Texas Instruments LP3943ISQX/NOPB

Overview

LP3943ISQX/NOPB from Texas Instruments is a 16-channel SMBus/I²C-controlled LED driver IC with independent per-channel dimming control, 25mA sink capability per output, internal precision oscillator (0.625Hz–160Hz), and programmable PWM frequency/duty cycle via two prescaler-PWM register pairs. It serves as an RGB/white LED lighting controller and GPIO expander in space-constrained portable electronics.

For engineers reviewing the LP3943ISQX/NOPB datasheet, LP3943ISQX/NOPB pinout, LP3943ISQX/NOPB application, or LP3943ISQX/NOPB equivalent, key selection criteria include per-output dimming state control (ON/OFF/DIM0/DIM1), I²C slave address configurability (A0–A2), thermal performance in WQFN-24 (R_θJA = 45.0°C/W), and compliance with SMBus timing requirements (400kHz clock, t_HOLD ≥ 0.6µs).

Technical Context

The LP3943ISQX/NOPB integrates a precision internal oscillator to eliminate external timing components and supports dual independent PWM dimming profiles (DIM0/DIM1) via dedicated 8-bit prescaler and PWM registers. Each of its 16 open-drain outputs is individually assignable to one of four functional states-high-impedance (Hi-Z), active-low ON, or dimming at either DIM0 or DIM1 rate-enabling complex lighting sequences with minimal host bus traffic.

It implements auto-increment addressing for sequential register writes/reads, reduces I²C overhead by allowing single-command state changes after configuration, and provides read-only input status registers (0x00–0x01) for monitoring external signal levels on LED pins used as GPIO inputs. The device operates across −40°C to +85°C ambient with V_DD from 2.3V to 5.5V and includes active-low reset with 10ns minimum pulse width.

Key Specifications

Pinout & Package

LP3943ISQX/NOPB uses a 4.00mm × 4.00mm WQFN-24 package (RTW) with exposed thermal pad tied internally to GND. The 24-pin top-view layout includes 16 LED driver outputs, 3 address inputs (A0–A2), I²C interface (SCL/SDA), power (VDD), ground (GND), and active-low reset (RST).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLC59283DBQR and PCA9635D,118, the LP3943ISQX/NOPB uniquely combines per-pin 25mA sink, autonomous dual-PWM operation, and GPIO reuse - making it optimal for cost-sensitive, space-constrained portable designs requiring both indicator lighting and I/O expansion.

Availability

LP3943ISQX/NOPB is available at Aetrix Electronics and suitable for cellular phone indicator lighting, digital camera status feedback, and portable device flashlight functions requiring stable component supply across production lifecycles.

Supply support for LP3943ISQX/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 company specializing in analog, embedded processing, and connectivity technologies with broad industrial and consumer design support infrastructure.

The LP3943 product line was designed specifically for low-pin-count, I²C-managed LED lighting in portable electronics - prioritizing integration (oscillator, dual PWM, address selection), thermal efficiency in WQFN, and GPIO flexibility.

FAQ

What is the maximum number of LP3943ISQX/NOPB devices that can operate on a single I²C bus?

The LP3943ISQX/NOPB supports three hardware address inputs (A0, A1, A2), enabling eight unique I²C slave addresses (0x60–0x67). Therefore, up to eight LP3943ISQX/NOPB devices can coexist on one I²C bus without address collision, provided each has a distinct A0–A2 combination wired to VDD or GND.

Does LP3943ISQX/NOPB require external passive components for basic LED driving functionality?

No, the LP3943ISQX/NOPB does not require external timing components due to its integrated precision oscillator. For basic operation, only a 1µF VDD decoupling capacitor near the pin is mandatory per TI layout guidelines. External current-setting resistors may still be needed depending on LED forward voltage and desired brightness, but are not part of the IC's core timing or control circuitry.

Can unused LED output pins on LP3943ISQX/NOPB be repurposed as general-purpose inputs?

Yes, unused LED output pins on LP3943ISQX/NOPB can function as general-purpose inputs. When configured in Hi-Z state (B1/B0 = 00 in LS0–LS3 registers), the pins present high impedance and their logic levels are readable via the Input1 (0x00) and Input2 (0x01) registers - effectively providing up to 16 additional GPIO inputs without external components.

What thermal considerations apply when operating LP3943ISQX/NOPB at its maximum 200mA package current?

At 200mA total sink current and 5.5V VDD, LP3943ISQX/NOPB dissipates up to ~400mW. With R_θJA = 45.0°C/W, junction temperature rise could exceed 100°C above ambient. To maintain reliability, ensure the exposed thermal pad is soldered to a solid GND plane with ≥4 thermal vias, limit continuous 200mA operation to ambient ≤60°C, and verify PCB copper area meets TI's WQFN-24 thermal guidelines.

How does LP3943ISQX/NOPB reduce I²C bus traffic compared to shift-register-based LED drivers?

The LP3943ISQX/NOPB reduces I²C traffic by eliminating the need for continuous data streaming. After configuring PWM/dimming parameters and assigning output states via registers, the host only sends single-byte commands (e.g., "set LED5 ON") to change states - unlike shift registers (e.g., 74LS594) that require full 16-bit updates per frame. This cuts typical command overhead by >90% for static or slowly changing lighting patterns.