Diodes Incorporated AP7343D-18FS4-7

Overview

AP7343D-18FS4-7 from Diodes Incorporated is a 300mA, 1.8V fixed-output low-dropout linear regulator with high PSRR (75dB at 1kHz), ultra-low output noise (60µV_rms, 10Hz–100kHz), ±1% output voltage accuracy, and enable-controlled shutdown. Fabricated in CMOS, it delivers stable power to RF supplies and camera modules in space-constrained portable electronics using the X2-DFN1010-4 (Type B) package.

For engineers reviewing the AP7343D-18FS4-7 datasheet, AP7343D-18FS4-7 pinout, AP7343D-18FS4-7 application, or AP7343D-18FS4-7 equivalent, key selection criteria include dropout voltage (≤390mV at 300mA for V_OUT=1.8V), thermal shutdown threshold (+150°C), EN input logic thresholds (0–0.5V low, 1.3–5.25V high), and compatibility with 1µF ceramic input/output capacitors.

Technical Context

The AP7343D-18FS4-7 integrates a precision voltage reference, error amplifier, current-limit circuit, and thermal shutdown protection within a CMOS-based LDO architecture. Its internal discharge FET (enabled by the "D" suffix) actively pulls down V_OUT during shutdown, eliminating residual voltage on downstream loads.

It operates across a 1.7V–5.25V input range while maintaining 1.8V output regulation, with load transient response optimized for fast current steps (1mA ↔ 300mA) and line transients (e.g., VIN step from 2.8V to 5.25V). The device supports stable operation with minimal external components: only 1µF C_IN and 1µF C_OUT are required.

Key Specifications

Pinout & Package

X2-DFN1010-4 (Type B) package: 1.0mm × 1.0mm, 0.4mm pitch, exposed thermal pad (EP) - connect EP to GND plane for optimal thermal performance (R_θJA = 237°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP7343D-18FS4-7, AP7361D-18SAG-7 trades compact footprint and integrated discharge for higher current and larger thermal mass, while MCP1700T-1802E/MB sacrifices enable control and output drive to achieve nanoamp quiescent operation - making AP7343D-18FS4-7 the optimal balance for RF and imaging subsystems demanding size, noise, and controllability.

Availability

AP7343D-18FS4-7 is available at Aetrix Electronics and suitable for RF power amplifier biasing, CMOS image sensor core supply, wireless adapter baseband regulation, and portable media player audio codec powering requiring stable component supply across production lifecycles.

Supply support for AP7343D-18FS4-7 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 semiconductor company specializing in discrete, analog, and mixed-signal devices, with design and manufacturing operations across Asia and the Americas.

The AP7343 series targets portable and battery-powered applications requiring high PSRR, low noise, and small-footprint power management - specifically engineered for smartphones, tablets, and wireless communication equipment.

FAQ

What is the function of the exposed pad (EP) on the X2-DFN1010-4 (Type B) package?

The exposed pad is a thermal dissipation feature, not an electrical terminal. It must be soldered to a large GND copper area on the PCB to lower junction temperature. Diodes Incorporated specifies R_θJB = 85.72°C/W with proper board-level thermal design; leaving it unconnected degrades thermal performance by >40°C/W.

Does AP7343D-18FS4-7 require an external pull-up resistor on the EN pin?

No external pull-up is required. The EN pin has no internal pull-up or pull-down; however, it must never be left floating. For always-on operation, tie EN directly to VIN. For controlled enable/disable, drive it with a GPIO capable of meeting V_EN(H) ≥1.3V and V_EN(L) ≤0.5V thresholds.

Can AP7343D-18FS4-7 operate with input voltages below 1.7V?

No. The absolute minimum input voltage is 1.7V per the Recommended Operating Conditions table. Operation below this violates specification and may cause output dropout, regulation loss, or undefined behavior. At V_IN = 1.7V and V_OUT = 1.8V, the device cannot sustain 300mA due to insufficient headroom.

How does the "D" suffix affect the AP7343D-18FS4-7's behavior during shutdown?

The "D" denotes integrated discharge functionality: when EN is pulled low, an internal NMOS FET connects VOUT to GND, discharging external capacitance to <100mV within 100µs. This prevents back-powering of upstream circuitry and eliminates residual voltage that could interfere with power sequencing in multi-rail systems.