NXP Semiconductors LD6816CX4/C29P,315

Overview

LD6816CX4/C29P,315 from NXP Semiconductors is a 2.9 V fixed-output, 150 mA ultra-low-dropout linear regulator in WLCSP4 package with auto-discharge (pull-down) functionality. It delivers 45 mV dropout at full load, 30 µV_RMS output noise (10 Hz–100 kHz), and 55 dB PSRR at 1 kHz, enabling stable power for noise-sensitive analog circuits in space-constrained portable devices.

For engineers reviewing the LD6816CX4/C29P,315 datasheet, LD6816CX4/C29P,315 pinout, LD6816CX4/C29P,315 application, or LD6816CX4/C29P,315 equivalent, key selection criteria include its 2.9 V output accuracy (±2% over −30°C to +85°C), sub-1 µA shutdown quiescent current, 150 µs startup time, and integrated thermal/overcurrent protection - all critical for battery-powered mobile interface rails.

Technical Context

The LD6816CX4/C29P,315 implements a PMOS pass transistor architecture enabling ultra-low dropout and high PSRR across frequency. Its enable input (active HIGH) controls both regulation and the integrated pull-down switch, ensuring rapid output discharge during disable - essential for sequencing in multi-rail systems.

Designed for low-noise analog supply domains, it features internal voltage reference stabilization, precision resistor divider feedback, and ESD-hardened inputs (10 kV HBM). The WLCSP4 package's 0.4 mm pitch and 0.76 mm × 0.76 mm footprint support miniaturized PCB layouts without compromising thermal performance (R_th(j-a) = 130 K/W).

Key Specifications

Pinout & Package

LD6816CX4/C29P,315 uses a 0.4 mm pitch Wafer-Level Chip-Scale Package (WLCSP4) measuring 0.76 mm × 0.76 mm × 0.47 mm, with backside coating for enhanced mechanical robustness and moisture resistance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LDO regulator applications.

Compared with TPS7A0529PDBVR and MCP1700T-2902E/TT, LD6816CX4/C29P,315 offers the smallest footprint (0.58 mm² vs. 4.64 mm² and 2.4 mm²), lowest dropout (45 mV vs. 170 mV and 600 mV), and integrated auto-discharge - making it uniquely suited for space- and efficiency-critical portable analog rails.

Availability

LD6816CX4/C29P,315 is available at Aetrix Electronics and suitable for smartphone camera modules, portable audio codecs, wearable sensor hubs, and low-power MCU I/O rails requiring stable component supply with guaranteed long-term availability.

Supply support for LD6816CX4/C29P,315 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

NXP Semiconductors is a global semiconductor company specializing in secure connectivity solutions for automotive, industrial, and consumer electronics, with leadership in power management and RF technologies.

The LD6816 series was designed specifically for ultra-miniaturized, low-noise power regulation in portable consumer devices - targeting analog interface rails where dropout, noise, and footprint are critical constraints.

FAQ

What is the nominal output voltage and tolerance of the LD6816CX4/C29P,315?

The LD6816CX4/C29P,315 provides a fixed 2.9 V output voltage with ±2% tolerance over the operating temperature range of −30°C to +85°C. This accuracy is confirmed in Table 9 of the NXP datasheet under "Output voltage variation" for VOUT ≥ 1.8 V, ensuring reliable biasing for 2.8–3.0 V logic and analog components without external trimming.

Does the LD6816CX4/C29P,315 include an auto-discharge function, and how does it operate?

Yes, the LD6816CX4/C29P,315 integrates an auto-discharge function via an internal 100 Ω pull-down transistor on the OUT pin. When the EN pin is driven LOW, this transistor activates, discharging the output capacitance to 10% of nominal voltage within 300 µs - eliminating floating outputs and enabling clean power sequencing in multi-rail systems without external components.

What is the minimum external output capacitor required for stable operation of the LD6816CX4/C29P,315?

The LD6816CX4/C29P,315 requires a minimum 0.7 µF X7R ceramic capacitor on the OUT pin, with recommended value of 1.0 µF and ESR between 5 mΩ and 500 mΩ. This capacitor ensures loop stability, controls startup/shutdown transients, and maintains PSRR performance - per Table 10 and Section 10.1 of the NXP datasheet.

How does the LD6816CX4/C29P,315 compare to standard LDOs in terms of noise performance?

The LD6816CX4/C29P,315 delivers 30 µV_RMS output noise over 10 Hz–100 kHz, significantly lower than typical LDOs (often >100 µV_RMS). This ultra-low noise is achieved through optimized internal reference and error amplifier design, making LD6816CX4/C29P,315 suitable for powering high-resolution ADCs, precision op-amps, and RF synthesizers where noise directly impacts signal fidelity.

What package type and dimensions does the LD6816CX4/C29P,315 use, and what assembly process is required?

The LD6816CX4/C29P,315 uses a 0.4 mm pitch Wafer-Level Chip-Scale Package (WLCSP4) with backside coating, measuring 0.76 mm × 0.76 mm × 0.47 mm. It requires reflow soldering only - wave soldering is incompatible due to solder ball construction. The recommended footprint matches Figure 26 in the datasheet, with 0.25 mm solder land diameter and 0.325 mm pad-to-pad spacing.