IS80LV51 Datasheet, PDF (32/43 Pages) Integrated Silicon Solution, Inc – CMOS SINGLE CHIP LOW VOLTAGE 8-BIT MICROCONTROLLER

IS80LV51
IS80LV31
Table 10. Status of the External Pins During Idle and Power-down Modes.
Mode
Idle
Idle
Power-down
Power-down
Memory
Internal
External
Internal
External
ALE PSEN PORT 0
1
1
Data
1
1
Float
0
0
Data
0
0
Float
PORT 1
Data
Data
Data
Data
PORT 2
Data
Address
Data
Data
ISSI ^®
PORT 3
Data
Data
Data
Data
On-Chip Oscillators
The on-chip oscillator circuitry of the IS80LV51/31 is a
single stage linear inverter, intended for use as a crystal-
controlled, positive reactance oscillator (Figure 21). In this
application the crystal is operated in its fundamental
response mode as an inductive reactance in parallel
resonance with capacitance external to the crystal (Figure
24). Examples of how to drive the clock with external
oscillator are shown in Figure 22.
The crystal specifications and capacitance values (C1 and
C2 in Figure 21) are not critical. 20 pF to 30 pF can be used
in these positions at a12 MHz to 24 MHz frequency with
good quality crystals. (For ranges greater than 24 MHz
refer to Figure 23.) A ceramic resonator can be used in
place of the crystal in cost-sensitive applications. When a
ceramic resonator is used, C1 and C2 are normally selected
to be of somewhat higher values. The manufacturer of the
ceramic resonator should be consulted for recommendation
on the values of these capacitors.
C2
XTAL2
C1
XTAL1
GND
Figure 21. Oscillator Connections
NC
EXTERNAL
OSCILLATOR
SIGNAL
XTAL2
XTAL1
GND
Figure 22. External Clock Drive Configuration
32
Integrated Silicon Solution, Inc.
ADVANCE INFORMATION MC018-0A
10/01/98