Diodes Incorporated AP7340D-32FS4-7

Overview

AP7340D-32FS4-7 from Diodes Incorporated is a 3.2V fixed-output, 150mA low-dropout linear regulator with ±1% output voltage accuracy, 75dB PSRR at 1kHz, and 60µV_RMS output noise (10Hz–100kHz). It features enable control, 35µA quiescent current, and operates from 1.7V to 5.25V input. Designed for RF supply rails in portable wireless devices, it delivers stable biasing under fast load transients.

For engineers reviewing the AP7340D-32FS4-7 datasheet, AP7340D-32FS4-7 pinout, AP7340D-32FS4-7 application, or AP7340D-32FS4-7 equivalent, key selection criteria include dropout voltage at 150mA (0.21–0.27V), EN logic thresholds (0–0.5V low / 1.3–5.25V high), thermal performance in X2-DFN1010-4, and built-in auto-discharge functionality.

Technical Context

The AP7340D integrates a CMOS-based error amplifier, precision voltage reference, current-limit circuit, and active discharge path via an internal N-channel MOSFET (30Ω on-resistance when disabled). Its architecture supports fast line/load transient response without external compensation.

Unlike the non-discharge AP7340 variant, the "D" suffix denotes integrated output auto-discharge - critical for systems requiring rapid VOUT decay during shutdown to prevent back-powering or sequencing conflicts. The device maintains regulation down to 1.7V input and sustains ±1.5% output accuracy across –40°C to +85°C.

Key Specifications

Pinout & Package

AP7340D-32FS4-7 uses the X2-DFN1010-4 package: 1.0mm × 1.0mm, 0.4mm height, thermally enhanced with exposed pad (to be connected to GND or large copper pour).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700-3302E/TO and XC6219B322MR-G, AP7340D-32FS4-7 uniquely combines 3.2V precision, integrated enable, auto-discharge, and industry-leading 75dB PSRR - making it optimal for space-constrained, multi-rail wireless systems demanding clean, controllable bias.

Availability

AP7340D-32FS4-7 is available at Aetrix Electronics and suitable for RF transceiver biasing, camera sensor analog supplies, and portable media player audio codec rails requiring stable component supply, tight voltage tolerance, and fast transient response.

Supply support for AP7340D-32FS4-7 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' high-PSRR, low-noise LDO portfolio designed specifically for noise-sensitive analog and RF subsystems in battery-powered portable electronics.

FAQ

What is the purpose of the thermal pad on the AP7340D-32FS4-7 package?

The exposed thermal pad on the X2-DFN1010-4 package is a mechanical and thermal interface-not an electrical terminal. It must be soldered to a PCB copper area connected to GND or left floating, but never used as the sole GND connection. Proper thermal pad layout improves power dissipation capability from 400mW ambient-rated to >600mW in 2-layer boards with 1in² copper pour, preventing thermal shutdown during sustained 150mA loads.

How does the auto-discharge feature behave during shutdown?

When the EN pin is pulled low, the internal 30Ω N-channel MOSFET connects VOUT to GND, discharging the output capacitor. With a 1µF COUT, VOUT falls from 3.2V to <0.1V in approximately 0.8ms. This prevents back-powering downstream circuitry, avoids latch-up in powered-off sections, and satisfies strict power sequencing requirements in multi-voltage-domain systems like smartphones and modems.

Can AP7340D-32FS4-7 operate from a 3.0V lithium-ion battery throughout its discharge curve?

Yes. With a minimum input of 1.7V and a maximum dropout of 0.27V at 150mA, AP7340D-32FS4-7 maintains regulation down to VIN = 3.47V. Since a single Li-ion cell discharges from 4.2V to ~3.0V, the device operates continuously across the full usable battery range - unlike many 3.3V LDOs requiring ≥3.6V input. No brown-out or reset occurs until battery voltage drops below 3.47V.

Is an input capacitor mandatory, and what value is recommended?

Yes - a minimum 0.47µF ceramic capacitor is mandatory between VIN and GND, placed within 2mm of the pins. This capacitor stabilizes the input rail during sudden load steps (e.g., RF transmit bursts), prevents input voltage sag that could trigger dropout, and reduces high-frequency noise coupling into the regulator's control loop. Larger values (1–2.2µF) improve transient immunity but are not required for basic functionality.