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 (V
REF
) is
required, the V
TT
pin can be used. The V
TT
output pin
has an error relative to V
DDQ
/2 of up to
±
25mV, which
is well within most DDR system specs of
±
50mV. This
is because the V
TT
output internally tracks the V
DDQ
output very closely due to the matched on-chip resis-
tors R that tap down from the V
DDQ
rail, and the low
offset voltage of the V
TT
regulator. It is recommended
that the V
REF
trace be connected directly to the V
TT
pin, as shown in
to eliminate noise and ripple
on the V
TT
trace caused by current switching.
2.8V to 3.3V
C
VCC
V
CC
V
DDQ
REGULATOR
V
REF
V
DDQ
= 2.5V
Enable DDR
Memory
EN_DDR
C
DDQ
DDR-I
MEMORY
R
R
C
TT
V
TT
REGULATOR
V
REF
=1.25V
V
TT
=1.25V
V
REF
V
CORE
REGULATOR
V
CORE
=1.5V
CPU
CORE
+ I/O
Enable CORE
EN_CORE
SENSE_CORE
C
CORE
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
CALMIRCO [ CALIFORNIA MICRO DEVICES CORP ]
