Analog Devices Inc./Maxim Integrated

The MAX1638 is an ultra-high-performance, step-down DC-DC controller for CPU power in high-end computer systems. Designed for demanding applications in which output voltage precision and good transient response are critical for proper operation, it delivers over 35A from 1.3V to 3.5V with ±1% total accuracy from a +5V ±10% supply. Excellent dynamic response corrects output transients caused by the latest dynamically clocked CPUs. This controller achieves over 90% efficiency by using synchronous rectification. Flying-capacitor bootstrap circuitry drives inexpensive, external N-channel MOSFETs.The switching frequency is pin-selectable for 300kHz, 600kHz, or 1MHz. High switching frequencies allow the use of a small surface-mount inductor and decrease output filter capacitor requirements, reducing board area and system cost.The MAX1638 is available in 24-pin SSOP and QSOP (future package) packages, and offers additional features such as a digitally programmable output; adjustable transient response; and selectable 0.5%, 1%, or 2% AC load regulation. Fast recovery from load transients is ensured by a GlitchCatcher™ current-boost circuit that eliminates delays caused by the buck inductor. Output overvoltage protection is enforced by a crowbar circuit that turns on the low-side MOSFET with 100% duty factor when the output is 200mV above the normal regulation point. Other features include internal digital soft-start, a power-good output, and a 3.5V ±1% reference output.ApplicationsComputers: Desktop, Workstation, ServerGTL Bus TerminationLAN ServersPentium®Workstations

The MAX1639 is an ultra-high-performance, step-down DC-DC controller for CPU power in high-end computer systems. Designed for demanding applications in which output voltage precision and good transient response are critical for proper operation, it delivers over 35A from 1.1V to 4.5V with ±1% total accuracy from a +5V ±10% supply. Excellent dynamic response corrects output transients caused by the latest dynamically clocked CPUs. This controller achieves over 90% efficiency by using synchronous rectification. Flying-capacitor bootstrap circuitry drives inexpensive, external N-channel MOSFETs.The switching frequency is pin-selectable for 300kHz, 600kHz, or 1MHz. High switching frequencies allow the use of a small surface-mount inductor and decrease output filter capacitor requirements, reducing board area and system cost.Output overvoltage protection is enforced by a crowbar circuit that turns on the low-side MOSFET with 100% duty factor when the output is 200mV above the normal regulation point. Other features include internal digital soft-start, a power-good output, and a 3.5V ±1% reference output. The MAX1639 is available in a 16-pin narrow SOIC package.ApplicationsComputers: Desktop, Workstation, ServerGTL Bus TerminationLAN ServersLocal DC-DC Converters for CPUsWorkstations

The MAX16425/MAX16425A are fully-integrated, highly efficient step-down DC-DC switching regulators. These devices operate from 4.5V to 16V input supplies, and the output can be adjusted from 0.6V to 3.3V, delivering up to 25A of load current. These single-chip regulators provide a compact high-efficiency, power-delivery solution for precision outputs that demand fast transient response.The two devices have different programmability options (see Table 3a and 3b for details) to enable a wide range of configurations. The programmable features include: internal/external reference voltage, output voltage set-point, switching frequency, overcurrent protection level (OCP), and soft-start timing. Discontinuous current mode (DCM) operation can be enabled through pin-strapping to improve light-load efficiency.The MAX16425/MAX16425A include multiple protection and measurement features. Positive and negative cycleby- cycle OCP, short-circuit protection and overtemperature protection (OTP) ensure robust design. Input undervoltage and overvoltage lockout shut down the regulator to prevent damage when the input voltage is out of specification. Regulation is halted in case of an output overvoltage (OVP) event. A status pin indicates that the output voltage is within range and the output voltage is in regulation. The device has an analog output that can be configured to report output current or junction temperature with ±5% and ±8°C accuracy, respectively.The devices are available in a 27-bump (2.2mm x 3.8mm) WLCSP package that provides low thermal resistance and minimizes the PCB area.APPLICATIONSServers/μServersI/O and Chipset SuppliesGPU Core SupplyDDR Memory: VDDQ, VPP and VTTPoint-of-Load (PoL) Applications