Features: Up to 25A Output-Current Capability
Quick-PWM Control for Fast Loop Response
Up to 95% Efficiency
4.5V to 28V Input Voltage Range
No External Bias Supply Required
0 to 3.6V Input REFIN Range (MAX8553)
Automatically Sets VTT and VTTR to within ±1% of 1/2 VREFIN- (MAX8553)
Low 0.6V Feedback Threshold (MAX8554)
200kHz/300kHz/400kHz/550kHz Selectable Switching Frequencies
Adjustable Foldback Current Limit
Overvoltage Protection
Digital Soft-StartApplicationWide-Input Power Supplies
Servers and Storage Applications
ASIC and CPU Core Voltages
Notebook and LCD-PC Power Supplies
DDR I and DDR II Memory Power Supplies
AGTL Bus Termination SuppliesPinout
SpecificationsABSOLUTE MAXIMUM RATINGS
V+, EN/HSD, EN, HSD to GND.............................-0.3V to +30V
PGND to GND ...................................................-0.3V to +0.3V
VTT, REFIN, POK, OUT, FB, VL to GND...................-0.3V to +6V
REF, VTTR, DL, ILIM, FSEL to GND ...........-0.3V to (VVL + 0.3V)
LX to PGND ..........................................................-2V to +30V
BST to GND.........................................................-0.3V to +36V
DH to LX ..............................................................-0.3V to +6V
LX to BST..............................................................-6V to +0.3V
REF Short Circuit to GND ........................................Continuous
Continuous Power Dissipation (TA = +70°C)
16-Pin QSOP (derated 8.3mW/°C above +70°C) .......667mW
Operating Temperature Range ......................-40°C to +85°C
Junction Temperature..................................................+150°C
Storage Temperature Range .......................-65°C to +150°C
Lead Temperature (soldering, 10s) .............................+300°C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional peration of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. xposure to bsolute maximum rating conditions for extended periods may affect device reliability.
DescriptionThe MAX8553 is a 4.5V to 28V input-voltage, synchronous step-down controller that provides a complete power-management solution for DDR memory. The AX8553 generates 1/2 VREFIN voltage for VTT and TTR. The VTT and VTTR tracking voltages are maintained ithin 1% of 1/2 VREFIN. The MAX8554 is a 4.5V to 8V input voltage, nontracking step-down controller with low 0.6V feedback threshold voltage. The MAX8553/ MAX8554 use Maxim's proprietary Quick-PWM™ architecture or fast transient response and operate with electable pseudo-fixed frequencies. Both controllers an operate without an external bias supply.
The controllers MAX8554 operate in synchronous-rectification mode o ensure balanced current sourcing and sinking capability f up to 25A. The MAX8553/MAX8554 also provide up o 95% efficiency, making them ideal for server and pointof- oad applications. Additionally, a low 5µA shutdown urrent allows for longer battery life in notebook applications. ossless current monitoring is achieved by monitoring he low-side MOSFET's drain-to-source voltage. The AX8553/MAX8554 have an adjustable foldback current imit to withstand a continuous output overload and short ircuit. Digital soft-start provides control of inrush current uring power-up. Overvoltage protection shuts the converter own and discharges the output capacitor. The AX8553/MAX8554 come in space-saving 16-pin QSOP
packages.
MAX8554 Data Sheet
