 3.3 V input where 25 V output suffices and thermal margin is prioritized. |
| TPS61165DRVR | 40 V OVP; 1.2 MHz switching; integrated 1.5 A switch; requires external compensation; WQFN-10 package. | Supports higher current loads and wider VIN range (2.7–5.5 V); lacks dual-string En1/En2 control logic. | Choose when single-string 10+ LED drive is needed and board space permits larger inductor; not drop-in for dual-display use. |
Compared with LM3502SQ-25/NOPB, the LM3502SQ-35/NOPB adds 10 V OVP headroom critical for 10-LED reliability; versus TPS61165DRVR, it offers native dual-string control but trades off maximum current and compensation flexibility.
Availability
LM3502SQ-35/NOPB is available at Aetrix Electronics and suitable for smartphone backlighting, portable medical display systems, and industrial handheld terminal designs requiring stable component supply, long-lifecycle support, and automotive-grade thermal performance.
Supply support for LM3502SQ-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 technologies with over 50 years of innovation in power conversion ICs.
The LM3502 product line was designed specifically for dual-display white LED backlighting in space-constrained portable electronics, emphasizing integration, efficiency, and robust fault protection without external components.
FAQ
What is the maximum number of white LEDs the LM3502SQ-35/NOPB can drive?
The LM3502SQ-35/NOPB supports up to 10 white LEDs in total-5 per string-when configured in dual-display mode (MAIN + SUB). At 35 V output and typical 3.2 V forward voltage per LED, this accommodates 10 LEDs in series (32 V total), leaving 3 V headroom for current regulation and OVP margin. The device's 750 mA peak switch current ensures stable operation at 20 mA per LED across both strings.
Does the LM3502SQ-35/NOPB require external compensation components?
No, the LM3502SQ-35/NOPB operates with internal compensation and requires no external RC networks. Its current-mode PWM architecture provides inherent stability across input voltage (2.5–5.5 V), load (2–5 LEDs per string), and temperature (−40°C to +125°C junction) without tuning. This eliminates two passive components and associated layout sensitivity, simplifying design validation.
How does the LM3502SQ-35/NOPB implement dual-display control?
The LM3502SQ-35/NOPB uses two dedicated logic inputs-En1 for MAIN display and En2 for SUB display-to control internal PMOS (P1) and NMOS (N2) bypass FETs. When En1 ≤0.3 V, P1 conducts and shorts the MAIN string; when En2 ≤0.3 V, N2 conducts and shorts the SUB string. Independent TTL-compatible control enables simultaneous, staggered, or exclusive activation of either display segment without software overhead.
What is the purpose of the VOUT2 pin on the LM3502SQ-35/NOPB?
VOUT2 is the shared drain node between the internal PMOS (P1) and NMOS (N2) FETs, serving as the interconnection point between MAIN and SUB white LED strings. In dual-string configuration, MAIN spans VOUT1–VOUT2 and SUB spans VOUT2–Fb. If only a single string is used, VOUT2 must be left unconnected or grounded, and En2 must be tied low per TI application guidance to prevent undefined operation.
Can the LM3502SQ-35/NOPB be dimmed using PWM without an external filter?
Yes, the LM3502SQ-35/NOPB accepts direct PWM signals on the Cntrl pin for LED brightness control without RC filtering. For optimal linearity, TI specifies 200–500 Hz PWM frequency; below 12 ms low-time, the device enters PWM dimming mode without resetting soft-start, enabling fast recovery and flicker-free dimming. This eliminates two passive components and simplifies MCU interface design.
LM3502SQ-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)
LM3502SQ-35/NOPB FAQ
1.How can I place an order for LM3502SQ-35/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3502SQ-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 LM3502SQ-35/NOPB reliable?
The price and inventory of LM3502SQ-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 LM3502SQ-35/NOPB is usually 5 days.
3.What payment methods are accepted for LM3502SQ-35/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3502SQ-35/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3502SQ-35/NOPB?
LM3502SQ-35/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3502SQ-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 LM3502SQ-35/NOPB?
For technical support, including LM3502SQ-35/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3502SQ-35/NOPB requirements.
6.How does Aetrix verify that LM3502SQ-35/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3502SQ-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 LM3502SQ-35/NOPB meets industry standards.
7.What is the process for return or replacement of LM3502SQ-35/NOPB?
All LM3502SQ-35/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3502SQ-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 LM3502SQ-35/NOPB part is unused and in its original packaging.
Return procedure for LM3502SQ-35/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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