MAX1945S

` 6A PWM Step-Down Regulator with 95% Efficiency
` 1MHz/500kHz Switching for Small External Components
` 0.76in<sup>2</sup> Complete 6A Regulator Footprint
` External Components' Height <3mm
` ±1% Output Accuracy over Load and Line
` Operate from 2.6V to 5.5V Supply
` Operate from 2.5V Input with V<sub>CC</sub> at 3.3V/5V
` Preset Output Voltage of 1.8V or 2.5V
` Adjustable Output from 0.8V to 85% of Input
` Voltage Margining: ±4% (MAX1945R) or ±9% (MAX1945S)
` Synchronize to External Clock
` SYNCOUT Provides 180-Degree Out-of-Phase Clock Output
` All-Ceramic or Electrolytic Capacitor Designs

· Low-Voltage, High-Density Distributed Power Supplies
· ASIC, CPU, and DSP Core Voltages RAM Power Supply
· Base Station, Telecom, and Networking
· Equipment Power Supplies
· Server and Notebook Power Supplies

CTL1, CTL2, IN, SYNC, V_CC, V_DD to GND..................-0.3V to +6V
SYNCOUT, COMP, FB, FBSEL,
REF to GND................................................-0.3V to (V_CC + 0.3V)
LX Current (Note 1) ...................................................-9A to +9A
BST to LX.................................................................-0.3V to +6V
PGND to GND .......................................................-0.3V to +0.3V
Continuous Power Dissipation (T_A = +85)
(derate 23.8mW/ above +70).................................1191mW
Operating Temperature Range ............................-40 to +85
Storage Temperature Range .............................-65 to +150
Lead Temperature (soldering, 10s) .................................+300
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

Note 1: LX has internal clamp diodes to PGND and IN. Applications that forward bias these diodes should take care not to exceed the IC's package power dissipation limits.

The MAX1945R/MAX1945S high-efficiency pulse-width modulation (PWM) switching regulators deliver up to 6A of output current. The devices operate from an input supply range of 2.6V to 5.5V and provide selectable output voltages of 1.8V, 2.5V, and adjustable output voltages from 0.8V to 85% of the supply voltage. With V_CC at 3.3V/5V, the input voltage can be as low as 2.25V. The MAX1945R/MAX1945S are ideal for onboard post-regulation applications. Total output voltage error is less than ±1% over load, line, and temperature.

The MAX1945R/MAX1945S operate at a selectable fixed frequency (500kHz or 1MHz) or can be synchronized to an external clock (400kHz to 1.2MHz). The high operating frequency minimizes the size of external components. The high bandwidth of the internal error amplifier provides excellent transient response. The MAX1945R/MAX1945S have internal dual N-channel MOSFETs to lower heat dissipation at heavy loads. Two MAX1945R/MAX1945Ss can operate 180 degrees outof- phase of each other to minimize input capacitance.

The devices provide output voltage margining for board-level testing. The MAX1945R provides a ±4% voltage margining. The MAX1945S provides a ±9% voltage margining.The MAX1945R/MAX1945S are available in 28-pin TSSOP-EP packages and are specified over the -40 to +85 industrial temperature range. An evaluation kit is available to speed designs.