The **AS1353-04** is a high-performance, low-dropout (LDO) voltage regulator part of the AS1353 series manufactured by **ams OSRAM**. It is designed specifically for battery-powered applications where low noise and low quiescent current are critical. --- ### 1. Key Technical Specifications The "04" suffix typically refers to a specific output voltage variant or a specific packaging/revision detail (often associated with 3.3V or 4.0V depending on the specific datasheet revision). | Parameter | Value | | :--- | :--- | | **Input Voltage Range** | 2.5V to 5.5V | | **Output Voltage (Typical)** | 3.3V / 4.0V (Fixed) | | **Maximum Output Current** | 150mA | | **Dropout Voltage** | ~40mV @ 100mA | | **Quiescent Current** | 40µA (Typical) | | **Shutdown Current** | < 1µA | | **Package Type** | SOT-23 (5-pin) | --- ### 2. Functional Components The internal electronic architecture of the AS1353 consists of several critical stages: 1. **Internal Reference Voltage:** A high-precision bandgap reference that provides a stable voltage regardless of temperature fluctuations. 2. **Error Amplifier:** Compares the output voltage (via a feedback loop) to the internal reference to maintain a constant output. 3. **P-Channel Pass Transistor:** Unlike NPN-based regulators, the AS1353 uses a P-channel MOSFET, which allows for a very low dropout voltage. 4. **Protection Circuitry:** * **Thermal Overload Protection:** Shuts down the device if the junction temperature exceeds ~140°C. * **Current Limiting:** Protects the device during short-circuit conditions. --- ### 3. Pin Configuration (SOT-23-5) The device is standardly mapped to a 5-pin configuration to save PCB real estate. | Pin Number | Name | Description | | :--- | :--- | :--- | | 1 | **IN** | Input supply voltage | | 2 | **GND** | Ground | | 3 | **EN** | Enable input (Active High) | | 4 | **BP** | Bypass capacitor (Optional for low-noise) | | 5 | **OUT** | Regulated output voltage | --- ### 4. Application Use Cases Due to its high Ripple Rejection (PSRR) and low noise, the AS1353-04 is commonly found in: * **Mobile Handsets:** Powering RF stages or analog-to-digital converters. * **Medical Equipment:** Portable monitors requiring stable, low-noise power rails. * **IoT Sensors:** Devices that spend most of their time in sleep mode (benefiting from <1µA shutdown current).