## RPM7138-R Electronic Component Overview The **RPM7138-R** is a high-performance infrared (IR) receiver module designed for remote control systems. It is manufactured by **ROHM Semiconductor** and integrates several functional blocks into a single side-mold package to simplify the design of wireless control interfaces. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Carrier Frequency** | 37.9 kHz | | **Operating Voltage** | 4.5V to 5.5V | | **Current Consumption** | 0.9 mA (Typ.) to 1.5 mA (Max) | | **Detection Distance** | Up to 15 Meters | | **Package Type** | Side-facing Mold (RSIP-A3) | | **Output Type** | Active Low (Digital) | --- ### 2. Internal Block Diagram Functions The RPM7138-R contains several integrated stages to process the optical signal into a clean digital pulse: 1. **PIN Photodiode:** Converts incoming infrared light (wavelength approx. 950nm) into an electrical signal. 2. **Preamplifier:** Boosts the weak signal from the photodiode. 3. **Automatic Gain Control (AGC):** Adjusts sensitivity to compensate for ambient light noise and distance variations. 4. **Band Pass Filter (BPF):** Specifically tuned to **37.9 kHz** to filter out interference from fluorescent lights and other IR sources. 5. **Demodulator & Output:** Removes the carrier frequency and outputs a digital logic signal (0V or Vcc) corresponding to the original remote control code. --- ### 3. Pin Configuration | Pin Number | Name | Description | | :---: | :--- | :--- | | 1 | **Vout** | Demodulated digital output signal. | | 2 | **GND** | Ground (0V). | | 3 | **Vcc** | Power Supply (Typically 5V). | --- ### 4. Circuit Implementation Requirements To ensure stable operation, a simple RC filter is recommended for the power line to prevent noise interference. ```c // Typical Connection Schematic [IR Remote] >>> (Wireless IR) >>> [RPM7138-R] | Vcc (5V) ----[ 100 Ohm Resistor ]---- Pin 3 (Vcc) | [ 47uF Cap ] | GND --------------------------------- Pin 2 (GND) | MCU Signal Pin <--------------------- Pin 1 (Vout) ``` --- ### 5. Primary Applications * **Consumer Electronics:** TV, DVD players, Air conditioners, and Set-top boxes. * **Home Automation:** IR-controlled lighting and smart home hubs. * **Industrial:** Remote sensor triggering and simple wireless data transmission.