The **CS5484** is a high-accuracy, four-channel energy measurement Analog Front End (AFE) designed by Cirrus Logic. It is specifically engineered for power monitoring in single-phase, two-wire or three-wire systems. --- ## 1. Core Technical Specifications The CS5484 integrates high-performance ADCs with a digital signal processor to calculate power metrics. | Feature | Specification | | :--- | :--- | | **Input Channels** | 4 Differential Channels (Current & Voltage) | | **ADC Resolution** | 24-bit Delta-Sigma | | **Dynamic Range** | 2000:1 | | **Accuracy** | 0.1% error over dynamic range | | **Interface** | UART / SPI (Selectable) | | **Power Supply** | Single 3.3V source | --- ## 2. Key Internal Electronic Blocks The chip is divided into several functional blocks that handle the conversion from raw analog signals to digital power data: ### A. Analog Front End (AFE) * **PGA (Programmable Gain Amplifiers):** Located on the current channels to support low-resistance shunts or current transformers. * **Delta-Sigma Modulators:** Four independent 4th-order modulators that sample analog inputs at high speeds. ### B. Digital Signal Processor (DSP) The onboard DSP performs real-time calculations, reducing the overhead on the host microcontroller (MCU). It computes: * **RMS Values:** Root Mean Square of Voltage ($V_{rms}$) and Current ($I_{rms}$). * **Power Metrics:** Active, Reactive, and Apparent Power. * **Power Factor:** Calculation of $\cos \phi$. * **Line Frequency:** Precise frequency detection for grid monitoring. ### C. Reference & Clock * **Voltage Reference:** Includes an on-chip $1.2V$ bandgap reference with low temperature drift. * **Oscillator:** Can use an external crystal or a CMOS clock source. --- ## 3. Pin Configuration Categories The CS5484 is typically housed in a **28-pin SSOP package**. | Pin Group | Function | | :--- | :--- | | **Analog Inputs** | `I1+/-`, `I2+/-`, `V1+/-`, `V2+/-` (Differential measurement) | | **Communication** | `TX/SDO`, `RX/SDI`, `SCLK`, `SS` (SPI/UART pins) | | **Control** | `RESET`, `INT` (Interrupt for zero-crossing or faults) | | **Power** | `VA+`, `VD+`, `AGND`, `DGND` (Separated Analog/Digital rails) | --- ## 4. Typical Application Circuit When designing with the CS5484, the following external components are essential: ```cpp // Schematic Design Considerations: 1. Current Sensing: Use a Shunt Resistor (low mOhm) or Current Transformer. 2. Voltage Sensing: Use a Resistor Divider network to scale line voltage to ±250mV. 3. Decoupling: 0.1uF and 10uF capacitors on VA+ and VD+ pins to ground. 4. Protection: MOV (Metal Oxide Varistors) for surge protection on inputs. ``` ---