HD6433644R datasheet(105/549 Pages) RENESAS

105 / 549 page

Section 4 Clock Pulse Generators

Rev. 6.00 Sep 12, 2006 page 85 of 526

REJ09B0326-0600

Figure 4.8 shows the equivalent circuit of the 32.768-kHz crystal resonator.

LRS

C = 1.5 pF (typ.)

R = 14 k

(typ.)

= 32.768 kHz

Crystal resonator:

Ω

MX38T

(Nihon Denpa Kogyo)

Figure 4.8 Equivalent Circuit of 32.768-kHz Crystal Resonator

Pin Connection when Not Using Subclock: When the subclock is not used, connect pin X1 to

VCC and leave pin X2 open, as shown in figure 4.9.

VCC

Open

Figure 4.9 Pin Connection when not Using Subclock

4.4

Prescalers

The H8/3644 Group is equipped with two on-chip prescalers having different input clocks

(prescaler S and prescaler W). Prescaler S is a 13-bit counter using the system clock (

φ) as its

input clock. Its prescaled outputs provide internal clock signals for on-chip peripheral modules.

Prescaler W is a 5-bit counter using a 32.768-kHz signal divided by 4 (

φW/4) as its input clock. Its

prescaled outputs are used by timer A as a time base for timekeeping.

Prescaler S (PSS): Prescaler S is a 13-bit counter using the system clock (

φ) as its input clock. It

is incremented once per clock period.

Prescaler S is initialized to H'0000 by a reset, and starts counting on exit from the reset state.

HD6433644R Datasheet(PDF) 105 Page - Renesas Technology Corp