HMS87C1102 datasheet(41/88 Pages) HYNIX

41 / 88 page

Apr. 2001 ver 1.0

HMS87C130XA/120XA/110XA

10. CLOCK GENERATOR

The clock generator produces the basic clock pulses which

provide the system clock to be supplied to the CPU and pe-

ripheral hardware. The main system clock oscillator oscillates

with a crystal resonator or a ceramic resonator

connected to the

Xin and Xout pins. External clocks can be input to the main

system clock oscillator. In this case, input a clock signal to

the Xin pin and open the Xout pin.

Figure 10-1 Block Diagram of Clock Pulse Generator

10.1 Oscillation Circuit

XIN and XOUT are the input and output, respectively, a in-

verting amplifier which can be set for use as an on-chip os-

cillator, as shown in Figure 10-2.

Figure 10-2 Oscillator Connections

To drive the device from an external clock source, Xout

should be left unconnected while Xin is driven as shown in

Figure 10-3. There are no requirements on the duty cycle

of the external clock signal, since the input to the internal

clocking circuitry is through a divide-by-two flip-flop, but

minimum and maximum high and low times specified on

the data sheet must be observed.

Oscillation circuit is designed to be used either with a ce-

ramic resonator or crystal oscillator. Since each crystal and

ceramic resonator have their own characteristics, the user

should consult the crystal manufacturer for appropriate

values of external components.

Figure 10-3 External Clock Connections

Note: When using a system clock oscillator, carry out wir-

ing in the broken line area in Figure 10-2 to prevent

any effects from wiring capacities.

- Minimize the wiring length.

- Do not allow wiring to intersect with other signal

conductors.

- Do not allow wiring to come near changing high

current.

- Set the potential of the grounding position of the

oscillator capacitor to that of VSS. Do not ground to

any ground pattern where high current is present.

- Do not fetch signals from the oscillator.

In addition, the HMS87C1X0XA has an ability for the ex-

ternal RC oscillated operation. It offers additional cost sav-

ings for timing insensitive applications. The RC

Internal system clock

PRESCALER

CLOCK PULSE

÷1

Peripheral clock

÷2

÷4

÷8

÷16

÷128 ÷256 ÷512 ÷1024

÷32

÷64

GENERATOR

÷2048

STOP

WAKEUP

fXIN

OSCILLATION

CIRCUIT

XOUT

XIN

Vss

Recommended: C1, C2 = 30pF±10pF for Crystals

R1 = 1M

Ω

XOUT

XIN

Vss

OPEN

External

Clock

Source

HMS87C1102 Datasheet(PDF) 41 Page - Hynix Semiconductor

HMS87C1102 Datasheet(HTML) 41 Page - Hynix Semiconductor

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88

Datasheet Download

Link URL