Texas Instruments LM3508TLX/NOPB

Overview

LM3508TLX/NOPB from Texas Instruments is a synchronous boost LED driver IC designed to deliver constant-current drive for up to four series white LEDs at 30mA from a 2.7V–5.5V single-cell Li-ion supply. It integrates internal NMOS/PMOS power switches, provides ±5% LED current regulation across input voltage range, features 850kHz fixed-frequency operation, and includes output over-voltage (17.5V) and short-circuit protection - used in handheld device backlighting.

For engineers reviewing the LM3508TLX/NOPB datasheet, LM3508TLX/NOPB pinout, LM3508TLX/NOPB application, or LM3508TLX/NOPB equivalent, key selection considerations include PWM dimming support up to 100kHz, internal soft-start (470µs), true shutdown isolation (<1µA quiescent current), and compatibility with low-profile 9-bump DSBGA packaging (1.514mm × 1.514mm × 0.6mm).

Technical Context

The LM3508TLX/NOPB implements a current-mode synchronous boost topology with integrated NMOS switch (500mA peak limit) and PMOS synchronous rectifier (no external Schottky diode required). Its control loop regulates ILED by maintaining 500mV at the ILED pin and uses a 200mV reference at SET to set current via RSET = 200mV / ILED.

Dimming is achieved through direct modulation of the 200mV reference using a logic-level PWM signal applied to DIM, with internal RC filtering (≈500Hz cutoff); EN enables/disables full operation including current sink and switching, delivering true output isolation during shutdown.

Key Specifications

Pinout & Package

LM3508TLX/NOPB is housed in a 9-bump DSBGA package (1.514mm × 1.514mm × 0.6mm, YZR000911A), optimized for ultra-compact portable PCB layouts with minimal thermal resistance (θJA = 64.7°C/W on 4-layer board).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar white LED constant-current boost driver applications.

Compared with TPS61160DRVR and MAX16832ATA+T, LM3508TLX/NOPB uniquely combines single-cell compatibility (2.7V start), fully integrated power stage, ±5% current accuracy, and safety features (OVP, short-circuit, thermal shutdown) in a 1.5mm² DSBGA - making it the only drop-in solution for space- and battery-constrained portable backlighting.

Availability

LM3508TLX/NOPB is available at Aetrix Electronics and suitable for handheld device backlighting, digital camera displays, and portable medical instrumentation requiring stable component supply, long-lifecycle assurance, and RoHS-compliant packaging.

Supply support for LM3508TLX/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 decades of expertise in precision power conversion and LED lighting solutions.

The LM3508TLX/NOPB belongs to TI's white LED backlight driver product line, engineered specifically for high-efficiency, low-noise, space-constrained portable applications powered by single-cell batteries.

FAQ

What is the maximum number of white LEDs the LM3508TLX/NOPB can drive, and at what current?

The LM3508TLX/NOPB is specified to drive up to four white LEDs in series at a maximum regulated current of 30mA, assuming typical forward voltage of ~3.2V per LED (total VOUT ≈ 12.8V). At lower currents (e.g., 20mA), it supports longer strings depending on available headroom and input voltage - verified in TI's typical application circuits and efficiency curves.

Does the LM3508TLX/NOPB require external compensation components?

No, the LM3508TLX/NOPB features internal compensation, eliminating the need for external RC networks. This simplifies design, reduces bill-of-materials cost, and improves layout robustness - confirmed in the block diagram (Figure 27) and "Operation" section of the SNVS494C datasheet.

How does the LM3508TLX/NOPB achieve LED current dimming?

The LM3508TLX/NOPB uses PWM dimming applied directly to the DIM pin, which modulates the internal 200mV reference voltage via an integrated RC filter. LED current scales linearly with PWM duty cycle: ILED = D × 200mV / RSET - validated in Figure 13 (SET voltage vs DIM duty cycle) and the "DIM Operation" section.

What protection features are built into the LM3508TLX/NOPB?

The LM3508TLX/NOPB integrates output over-voltage protection (17.5V threshold), output short-circuit protection (limits current to ~35mA when VOUT < 0.93×VIN), thermal shutdown (150°C trip), and true shutdown isolation (<1µA IQ). All are documented in the Absolute Maximum Ratings, Electrical Characteristics, and "Operation" sections of SNVS494C.

Is the LM3508TLX/NOPB compatible with ceramic output capacitors?

Yes - the LM3508TLX/NOPB is optimized for 1µF ceramic output capacitors (e.g., Murata GRM39X5R105K25D539, 0603, 25V), as specified in Table 1 of the datasheet. Ceramic caps ensure stability, low ESR, and minimal output ripple without requiring additional damping networks.