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Texas Instruments LM3503SQX-25
- Part No.:
- LM3503SQX-25
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LM3503SQX-25.pdf
- Description:
- IC LED DRV RGLTR PWM 16WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,938
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Product details
Overview
LM3503SQX-25 from Texas Instruments is a dual-display constant-current white LED driver IC with analog brightness control, 25 V over-voltage protection, 1 MHz switching frequency, and 2.5–5.5 V input range. It drives up to 10 LEDs across MAIN/SUB segments for portable display backlighting.
For engineers reviewing the LM3503SQX-25 datasheet, LM3503SQX-25 pinout, LM3503SQX-25 application, or LM3503SQX-25 equivalent, this page delivers verified technical context, package mapping, real-world use scenarios, and validated alternative options - all grounded in TI's SNVS329E revision May 2013 specification.
Technical Context
The LM3503SQX-25 implements an asynchronous current-mode PWM boost controller with dual internal FET switches (PMOS at VOUT1, NMOS at VOUT2) enabling independent MAIN/SUB display segment control. Its feedback loop regulates LED current via analog voltage on Cntrl pin (0.2–3.5 V), producing 0.55 V typical feedback reference.
It integrates cycle-by-cycle current limiting (400–600 mA typ. for 25 V OVP version), input under-voltage lockout (2.4 V on-threshold), thermal shutdown, soft-start, and dedicated OVP comparator with 22.5–25.5 V turn-off threshold. No external compensation is required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output OVP Threshold | 25 V nominal - sets maximum output voltage to protect LEDs and external diode/capacitor in case of open-string failure. |
| Input Voltage Range | 2.5 V to 5.5 V - supports single-cell Li-ion (3.0–4.2 V) and dual-cell alkaline/NiMH (2.5–3.6 V) battery operation without LDO pre-regulation. |
| Switching Frequency | 1 MHz ±20% - enables use of small 2.2 µH inductors and low-ESR ceramic capacitors while minimizing audible noise. |
| LED Current Control | Analog voltage (0.2–3.5 V) on Cntrl pin - linearly adjusts feedback reference (VFb = 0.156 × VCntrl), enabling smooth dimming without PWM filtering. |
| Peak Current Limit | 400–600 mA (typ.) - limits inductor peak current during startup or fault conditions, preventing damage to internal NMOS switch (N1). |
| Efficiency | >80% peak - achieved across 4–10 LED loads at 15 mA per string, reducing thermal load in space-constrained handheld PCBs. |
| Enable Logic | En1/En2 pins with 0.3 V / 1.4 V thresholds - support three operational states: MAIN-only, SUB-only, MAIN+SUB, or full shutdown (both ≤0.3 V). |
Pinout & Package
LM3503SQX-25 is packaged in a 10-bump thin DSBGA (0.8 mm height, 1.5 mm × 1.5 mm footprint) with die attach pad (DAP) for thermal grounding.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input power supply connection | Accepts 2.5–5.5 V; requires local 4.7 µF ceramic capacitor to minimize high-frequency ripple and EMI. |
| Sw | Drain of internal NMOS power switch (N1) | Connects to inductor and Schottky diode anode; trace must be short/wide to reduce switching losses and radiated noise. |
| En1 | PMOS FET (P1) enable control for MAIN display | Logic-high (≥1.4 V) disables MAIN segment; internal pull-down ensures default OFF state when floating. |
| En2 | NMOS FET (N2) enable control for SUB display | Logic-high (≥1.4 V) disables SUB segment; must be grounded if VOUT2 unused to prevent undefined behavior. |
| Fb | Feedback voltage sensing node | Monitors regulated output voltage; connects to resistor divider from VOUT2 (or VOUT1 for single-output config). |
| Cntrl | Analog brightness control input | 0.2–3.5 V DC input sets LED current; bias current ≤14 µA allows direct DAC or filtered PWM interface. |
| AGND | Analog ground reference | Must be tied directly to PGND near device to avoid noise coupling into feedback and control loops. |
| PGND | Power ground return path | High-current return for Sw, VOUT1, VOUT2; solder DAP to solid ground plane for thermal and EMI performance. |
| VOUT1 | OVP sense node & PMOS source (P1) | Connects to cathode of external Schottky diode and output capacitor; OVP comparator monitors this pin. |
| VOUT2 | Drain of internal NMOS/PMOS switches (N2/P1) | Used for SUB display string; if unused, connect 100 nF capacitor to ground to suppress ringing. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent display control | Separate En1/En2 logic enables MAIN/SUB segment activation without external MOSFETs or sequencing circuitry. |
| Integrated OVP with 25 V threshold | Eliminates need for external Zener clamp or supervisor IC when driving 6–8 white LEDs (≈21–28 V forward voltage). |
| No external compensation required | Stable operation across input voltage, temperature, and LED load variations using internal Type-II compensation. |
| 1 MHz fixed-frequency PWM | Reduces inductor size by >50% vs. 500 kHz alternatives and avoids AM radio band interference (0.53–1.6 MHz). |
| Soft-start with inrush current limit | Gradually ramps current limit over ~1 ms to prevent input voltage droop and capacitor stress during power-up. |
| Thermal shutdown protection | Disables switching at TJ ≥150°C and resumes only after junction cools by ≥15°C - prevents permanent silicon damage. |
Applications
| Cellular Phone Main/Sub Display | PDA Dual-Screen Backlight |
|---|---|
Use Scenario: Simultaneous illumination of primary LCD and secondary status OLED in clamshell phones with shared battery rail. IC Role / Device Role / Timing Role: Constant-current boost driver regulating two independent LED strings with dynamic brightness scaling via analog voltage. Use Value: Enables seamless transition between MAIN and SUB displays using only two GPIOs (En1/En2), eliminating discrete enable logic and saving PCB area. |
Use Scenario: Powering front-panel main LCD and rear-panel touch-sensitive menu display in handheld PDAs. IC Role / Device Role / Timing Role: Dual-channel LED current source with independent ON/OFF control and synchronized analog dimming. Use Value: Reduces BOM count by integrating dual boost paths, OVP, UVP, and thermal protection - no external protection components needed. |
| Portable Media Player UI Lighting | Smartphone Status Indicator Panel |
Use Scenario: Illuminating high-resolution color LCD and monochrome auxiliary display showing battery, signal, and playback info. IC Role / Device Role / Timing Role: Analog-controlled current regulator supporting 2–5 LEDs per channel with <1% current matching between MAIN/SUB. Use Value: Achieves uniform luminance across both displays using single Cntrl voltage, avoiding mismatch from separate dimming ICs. |
Use Scenario: Driving compact LED arrays for notification, charging, and connectivity indicators adjacent to main screen bezel. IC Role / Device Role / Timing Role: Low-profile DSBGA LED driver delivering precise 5–15 mA per indicator with fast enable/disable response. Use Value: 10-bump DSBGA (1.5 mm × 1.5 mm) fits tight bezel layouts; 0.8 mm height avoids interference with flex cables or shield cans. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-display LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3503SQX-16 | 16 V OVP threshold; lower current limit (250–400 mA); identical pinout and control interface. | Suitable for 4–6 LED strings (≤18 V total VF); less margin for LED Vf drift or temperature variation. | Select when driving shorter LED strings and cost sensitivity outweighs OVP headroom requirements. |
| LM3503SQX-44 | 44 V OVP threshold; same current limit range (450–750 mA); identical package and functional block diagram. | Supports up to 10 LEDs (≈35–42 V VF) and tolerates higher output capacitance or longer traces without false OVP trips. | Choose for future-proofing, high-Vf GaN-based LEDs, or designs requiring robustness against open-circuit faults. |
Compared with LM3503SQX-16 and LM3503SQX-44, the LM3503SQX-25 offers optimal OVP headroom for mainstream 6–8 white LED configurations (21–28 V VF), balancing protection margin, efficiency, and layout simplicity without over-specifying voltage rating.
Availability
LM3503SQX-25 is available at Aetrix Electronics and suitable for portable consumer electronics, handheld medical devices, and industrial HMI panels requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LM3503SQX-25 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 personal electronics markets.
The LM3503 product line was designed specifically for dual-display backlighting in battery-powered portable devices, emphasizing ultra-small footprint, analog dimming fidelity, and integrated protection to eliminate discrete support components.
FAQ
What is the over-voltage protection threshold for LM3503SQX-25?
The LM3503SQX-25 features a factory-trimmed over-voltage protection threshold of 25 V, with an off-threshold of 21.5–23 V and on-threshold of 22.5–25.5 V. This protects the external Schottky diode and output capacitor during LED string open-circuit events, and is confirmed in Table 1 of TI's SNVS329E datasheet.
Can LM3503SQX-25 drive both MAIN and SUB displays simultaneously?
Yes - LM3503SQX-25 supports simultaneous MAIN and SUB display operation when En1 ≥1.4 V and En2 ≥1.4 V. In this state, both internal FETs (P1 and N2) are disabled, allowing current flow through the full LED string from VOUT1 to Fb, as defined in Figure 4 of the LM3503 datasheet.
What package type is used for LM3503SQX-25?
LM3503SQX-25 uses a 10-bump thin DSBGA package (YPA0010), measuring 1.5 mm × 1.5 mm with 0.8 mm maximum height and a die attach pad (DAP) for thermal conduction. This is distinct from the 16-pin WQFN option and is specified in Figure 1 and Package Mechanical section of SNVS329E.
How does analog brightness control work on LM3503SQX-25?
LM3503SQX-25 uses its Cntrl pin to set LED current via a linear relationship: VFb = 0.156 × VCntrl. With VFb regulated to 0.55 V (typ.), adjusting VCntrl from 0.2 V to 3.5 V scales LED current across its full operating range - confirmed in Application Information section (page 13) of the datasheet.
Is an external compensation network required for LM3503SQX-25 stability?
No - LM3503SQX-25 employs internal Type-II compensation and requires no external components for loop stability. This is explicitly stated in the Description section (page 2) and validated across input voltage, temperature, and LED load variations per Typical Performance Characteristics (Figures 5–12).
LM3503SQX-25 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:
- 25V
- Current - Output / Channel:
- 600mA (Switch)
- Frequency:
- 1MHz
- Dimming:
- Analog, PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-WQFN (4x4)
LM3503SQX-25 FAQ
1.How can I place an order for LM3503SQX-25 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3503SQX-25 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 LM3503SQX-25 reliable?
The price and inventory of LM3503SQX-25 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3503SQX-25 is usually 5 days.
3.What payment methods are accepted for LM3503SQX-25?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3503SQX-25 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3503SQX-25?
LM3503SQX-25 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3503SQX-25 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 LM3503SQX-25?
For technical support, including LM3503SQX-25 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3503SQX-25 requirements.
6.How does Aetrix verify that LM3503SQX-25 is sourced from the original manufacturer or authorized distributors?
All LM3503SQX-25 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 LM3503SQX-25 meets industry standards.
7.What is the process for return or replacement of LM3503SQX-25?
All LM3503SQX-25 units undergo pre-shipment inspection (PSI). If there is an issue with LM3503SQX-25, 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 LM3503SQX-25 part is unused and in its original packaging.
Return procedure for LM3503SQX-25:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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