High Efficiency Dual-Channel Synchronous Buck PWM Controller with Phase Interleaving and Two LDO Regulators

The RT8122 is a high efficiency dual-channel synchronous Buck PWM controller with integrated MOSFET drivers and two LDOs. The controller features Green Voltage Mode (GVM^TM) control, which is specifically designed to improve efficiency at light load condition. At light load condition, the RT8122 is pin configurable to automatically operate in diode emulation mode with constant on-time PFM to reduce switching frequency so as to improve conversion efficiency. As the load current increases, the RT8122 leaves the diode emulation mode and operates in Continuous Conduction Mode (CCM) with fixed-frequency, 180° out of phase interleaved PWM to reduce input capacitance. The RT8122 supports 4.5V to 26V input voltage range and has integrated 5V LDO which powers the integrated 5V MOSFET gate drivers as well as the controller. When channel 1 Buck regulator output voltage is set to 5V, the controller supply voltage automatically switches between the Buck regulator output and the integrated 5V LDO. The RT8122 supports enable/disable function for each channel and also features external soft-start, adjustable switching frequency and power good indication. This device utilizes lossless inductor DCR current sensing for over current protection. Other protections include over voltage, under voltage, thermal shutdown and under voltage lockout. The RT8122 is available in a WQFN-28L 4x4 package.