Infineon IR21271STRPBF High- and Low-Side Driver IC Datasheet and Application Circuit Design Guide
The Infineon IR21271STRPBF is a specialized high-voltage, high-speed power MOSFET and IGBT driver capable of driving both high-side and low-side switches configured in a half-bridge arrangement. It is engineered with a floating channel design for bootstrap operation, allowing it to efficiently drive an N-channel power MOSFET or IGBT in the high-side configuration. This driver IC is integral in applications such as motor drives, switch-mode power supplies (SMPS), and inverters, where robust performance and reliability are paramount.
A critical feature of the IR21271 is its integrated bootstrap functionality. This eliminates the need for an external high-side supply by generating the necessary gate drive voltage through a bootstrap capacitor and diode. The device incorporates a high-voltage level-shifter that translates the high-side gate drive signals across the IC’s internal potential barrier. Furthermore, it offers robust protection with undervoltage lockout (UVLO) for both the high-side and low-side channels. This feature ensures the power switch is only turned on when the gate drive voltage is sufficient, preventing dangerous operation in high-resistance mode and enhancing system safety.
The propagation delay of the IR21271 is exceptionally matched between the high-side and low-side channels, which is crucial for minimizing dead time in half-bridge circuits. This precise timing helps reduce switching losses and improves overall efficiency. The driver accepts logic-level inputs (3.3V/5V compatible) and provides high peak output current (typically >2A), enabling fast turn-on and turn-off of large power switches, which is essential for high-frequency switching applications.
Application Circuit Design Guide
A typical half-bridge application circuit using the IR21271 is central to many power conversion systems. The design centers around the bootstrap power supply method for the high-side driver. Key external components include:
Bootstrap Diode (D_BOOT): A fast-recovery or ultra-fast recovery diode is mandatory to block high voltage and efficiently charge the bootstrap capacitor.
Bootstrap Capacitor (C_BOOT): This capacitor acts as the temporary power source for the high-side driver. Its value must be carefully calculated to maintain sufficient charge to keep the high-side switch fully enhanced during its on-time, even accounting for leakage and gate charge requirements.
Gate Resistor (R_G): A small series resistor is placed between the driver’s output and the power switch’s gate. This resistor is critical for controlling the switching speed, damping ringing, and preventing oscillations that can lead to electromagnetic interference (EMI) and unstable operation.
Design considerations must account for dV/dt immunity. The high-side section of the IC is subjected to high switching transients. Proper PCB layout is vital to minimize parasitic inductance and loop areas. The bootstrap capacitor must be placed as close as possible to the V_B and V_S pins of the IC to ensure stable operation. The selection of the bootstrap capacitor’s value is a balance between size and its ability to hold a charge without excessive droop.
ICGOODFIND: The Infineon IR21271STRPBF stands out as a highly integrated and robust solution for driving half-bridge stages. Its combination of high noise immunity, matched propagation delays, and critical protection features like UVLO makes it a preferred choice for designers aiming to build efficient, compact, and reliable high-power switching systems. Proper attention to the bootstrap component selection and PCB layout is the key to unlocking its full performance potential.
Keywords: Half-Bridge Driver, Bootstrap Circuit, Undervoltage Lockout (UVLO), High-Side Switching, Gate Driver IC.
