Diodes Incorporated AP7375-33Y-13

Overview

AP7375-33Y-13 from Diodes Incorporated is a 3.3V fixed-output, wide-input (3–45V), 300mA ultra-low-dropout linear regulator in SOT89 package with 2.1μA quiescent current, 35mV dropout at 10mA, and integrated enable pin rated to 45V - designed for battery-powered smoke detectors requiring stable low-power 3.3V rail under variable input conditions.

For engineers reviewing the AP7375-33Y-13 datasheet, AP7375-33Y-13 pinout, AP7375-33Y-13 application, or AP7375-33Y-13 equivalent, key selection criteria include input voltage range up to 45V, EN pin tolerance to full VIN, thermal shutdown at +150°C, ±2% output accuracy, and fast transient response without overshoot during start-up or short-circuit recovery.

Technical Context

The AP7375-33Y-13 implements a PMOS pass transistor architecture enabling ultra-low dropout (35mV @ 10mA) and high PSRR (85dB @ 1kHz), with internal compensation ensuring stability with 1μF–10μF ceramic output capacitors. Its EN pin accepts up to 45V directly, eliminating level-shifting circuitry in high-voltage enable paths.

Line regulation is 0.01%/V and load regulation is 0.02%/mA over 1–100mA, while thermal shutdown activates at +150°C with +20°C hysteresis. Short-circuit protection limits output current to ~500mA and clamps VOUT to prevent damage during fault conditions.

Key Specifications

Pinout & Package

SOT89-3 package (Package Code: Y), 3-pin surface-mount device with exposed thermal pad (EP). Thermal resistance θ_JA = 95°C/W on JEDEC-standard board; recommended PCB layout uses large copper area connected to EP for enhanced heat dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultra-low-quiescent-current LDO applications.

Compared with MCP1703T-3302E/MB and TPS7B8733QKVURQ1, the AP7375-33Y-13 uniquely combines 45V input/enable tolerance, 2.1μA I_Q, and ±2% accuracy in SOT89 - making it the only option for long-life, high-input-voltage industrial smoke detectors without derating or external protection.

Availability

AP7375-33Y-13 is available at Aetrix Electronics and suitable for battery-powered equipment, smoke detectors and sensors, and microcontroller applications requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for AP7375-33Y-13 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 ICs, with design centers in Asia, Europe, and the U.S., and manufacturing in China, Taiwan, and Malaysia.

The AP7375 series belongs to Diodes' high-voltage, ultra-low-I_Q LDO product line, engineered specifically for battery longevity and robust operation in safety-critical, always-on sensing and alarm systems.

FAQ

What is the minimum input voltage required for AP7375-33Y-13 to regulate 3.3V output?

The AP7375-33Y-13 requires VIN ≥ VOUT + V_DROP(max). At 100mA load, V_DROP is 360mV max, so minimum VIN is 3.66V. At light loads (10mA), V_DROP drops to 50mV max, allowing regulation down to 3.35V. The datasheet specifies absolute minimum VIN as 3.0V, but regulation begins only above VOUT + V_DROP.

Can the EN pin be left floating, or does it require a pull-up/down resistor?

The EN pin must not be left floating. It is an active-high enable with V_ENL = 0.4V max (disabled) and no internal pull-up. To ensure reliable startup, tie EN to VIN through a 100kΩ resistor or drive it actively. Floating EN may cause erratic enable/disable behavior due to noise coupling.

Is the exposed pad (EP) on the SOT89 package electrically connected internally?

No - the exposed pad is thermally conductive only and not electrically connected to any internal node. Diodes recommends connecting it to PCB ground plane for optimal thermal performance, but it must not be used as the sole GND connection; the dedicated Pin 2 (GND) remains the primary electrical ground path.

Does AP7375-33Y-13 require an input capacitor, and what type is recommended?

Yes - a 1μF ceramic capacitor (X5R or X7R dielectric) is required between VIN and GND, placed as close as possible to the pins. This decouples high-frequency noise and stabilizes the input supply. Larger values improve noise immunity but are not mandatory; tantalum or electrolytic caps are not recommended due to ESR and reliability concerns.