UCD7242RSJR

The UCD7242 is a complete power system capable of driving two independent buck power supplies. The high-side MOSFET, low-side MOSFET, driver, current sensing circuit, and necessary protection features are all integrated in a monolithic solution to achieve minimum size and maximum efficiency. The drive circuit provides high charge and discharge currents for the high-side NMOS switch and low-side NMOS synchronous rectifier in a synchronous buck circuit. The MOSFET gates are driven to +6.25 V by an internally regulated VGG supply. The internal VGG regulator can be disabled, allowing the user to supply an independent gate drive voltage. This flexibility enables a wide range of power conversion input voltages from 2.2 V to 18 V. Internal UVLO logic ensures VGG is valid before the device operates. The synchronous rectification enable (SRE) pin controls whether the low-side MOSFET turns on when the PWM signal is low. When SRE is high, the device operates in continuous conduction mode under all load conditions. In this mode, the drive logic block uses the PWM signal to control the gate drive signals for both the high side and low side. Dead time is also optimized to prevent shoot-through. When SRE is low, the device operates in discontinuous conduction mode under light load. In this mode, the low-side MOSFET remains off at all times. An onboard comparator monitors the current through the high-side switch to protect the power stage against sudden high-current load events. A blanking delay is set for the high-side comparator to avoid false reporting coincident with switching edge noise. In the event of an overcurrent fault, the high-side FET is turned off and the fault flag (FLT) is asserted to alert the controller. MOSFET current is measured and monitored by a precision integrated current sensing element. This method provides ±5% accuracy over most of the load range. The amplified signal is available to the controller via the IMON pin. An on-chip temperature sensor converts the die temperature to a voltage on the TMON pin for use by the controller. If the die temperature exceeds 170℃, the temperature sensor initiates a thermal shutdown, halting output switching and setting the FLT flag. Normal operation resumes when the die temperature falls below the thermal hysteresis band.

Applications

• Digitally controlled synchronous buck power stage
• High-current dual-phase VRM/EVRD regulator for desktop, server, telecom, and notebook processors

Key features

• Fully integrated power switch with drivers for dual synchronous buck converters
• Fully compatible with TI Fusion digital power controllers (e.g., UCD92xx series)
• Wide input voltage range: 4.75 V to 18 V
• Input voltage down to 2.2 V with external bias supply
• Up to 10A output current per channel
• Switching frequency up to 2 MHz
• High-side current limiting with current limit flag
• On-board regulated 6 V gate drive supply generated from VIN
• Thermal protection
• Temperature sense output — voltage proportional to die temperature
• UVLO and OVLO circuits ensure proper gate drive voltage
• Junction temperature range: -40℃ to 125℃
• RoHS compliant
• Accurate on-chip current sensing (±5%)