Z51F3220FNX Datasheet, PDF (284/312 Pages) Zilog, Inc. – Z8051 Series 8-Bit Microcontrollers

Z51F3220
Product Specification
13.7 Brown Out Detector Processor
The Z51F3220 has an On-chip brown-out detection circuit (BOD) for monitoring the VDD level during operation
by comparing it to a fixed trigger level. The trigger level for the BOD can be selected by LVRVS[3:0] bit to be
1.60V, 2.00V, 2.10V, 2.20V,2.32V, 2.44V, 2.59V, 2.75V, 2.93V, 3.14V, 3.38V, 3.67V, 4.00V, 4.40V. In the STOP
mode, this will contribute significantly to the total current consumption. So to minimize the current consumption,
the LVREN bit is set to off by software.
External VDD
LVRVS[3:0]
LVREN
Brown Out
Detector
(BOD)
RESET_BODB
CPU
Write
SCLK
(System CLK)
DQ
CP
r
LVRF
(Low Voltage
Reset Flag)
Figure 13.9 Block Diagram of BOD
nPOR
VDD
Internal
RESETB
VDD
Internal
RESETB
16ms
t < 16ms
16ms
VBODMAX
VBODMIN
VBODMAX
VBODMIN
Figure 13.10 Internal Reset at the power fail situation
PS029902-0212
PRELIMINARY
282