onsemi NCP4688DSN33T1G

Overview

NCP4688DSN33T1G from onsemi is a 150 mA, low-noise CMOS LDO linear voltage regulator delivering a fixed 3.3 V output with ±1% accuracy over −40°C to +85°C, 10 µV_RMS output noise, and 80 dB PSRR at 1 kHz - designed for powering noise-sensitive RF modules and portable communication equipment.

For engineers reviewing the NCP4688DSN33T1G datasheet, pinout, applications, or equivalent options, key selection criteria include dropout voltage (0.20–0.28 V at 150 mA), auto-discharge NMOS (60 Ω), CE pin threshold (1.0 V min "H"), thermal resistance (238 °C/W in SOT-23-5), and Pb-free SOT-23-5 package compatibility with space-constrained industrial and consumer PCB layouts.

Technical Context

The NCP4688DSN33T1G integrates a precision bandgap reference, error amplifier, pass transistor, current-limit circuit, and chip-enable logic with internal pull-down. Its low-noise architecture suppresses internally generated ripple and maintains stable regulation under dynamic load steps up to 150 mA.

It features an active auto-discharge NMOS between VOUT and GND activated during disable mode, enabling rapid output capacitor discharge. The CE pin operates with TTL-compatible thresholds (V_CEH ≥ 1.0 V, V_CEL ≤ 0.4 V) and draws only 0.3–0.6 µA pull-down current - supporting reliable power sequencing in battery-powered systems.

Key Specifications

Pinout & Package

SOT-23-5 package (Case 1212), 2.7 mm × 2.5 mm footprint, Pb-free, with exposed pad (EP) recommended to be left floating or connected to GND for thermal relief.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700T-3302E/MB and TCS2117-3300CV, the NCP4688DSN33T1G uniquely combines 3.3 V precision regulation, ultra-low noise, high PSRR, CE control, and integrated auto-discharge - making it optimal for RF-critical, battery-conscious, and sequenced-power applications where output collapse speed and supply cleanliness are design-critical.

Availability

NCP4688DSN33T1G is available at Aetrix Electronics and suitable for RF modules, portable audio systems, and industrial sensor nodes requiring stable component supply, long-term manufacturability, and AEC-Q100-aligned thermal performance.

Supply support for NCP4688DSN33T1G 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The NCP4688DSN33T1G belongs to the NCP4688 family of low-noise, high-PSRR LDOs engineered specifically for noise-sensitive RF and portable communication applications demanding precision, small size, and robust enable control.

FAQ

What is the maximum input voltage rating for the NCP4688DSN33T1G?

The NCP4688DSN33T1G has an absolute maximum input voltage of 6 V. Operation is specified across 2.0 V to 5.25 V, with recommended derating above 5.25 V to ensure reliability and thermal safety. Exceeding 6 V risks permanent damage per the Absolute Maximum Ratings table in the datasheet.

Does the NCP4688DSN33T1G require external capacitors, and what values are recommended?

Yes, the NCP4688DSN33T1G requires both input and output ceramic decoupling capacitors. A 1.0 µF X5R/X7R ceramic capacitor is recommended for both C_IN (between VIN and GND) and C_OUT (between VOUT and GND), placed as close as possible to their respective pins. Larger values or lower-ESR types improve transient response but are not mandatory for basic stability.

How does the auto-discharge feature work in the NCP4688DSN33T1G?

The NCP4688DSN33T1G integrates an NMOS transistor between VOUT and GND that activates automatically when the CE pin is driven low. With R_DS(ON) ≈ 60 Ω, this path rapidly discharges the output capacitor, reducing VOUT decay time - critical for clean system resets and avoiding latch-up in downstream logic. This function is exclusive to the "D" version (e.g., NCP4688DSN33T1G).

Is the NCP4688DSN33T1G compatible with lead-free reflow soldering processes?

Yes, the NCP4688DSN33T1G is a Pb-free device packaged in RoHS-compliant SOT-23-5 (Case 1212) and qualified for standard lead-free reflow profiles per J-STD-020. Its maximum peak reflow temperature is 260°C, and the package supports IPC/JEDEC moisture sensitivity level (MSL) 1 - no dry-bag storage or baking required prior to assembly.

What is the thermal resistance (R_JA) of the NCP4688DSN33T1G in its SOT-23-5 package?

The NCP4688DSN33T1G in SOT-23-5 has a junction-to-air thermal resistance (R_JA) of 238 °C/W under standard JEDEC test conditions (single-layer 1-in² copper pad). Actual board-level R_JA depends on PCB layout - adding thermal vias to inner ground planes can reduce it by 30–50%, enabling higher sustained load currents without exceeding 150°C junction temperature.