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Texas Instruments LM3502SQX-44
- Part No.:
- LM3502SQX-44
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LM3502SQX-44.pdf
- Description:
- IC LED DRV RGLTR PWM 16WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,499
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Product details
Overview
LM3502SQX-44 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 up to 10 white LEDs (5 per string) in portable dual-display applications such as cellular phones and PDAs.
For engineers reviewing the LM3502SQX-44 datasheet, LM3502SQX-44 pinout, LM3502SQX-44 application, or LM3502SQX-44 equivalent, key selection criteria include its 44V OVP threshold (40.5–43.5V), dual enable logic (En1/En2), feedback voltage of 0.25V, and compatibility with PWM dimming without external RC filtering.
Technical Context
The LM3502SQX-44 implements asynchronous current-mode PWM control with cycle-by-cycle current limiting and dedicated over-voltage protection (OVP) set to 44V nominal. Its internal architecture integrates two independent NMOS/PMOS FET switches (P1 and N2) for selective activation of MAIN and SUB LED strings, enabling dynamic dual-display backlight management.
It features integrated soft-start, under-voltage lockout (UVP at 2.4–2.5V), thermal shutdown, and light-load pulse-frequency modulation (PFM) mode. The device requires no external compensation and uses a single feedback resistor to set LED current via VFb = 0.25V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 44 V nominal; OVP threshold 40.5–43.5 V - ensures safe operation when LED string opens or fails. |
| 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 magnetics and low-profile ceramic output capacitors. |
| Feedback Voltage | 0.25 V typical - sets LED current via external resistor R1 = VFb / ILED, simplifying precision current programming. |
| Efficiency | >80% typical at full load - reduces thermal stress and extends battery life in portable devices. |
| Current Limit | 450–1050 mA (typical 750 mA) - protects internal NMOS switch (N1) during startup or short-circuit conditions. |
| Shutdown Current | 0.1–3 µA - minimizes battery drain in standby mode for always-on display systems. |
Pinout & Package
LM3502SQX-44 is packaged in a 10-bump thin DSBGA (package number YPA0010), height <1 mm, suitable for space-constrained mobile PCBs. Thermal performance is enhanced by soldering the DAP (die attach pad) directly to the PCB ground plane (θJA = 65°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input supply connection | Accepts 2.5–5.5 V; requires local 4.7 µF ceramic capacitor to minimize input ripple and EMI. |
| Sw | Drain of power NMOS switch (N1) | Connects to inductor and Schottky diode anode; trace must be short/wide to reduce switching losses and radiation. |
| En1 | PMOS FET (P1) enable control | ≤0.3 V turns on MAIN display; ≥1.4 V disables MAIN; internal pull-down defaults to MAIN OFF. |
| En2 | NMOS FET (N2) enable control | ≤0.3 V turns on SUB display; ≥1.4 V disables SUB; internal pull-down defaults to SUB OFF. |
| Fb | Feedback node for LED current regulation | 0.25 V reference; current set by resistor to AGND; determines ILED = 0.25 V / R1. |
| Cntrl | Global shutdown control | ≥1.4 V enables device; ≤0.3 V forces shutdown; supports PWM dimming without RC filter. |
| AGND | Analog ground reference | Must connect directly to PGND to avoid noise coupling into feedback path. |
| PGND | Power ground return | High-current return path for Sw, VOUT1, VOUT2; requires low-impedance connection to PCB ground plane. |
| VOUT1 | OVP sense node & PMOS source | Connects to cathode of Schottky diode and output capacitor; OVP triggers at 40.5–43.5 V. |
| VOUT2 | Drain of PMOS/NMOS bypass FETs (P1/N2) | Used for SUB display string; if unused, must be grounded or left floating with En2 tied low. |
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 | Internal circuitry accepts direct microcontroller PWM (200–500 Hz optimal) on Cntrl pin-eliminates board area and component count. |
| Integrated OVP at 44 V | Hardware-level protection prevents damage during open-string or LED failure; avoids need for external clamping circuits. |
| No external compensation required | Stable operation across input/output ranges with only 4 external components (inductor, diode, Cin, Cout)-reduces BOM and layout complexity. |
| Low-profile DSBGA package | 10-bump, <1 mm height package enables ultra-thin handheld designs while maintaining thermal performance via DAP grounding. |
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 or slider phones. IC Role / Device Role / Timing Role: LM3502SQX-44 acts as dual-channel boost converter and current regulator, independently driving two LED strings with En1/En2 logic. Use Value: Enables dynamic brightness scaling per display using PWM on Cntrl, reducing total system power by 30% vs. single-string solutions. | Use Scenario: Powering high-resolution main LCD and secondary status display in handheld PDAs with shared battery. IC Role / Device Role / Timing Role: LM3502SQX-44 provides regulated 44 V boost and dual-FET bypass to isolate displays during sleep mode. Use Value: Achieves <1 µA shutdown current when both displays are off, extending standby time beyond 72 hours. |
| Portable Media Player UI + Screen | Smartphone Status Indicator + Main Panel |
Use Scenario: Driving small indicator LEDs (UI) and large main panel backlight from one Li-ion cell in media players. IC Role / Device Role / Timing Role: LM3502SQX-44 functions as programmable current source with 0.25 V feedback reference and 44 V headroom. Use Value: Eliminates need for separate DC/DC and current regulators-reducing solution size by 40% and component count by 6. | Use Scenario: Managing notification LED ring and primary OLED/LCD backlight in smartphones with adaptive brightness. IC Role / Device Role / Timing Role: LM3502SQX-44 serves as dual-path LED driver with hardware-enforced OVP and UVP for safety-critical lighting. Use Value: Guarantees fail-safe shutdown at <2.4 V input or >43.5 V output-meeting IEC 62368-1 requirements for portable electronics. |
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-35 | 35 V OVP threshold (31–34 V); lower current limit (450–1050 mA same), identical pinout and control logic. | Suitable for 8-LED strings requiring ≤35 V compliance; not safe for 44 V-rated LED stacks. | Select LM3502SQX-35 only if maximum output voltage requirement is ≤35 V and system-level OVP margin allows. |
| TPS61165DRVR | 40 V OVP; integrated 1.2 A switch; requires external compensation; no dual-FET bypass logic. | Lacks independent En1/En2 control-requires external logic or MCU GPIOs to manage dual displays. | Choose TPS61165DRVR when higher peak current (1.2 A) is needed but dual-display hardware control is unnecessary. |
Compared with LM3502SQX-35 and TPS61165DRVR, the LM3502SQX-44 uniquely combines 44 V OVP headroom, dual-FET display select logic, and zero-compensation stability-making it the only drop-in solution for 10-LED dual-string portable backlighting where output voltage margin and hardware-level display isolation are mandatory.
Availability
LM3502SQX-44 is available at Aetrix Electronics and suitable for cellular phone backlighting, PDA dual-display systems, and portable media player LED drivers requiring stable component supply, long-lifecycle support, and automotive-grade reliability screening.
Supply support for LM3502SQX-44 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, with decades of expertise in portable power conversion and LED lighting solutions.
The LM3502 product line was designed specifically for dual-display white LED backlighting in battery-powered portable devices, emphasizing ultra-low profile packaging, high efficiency, and hardware-based display control without MCU intervention.
FAQ
What is the maximum output voltage supported by the LM3502SQX-44?
The LM3502SQX-44 has an over-voltage protection (OVP) threshold of 40.5 V (minimum) to 43.5 V (maximum), with nominal 44 V rating. This allows safe operation with 10-white-LED strings (typically ~3.8 V per LED × 10 = 38 V forward voltage) while providing margin for temperature drift and tolerance. The device regulates based on feedback voltage, not fixed output voltage.
How does the LM3502SQX-44 control two independent LED strings?
The LM3502SQX-44 uses two dedicated enable pins: En1 controls the PMOS FET (P1) for the MAIN display string between VOUT1 and VOUT2, while En2 controls the NMOS FET (N2) for the SUB display string between VOUT2 and Fb. Each pin responds to logic thresholds (≤0.3 V ON, ≥1.4 V OFF), enabling independent hardware-level control without software overhead.
Can the LM3502SQX-44 be dimmed using PWM, and what is the recommended frequency range?
Yes, the LM3502SQX-44 supports direct PWM dimming on the Cntrl pin without external RC filtering. Texas Instruments recommends 200–500 Hz for optimal linearity between duty cycle and LED current. Frequencies below 200 Hz may cause audible coil whine; above 500 Hz, dimming linearity degrades due to internal soft-start reset behavior when low-time exceeds 12 ms.
What is the purpose of the VOUT2 pin on the LM3502SQX-44, and how should it be handled if unused?
VOUT2 is the common drain node of the internal PMOS (P1) and NMOS (N2) bypass FETs, used to route current through the SUB display string. If the SUB display is not implemented, VOUT2 must be grounded or left floating-and En2 must be tied to GND (not left floating) to prevent unintended FET conduction and ensure predictable shutdown behavior per datasheet Figure 30.
Does the LM3502SQX-44 require external compensation components?
No, the LM3502SQX-44 is internally compensated and requires no external compensation network. Stability is guaranteed across its full operating range (2.5–5.5 V input, 44 V output) with only four external components: input capacitor (4.7 µF), output capacitor (1 µF), power inductor, and Schottky diode-reducing design risk and board area.
LM3502SQX-44 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)
LM3502SQX-44 FAQ
1.How can I place an order for LM3502SQX-44 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3502SQX-44 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-44 reliable?
The price and inventory of LM3502SQX-44 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3502SQX-44 is usually 5 days.
3.What payment methods are accepted for LM3502SQX-44?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3502SQX-44 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3502SQX-44?
LM3502SQX-44 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3502SQX-44 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-44?
For technical support, including LM3502SQX-44 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3502SQX-44 requirements.
6.How does Aetrix verify that LM3502SQX-44 is sourced from the original manufacturer or authorized distributors?
All LM3502SQX-44 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-44 meets industry standards.
7.What is the process for return or replacement of LM3502SQX-44?
All LM3502SQX-44 units undergo pre-shipment inspection (PSI). If there is an issue with LM3502SQX-44, 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-44 part is unused and in its original packaging.
Return procedure for LM3502SQX-44:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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