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Texas Instruments LM3502SQX-25/NOPB
- Part No.:
- LM3502SQX-25/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LM3502SQX-25/NOPB.pdf
- Description:
- IC LED DRV RGLTR PWM 16WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,393
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Product details
Overview
LM3502SQX-25/NOPB from Texas Instruments is a 25V-output, asynchronous current-mode step-up DC/DC converter optimized for dual white LED backlighting in portable devices. It integrates dual internal FET switches (PMOS and NMOS), operates from 2.5V–5.5V input, delivers >80% efficiency at 1 MHz fixed switching frequency, and supports PWM dimming without external RC filtering - used in cellular phone main/sub display backlight systems.
For engineers reviewing the LM3502SQX-25/NOPB datasheet, LM3502SQX-25/NOPB pinout, LM3502SQX-25/NOPB application, or LM3502SQX-25/NOPB equivalent, key selection criteria include output voltage rating (25 V), integrated dual-FET control logic for independent MAIN/SUB LED string management, over-voltage protection thresholds (22.5–25.5 V), and thermal shutdown with junction temperature limit of +125°C.
Technical Context
The LM3502SQX-25/NOPB implements an asynchronous current-mode PWM control architecture with cycle-by-cycle current limiting, internal soft-start, and dedicated UVP/OVP comparators. Its feedback loop regulates LED current via a 0.25 V reference at the FB pin, while dual enable pins (En1, En2) independently control PMOS and NMOS bypass FETs to isolate MAIN and SUB LED segments.
It features fixed 1 MHz switching frequency, no external compensation required, and operates in continuous or discontinuous conduction mode depending on inductor value, load current, and input/output voltage ratio. Protection includes thermal shutdown, under-voltage lockout (2.4–2.5 V turn-on), and over-voltage protection with hysteresis (21.5–24.5 V turn-off for 25 V version).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 25 V nominal; OVP threshold 22.5–25.5 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 dual-cell alkaline (2.4–3.2 V) supplies. |
| Switching Frequency | 1 MHz ±20%; enables use of small 2.2 µH inductors and reduces EMI filtering requirements. |
| Feedback Reference | 0.25 V typical at FB pin; sets LED current via external resistor (ILED = 0.25 V / RSET). |
| Current Limit | 400–800 mA (typical); protects power NMOS switch (N1) during startup or overload conditions. |
| Efficiency | >80% typical at 50 mA LED current; peak efficiency maintained across 2.7–5.5 V input range per test data. |
| Shutdown Current | 0.1–3 µA; ultra-low quiescent draw extends battery life in standby mode. |
Pinout & Package
LM3502SQX-25/NOPB is housed in a 10-bump, low-profile (<1 mm height) thin DSBGA package (package number YPA0010), optimized for space-constrained portable applications.
| 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 | Power NMOS drain node | Connects to inductor and Schottky diode anode; high dI/dt path requiring short, wide PCB traces. |
| En1 | PMOS FET control (MAIN display) | Logic-level enable: ≤0.3 V turns MAIN LED string ON; ≥1.4 V disables MAIN segment. |
| En2 | NMOS FET control (SUB display) | Logic-level enable: ≤0.3 V turns SUB LED string ON; ≥1.4 V disables SUB segment. |
| Fb | Current-sense feedback input | 0.25 V reference node; connects to current-set resistor to ground to program LED current. |
| Cntrl | Global enable/shutdown control | ≥1.4 V enables device; ≤0.3 V forces shutdown; internal pull-down keeps default OFF state. |
| AGND | Analog ground reference | Must be tied directly to PGND to prevent noise coupling into feedback and control circuitry. |
| PGND | Power ground return | High-current return path for NMOS switch and output capacitor; requires low-impedance connection to PCB ground plane. |
| VOUT1 | OVP sense / PMOS source | Primary output node; connects to cathode of main LED string and OVP sensing network. |
| VOUT2 | NMOS/PMOS drain junction | Intermediate node between MAIN and SUB LED strings; unused in single-string configurations. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent LED string control | En1 and En2 pins allow hardware-selectable MAIN/SUB backlight activation without microcontroller GPIO overhead. |
| PWM dimming without RC filter | Internal circuitry accepts direct 200–500 Hz PWM on Cntrl pin for linear brightness control and fast recovery. |
| Integrated over-voltage protection | OVP threshold fixed at 22.5–25.5 V for LM3502SQX-25/NOPB prevents damage during open-circuit LED failure. |
| No external compensation required | Stable operation with minimal external components - only inductor, diode, input/output caps, and current-set resistor. |
| Low-profile DSBGA packaging | 10-bump, <1 mm height package enables ultra-thin mobile designs and improves thermal dissipation via DAP soldering. |
Applications
| Cellular Phone Dual Display | Portable Media Player Backlight |
|---|---|
Use Scenario: Simultaneous illumination of main LCD and secondary status OLED in clamshell or slider phones. IC Role / Device Role / Timing Role: Step-up converter with dual-FET bypass logic to independently power MAIN (VOUT1→Fb) and SUB (VOUT2→Fb) LED strings. Use Value: Enables dynamic display partitioning - e.g., MAIN active during call, SUB active in standby - reducing system power by >40% vs. always-on dual strings. | Use Scenario: Brightness-controlled backlight for 3.5"–4.3" TFT-LCD in MP4 players with battery life target >10 hours. IC Role / Device Role / Timing Role: Constant-current LED driver delivering regulated 25 V output to 6–8 white LEDs in series. Use Value: >80% efficiency across 2.7–4.2 V battery range maintains consistent brightness and minimizes thermal load on compact PCB. |
| Smartphone Secondary Display | Handheld GPS Navigator |
Use Scenario: Powering always-on notification bar (e.g., 2–5 LEDs) while main screen is off in modern smartphones. IC Role / Device Role / Timing Role: Low-IQ shutdown mode (6–15 µA) activated via En1/En2/Cntrl coordination to isolate inactive segments. Use Value: Enables persistent visual indicators with sub-10 µA total system standby current - critical for multi-day battery endurance. | Use Scenario: Sunlight-readable LCD backlight in automotive-grade handheld GPS units operating from 3.3 V LDO or battery. IC Role / Device Role / Timing Role: 25 V boost converter driving 4–6 white LEDs with built-in UVP (2.4 V) and thermal shutdown (+125°C). Use Value: Ensures reliable operation across −40°C to +85°C ambient, eliminating need for external protection circuitry. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar white LED boost driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3502SQX-16/NOPB | 16 V output rating; lower OVP threshold (14.5–16.5 V); identical pinout and control logic. | Suitable for shorter LED strings (4–6 LEDs) with lower forward voltage drop; reduced component stress at output. | Select when total LED VF ≤14 V to improve efficiency and reduce thermal load vs. 25 V variant. |
| LM3502SQX-35/NOPB | 35 V output rating; higher OVP threshold (32–35 V); same DSBGA-10 package and functional interface. | Required for longer LED strings (8–10 LEDs) or high-VF LEDs (e.g., green/amber); wider safety margin for transient overvoltage. | Choose for designs needing >28 V headroom or future-proofing for LED technology upgrades. |
Compared with LM3502SQX-16/NOPB and LM3502SQX-35/NOPB, the LM3502SQX-25/NOPB provides optimal balance for 7–8 white LED strings (VF ≈ 3.2–3.6 V each), delivering best-in-class efficiency at mid-range output voltage while maintaining compatibility with existing PCB layouts and firmware control sequences.
Availability
LM3502SQX-25/NOPB is available at Aetrix Electronics and suitable for cellular phone backlighting, portable media player displays, and handheld GPS navigation systems requiring stable component supply and long-term production continuity.
Supply support for LM3502SQX-25/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 ICs, with decades of expertise in power conversion and LED lighting solutions.
The LM3502 product line was designed specifically for dual-display white LED backlighting in battery-powered portable electronics, emphasizing integration, efficiency, and ease of implementation in space- and power-constrained designs.
FAQ
What is the maximum LED string voltage supported by LM3502SQX-25/NOPB?
The LM3502SQX-25/NOPB supports up to 25 V output with over-voltage protection triggered between 22.5 V and 25.5 V. This allows safe operation with 7–8 standard white LEDs (VF ≈ 3.2–3.6 V each) in series. Exceeding the OVP threshold will disable switching to protect the IC and external components. The absolute maximum Sw pin rating is +48 V, but sustained operation above 25 V violates the device's specified output configuration.
How does LM3502SQX-25/NOPB implement dual-display control without external logic?
The LM3502SQX-25/NOPB uses two dedicated enable pins - En1 controls the PMOS FET for the MAIN LED string (VOUT1 to Fb), and En2 controls the NMOS FET for the SUB string (VOUT2 to Fb). Each pin responds to logic thresholds (≤0.3 V = ON, ≥1.4 V = OFF), allowing independent hardware-based activation of either display segment. No external gate drivers or level shifters are needed, reducing BOM count and layout complexity.
Can LM3502SQX-25/NOPB be dimmed using PWM, and what frequency range is recommended?
Yes, LM3502SQX-25/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. Below 200 Hz may cause visible flicker; above 500 Hz degrades linearity and increases audible noise risk. The device distinguishes short low pulses (<12 ms) for dimming vs. long low pulses (>12 ms) for full shutdown with soft-start reset.
What thermal considerations apply to LM3502SQX-25/NOPB in a 10-bump DSBGA package?
The LM3502SQX-25/NOPB in its 10-bump DSBGA package has a junction-to-ambient thermal resistance (θJA) of 65°C/W. To maintain TJ ≤ +125°C at +85°C ambient, average power dissipation must stay below ~615 mW. This requires proper DAP soldering to the PCB ground plane, minimized trace resistance on PGND/VOUT1 paths, and adequate copper area for heat spreading - especially critical at high LED currents (>60 mA) and low input voltages (<3.0 V).
Is LM3502SQX-25/NOPB compatible with ceramic output capacitors, and what value is typical?
Yes, LM3502SQX-25/NOPB is fully compatible with ceramic output capacitors due to its integrated over-voltage protection, which eliminates reliance on electrolytic capacitor ESR for stability. A typical value is 1 µF X5R/X7R ceramic placed as close as possible to the VOUT1 and PGND pins. Larger values (e.g., 2.2 µF) further reduce output ripple but do not affect regulation stability, as no external compensation is required.
LM3502SQX-25/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:
- 25V
- Current - Output / Channel:
- 600mA (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-25/NOPB FAQ
1.How can I place an order for LM3502SQX-25/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3502SQX-25/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 LM3502SQX-25/NOPB reliable?
The price and inventory of LM3502SQX-25/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3502SQX-25/NOPB is usually 5 days.
3.What payment methods are accepted for LM3502SQX-25/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3502SQX-25/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3502SQX-25/NOPB?
LM3502SQX-25/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3502SQX-25/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 LM3502SQX-25/NOPB?
For technical support, including LM3502SQX-25/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3502SQX-25/NOPB requirements.
6.How does Aetrix verify that LM3502SQX-25/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3502SQX-25/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 LM3502SQX-25/NOPB meets industry standards.
7.What is the process for return or replacement of LM3502SQX-25/NOPB?
All LM3502SQX-25/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3502SQX-25/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 LM3502SQX-25/NOPB part is unused and in its original packaging.
Return procedure for LM3502SQX-25/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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