TMS370Cx1x

8-BIT MICROCONTROLLER

SPNS012F – MAY 1987 – REVISED FEBRUARY 1997

39

POST OFFICE BOX 1443

External

Clock Signal

XTAL1

XTAL2/CLKIN

C2

(see Note B)

C1

(see Note B)

Crystal/Ceramic

Resonator

(see Note A)

XTAL1

XTAL2/CLKIN

C3

(see Note B)

NOTES: A. The crystal/ceramic resonator frequency is four times the reciprocal of the system clock period.

B. The values of C1 and C2 are typically 15 pF and the value of C3 is typically 50 pF. See the manufacturer’s recommendations for

ceramic resonators.

Figure 14.

Recommended Crystal/Clock Connections

1.2 k

Ω

20 pF

VO

Load Voltage

Case 1: VO = VOH = 2.4 V; Load Voltage = 0 V

Case 2: VO = VOL = 0.4 V; Load Voltage = 2.1 V

NOTE A: All measurements are made with the pin loading as shown unless otherwise noted. All measurements are made with XTAL2/CLKIN

driven by an external square wave signal with a 50% duty cycle and rise and fall times less than 10 ns unless otherwise stated.

Figure 15. Typical Output Load Circuit (See Note A)

VCC

GND

300

Ω

20

Ω

I/O

Pin Data

Output

Enable

VCC

GND

INT1

6 k

Ω

20

Ω

30

Ω

Figure 16. Typical Buffer Circuitry