Z86L79 Datasheet, PDF (48/58 Pages) Zilog, Inc. – Low-Voltage Microcontroller

Z86L79/80
Low-Voltage Microcontroller
Zilog
FUNCTIONAL DESCRIPTION (Continued)
Low Voltage Protection. An on-board Voltage Compara-
tor checks that V_CC is at the required level to ensure cor-
rect operation of the device. Reset is globally driven if V_CC
is below V_LV (Low Voltage). The minimum operating volt-
age varies with the temperature and operating frequency,
while V_LV varies with temperature only.
Mask Selectable Options. There are six Mask Selectable
Options to choose from based on ROM code require-
ments. These are:
The device functions normally at or above 2.0V under all
conditions. Below 2.0V, the device is guaranteed to func-
tion normally until the Low Voltage Protection trip point V_LV
is reached, below which reset is globally driven and then
the device is put in a low current stand by mode with the
oscillator stopped. The device is guaranteed to function
normally at supply voltages above the V_LV trip point for the
temperatures and operating frequencies in maximum V_LV
conditions. The actual V_LV trip point is a function of tem-
perature and process parameters (Figure 39).
Clock Source
Port 0 Pull-ups (lower nibble)
Port 0 Pull-ups (upper nibble)
Port 2 Pull-ups
Port 3 Pull-ups
Mouse/Normal
WDT Always On
RC/Other
On/Off
On/Off
On/Off
On/Off
M/N
On/Off*
*When WDT is selected as always on, the WDT will run in
HALT or STOP mode regardless of the settings in the
WDTMR Register Bits D2&D3.
The Low Voltage trip voltage (V_LV) is less than 2.1V under
the following conditions:
Maximum (V_LV) Conditions:
T_A = 0°C, +55°C Internal clock frequency equal to or less
than 4.0 MHz
Note: The internal clock frequency is one-half the external
clock frequency.
1.8
1.6
1.4
VLV
1.2
1
1.8
0.6
0.4
0.2
0
0
15
25
35
45
55
Temperature
Figure 39. Typical Z86L7X Low Voltage vs.
Temperature at 8 MHz
3-48
PRELIMINARY
DS97LVO0601