## ADM7172ACPZ-R7: Ultra-Low Noise, High PSRR LDO Regulator The **ADM7172ACPZ-R7** is a high-performance CMOS Low Dropout (LDO) linear regulator. It is designed to provide a stable, low-noise power supply for high-speed analog and mixed-signal circuits. --- ### 1. Key Technical Specifications The following table summarizes the primary electrical characteristics of the ADM7172 series: | Parameter | Specification | | :--- | :--- | | **Input Voltage Range** | 2.3 V to 6.5 V | | **Maximum Output Current** | 2 Amps | | **Output Voltage Options** | Adjustable (1.2V to VIN - V_dropout) or Fixed | | **PSRR (Power Supply Rejection Ratio)** | 80 dB at 1 kHz; 60 dB at 1 MHz | | **Output Noise** | 5 μV rms (10 Hz to 100 kHz) | | **Dropout Voltage** | 170 mV (typical at 2 A load) | | **Package Type** | 8-lead LFCSP (3mm x 3mm) | | **Operating Temperature** | -40°C to +125°C | --- ### 2. Functional Features The ADM7172ACPZ-R7 is engineered with several advanced features to ensure circuit protection and signal integrity: * **Ultra-Low Noise:** The 5 μV rms noise performance makes it ideal for noise-sensitive components like ADCs, DACs, and precision amplifiers. * **High PSRR:** Excellent rejection of high-frequency noise from switching power supplies. * **Precision Enable:** Allows for controlled power sequencing via a specific threshold on the EN pin. * **Programmable Soft Start:** Uses an external capacitor to control the voltage ramp-up speed, reducing inrush current. * **Safety Protections:** * *Thermal Shutdown:* Prevents damage from overheating. * *Current Limit:* Protects the device during short-circuit conditions. --- ### 3. Pin Configuration (LFCSP Package) The device utilizes an 8-lead Lead Frame Chip Scale Package (LFCSP) with an exposed pad for thermal dissipation. | Pin Number | Name | Description | | :--- | :--- | :--- | | 1 | VOUT | Regulated Output Voltage. | | 2 | VOUT | Regulated Output Voltage (Internally connected to Pin 1). | | 3 | SENSE/ADJ | Connect to VOUT (fixed) or external resistor divider (adj). | | 4 | GND | Ground. | | 5 | SS | Soft Start pin (connect capacitor to GND). | | 6 | EN | Enable Input (Active High). | | 7 | VIN | Input Voltage Supply. | | 8 | VIN | Input Voltage Supply (Internally connected to Pin 7). | | EP | PAD | Exposed Pad; must be soldered to GND for thermal relief. | --- ### 4. Typical Application Circuit Below is a conceptual representation of how to wire the adjustable version of the ADM7172: ```python # Conceptual Schematic for Adjustable Output # V_out = 1.2V * (1 + R1 / R2) Input (VIN) ----[ C_in: 4.7uF ]----( PIN 7/8 ) | [ ADM7172 ]----( PIN 1/2 )---- Output (VOUT) | | ( PIN 3: ADJ )-----+----[ R1 ]---+ | | +----[ R2 ]---+--- GND ``` --- ### 5. Common Use Cases 1. **RF and Sensitive Analog:** Powering VCOs, PLLs, and Low Noise Amplifiers (LNAs). 2. **Data Converters:** Providing clean rails for high-speed 16-bit to 24-bit ADCs/DACs. 3. **Medical Imaging:** Used in ultrasound and MRI signal processing where noise is critical. 4. **Communications:** Infrastructure equipment requiring high current (2A) with low ripple.