CM313202SB Ver la hoja de datos (PDF) - California Micro Devices Corp

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CM313202SB

Triple Linear Voltage Regulator for DDR-I Memory and CPU

California Micro Devices Corp 

PRELIMINARY

CM3132

Application Information

Other Applications

The CM3132 can be used without any external resis-

tors if a core voltage of 1.5V is required, the

SENSE_CORE pin is connected to GND.

In applications where a reference voltage (VREF) is

required, the VTT pin can be used. The VTT output pin

has an error relative to VDDQ/2 of up to ±25mV, which

is well within most DDR system specs of ±50mV. This

is because the VTT output internally tracks the VDDQ

output very closely due to the matched on-chip resis-

tors R that tap down from the VDDQ rail, and the low

offset voltage of the VTT regulator. It is recommended

that the VREF trace be connected directly to the VTT

pin, as shown in Figure 5, to eliminate noise and ripple

on the VTT trace caused by current switching.

2.8V to 3.3V

CVCC

Enable DDR

Memory

VCC

VREF

EN_DDR

R

R

VDDQ

REGULATOR

VDDQ = 2.5V

CDDQ

VTT

REGULATOR

VREF=1.25V

VTT=1.25V

DDR-I

MEMORY

CTT

Enable CORE

VREF

EN_CORE

VCORE

REGULATOR

VCORE=1.5V

SENSE_CORE

CCORE

CPU

CORE

+ I/O

GND

Figure 5. Minimal cost solution for CM3132 supplying DDR memory and core CPU.

© 2004 California Micro Devices Corp. All rights reserved.

10/13/04 430 N. McCarthy Blvd., Milpitas, CA 95035-5112 ● Tel: 408.263.3214 ● Fax: 408.263.7846 ● www.calmicro.com 9

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