My Inquiry
My Account
Texas Instruments LM3503SQX-44
- Part No.:
- LM3503SQX-44
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LM3503SQX-44.pdf
- Description:
- IC LED DRV RGLTR PWM 16WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,340
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LM3503SQX-44 from Texas Instruments is a dual-display constant-current white LED driver IC with analog brightness control, 44 V over-voltage protection (OVP), 1 MHz switching frequency, and support for up to 10 LEDs (5 per display). It operates from 2.5 V to 5.5 V input and delivers precise current regulation for portable device backlighting.
For engineers reviewing the LM3503SQX-44 datasheet, LM3503SQX-44 pinout, LM3503SQX-44 application, or LM3503SQX-44 equivalent, key selection considerations include OVP threshold (40.5–43.5 V), dual independent enable logic (En1/En2), analog dimming via Cntrl pin (0.2–3.5 V), and thermal shutdown at +150°C junction temperature.
Technical Context
The LM3503SQX-44 implements an asynchronous current-mode PWM boost controller with cycle-by-cycle current limiting, internal soft start, and dedicated OVP comparator set for 44 V nominal trip. Its dual-FET architecture integrates separate PMOS (VOUT1) and NMOS (VOUT2) switches to independently drive MAIN and SUB LED strings in a single cascaded topology.
Control is achieved through analog voltage on Cntrl (0.2–3.5 V) modulating feedback reference (VFb = 0.156 × VCntrl), while En1 and En2 pins provide discrete logic-level enable/disable of each FET switch - enabling four operational states including full shutdown when both are ≤0.3 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| OVP Threshold | 40.5–43.5 V (enables safe operation with 44 V-rated output capacitors and diodes) |
| Switching Frequency | 0.8–1.2 MHz (supports compact external components; fixed-frequency avoids EMI band clustering) |
| Input Voltage Range | 2.5 V to 5.5 V (direct compatibility with Li-ion, Li-poly, and regulated 3.3 V/5 V rails) |
| Cntrl Pin Range | 0.2 V to 3.5 V (maps linearly to LED current via VFb = 0.156 × VCntrl; enables smooth analog dimming) |
| Peak Efficiency | >80% (achieved at mid-load currents with typical 2–5 LED strings per display) |
| Junction Temp Range | −40°C to +125°C (supports industrial-grade portable electronics operating in extended ambient conditions) |
| Current Limit (Typ) | 750 mA (ensures robust inductor and switch sizing for 10-LED configurations at 44 V OVP) |
Pinout & Package
LM3503SQX-44 is packaged in a 10-bump thin DSBGA (0.9 mm height, 1.5 mm × 1.5 mm footprint) with die attach pad (DAP) for thermal enhancement.
| 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 |
| Sw | Drain of internal NMOS power switch (N1) | Connects to inductor; low RDS(ON) (0.55–1.1 Ω) reduces conduction loss and thermal stress |
| En1 | PMOS FET (P1) enable / MAIN display control | ≥1.4 V enables MAIN string; ≤0.3 V disables MAIN; internal pull-down ensures default OFF state |
| En2 | NMOS FET (N2) enable / SUB display control | ≥1.4 V enables SUB string; ≤0.3 V disables SUB; floating or grounded if VOUT2 unused |
| Fb | Feedback node for current regulation | Senses voltage across current-sense resistor; sets LED current via VFb = 0.156 × VCntrl |
| Cntrl | Analog brightness control input | DC voltage input (0.2–3.5 V); no external RC filter needed for analog dimming |
| AGND | Analog ground reference | Must be shorted directly to PGND to prevent noise coupling into feedback path |
| PGND | Power ground return | High-current return path for Sw, VOUT1, VOUT2; connect to PCB ground plane under DAP |
| VOUT1 | Source of PMOS switch (P1) / OVP sense node | OVP sensing occurs here; connect Schottky diode and output capacitor as close as possible |
| VOUT2 | Drain of NMOS switch (N2) / SUB string output | Used only when SUB display is active; 100 nF capacitor recommended if unused |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent display control | Separate En1/En2 logic enables MAIN/SUB LED strings without external MOSFETs or sequencing circuitry |
| 44 V over-voltage protection | Hard-clamped OVP threshold prevents damage during open-circuit LED failure or hot-plug events |
| 1 MHz fixed-frequency PWM | Enables use of small, low-ESR ceramic capacitors and miniature inductors (e.g., DO1608C-223) |
| Analog brightness control | Direct DC voltage input (Cntrl pin) eliminates need for external DAC or PWM filtering components |
| Internal soft start | Gradually ramps current limit at startup to suppress inrush current and avoid input rail droop |
| Thermal shutdown | Protects die at +150°C junction temperature; automatically recovers after cooling below hysteresis threshold |
Applications
| Cellular Phone Main/Sub Display | PDA Dual-Screen Backlight |
|---|---|
Use Scenario: Simultaneous illumination of primary LCD and secondary status OLED in clamshell or slider phones. IC Role / Device Role / Timing Role: Constant-current boost driver regulating two independent LED strings with shared inductor and diode. Use Value: Reduces BOM count by eliminating second boost converter; En1/En2 logic enables dynamic display priority switching. | Use Scenario: Powering main touchscreen backlight and auxiliary keypad or notification LED array in handheld PDAs. IC Role / Device Role / Timing Role: Dual-output LED driver with independent enable control and analog dimming for user-adjustable brightness zones. Use Value: Enables independent brightness scaling per zone using single Cntrl voltage; supports 2–5 LEDs per string without redesign. |
| Portable Media Player UI Lighting | Smartwatch Dual-Panel Backlight |
Use Scenario: Driving front-panel navigation LEDs and rear touch-sensitive overlay illumination in compact media players. IC Role / Device Role / Timing Role: High-efficiency boost regulator delivering stable current to segmented LED arrays with minimal footprint. Use Value: 10-bump DSBGA package (1.5 mm × 1.5 mm) fits tight space constraints; >80% efficiency extends battery life. | Use Scenario: Illuminating circular main display and rectangular secondary status bar in round-form-factor smartwatches. IC Role / Device Role / Timing Role: Dual-channel LED driver supporting asymmetric LED counts (e.g., 5-main + 3-sub) with shared power stage. Use Value: 44 V OVP allows use of higher-Vf white LEDs in compact strings; thermal shutdown ensures reliability in sealed enclosures. |
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-25 | OVP threshold 22.5–25.5 V; lower max output voltage capability | Suitable for 2–3 LED strings per display; not rated for 44 V fault conditions | Select when system-level OVP margin is ≤25 V and cost optimization is prioritized over headroom |
| LM3503SQX-35 | OVP threshold 32.0–35.0 V; intermediate protection level between -25 and -44 versions | Supports 4–5 LED strings per display with moderate Vf headroom; less margin than -44 version | Choose for balanced OVP safety and component stress in mid-range LED configurations |
Compared with LM3503SQX-25 and LM3503SQX-35, the LM3503SQX-44 provides highest OVP headroom for fault-tolerant designs with longer LED strings or higher forward voltages, making it optimal for ruggedized portable devices where open-circuit protection is critical.
Availability
LM3503SQX-44 is available at Aetrix Electronics and suitable for cellular phone backlighting, PDA dual-screen systems, and portable media player UI lighting requiring stable component supply and long-term production continuity.
Supply support for LM3503SQX-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 technologies with decades of LED driver innovation.
The LM3503 product line was designed specifically for dual-display portable electronics, integrating dual-FET control, analog dimming, and programmable OVP to eliminate discrete enable logic and reduce total solution size.
FAQ
What is the OVP threshold for LM3503SQX-44?
The LM3503SQX-44 has a guaranteed over-voltage protection threshold of 40.5 V (minimum), 42 V (typical), and 43.5 V (maximum). This OVP circuit disables switching when VOUT1 exceeds the threshold, protecting external components during LED open-circuit faults. The LM3503SQX-44 uses this specific 44 V rating to support higher-forward-voltage LED strings safely.
How does analog brightness control work on LM3503SQX-44?
Analog brightness control on the LM3503SQX-44 is implemented via the Cntrl pin: applying a DC voltage from 0.2 V to 3.5 V sets the feedback reference (VFb = 0.156 × VCntrl), which directly scales LED current. No external DAC or RC filter is required. The LM3503SQX-44 maintains regulation accuracy across temperature and input voltage variations, enabling flicker-free dimming.
Can LM3503SQX-44 drive different numbers of LEDs on MAIN and SUB displays?
Yes - the LM3503SQX-44 supports asymmetric LED counts: MAIN display (VOUT1–VOUT2) and SUB display (VOUT2–Fb) can each drive 2–5 white LEDs independently. The current is set by the same Cntrl voltage, but string voltage requirements differ. The LM3503SQX-44's 44 V OVP and internal FET RDS(ON) values ensure stable operation even with mismatched forward voltages.
What package type is used for LM3503SQX-44?
The LM3503SQX-44 uses a 10-bump thin DSBGA package (1.5 mm × 1.5 mm, 0.9 mm height) with exposed die attach pad (DAP) for thermal dissipation. This ultra-low-profile package meets stringent thickness requirements in slim portable devices. The LM3503SQX-44 pinout matches TI's standard DSBGA mapping for LM3503 variants, ensuring layout compatibility across voltage grades.
How do En1 and En2 pins control display operation on LM3503SQX-44?
En1 controls the PMOS switch (P1) powering the MAIN display (VOUT1–VOUT2); En2 controls the NMOS switch (N2) powering the SUB display (VOUT2–Fb). Logic thresholds are 0.3 V (OFF) and 1.4 V (ON). Both ≤0.3 V places LM3503SQX-44 in shutdown. The LM3503SQX-44 supports four functional states: MAIN-only, SUB-only, both-on, or shutdown - all configurable without firmware.
LM3503SQX-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:
- Analog, PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-WQFN (4x4)
LM3503SQX-44 FAQ
1.How can I place an order for LM3503SQX-44 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3503SQX-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 LM3503SQX-44 reliable?
The price and inventory of LM3503SQX-44 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3503SQX-44 is usually 5 days.
3.What payment methods are accepted for LM3503SQX-44?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3503SQX-44 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3503SQX-44?
LM3503SQX-44 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3503SQX-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 LM3503SQX-44?
For technical support, including LM3503SQX-44 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3503SQX-44 requirements.
6.How does Aetrix verify that LM3503SQX-44 is sourced from the original manufacturer or authorized distributors?
All LM3503SQX-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 LM3503SQX-44 meets industry standards.
7.What is the process for return or replacement of LM3503SQX-44?
All LM3503SQX-44 units undergo pre-shipment inspection (PSI). If there is an issue with LM3503SQX-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 LM3503SQX-44 part is unused and in its original packaging.
Return procedure for LM3503SQX-44:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM3503SQX-44 Tags
-
BCR402RE6327HTSA1
Infineon Technologies
-
BCR430UXTSA2
Infineon Technologies
-
BCR420UE6433HTMA1
Infineon Technologies
-
BCR420UE6327HTSA1
Infineon Technologies
-
BCR421UE6327HTSA1
Infineon Technologies
-
LYT1604D-TL
Power Integrations
-
HV9910CLG-G
Microchip Technology
-
CL2N8-G
Microchip Technology
-
BCR420UW6-7
Diodes Incorporated
-
BCR421UW6-7
Diodes Incorporated
-
BCR420UFD-7
Diodes Incorporated
-
BCR421UFD-7
Diodes Incorporated
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
