III PERIPHERAL BLOCK: LOW-SPEED (OSC1) OSCILLATION CIRCUIT

Oscillator Types

In the low-speed (OSC1) oscillation circuit, either a crystal oscillation or an external clock input can be selected as the type of oscillation circuit.

Figure 6.2 shows the structure of the low-speed (OSC1) oscillation circuit.

CG1

OSC1

 

OSC1

 

 

VDD

 

 

 

fOSC1

VSS

fOSC1

Rf

X'tal1

External

 

clock

 

 

OSC2

Oscillation circuit

N.C.

Oscillation circuit

CD1

 

control signal

OSC2

control signal

 

VSS

 

 

 

 

 

 

(1) Crystal oscillation circuit

 

(2) External clock input

OSC1

Low level

OSC2

Oscillation circuit

control signal

 

VSS

(3) When not used

Figure 6.2 Low-Speed (OSC1) Oscillation Circuit

When using a crystal oscillation for this circuit, connect a crystal resonator X'tal1 (32.768 kHz, Typ.) and feedback resistor (Rf) between the OSC1 and OSC2 pins, and two capacitors (CG1, CD1) between the OSC1 pin and VSS and the OSC2 pin and VSS, respectively.

When an external clock source is used, leave the OSC2 pin open and input a square-wave clock to the OSC1 pin. If the low-speed (OSC1) oscillation circuit is not used, connect the OSC1 pin to VSS and leave the OSC2 pin open.

The oscillation frequency is 32.768 kHz (Typ.). Use a crystal resonator or external clock that oscillates at this frequency. No other frequency can be used for clock applications.

For details on oscillation characteristics and the external clock input characteristics, refer to "Electrical Characteristics".

B-III-6-2

EPSON

S1C33L03 FUNCTION PART