COP87L88CL Datasheet, PDF (8/34 Pages) National Semiconductor (TI) – 8-Bit One-Time Programmable OTP Microcontroller

Reset (Continued)
error will cause an active low error output on pin G1 This
error output will continue until 16 – 32 t_c clock cycles follow-
ing the clock frequency reaching the minimum specified val-
ue at which time the G1 output will enter the TRI-STATE
mode
The external RC network shown in Figure 4 should be used
to ensure that the RESET pin is held low until the power
supply to the chip stabilizes
Note In continual state of reset the device will draw excessive current
RC l 5 c Power Supply Rise Time
TL DD 12524–6
FIGURE 4 Recommended Reset Circuit
Oscillator Circuits
The chip can be driven by a clock input on the CKI input pin
which can be between DC and 10 MHz The CKO output
clock is on pin G7 (crystal configuration) The CKI input fre-
quency is divided down by 10 to produce the instruction
cycle clock (1 t_c)
Figure 5 shows the Crystal and R C diagrams
TL DD 12524–7
FIGURE 5 Crystal and R C Oscillator Diagrams
CRYSTAL OSCILLATOR
CKI and CKO can be connected to make a closed loop
crystal (or resonator) controlled oscillator
Table I shows the component values required for various
standard crystal values
TABLE I Crystal Oscillator Configuration T_A e 25 C
R1 R2 C1
C2 CKI Freq
Conditions
(kX) (MX) (pF) (pF)
(MHz)
0
1 30 30 – 36
10
V_CC e 5V
0
1 30 30 – 36
4
V_CC e 5V
0
1 200 100 – 150 0 455 V_CC e 5V
R C OSCILLATOR
By selecting CKI as a single pin oscillator input a single pin
R C oscillator circuit can be connected to it CKO is avail-
able as a general purpose input and or HALT restart pin
Table II shows the variation in the oscillator frequencies as
functions of the component (R and C) values
TABLE II R C Oscillator Configuration T_A e 25 C
R
C CKI Freq Instr Cycle _Conditions
(kX) (pF) (MHz)
(ms)
3 3 82 2 2 – 2 7
3 7–4 6
5 6 100 1 1 – 1 3
7 4–9 0
6 8 100 0 9 – 1 1
8 8 – 10 8
Note 3k s R s 200k 50 pF s C s 200 pF
V_CC e 5V
V_CC e 5V
V_CC e 5V
Control Registers
CNTRL Register (Address X 00EE)
The Timer1 (T1) and MICROWIRE PLUS control register
contains the following bits
SL1 SL0 Select the MICROWIRE PLUS clock divide
by (00 e 2 01 e 4 1x e 8)
IEDG
External interrupt edge polarity select
(0 e Rising edge 1 e Falling edge)
MSEL
Selects G5 and G4 as MICROWIRE PLUS
signals
SK and SO respectively
http www national com
8