MC68HC908JK1 Datasheet, PDF (103/210 Pages) Motorola, Inc – MC68HC908JK1

Monitor ROM (MON)
Functional Description
RC CIRCUIT
V_DD
(FOR MC68HRC908xxx)
V_DD
V_DD + V_HI
0.1 µF
See Figure 18-1 for component
values vs. frequency.
10k Ω
10k Ω
C
OSC1
OSC2
V_DD
D
(SEE NOTE 4 AND 5)
SW2
V_DD
(SEE NOTE 2)
0.1 µF
1
+
10 µF
3
4
10 µF
+2
DB-25
2
5
3
6
7
MC145407
20
(SEE NOTE 1)
C
+
9.8304 MHz
10 µF
D
18
20 pF
C
17
10 µF ^VDD
19 ⁺
X-TAL CIRCUIT
D
20 pF
V_DD
10 kΩ
A
SW1
16
(SEE NOTE 3)
B
15
10 kΩ
V_DD
1
14
V_DD
MC74HC125
2
3
10 kΩ
6
5
4
V_DD
10 kΩ
7
NOTES:
1. X-tal circuit replaced by RC circuit for MC68HRC908xxx
2. External oscillator must have a 50% duty cycle.
3. Affects high voltage entry to monitor mode only (SW2 at position C):
SW1: Position A — Bus clock = OSC1 ÷ 4
SW1: Position B — Bus clock = OSC1 ÷ 2
4. SW2: Position C — High voltage entry to monitor mode.
Input clock = OSC1; Bus clock depends on SW1.
SW2: Position D — Bus clock source = X-TAL or RC oscillator.
Bus clock = XTALCLK ÷ 4 or RCCLK ÷ 4.
5. See Table 18-4 for IRQ1 voltage level requirements.
10 kΩ
Figure 9-1. Monitor Mode Circuit
RST
HC908JL3
HC908JK3
HC908JK1
IRQ1
V_DD
V_SS
OSC1
OSC2
PTB3
PTB0
PTB1
PTB2
MC68H(R)C908JL3 — Rev. 1.0
MOTOROLA
Monitor ROM (MON)
Technical Data
103