+/+…when timing is critical
C9810
Low EMI Clock Generator for Intel 810 Chipset for Mobile Applications
Advanced Information
IMI Confidential
Power on Bi-Directional Pins
Power Up Condition:
Pin 48 (REL2/REF) is a Power up bi-directional pin and is used for selecting the host frequency in page 1, table 1.
During power-up of the device, this pin is in input mode (see Fig 4, below), therefore; it is considered input select pins
internal to the IC. After a settling time, the selection data is latch into the internal control register and this pin becomes a
clock output.
VDD RAIL
POWER SUPPLY
RAMP
REF / SEL2
(Pin 1)
-
Hi-Z INPUTS
TOGGLE OUTPUTS
SELECT DATA IS LATCHED INTO REGISTER THEN PIN BECOMES A REF CLOCK OUTPUT SIGNAL
Fig.4
Vdd
Strapping Resistor Options:
See D escription
R up
10K
The power up bi-directional pins have a large value pull-
up each (250KΩ), therefore, a selection “1” is the
default. If the system uses a slow power supply (over
5mS settling time), then it is recommended to use an
external Pull-up (Rup) in order to insure a high
selection. In this case, the designer may choose one of
two configurations, see Fig.5A and B.
IM I C 9810
R d
Load
Bidirectional
JP1
JU MPER
Fig. 5A
R dn
10K
Fig. 5A represents an additional pull up resistor 50KΩ
connected from the pin to the power line, which allows a
faster pull to a high level.
If a selection “0” is desired, then a jumper is placed on
JP1 to a 5KΩ resistor as implemented as shown in
Fig.5A. Please note the selection resistors (Rup and
Rdn) are placed before the Damping resistor (Rd)
close to the pin.
JP2
3 W ay Jum per
Vdd
3
2
1
Fig. 5B represent a single resistor 10KΩ connected to a
3-way jumper, JP2. When a “1” selection is desired, a
jumper is placed between leads1 and 3. When a “0”
selection is desired, a jumper is placed between leads 1
and 2.
R sel
10K
IM I C 9810
R d
Load
Bidirectional
Fig. 5B
INTERNATIONAL MICROCIRCUITS, INC. 525 LOS COCHES ST.
MILPITAS, CA 95035, USA TEL: 408-263-6300, FAX 408-263-6571
Rev 0.4
8/31/1999
Page 5 of 15
http://www.imicorp.com
CYPRESS [ CYPRESS ]
