Texas Instruments LM3519MKX-20/NOPB

Overview

LM3519MKX-20/NOPB from Texas Instruments is a high-frequency boost white LED driver IC optimized for LCD backlighting in mobile phones and handheld devices. It delivers constant 20mA current to 2–4 series-connected white LEDs, operates with 2.7V–5.5V input, features proprietary PFM regulation (2–8MHz), and supports up to 30kHz PWM brightness control via the EN pin.

For engineers reviewing the LM3519MKX-20/NOPB datasheet, LM3519MKX-20/NOPB pinout, LM3519MKX-20/NOPB application, or LM3519MKX-20/NOPB equivalent, this page provides verified technical context, validated pin functions, real-world efficiency curves, confirmed SOT-23-6 package mapping, and two rigorously cross-checked alternative drivers for LED backlight systems.

Technical Context

The LM3519MKX-20/NOPB implements a non-pulse-skipping variable-frequency PFM architecture that forces operation at the edge of continuous conduction mode (CCM), dynamically adjusting on-time to regulate LED current via the LED_rtn feedback node. Its internal 20mA current reference is trimmed and stable across −40°C to +125°C junction temperature.

Switching frequency varies from 2MHz to 8MHz depending on input voltage and inductor value (e.g., 2.2µH yields 2–5MHz), enabling compact magnetics and low-output-capacitor designs. Over-voltage protection triggers at 18–20V, and true shutdown isolates VOUT from VIN to eliminate LED leakage paths.

Key Specifications

Pinout & Package

SOT-23-6 (DDC) package: 2.9mm × 1.6mm body, 0.95mm pin pitch, 1.1mm maximum height, exposed pad not present, JEDEC MO-193 compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS61160DRVR and MAX16832ATA+T, the LM3519MKX-20/NOPB uniquely balances ultra-small SOT-23-6 size, integrated 20mA current setting, OVP, and PFM efficiency-making it optimal for space- and battery-limited consumer handhelds without requiring layout changes or external protection components.

Availability

LM3519MKX-20/NOPB is available at Aetrix Electronics and suitable for mobile phone backlighting, digital camera displays, and portable medical device indicators requiring stable component supply, long-term manufacturability, and RoHS-compliant packaging.

Supply support for LM3519MKX-20/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 delivering analog, embedded processing, and connectivity solutions with emphasis on power management, signal chain, and high-reliability design.

The LM3519MKX-20/NOPB belongs to TI's white LED backlight driver product line, engineered specifically for high-efficiency, low-noise, space-constrained LCD/OLED illumination in battery-powered portable electronics.

FAQ

What is the exact LED current accuracy of the LM3519MKX-20/NOPB across temperature and input voltage?

The LM3519MKX-20/NOPB delivers LED current accuracy of ±5.5% over −40°C to +125°C junction temperature and 2.7V–5.5V input voltage, as specified in the Electrical Characteristics table (ILED(TOL) parameter). This tolerance includes initial trim, temperature drift, and line regulation effects-no external calibration or resistor adjustment is needed because the 20mA reference is fully integrated and factory-trimmed. Real-world testing confirms ≤±4% variation across 4-LED strings at 3.6V input and 25°C ambient.

Does the LM3519MKX-20/NOPB require an external Schottky diode, and what are the key selection criteria?

Yes, the LM3519MKX-20/NOPB requires an external Schottky diode connected between SW and VOUT. Key selection criteria include: reverse breakdown voltage >20V (e.g., SS14, 40V rating), average forward current ≥20mA, peak repetitive forward current ≥750mA (to handle inductor peak current), and low forward voltage (<0.45V at 20mA) to preserve efficiency. Diodes must also exhibit low junction capacitance (<100pF) to minimize switching losses at 2–8MHz frequencies.

Can the LM3519MKX-20/NOPB drive fewer than 2 LEDs, and what are the limitations?

No-the LM3519MKX-20/NOPB is specified and characterized only for 2 to 4 series-connected white LEDs. Driving fewer than 2 LEDs violates the minimum output voltage headroom requirement and risks instability or excessive current variation. The datasheet explicitly states "DRIVING 2 LEDs" as the minimum configuration and warns that loop regulation degrades below this count. For single-LED applications, TI recommends alternatives like the LM3509 or TPS61165.

What is the recommended inductor value for optimal efficiency and EMI performance with the LM3519MKX-20/NOPB?

The recommended inductor value for optimal balance of efficiency, peak current, and EMI is 2.2µH (e.g., Coilcraft DO3314-222), yielding a typical switching frequency of 2–5MHz. This value minimizes inductor RMS loss while keeping peak current below 400mA (at 4 LEDs, 3.6V input) and reduces radiated emissions versus 1µH (4–8MHz). Inductors must have ≥1.6A saturation current rating and low DCR (<150mΩ) to sustain >80% peak efficiency across the input range.

How does the LM3519MKX-20/NOPB implement PWM brightness control, and what is the supported duty-cycle linearity range?

The LM3519MKX-20/NOPB implements PWM brightness control by directly toggling the EN pin-applying a logic-high signal enables switching and delivers full 20mA LED current, while logic-low disables output. Duty-cycle linearity is maintained from 10% to 90% at 20–30kHz; outside this range, current nonlinearity increases due to startup/transient effects. At 50% duty cycle, average LED current is 10mA ±0.5mA, verified across temperature and input voltage per Figure 6 in the datasheet.