Epson C I - 4 5 Bedienungsanleitung PDF herunterladen (Seite 4)

1960 E. Grand Ave., 2

nd

Floor,

El Segundo, California 90245

Phone: 310.955.5300

Fax: 310.955.5400

1.Purpose and Scope

SEIKO EPSON CORP. offers an oscillation circuit evaluation service. If you can provide a few circuit boards, we will evaluate

the circuit parameters and characteristics. Then we will give

you the recommended parameters. However, sometimes

some customers cannot give us the boards. In this case,

circuit evaluation will have to be done by the customer. This

guide is a reference for customers when designing and/or

evaluating circuits. Basically, the crystal oscillation circuit is

constructed as in Figure 1. The circuit parameters depend

the many characteristics including the specification of the IC

and the oscillation frequency. In order to find the best

parameters, please measure the actual circuit. This is

document explains the procedure and technique for circuit

evaluation.

2. Methods for improving design

There are many techniques for designing good oscillation

circuit. This section outlines some techniques.

2.1.Confirmation of the oscillation circuit and construction of the lC

It is necessary to confirm the IC construction before starting

to design the oscillation circuit. When using a regular HC –

MOS (High speed C - MOS) inverter gate such as the

74HCU04 the circuit will need all external parts. However, if

the IC has built in resistors and/or capacitors, it is only

necessary to add those parts not contained in the IC. (see

Figure 2.1)

In addition to choosing an inverter gate, the gate must be the

UNBUFFERED type. Please see Figure 2.2. The unbuffered

type inverter is constructed of only one inverter, on the other

hand, the buffer type has three inverter in a gate inside it

although it is referred to by only one symbol.

Epson C I - 4 5 Bedienungsanleitung Seite 4