MAX8538

The MAX8537/MAX8539 controllers provide a complete power-management solution for both double-data-rate (DDR) and combiner supplies. The MAX8537 and MAX8539 are configured for out-of-phase and in-phase DDR power-supply operations, respectively, and generate three outputs: the main memory  oltage (^VDDQ), the tracking sinking/sourcing termination voltage (VTT), and the termination reference voltage (VTT). The MAX8538 is configured as a dual out-of-phase controller for pointof- load supplies. Each buck controller can source or sink up to 25A of current, while the termination reference can supply up to 15mA output.

The MAX8537/MAX8538/MAX8539 use constantfrequency voltage-mode architecture with operating frequencies of 200kHz to 1.4MHz. An internal  ighbandwidth (25MHz) operational amplifier is used as an error amplifier to regulate the output voltage. This allows fast transient response, reducing the  umber of output capacitors. An all-N-FET design optimizes efficiency and cost. The MAX8537/MAX8538/MAX8539 have a 1% accurate reference. The second synchronous buck controller in the MAX8537/MAX8539 and the VTTR amplifier generate 1/2 VDDQ voltage for VTT and VTTR, and track the VDDQ within ± %.

This family of controllers uses a high-side current-sense architecture for current limiting. ILIM pins allow the setting of an adjustable, lossless current limit for different combinations of load current and RDSON. Alternately, more accurate overcurrent limit is achieved by using a sense resistor in series with the high-side FET. Overvoltage protection is achieved by latching off the high-side MOSFET and latching on the low-side MOSFET when the output voltage exceeds  7% of its set output. Independent enable, power-good, and soft-start features enhance flexibility.