Diodes Incorporated AP7340D-185FS4-7

Overview

AP7340D-185FS4-7 from Diodes Incorporated is a 150mA low-dropout linear regulator with fixed 1.85V output, ±1% accuracy over -40°C to +85°C, 75dB PSRR at 1kHz, 60µV_rms output noise (10Hz–100kHz), and 35µA quiescent current. It features enable control, thermal shutdown, short-circuit protection, and an integrated auto-discharge function for rapid V_OUT discharge during shutdown-optimized for RF supply and portable media player power rails.

For engineers reviewing the AP7340D-185FS4-7 datasheet, AP7340D-185FS4-7 pinout, AP7340D-185FS4-7 application, or AP7340D-185FS4-7 equivalent, key selection criteria include dropout voltage at 150mA (0.21–0.27V for 1.85V output), EN input thresholds (0.5V max low, 1.3V min high), thermal pad layout requirements, and compatibility with 0.47µF ceramic input/output capacitors.

Technical Context

The AP7340D integrates a CMOS-based error amplifier, precision voltage reference, current-limit circuit, and active pull-down transistor for output discharge upon disable. Its architecture enables fast load transient response (<100µs settling) while maintaining stability with minimal 0.47µF ceramic capacitors on both input and output.

Unlike the non-discharge AP7340 variant, the 'D' suffix denotes built-in 30Ω N-channel discharge FET between V_OUT and GND, activated when EN = low-reducing residual output voltage to <100mV within microseconds, critical for sequencing-sensitive RF and camera modules.

Key Specifications

Pinout & Package

The AP7340D-185FS4-7 uses the X2-DFN1010-4 package: 1.0mm × 1.0mm, 0.4mm height, 0.65mm pitch, with exposed thermal pad (connected to GND for optimal thermal performance).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP7340-185FS4-7, the AP7340D-185FS4-7 adds critical discharge functionality without increasing footprint or quiescent current-making it superior for multi-rail portable systems requiring strict power sequencing, while the XC6210B185MR-G trades PSRR and discharge capability for marginally lower unit cost.

Availability

AP7340D-185FS4-7 is available at Aetrix Electronics and suitable for RF power amplifier bias, CMOS image sensor core supply, portable media player audio codec, and Bluetooth SoC I/O domain supply requiring stable component supply, tight output accuracy, and fast enable/disable control.

Supply support for AP7340D-185FS4-7 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability power management, signal integrity, and protection solutions for consumer, industrial, and communications markets.

The AP7340 series belongs to Diodes' precision LDO portfolio, designed specifically for noise-sensitive, battery-powered portable electronics where ultra-low noise, high PSRR, and fast transient response are mandatory for RF, imaging, and audio subsystems.

FAQ

What is the minimum input voltage required for AP7340D-185FS4-7 to maintain regulation at 150mA load?

The minimum input voltage is calculated as V_OUT + V_DROP = 1.85V + 0.27V = 2.12V. At 150mA and T_A = +25°C, the maximum dropout is 0.27V per datasheet Table 3. Below this VIN, output voltage drops below 1.8315V (–1% of 1.85V), violating regulation specification.

Can the thermal pad of AP7340D-185FS4-7 be left unconnected in PCB layout?

No. The thermal pad must be soldered to a dedicated GND copper pour of ≥25mm². Leaving it unconnected degrades thermal resistance by >40°C/W, risking thermal shutdown above 80mW power dissipation. It is not electrically functional as a standalone GND electrode but must be thermally coupled to the system ground plane.

Does AP7340D-185FS4-7 require external compensation components for stability?

No. The device is internally compensated and stable with 0.47µF ±20% X5R/X7R ceramic capacitors on both input and output. Adding larger bulk capacitance (>10µF) or high-ESR capacitors may degrade phase margin and cause oscillation-only low-ESR ceramics are recommended per datasheet Section 9.

How does the auto-discharge function behave when EN is pulled low during heavy load?

When EN goes low, the internal 30Ω discharge FET activates immediately, sinking current from V_OUT to GND. With a 10µF output capacitor, V_OUT decays from 1.85V to <100mV in under 10µs-even under 150mA steady-state load-preventing back-powering of upstream circuits and ensuring deterministic power-down sequencing.