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Texas Instruments LM3502SQ-44/NOPB
- Part No.:
- LM3502SQ-44/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LM3502SQ-44/NOPB.pdf
- Description:
- IC LED DRV RGLTR PWM 16WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,963
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Product details
Overview
LM3502SQ-44/NOPB from Texas Instruments is a 44V-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 fixed switching frequency, and supports 2–5 LEDs per string in portable dual-display applications.
For engineers reviewing the LM3502SQ-44/NOPB datasheet, LM3502SQ-44/NOPB pinout, LM3502SQ-44/NOPB application, or LM3502SQ-44/NOPB equivalent, key selection criteria include output voltage rating (44 V), dual-FET enable logic (En1/En2), feedback reference (0.25 V), over-voltage protection thresholds (40.5–43.5 V), and thermal performance (θJA = 65°C/W in DSBGA).
Technical Context
The LM3502SQ-44/NOPB implements current-mode PWM control with cycle-by-cycle current limiting and internal soft-start. Its architecture integrates two independent NMOS/PMOS bypass switches (N2/P1) to selectively route current through MAIN (VOUT1–VOUT2) or SUB (VOUT2–Fb) LED strings.
It features dedicated protection blocks: under-voltage lockout (2.4–2.5 V turn-on), over-voltage protection (40.5–43.5 V trip), and thermal shutdown. The device accepts direct PWM dimming on the Cntrl pin without external RC filtering and enters low-IQ shutdown (6–15 µA) when En1 = En2 = 0 V and Cntrl = 1.5 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 44 V - OVP threshold set for high-string-count white LED arrays (e.g., 10× 4.2 V LEDs) |
| 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 (2.4–3.2 V) supplies |
| Switching Frequency | 1 MHz (±20%) - Enables use of small 22 µH inductors and reduces EMI filter size |
| Feedback Voltage | 0.25 V (typ) - Sets LED current via external resistor R1 = 0.25 V / ILED, minimizing power loss |
| Efficiency | >80% - Measured at full load across VIN range; enables longer battery life in handheld devices |
| Shutdown Current | 0.1–3 µA - Ensures minimal battery drain during display-off states |
| Thermal Resistance | 65°C/W (DSBGA) - Requires PCB ground plane connection to DAP for reliable operation at 125°C junction |
Pinout & Package
LM3502SQ-44/NOPB uses a 10-bump thin DSBGA package (YPA0010), height <1 mm, with die attach pad (DAP) soldered to PCB ground 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 NMOS drain | Drives external inductor; minimize trace length/width to reduce EMI and conduction loss |
| En1 | PMOS FET control (MAIN) | ≤0.3 V enables MAIN string; ≥1.4 V disables MAIN; internal pull-down defaults to ON |
| En2 | NMOS FET control (SUB) | ≤0.3 V enables SUB string; ≥1.4 V disables SUB; internal pull-down defaults to ON |
| Fb | Current-sense feedback | 0.25 V reference node; connects to ground via R1 to set LED current |
| Cntrl | Global enable/shutdown | ≥1.4 V enables device; ≤0.3 V forces shutdown; supports direct PWM dimming |
| AGND | Analog ground | Must be shorted to PGND at single point to avoid noise coupling into feedback path |
| PGND | Power ground | High-current return path for Sw, VOUT1, VOUT2; connect directly to PCB ground plane |
| VOUT1 | OVP sense & PMOS source | Connects to cathode of Schottky diode and output capacitor; senses OVP at 44 V threshold |
| VOUT2 | Dual-FET drain node | Interconnect point between MAIN and SUB strings; 100 nF cap recommended if unused |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent LED string control | En1 and En2 pins allow simultaneous or selective MAIN/SUB backlight activation without external logic |
| Direct PWM dimming interface | Cntrl pin accepts 200–500 Hz PWM signals without RC filter, enabling fast brightness transitions |
| Integrated over-voltage protection | 44 V OVP threshold prevents damage during open-circuit LED failure or hot-plug events |
| No external compensation required | Stable operation with only input/output capacitors and inductor-reduces BOM count and layout complexity |
| Low-profile DSBGA packaging | 10-bump, <1 mm height package enables ultra-thin portable designs (e.g., smartphones, PDAs) |
Applications
| Cellular Phone Dual Display | PDA Main/Sub Backlight |
|---|---|
Use Scenario: Simultaneous illumination of front-facing keypad display and rear-facing main screen in clamshell phones. IC Role / Device Role / Timing Role: LM3502SQ-44/NOPB regulates current through two independent LED strings using En1/En2 logic while maintaining 44 V headroom for aging LEDs. Use Value: Eliminates need for discrete enable logic and dual boost converters, reducing component count by ≥30%. | Use Scenario: Adaptive backlighting where PDA main display remains active while sub-display (e.g., status bar) dims during low-power mode. IC Role / Device Role / Timing Role: LM3502SQ-44/NOPB acts as dual-channel current source with independent En1/En2 control, enabling dynamic power partitioning. Use Value: Achieves >80% efficiency at 5 mA–80 mA per string, extending battery runtime by up to 22% versus discrete solutions. |
| Portable Media Player UI | Handheld Gaming Device |
Use Scenario: Brightness-matched illumination of primary media screen and secondary touch-control panel in MP4 players. IC Role / Device Role / Timing Role: LM3502SQ-44/NOPB provides synchronized PWM dimming across both strings via shared Cntrl signal, preserving color uniformity. Use Value: Maintains ±3% LED current matching between strings, preventing visible luminance disparity during video playback. | Use Scenario: Rapid on/off toggling of game HUD overlay and main gameplay screen during scene transitions. IC Role / Device Role / Timing Role: LM3502SQ-44/NOPB executes sub-12 ms shutdown/restart cycles via Cntrl pin, enabling flicker-free UI updates. Use Value: Supports 85 Hz+ refresh rates without perceptible lag, critical for responsive gaming interfaces. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar white LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3502TME-44/NOPB | 16-pin WQFN package (RGH0016A); θJA = 49°C/W; identical electrical specs | Better thermal performance but larger footprint; requires different PCB layout | Select when higher power dissipation or board space permits larger package |
| TPS61165DRVR | Single-output 38 V boost driver; no dual-FET bypass; 1.2 MHz switching; integrated MOSFET | Lacks independent MAIN/SUB control; requires external logic for dual-string operation | Choose for cost-sensitive single-display systems where dual control is unnecessary |
Compared with LM3502TME-44/NOPB, the LM3502SQ-44/NOPB offers lower profile and smaller area but higher thermal resistance; versus TPS61165DRVR, it provides native dual-string control without added components but targets legacy portable designs rather than newer high-efficiency platforms.
Availability
LM3502SQ-44/NOPB is available at Aetrix Electronics and suitable for cellular phone backlighting, PDA display systems, and portable media player UIs requiring stable component supply and long-term industrial availability.
Supply support for LM3502SQ-44/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 digital signal technologies for industrial, automotive, and consumer markets.
The LM3502 product line was designed specifically for dual-display white LED backlighting in space-constrained portable electronics, emphasizing integration, low IQ, and robust protection.
FAQ
What is the maximum output voltage supported by the LM3502SQ-44/NOPB?
The LM3502SQ-44/NOPB has a 44 V over-voltage protection threshold, meaning it is rated for applications requiring up to 44 V output-sufficient for driving 10-series white LEDs (typically 4.2 V each at forward current). This version is part of the LM3502 family with fixed OVP levels; other variants offer 16 V, 25 V, or 35 V ratings. The actual regulated output depends on LED string configuration and feedback resistor value.
How does the LM3502SQ-44/NOPB control two independent LED strings?
The LM3502SQ-44/NOPB controls two LED strings using its internal PMOS (P1) and NMOS (N2) bypass FETs. En1 enables/disables the MAIN string (between VOUT1 and VOUT2), while En2 controls the SUB string (between VOUT2 and Fb). When both En1 and En2 are low, both strings are active; setting either high disconnects that segment. This eliminates external switching transistors and simplifies dual-display power management in the LM3502SQ-44/NOPB design.
Can the LM3502SQ-44/NOPB be dimmed using PWM, and what frequency range is recommended?
Yes, the LM3502SQ-44/NOPB supports direct PWM dimming on the Cntrl pin without external RC filtering. For optimal linearity between duty cycle and LED current, TI recommends 200–500 Hz. At tL < 12 ms (low-time), the device maintains soft-start state for fast recovery; above 12 ms, it fully shuts down and resets soft-start. This behavior ensures consistent dimming response across battery voltage variations in the LM3502SQ-44/NOPB implementation.
What package type and thermal requirements apply to the LM3502SQ-44/NOPB?
The LM3502SQ-44/NOPB uses a 10-bump thin DSBGA package (YPA0010) with height <1 mm. Its junction-to-ambient thermal resistance is 65°C/W, requiring the die attach pad (DAP) to be soldered to the PCB ground plane for effective heat dissipation. Without proper DAP grounding, junction temperature may exceed 125°C under sustained 80 mA per string, risking thermal shutdown. This thermal requirement is specific to the LM3502SQ-44/NOPB DSBGA variant.
Does the LM3502SQ-44/NOPB require external compensation components?
No, the LM3502SQ-44/NOPB is internally compensated and requires no external compensation network. Stability is ensured with only three external passive components: input capacitor (4.7 µF), output capacitor (1 µF), and power inductor (22 µH). This simplifies layout, reduces bill-of-materials cost, and eliminates tuning effort-key advantages confirmed in the LM3502SQ-44/NOPB datasheet Figure 1 and Section 8.2.2.
LM3502SQ-44/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:
- 44V
- 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-44/NOPB FAQ
1.How can I place an order for LM3502SQ-44/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3502SQ-44/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-44/NOPB reliable?
The price and inventory of LM3502SQ-44/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-44/NOPB is usually 5 days.
3.What payment methods are accepted for LM3502SQ-44/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3502SQ-44/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3502SQ-44/NOPB?
LM3502SQ-44/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3502SQ-44/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-44/NOPB?
For technical support, including LM3502SQ-44/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3502SQ-44/NOPB requirements.
6.How does Aetrix verify that LM3502SQ-44/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3502SQ-44/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-44/NOPB meets industry standards.
7.What is the process for return or replacement of LM3502SQ-44/NOPB?
All LM3502SQ-44/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3502SQ-44/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-44/NOPB part is unused and in its original packaging.
Return procedure for LM3502SQ-44/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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