### Overview of the AD5165BUJZ100-R7 The **AD5165BUJZ100-R7** is a compact, low-power **Digital Potentiometer** (digipot) manufactured by Analog Devices. It is designed to replace mechanical potentiometers or variable resistors in electronic circuits, allowing for automated calibration or adjustment via a digital interface. --- ### Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Resistance** | 100 kΩ | | **Resolution** | 256 Positions (8-bit) | | **Interface** | SPI (3-wire, Serial) | | **Supply Voltage** | 2.7 V to 5.5 V | | **Temperature Coefficient** | 35 ppm/°C | | **Package** | TSOT-23-8 (Ultra-compact) | | **Operating Temp** | -40°C to +125°C | --- ### Internal Electronic Architecture The device functions as a variable resistor or voltage divider using a string of resistors and CMOS switches: 1. **Resistor Ladder:** A string of 256 high-precision internal resistors totaling 100 kΩ. 2. **CMOS Switches:** These act as the "wiper." Depending on the 8-bit digital word sent via SPI, a specific switch closes to connect the wiper terminal to a point on the resistor ladder. 3. **Control Logic:** A shift register and decoder that translate the SPI signal into the physical switch configuration. --- ### Pin Configuration (TSOT-23-8) | Pin No. | Mnemonic | Description | | :--- | :--- | :--- | | 1 | **W** | Wiper terminal. | | 2 | **VDD** | Positive Power Supply. | | 3 | **GND** | Ground. | | 4 | **CS** | Chip Select (Active Low). | | 5 | **SDI** | Serial Data Input. | | 6 | **CLK** | Serial Clock Input. | | 7 | **B** | Bottom terminal of resistor. | | 8 | **A** | Top terminal of resistor. | --- ### Typical Applications * **LCD Contrast Control:** Adjusting the bias voltage for displays. * **Programmable Filters:** Setting the cutoff frequency in analog filters. * **Gain Control:** Replacing fixed resistors in Op-Amp circuits to create a Programmable Gain Amplifier (PGA). * **Sensor Calibration:** Zeroing out offsets in bridge sensors or transducers. --- ### Implementation Example (Simplified Logic) To set the wiper to the mid-point (50 kΩ), a microcontroller would send the hex value `0x80` (128 in decimal) over the SPI bus while the `CS` pin is pulled low. ```c // Pseudo-code for SPI Transmission digitalWrite(CS_PIN, LOW); // Select the AD5165 SPI.transfer(0x80); // Send 128 (Middle Position) digitalWrite(CS_PIN, HIGH); // Update the Wiper ```