3 .0 V/3 .3 V Ad ju s t a b le Mic ro p ro c e s s o r
S u p e rvis o ry Circ u it s
34/MAX795
have without causing a reset pulse to be issued. As
the amplitude of the transient increases (i.e., goes far-
ther below the reset threshold), the maximum allowable
_________________P in Co n fig u ra t io n s
pulse width decreases. Typically, a V transient that
goes 40mV below the reset threshold and lasts for
10µs or less will not cause a reset pulse to be issued.
CC
TOP VIEW
OUT
BATT
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
RESET
LOWLINE
RESET
CE OUT
CE IN
A 0.1µF bypass capacitor mounted close to the V
CC
pin provides additional transient immunity.
CC
(RESET IN) BATT OK
PFI
BATT ON
GND
MAX793
MAX794
Wa t c h d o g S o ft w a re Co n s id e ra t io n s
There is a way to help the watchdog timer monitor soft-
ware execution more closely, which involves setting
and resetting the watchdog input at different points in
the program rather than “pulsing” the watchdog input
high-low-high or low-high-low. This technique avoids a
“stuck” loop, in which the watchdog timer would con-
tinue to be reset within the loop, keeping the watchdog
from timing out. Figure 19 shows an example of a flow
diagram where the I/O driving the watchdog input is
set high at the beginning of the program, set low at the
beginning of every subroutine or loop, then set high
again when the program returns to the beginning. If
the program should “hang” in any subroutine, the prob-
lem would quickly be corrected, since the I/O is contin-
ually set low and the watchdog timer is allowed to time
out, causing a reset or interrupt to be issued.
PFO
WDI
MR
WDO
DIP / Narrow SO
BATT
RESET
CE OUT
CE IN
OUT
1
8
7
6
5
V
2
3
4
CC
MAX795
BATT ON
GND
DIP/SO
( ) ARE FOR MAX794
___________________Ch ip In fo rm a t io n
_Ord e rin g In fo rm a t io n (c o n t in u e d )
PART*
TEMP. RANGE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 Plastic DIP
16 Narrow SO
16 Plastic DIP
16 Narrow SO
8 Plastic DIP
8 SO
TRANSISTOR COUNT: 1271
MAX794CPE
MAX794CSE
MAX794EPE
MAX794ESE
MAX795_CPA
MAX795_CSA
MAX795_EPA
MAX795_ESA
8 Plastic DIP
8 SO
* The MAX793/MAX795 offer a choice of reset threshold voltage.
Select the letter corresponding to the desired reset threshold volt-
age range (T = 3.00V to 3.15V, S = 2.85V to 3.00V, R = 2.55V
to 2.70V) and insert it into the blank to complete the part number.
The MAX794’s reset threshold is adjustable.
______________________________________________________________________________________ 19
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
