The ISL6225 dual PWM controller delivers high efficiency and tight regulation from two voltage regulating synchronous buck DC/DC converters. The ISL6225 PWM power supply controller was designed especially for DDR DRAM, SDRAM, and graphic chipset applications in high performance desknote PCs, notebook PCs, sub-notebook PCs, and PDAs.

Automatic mode selection of constant-frequency synchronous rectification at heavy load, and hysteretic diode-emulation at light load, assure high efficiency over a wide range of conditions. The hysteretic mode of operation can be disabled separately on each PWM converter if constant-frequency continuous-conduction operation is desired for all load levels. Efficiency is further enhanced by using the lower MOSFET rDS(ON) as the current sense element.

Features

• Provides regulated output voltage in the range of 0.9V-5.5V

   - High efficiency over wide load range

   - Synchronous buck converter with hysteretic operation at light load

   - Inhibit Hysteretic mode on one, or both channels

• Complete DDR memory power solution

   - VTT tracks VDDQ/2

   - VDDQ/2 buffered reference output

• No current-sense resistor required

   - Uses MOSFET rDS(ON)

   - Optional current-sense resistor for precision overcurrent

• Under-voltage lock-out on VCC pin

• Dual input voltage mode operation

   - Operates directly from battery 5V to 24V input

   - Operates from 3.3V or 5V system rail

   - VCC from 5V only

• Excellent dynamic response

   - Combined voltage feed-forward and average current mode control

• Power-good signal for each channel

• 300kHz switching frequency

   - 180° channel to channel phase operation for reduced input ripple when not in DDR mode

   - 0° channel to channel phase operation in DDR mode for reduced channel interference

   - 90° channel to channel phase operation for reduced input ripple in DDR mode when VIN is at GND.

• Pb-Free Available (RoHS Compliant)

Applications

• Mobile PCs

• PDAs

• Hand-held portable instruments