Texas Instruments LP3944ISQX

Overview

LP3944ISQX from Texas Instruments is an 8-channel I²C-compatible LED driver IC with programmable PWM dimming, open-drain outputs (25 mA per channel), internal oscillator, and integrated power-on reset. It drives RGB/white/blue LEDs in mobile accessories and enables GPIO expansion via unused LED pins. Designed for low-bus-traffic LED control in space-constrained portable devices.

For engineers reviewing the LP3944ISQX datasheet, LP3944ISQX pinout, LP3944ISQX application, or LP3944ISQX equivalent, key selection criteria include its WQFN-24 package, dual-dimming-rate capability (6.25 ms–1.6 s), SMBus/I²C address configuration (A2–A0), 2.3–5.5 V operation, and 200 mA total package sink current limit.

Technical Context

The LP3944ISQX integrates a precision internal oscillator and two independent prescaler-PWM register pairs (PSC0/PWM0 and PSC1/PWM1) to generate two distinct dimming frequencies and duty cycles. Each of the eight open-drain outputs is individually configurable via selector registers (LS0/LS1) into one of four states: high-impedance (off), active-low (on), DIM0 rate, or DIM1 rate.

It implements standard SMBus/I²C protocol with 400 kHz max clock frequency, supports auto-increment addressing across nine registers (0x00–0x09), and includes hardware reset (active-low RST) with 10 ns minimum pulse width. All digital inputs (A0–A2, SCL, SDA, RST) tolerate up to 6 V, while LED outputs support 0.4 V VOL at 25 mA (VDD = 5.0 V).

Key Specifications

Pinout & Package

LP3944ISQX uses a 24-pin WQFN package (RTW0024A), 4.0 × 4.0 mm, 0.5 mm pitch, with exposed thermal pad. Pin 1 is located in quadrant Q1; the thermal pad must be soldered to PCB ground for thermal and mechanical integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLC59116IPWR and PCA9635D,118, the LP3944ISQX uniquely combines dual independent dimming engines, GPIO expansion, and internal oscillator in a compact WQFN-24 package-making it optimal for cost-sensitive, space-constrained portable products needing rich LED effects with minimal host intervention.

Availability

LP3944ISQX is available at Aetrix Electronics and suitable for cellular phone accessories, portable gaming devices, digital camera indicators, and USB-C peripheral status panels requiring stable component supply and long-term manufacturability.

Supply support for LP3944ISQX 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, personal electronics, and communications markets.

The LP3944ISQX belongs to TI's LED driver product line, engineered specifically for low-pin-count, low-bus-traffic LED control in battery-powered portable devices-emphasizing integration, configurability, and ease of implementation.

FAQ

What is the maximum total current the LP3944ISQX can sink across all channels?

The LP3944ISQX supports up to 25 mA per LED output pin, with a hard limit of 200 mA total package sink current. This means no more than eight channels may operate simultaneously at full 25 mA, and thermal design (including proper soldering of the exposed thermal pad) is essential to sustain this load at ambient temperatures up to +85°C. Exceeding 200 mA risks thermal shutdown or parametric drift.

Does the LP3944ISQX require an external clock source?

No, the LP3944ISQX does not require an external clock source. It contains an internal precision oscillator that generates all timing signals needed for PWM dimming and register operation. This eliminates external crystal or RC networks, simplifying BOM and layout-especially critical in ultra-compact portable designs where board space is at a premium.

Can unused LED pins on the LP3944ISQX be used as general-purpose I/O?

Yes, unused LEDx pins on the LP3944ISQX function as general-purpose open-drain I/O. When configured in high-impedance state via the LS0/LS1 selector registers, they can serve as inputs (with external pull-up) or outputs (sinking current to GND). This provides up to eight additional flexible digital interfaces-ideal for button sensing, status signaling, or simple peripheral control without adding a separate I/O expander IC.

What I²C address options are supported by the LP3944ISQX?

The LP3944ISQX supports seven user-configurable I²C slave addresses (0x60–0x66) via pins A0, A1, and A2. Address bit 7 is fixed at '1', bits 6–4 are hardwired to '100', and bits 3–1 are set by A2–A0. The eighth address (0x67) is reserved for special functions and not available for standard write operations. This allows up to seven LP3944ISQX devices on a single I²C bus without address conflict.

How does the LP3944ISQX reduce I²C bus traffic compared to traditional LED drivers?

The LP3944ISQX reduces I²C bus traffic by implementing autonomous PWM generation internally. After initial configuration of prescaler and PWM registers, the host MCU sends only single-byte commands (e.g., "turn LED3 on" or "cycle LED5 at DIM1 rate")-no continuous streaming of timing data is needed. In contrast, shift-register-based drivers require full byte-by-byte updates for every frame, increasing bus load by orders of magnitude during dynamic LED effects.