RT9246

Features:

· Multi-Phase Power Conversion with Automatic Phase Selection
· K8 DAC Output with Active Droop Compensation for Fast Load Transient
· Smooth VCORE Transition at VID Jump
· Power Stage Thermal Balance by RDS(ON) Current Sense
· Hiccup Mode Over-Current Protection
· Programmable Switching Frequency (50kHz to 400kHz per Phase), Under-Voltage Lockout and Soft-Start
· High Ripple Frequency Times Channel Number
· RoHS Compliant and 100% Lead (Pb)-Free




Application

· AMD^® Athlon^TM 64 and Opteron^TMProcessors Voltage Regulator
· Low Output Voltage, High Current DC-DC Converters
· Voltage Regulator Modules




Pinout






Specifications

` Supply Voltage, VCC ------------------------------------------------------------ 7V
` Input, Output or I/O Voltage ------------------------------GND-0.3V to V_CC+0.3V
` Power Dissipation, PD @ T<sub>A</sub> = 25°C
TSSOP-28 -----------------------------------------------------------------------1W
` Package Thermal Resistance (Note 4)
TSSOP-28, JA ---------------------------------------------------------- 100°C/W
` Junction Temperature ------------------------------------------------------ 150°C
` Lead Temperature (Soldering, 10 sec.) -------------------------------------260°C
` Storage Temperature Range ----------------------------------- −65°C to 150°C
` ESD Susceptibility (Note 2)
HBM (Human Body Mode) ------------------------------------------------------2kV
MM (Machine Mode) ---------------------------------------------------------- 200V




Description

The RT9246 is a multi-phase buck DC/DC controller integrated with all control functions for GHz CPU VRM. The RT9246 controls 2 or 3 buck switching stages operating in interleaved phase set automatically. The multi-phase architecture provides high output current while maintaining low power dissipation on power devices and low stress on input and output capacitors. The high equivalent operating frequency also reduces the component dimension and the output voltage ripple in load transient.
RT9246 controls both voltage and current loops to achieve good regulation, response & power stage thermal balance. Precise current loop using R_DS(ON) as sense component builds precise load line for strict VRM DC & transient specification and also ensures thermal balance of different power stages. The settings of current sense, droop tuning, V_CORE initial offset and over current protection are independent to compensation circuit of voltage loop. The feature greatly facilitates the flexibility of CPU power supply design and tuning.
The DAC output of RT9246 supports K8 CPU by 5-bit VID input, precise initial value & smooth V_CORE transient at VID jump. The IC monitors the V_CORE voltage for PGOOD and over-voltage protection. Soft-start, over-current protection and programmable under-voltage lockout are also provided to assure the safety of microprocessor and power system.