Diodes Incorporated AP7315D-135FS4-7B

Overview

AP7315D-135FS4-7B from Diodes Incorporated is a 1.35V fixed-output, 150mA low-dropout linear regulator with enable control, ±1% output voltage accuracy, 75dB PSRR at 1kHz, and 60µV_rms output noise (10Hz–100kHz). It operates from 1.7V to 5.25V input and features auto-discharge functionality, making it suitable for RF supply rails in compact portable devices where clean, stable biasing is critical.

For engineers reviewing the AP7315D-135FS4-7B datasheet, AP7315D-135FS4-7B pinout, AP7315D-135FS4-7B application, or AP7315D-135FS4-7B equivalent, key selection criteria include dropout voltage at 150mA (max 0.50V for 1.35V V_OUT), EN logic thresholds (V_IL ≤ 0.5V, V_IH ≥ 1.3V), thermal performance in X2-DFN1010-4, and discharge path resistance (30Ω typical).

Technical Context

The AP7315D-135FS4-7B integrates a CMOS-based LDO architecture with an internal voltage reference, error amplifier, current-limit circuit, and active discharge FET tied to the EN pin. Its fixed 1.35V output is set by an on-die resistor network, eliminating external feedback components.

Unlike the non-discharge AP7315 variant, the "D" suffix denotes integrated N-channel discharge transistor (R_ON = 30Ω typ) that rapidly sinks V_OUT to GND when EN is pulled low-critical for sequencing-sensitive systems and preventing back-powering of downstream circuitry.

Key Specifications

Pinout & Package

AP7315D-135FS4-7B is housed in a 1.0mm × 1.0mm, 0.4mm pitch X2-DFN1010-4 package with wettable flanks and an exposed thermal pad. The pad must be connected to PCB ground plane for optimal thermal dissipation (θ_JA ≈ 220°C/W on JEDEC High-K board).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output LDO applications.

Compared with MCP1700T-1302E/MB and XC6210B132MR-G, AP7315D-135FS4-7B uniquely combines 1.35V precision, integrated discharge, and X2-DFN1010-4's 1.0mm² footprint-making it the only choice for space-constrained, sequenced RF bias applications demanding sub-10µs shutdown.

Availability

AP7315D-135FS4-7B is available at Aetrix Electronics and suitable for RF power amplifier bias, low-voltage memory I/O supply, and wearable sensor hub core supply requiring stable component supply, consistent parametric performance, and long-term production continuity.

Supply support for AP7315D-135FS4-7B 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 solutions for power management, signal integrity, and connectivity applications.

The AP7315 series belongs to Diodes' high-PSRR, low-noise LDO product line, designed specifically for noise-sensitive RF, audio, and portable computing applications where compact size and precise voltage regulation are mandatory.

FAQ

What is the maximum allowable input voltage for AP7315D-135FS4-7B?

The absolute maximum input voltage is 6.0V, but the recommended operating range is 1.7V to 5.25V. Exceeding 5.25V risks violating the specified dropout margin and may degrade long-term reliability-even if within absolute ratings-due to increased junction temperature and accelerated electromigration in the pass device.

Does the thermal pad on the X2-DFN1010-4 package require an electrical connection?

No-the thermal pad is not electrically functional and must not be used as a GND electrode. It should be soldered to a dedicated PCB copper pour (≥25mm²) connected to system ground solely for thermal conduction. Using it as a signal return path introduces ground loop noise and compromises PSRR performance.

How does the discharge function behave during EN deactivation?

When EN is pulled low, the internal N-channel FET turns on, discharging VOUT through a 30Ω typical path to GND. This reduces VOUT to <100mV within 5µs (typical) at 100µF load capacitance. Discharge current is limited to prevent excessive inrush, and the FET remains off when EN is high or floating.

Can AP7315D-135FS4-7B be used with ceramic output capacitors smaller than 0.47µF?

Yes-stability is guaranteed with 0.47µF ceramic capacitors, but the device remains stable down to 0.22µF (per Diodes' application note AN-3001). However, using <0.47µF increases output impedance at high frequencies and degrades load transient response; 0.47µF is the minimum recommended for robust performance across –40°C to +85°C.