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Texas Instruments LM3503ITLX-16/NOPB
- Part No.:
- LM3503ITLX-16/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 10-WFBGA, DSBGA
- Datasheet:
-
LM3503ITLX-16/NOPB.pdf
- Description:
- IC LED DRVR RGLTR PWM 10TUSMD
- Quantity:
- Payment:
- Shipping:
Inventory:3,980
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Product details
Overview
LM3503ITLX-16/NOPB from Texas Instruments is a dual-display constant-current white LED driver IC with analog brightness control, 16 V over-voltage protection, 1 MHz switching frequency, and 2.5–5.5 V input range. It drives up to 10 LEDs (5 per display) in portable dual-backlight systems such as cellular phones and PDAs.
For engineers reviewing the LM3503ITLX-16/NOPB datasheet, LM3503ITLX-16/NOPB pinout, LM3503ITLX-16/NOPB application, or LM3503ITLX-16/NOPB equivalent, key selection criteria include OVP threshold (16 V), dual enable logic for MAIN/SUB display segmentation, analog dimming via Cntrl pin (0.2–3.5 V), and WQFN-16 thermal performance (θJA = 49°C/W).
Technical Context
The LM3503ITLX-16/NOPB implements an asynchronous current-mode PWM boost controller with integrated NMOS power switch (N1), PMOS (P1), and NMOS bypass FET (N2). Its dual-output architecture supports independent MAIN (VOUT1–VOUT2) and SUB (VOUT2–Fb) LED string segments, controlled by En1 and En2 logic thresholds (≤0.3 V / ≥1.4 V).
It features cycle-by-cycle current limiting, internal soft start, under-voltage protection (2.4–2.5 V turn-on), and dedicated OVP comparator set to 14.5–16.5 V (on-threshold). Feedback regulation uses a 0.55 V typical reference at Fb, dynamically scaled by Cntrl voltage (VFb = 0.156 × VCntrl), enabling precise analog current control without external DAC.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| OVP Threshold | 16 V nominal; disables switching when VOUT1 exceeds 14.5–16.5 V, protecting LEDs and output capacitor |
| 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 (e.g., 2.2 µH) and reduces EMI filtering burden |
| Feedback Reference | 0.55 V typical at Fb pin; sets LED current via ILED = VFb/RSET, scaled linearly by Cntrl voltage |
| Current Limit (16V version) | 250–650 mA; peak NMOS switch limit ensures safe inductor current handling for 2–5 LED strings |
| Thermal Resistance θJA | 49°C/W (WQFN-16); supports >300 mW continuous dissipation at +85°C ambient with PCB copper pour |
| Enable Logic Thresholds | En1/En2 ≤0.3 V = ON for respective FET; ≥1.4 V = OFF; dual-low = full shutdown (≤0.3 µA IQ) |
Pinout & Package
LM3503ITLX-16/NOPB uses a 16-pin Thin WQFN package (RGH0016A) with 0.4 mm pitch and exposed DAP for thermal management. Pin 1 is located at bottom-left corner (marking dot adjacent).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input supply connection | Accepts 2.5–5.5 V; requires local 4.7 µF ceramic capacitor to PGND |
| Sw | Power NMOS drain | Connects to inductor; high dv/dt node-minimize trace length and maximize width |
| En1 | PMOS FET (MAIN) enable | Controls MAIN segment (VOUT1–VOUT2); ≤0.3 V enables, ≥1.4 V disables |
| En2 | NMOS FET (SUB) enable | Controls SUB segment (VOUT2–Fb); ≤0.3 V enables, ≥1.4 V disables |
| Fb | Feedback sensing node | Monitors regulated voltage across RSET; 0.55 V reference sets LED current |
| Cntrl | Analog brightness control | 0.2–3.5 V input scales Fb reference linearly; enables smooth DC dimming |
| AGND | Analog ground reference | Must be shorted directly to PGND to minimize noise coupling into feedback path |
| PGND | Power ground return | High-current return for Sw, VOUT1, VOUT2; connect to PCB ground plane under DAP |
| VOUT1 | MAIN string source/OVP sense | OVP sensing node and PMOS source; connects to anode of MAIN LED string |
| VOUT2 | Shared node between MAIN/SUB | Drain of P1 and N2; connects cathode of MAIN and anode of SUB strings |
| DAP | Die attach pad | Thermal and electrical ground; must be soldered to solid PCB ground plane |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent display control | En1/En2 pins enable selective MAIN-only, SUB-only, or both-on operation-no external logic required |
| Analog brightness scaling | Cntrl pin accepts 0.2–3.5 V DC to linearly adjust Fb reference from 0.03 V to 0.55 V, setting LED current from near-zero to full scale |
| Integrated protection suite | UVP (2.4 V), OVP (16 V), thermal shutdown, soft-start, and cycle-by-cycle current limit prevent fault propagation |
| High-efficiency boost topology | >80% peak efficiency at 15 mA per string; 1 MHz operation allows <2.2 µH inductors and low-ESR ceramics |
| Low-profile WQFN packaging | 3 mm × 3 mm × 0.8 mm footprint with exposed DAP delivers 49°C/W θJA for space-constrained handheld designs |
Applications
| Cellular Phone Dual Display | PDA Main/Sub Backlight |
|---|---|
Use Scenario: Simultaneous backlighting of main LCD and secondary status OLED in clamshell or slider phones. IC Role / Device Role / Timing Role: Constant-current boost driver delivering 15 mA per 4-LED string with independent En1/En2 enable sequencing. Use Value: Eliminates need for two discrete drivers; 16 V OVP protects against open-circuit LED failure during hinge flex events. | Use Scenario: Powering primary touchscreen backlight and auxiliary keypad illumination in legacy PDAs. IC Role / Device Role / Timing Role: Dual-channel analog-dimming LED driver with shared inductor and single Cntrl voltage for synchronized brightness control. Use Value: Reduces BOM count by 40% vs. dual-single-channel solutions; 1 MHz switching avoids audible noise in audio-sensitive environments. |
| Portable Media Player UI | Handheld Diagnostic Device |
Use Scenario: Driving high-contrast front-panel LCD and rear-panel battery-status indicator on MP3 players. IC Role / Device Role / Timing Role: Current-regulated boost converter with Cntrl-based dimming and En2-gated SUB display for low-power standby mode. Use Value: Enables <1 µA shutdown current when both displays are off-extending battery life by >12 hours in sleep state. | Use Scenario: Illuminating high-brightness diagnostic screen and tactile button indicators in medical field devices. IC Role / Device Role / Timing Role: Dual-output LED driver with 16 V OVP and thermal shutdown ensuring reliability in unventilated enclosures. Use Value: Maintains consistent luminance across −40°C to +85°C operating range via temperature-stable Fb reference and bias currents. |
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 |
|---|---|---|---|
| LM3503ITLX-25/NOPB | 25 V OVP threshold; higher current limit (400–800 mA); identical pinout and control interface | Suitable for longer LED strings (up to 8 LEDs per channel) or higher-current designs requiring >16 V headroom | Select when driving >5 LEDs per string or operating with higher forward voltage LEDs (e.g., blue/white with Vf ≥3.6 V) |
| TPS61165DRVR | Single-output, 36 V OVP, I²C programmable current; 2 mm × 2 mm WSON-6 package | Lacks dual-display segmentation logic; requires external MCU for multi-string coordination | Choose for space-constrained single-display systems where digital control and smaller footprint outweigh dual-enable functionality |
Compared with LM3503ITLX-25/NOPB, the LM3503ITLX-16/NOPB offers tighter OVP margin for shorter LED strings and lower quiescent current in light-load PFM mode; versus TPS61165DRVR, it provides hardware-enforced dual-display independence without firmware overhead but occupies larger board area.
Availability
LM3503ITLX-16/NOPB is available at Aetrix Electronics and suitable for cellular phone backlighting, PDA dual-display systems, and portable media player UI illumination requiring stable component supply and long-term industrial availability.
Supply support for LM3503ITLX-16/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 broad industrial and consumer design support.
The LM3503 product line delivers highly integrated, thermally optimized LED drivers for portable dual-display applications-designed to reduce system cost, simplify layout, and improve reliability in space- and power-constrained handheld devices.
FAQ
What is the exact over-voltage protection threshold for LM3503ITLX-16/NOPB?
The LM3503ITLX-16/NOPB has a nominal 16 V over-voltage protection threshold, with guaranteed on-threshold between 14.5 V and 16.5 V and off-threshold between 14.0 V and 16.0 V. This OVP circuit monitors the VOUT1 pin and disables switching if the voltage exceeds the upper limit, protecting external LEDs and capacitors from damage due to open-circuit conditions or LED failure. The LM3503ITLX-16/NOPB's OVP is factory-trimmed and does not require external components.
How does analog brightness control work on LM3503ITLX-16/NOPB?
Analog brightness control on the LM3503ITLX-16/NOPB is implemented via the Cntrl pin, which accepts a DC voltage from 0.2 V to 3.5 V. This voltage linearly scales the internal feedback reference: VFb = 0.156 × VCntrl. Since LED current is calculated as ILED = VFb/RSET, varying VCntrl directly adjusts output current without PWM artifacts. The LM3503ITLX-16/NOPB maintains regulation accuracy across temperature and input voltage variations, making it ideal for flicker-free dimming in sensitive UI applications.
Can LM3503ITLX-16/NOPB drive different numbers of LEDs on MAIN and SUB channels?
Yes, the LM3503ITLX-16/NOPB supports asymmetric LED configurations: MAIN (VOUT1–VOUT2) and SUB (VOUT2–Fb) strings may each contain 2 to 5 white LEDs, independently. The device regulates current in each string using separate internal FETs (P1 for MAIN, N2 for SUB), with shared feedback sensing at Fb. Total output voltage is limited by the 16 V OVP threshold, so combined forward voltage must remain below this value. The LM3503ITLX-16/NOPB's current limit and thermal design accommodate mixed-string loads without derating.
What is the recommended inductor value for LM3503ITLX-16/NOPB in a 3.6 V input, 4-LED per string design?
For a 3.6 V input driving two 4-LED strings (Vf ≈ 3.2 V total per string), the recommended inductor is 2.2 µH with ≥500 mA saturation current (e.g., DO1608C-223). This value balances ripple current (<30% of average), efficiency (>85%), and physical size in the LM3503ITLX-16/NOPB's 1 MHz topology. Inductor DCR should be <150 mΩ to minimize conduction loss. Layout best practices-short, wide Sw and PGND traces-are critical for stable operation of the LM3503ITLX-16/NOPB.
Does LM3503ITLX-16/NOPB support PWM dimming in addition to analog control?
Yes, the LM3503ITLX-16/NOPB supports PWM dimming via RC-filtered signals applied to the Cntrl pin. A PWM signal (≥10× the RC filter bandwidth) is low-pass filtered to generate a smoothed DC voltage that controls LED current. TI recommends adding a 1–2 ms delay between Cntrl signal assertion and En1 activation to allow output discharge and prevent flicker-especially with short SUB strings (2 LEDs). This dual-dimming capability gives designers flexibility: analog for smooth transitions, PWM for high-precision grayscale control. The LM3503ITLX-16/NOPB's internal architecture handles both modes seamlessly.
LM3503ITLX-16/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 10-WFBGA, DSBGA
- 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:
- 16V
- Current - Output / Channel:
- 400mA (Switch)
- Frequency:
- 1MHz
- Dimming:
- Analog, PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-TµSMD (1.9x2.07)
LM3503ITLX-16/NOPB FAQ
1.How can I place an order for LM3503ITLX-16/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3503ITLX-16/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 LM3503ITLX-16/NOPB reliable?
The price and inventory of LM3503ITLX-16/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3503ITLX-16/NOPB is usually 5 days.
3.What payment methods are accepted for LM3503ITLX-16/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3503ITLX-16/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3503ITLX-16/NOPB?
LM3503ITLX-16/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3503ITLX-16/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 LM3503ITLX-16/NOPB?
For technical support, including LM3503ITLX-16/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3503ITLX-16/NOPB requirements.
6.How does Aetrix verify that LM3503ITLX-16/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3503ITLX-16/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 LM3503ITLX-16/NOPB meets industry standards.
7.What is the process for return or replacement of LM3503ITLX-16/NOPB?
All LM3503ITLX-16/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3503ITLX-16/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 LM3503ITLX-16/NOPB part is unused and in its original packaging.
Return procedure for LM3503ITLX-16/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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