The **MC34063AL-S08-R** is a versatile monolithic control circuit containing the primary functions required for DC-to-DC converters. It is widely used for step-up (Boost), step-down (Buck), and voltage-inverting applications. --- ## 1. Key Specifications The following table summarizes the electrical characteristics of the MC34063AL-S08-R: | Parameter | Description | Typical Value | | :--- | :--- | :--- | | **Input Voltage Range** | The range of DC voltage the chip can accept | 3.0V to 40V | | **Output Current** | Maximum peak current of the internal switch | Up to 1.5A | | **Operating Frequency** | Controlled by an external capacitor | Up to 100 kHz | | **Package Type** | Surface mount package style | SOP-8 | | **Adjustable Output** | Voltage range determined by external resistors | 1.25V to 40V | --- ## 2. Internal Components The "AL" version (Lead-free) in the SOP-8 package contains several critical functional blocks integrated into a single chip: 1. **Temperature Compensated Reference:** A stable 1.25V internal reference used for comparing the output voltage feedback. 2. **Duty Cycle Oscillator:** An internal oscillator whose frequency is set by a single external capacitor ($C_T$) connected to Pin 3. 3. **Active Peak Current Limit:** Circuitry that senses the voltage drop across an external resistor to protect the chip from overcurrent. 4. **High Current Output Switch:** An internal Darlington pair transistor capable of switching up to 1.5A. --- ## 3. Pin Configuration (SOP-8) | Pin # | Symbol | Function | | :--- | :--- | :--- | | 1 | **Switch Collector** | Internal switch transistor collector | | 2 | **Switch Emitter** | Internal switch transistor emitter | | 3 | **Timing Capacitor** | Sets the oscillation frequency ($C_T$) | | 4 | **GND** | Ground | | 5 | **Comparator Inverting Input** | Feedback pin for output voltage sensing | | 6 | **Vcc** | Input supply voltage | | 7 | **Ipk Sense** | Peak current sense input | | 8 | **Driver Collector** | Collector of the internal driver transistor | --- ## 4. Typical Application Circuit To use the MC34063, you typically need a few external components: an inductor ($L$), a timing capacitor ($C_T$), an output filter capacitor ($C_O$), a Schottky diode ($D$), and a resistor divider ($R_1, R_2$) to set the output voltage. The formula for the output voltage is generally: `Vout = 1.25 * (1 + R2 / R1)` ---