LDO controllers drive NMOS, NPN pass transistors

The LDS124P and LDS128P complement an existing LDO controller, the LDS120P, and are targeted for applications including graphic cards, PC motherboards, switching power supply post-regulation, telecom equipment, and consumer applications such as LCD TV. The LDS124P and LDS128P are designed to drive NMOS or NPN pass transistors to regulate output voltages from 1.24V to 12V. The LDS124P is a single-channel LDO controller, the LDS128 is a dual-channel LDO controller.

The LDS124 is a single-channel LDO controller and has a precision temperature compensated 1.24 V reference. Its drive pin is capable of 100mA of sink current controlling up to 10A through a pass transistor. An NMOS pass transistor is preferred for load currents greater than 2.5A. This combination, available in SOT-23 or TO-92 packages makes a very flexible regulator in terms of V_OUT and I_OUT, which can be implemented where space is at a premium.

LDS128, on the other hand, is a dual-channel LDO controller in a SOT-23-5 package. The LDS128 has two independent precision temperature compensated LDO controllers for setting two output voltages from 1.24V to 12V. Each drive pin is capable of sinking 20mA, controlling two separate pass transistors. Ultra-low dropout operation is possible by taking the drive pin bias supply to a higher voltage than V_IN, to the 12V rail in a PCI-Express card for instance.

"As IC loads become complex and sophisticated the number of power rails in a system or on a card increases. Load current scalable solutions reduce inventory costs, eliminating circuit blocks that are redundant in the power chain, increasing power density and reliability," said Paul Greenland, senior director of power management at Leadis. "We believe these adaptable point of load regulation solutions will become an industry standard in a diverse range of multi-rail applications."