LR38637 Ver la hoja de datos (PDF) - Sharp Electronics

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componentes Descripción

Fabricante

LR38637

Digital Signal Processor For VGA/CIF CMOS Image Sensors

Sharp Electronics 

LR38637

FUNCTIONAL DESCRIPTION

Oscillation Circuit

Oscillation circuit leads the same frequency of the

quartz crystal connected to I/O pins and provides

the same frequency to the internal logic circuits as

shown in Fig. 1 and Fig. 2.

CKI

CKO

C1

C2

Oscillation Circuit

(I/O Buffer)

To Internal Logic

Y Fig. 1 Block Diagram of Oscillation Circuit

I N A R RD1

RD2

CKI

CKO

Fig. 2 Clock Input to Oscillation Circuit

I M Connection of Quartz Crystal (TA = –20 to +70˚C, DVDD2 = 2.7 to 3.6 V, DVDD = 2.25 to 2.75 V) :

Example of Oscillation under Fundamental Frequencies

L APPLICABLE PINS

CKI, CKO

FUNDAMENTAL

FREQUENCY [MHz]

24.5454 or 9.0000

C1 [pF]

10

RECOMMENDED COEFFICIENT

C2 [pF]

RD1 [$]

10

220

RD2 [$]

1M

E NOTES :

1. The oscillation circuit should be located as close to CKI, CKO as possible.

2. Do not install other signal lines in the shaded area.

3. Perform due evaluation on the match between the LR38637 and the quartz crystal.

R Clock

P Input clock from the CKI pin is supplied to CMOS

Power ON/OFF Sequence

Two power supplies are used with the LR38637.

image sensor through the SCKO pin after dividing One (DVDD2) is used for I/O buffer and the other

according to inside parameter of the LR38637.

(DVDD) is used for the core logic circuits.

Set the EXTCLK pin to open or "High level".

Power ON : Be sure to turn ON the internal power

The clock frequency which can be inputted to the

of DVDD first.

CKI input pin is 24.5454 MHz or 9 MHz.

Power OFF : Be sure to turn OFF the I/O buffer of

DVDD2 first.

8

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