UCD7242MRSJREP

The UCD7242 is a complete power system capable of driving two independent buck power supplies. It fully integrates high-side MOSFETs, low-side MOSFETs, drivers, current sensing circuits, and necessary protection features in a single monolithic solution to minimize size and maximize efficiency. The driver circuit provides high charge and discharge currents for the high-side NMOS switch and low-side NMOS synchronous rectifier in a synchronous buck circuit. MOSFET gates can be driven to +6.25V by an internal regulated VGG supply. The internal VGG regulator can be disabled to allow the user to provide an independent gate drive voltage. This high flexibility supports a wide power conversion input voltage range of 2.2V to 18V. Internal UVLO logic ensures VGG is valid before allowing the device to operate. The synchronous rectifier 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 for all loads. In this mode, the driver logic uses the PWM signal to control the high-side and low-side gate drive signals. Dead time is also optimized to prevent cross-conduction. When SRE is low, the device operates in discontinuous conduction mode under light loads. 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 from sudden high-current loads. A blanking delay is set for the high-side comparator to prevent fault reporting from coinciding with switching edge noise. If an overcurrent fault occurs, 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 high-accuracy integrated current sensing element. This method provides ±5% accuracy over most of the load range. The controller on the IMON pin can use this amplified signal. An on-chip temperature sensor converts die temperature to a voltage on TMON for use by the controller. If the die temperature exceeds 170℃, the temperature sensor initiates a thermal shutdown that suspends output switching and sets the FLT flag. Normal operation resumes when the die temperature drops below the thermal hysteresis band.

Applications

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

Key features

• Fully integrated power switches with drivers for dual synchronous buck converters
• Fully compatible with TI Fusion Digital Power controllers, such as the UCD92xx series
• Wide input voltage range: 4.75V to 18V
• Operation down to 2.2V input with one external bias supply
• Up to 10A output current per channel
• 2MHz operating switching frequency
• High-side current limit with current limit flag
• Onboard regulated 6V gate driver supply
• Overtemperature protection
• Thermal sensing output — voltage proportional to die temperature
• UVLO and OVLO for proper gate drive voltage assurance
• RoHS compliant
• Accurate on-chip current sensing (±5%)