COP87LXXCJ Datasheet, PDF (8/28 Pages) National Semiconductor (TI) – 8-Bit CMOS OTP Microcontrollers with 4k or 32k Memory and Comparator

Reset (Continued)
Multi-Input Wakeup Registers
WKEDG, WKEN
WKPND
Data and Configuration
Registers for L & G
WATCHDOG Timer
CLEARED
UNKNOWN
CLEARED
Prescalar/Counter
each loaded with FF
Oscillator Circuits
EXTERNAL OSCILLATOR
By selecting the external oscillator option, the CKI pin can be
driven by an external clock signal provided it meets the
specified duty cycle, rise and fall times, and input levels. The
G7/CKO is available as a general purpose input G7 and/or
HALT control.
CRYSTAL OSCILLATOR
By selecting the crystal oscillator option, the G7/CKO pin is
connected as a clock output, CKI and G7/CKO can be con-
nected to make a crystal controlled oscillator. Table 1 shows
the clock frequency for different component values. See Fig-
ure 5 for the connections.
R/C OSCILLATOR
By selecting R/C oscillator option, connecting a resistor from
the CKI pin to V_CC makes a R/C oscillator. The capacitor is
on-chip. The G7/CKO pin is available as a general purpose
input G7 and/or HALT control. Adding an external capacitor
will jeopardize the clock frequency tolerance and increase
EMI emissions.
Table 2 shows the clock frequency for the different resistor
values. The capacitor is on-chip. See Figure 5 for the
connections.
www.national.com
DS012529-6
FIGURE 5. Clock Oscillator Configurations
R1
(kΩ)
0
0
5.6
TABLE 1. Crystal Oscillator Configuration
R2
C1
C2
CKI Freq.
(MΩ)
(pF)
(pF)
(MHz)
1
30
30–36
10
1
30
30–36
4
1
100
100–156
0.455
Conditions
V_CC = 5V
V_CC = 5V
V_CC = 5V
TABLE 2. RC Oscillator Configuration (Part-To-Part Variation) T_A = 25˚C
R
CK1 Freq.
Instr. Cycle
Conditions
(kΩ)
8.2
2.2
3.9
(MHz)
3.3 ±10%
1.3 ±10%
0.75 ±10%
(µs)
3.0 ±10%
7.7 ±10%
13.3 ±10%
V_CC = 5V
V_CC = 5V
V_CC = 5V
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