## IR2153 Self-Oscillating Half-Bridge Driver The **IR2153** is an improved version of the popular IR2151 and IR2155 gate driver ICs. It is widely used in electronic ballasts and switching power supplies (SMPS) because it incorporates a high-voltage half-bridge gate driver with a front-end oscillator similar to the industry-standard CMOS 555 timer. --- ### 1. Key Internal Components The IR2153 integrates several functional blocks into an 8-pin package: | Component | Function | | :--- | :--- | | **Oscillator** | Uses an external resistor ($R_T$) and capacitor ($C_T$) to set the switching frequency. | | **Deadtime Control** | Provides a fixed internal deadtime (typically 1.2µs) to prevent "shoot-through" currents. | | **High-Side Driver** | A floating channel designed to drive an N-channel MOSFET up to 600V. | | **Low-Side Driver** | A standard ground-referenced driver for the bottom MOSFET. | | **Micropower Startup** | Low current consumption during startup, allowing for a high-value dropper resistor. | | **Zener Clamp** | Internal 15.6V zener clamp on the $V_{CC}$ pin to protect the IC. | --- ### 2. Pinout Configuration | Pin Number | Name | Description | | :--- | :--- | :--- | | 1 | **$V_{CC}$** | Logic and internal gate drive supply voltage. | | 2 | **$R_T$** | Oscillator timing resistor input. | | 3 | **$C_T$** | Oscillator timing capacitor input. | | 4 | **COM** | IC power and signal ground. | | 5 | **LO** | Low-side gate drive output. | | 6 | **$V_S$** | High-side floating supply return (Half-bridge midpoint). | | 7 | **HO** | High-side gate drive output. | | 8 | **$V_B$** | High-side floating supply (Bootstrap voltage). | --- ### 3. Essential External Parts To make the IR2153 functional, specific external components are required: #### A. Timing Network ($R_T$ and $C_T$) The frequency ($f$) is determined by the formula: $$f \approx \frac{1}{1.4 \times (R_T + 75\Omega) \times C_T}$$ #### B. Bootstrap Circuit Since the High-Side MOSFET requires a gate voltage higher than the rail voltage to turn on, a **Bootstrap Diode** and **Bootstrap Capacitor** are used. * **Diode:** Must be fast recovery (e.g., UF4007) and rated for the full DC rail voltage. * **Capacitor:** Stores charge to drive the HO pin; typically a 0.1µF to 1.0µF ceramic or film capacitor. #### C. Gate Resistors Small resistors (typically 10$\Omega$ to 47$\Omega$) placed between the HO/LO pins and the MOSFET gates to dampen oscillations and control switching speed. --- ### 4. Typical Application Circuit ```text +V_Bus (High Voltage) | ______|______ | | [ D ] [ D ] (High-Side MOSFET) | |____ To Transformer/Load | | [IR2153] [ D ] (Low-Side MOSFET) |_____________| | GND ``` ---