ne56605-42 NXP Semiconductors, ne56605-42 Datasheet - Page 11

• Manufacturer Part Number: ne56605-42
• Description: System Reset With Built-in Watchdog Timer
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Application information
The detection threshold voltage can be adjusted by externally
influencing the internal divider reference voltage. Figures 19 and 21
show a method to lower and raise the threshold voltage. Figures 20
and 22 show the influence of the pull-down and pull-up resistors on
the threshold voltage. The use of a capacitor (1000 pF or larger)
from Pin 7 to ground is recommended to filter out noise from being
imposed on the threshold voltages.
2003 Oct 15
System reset with built-in watchdog timer
V
V
CC
CC
Figure 19. Circuit to lower detection threshold.
Figure 21. Circuit to raise detection threshold.
1
2
3
4
1
2
3
4
8
7
6
5
8
7
6
5
1000 pF
1000 pF
R
1
R
2
LOGIC SYSTEM
LOGIC SYSTEM
RESET
CLK
RESET
RESET
CLK
RESET
SL01286
SL01287
GND
GND
11
The Reset Detection Threshold can be decreased by connecting an
external resistor R
Figure 20 to determine the approximate value of R
The Reset Detection Threshold can be increased by connecting an
external resistor R
See Figure 22 to determine the approximate value of R
Figure 20. Reset detection threshold versus external R
Figure 22. Reset detection threshold versus external R
5.0
4.0
3.5
3.0
5.1
5.0
4.9
4.8
4.7
4.6
4.5
4.4
4.3
0
0
T
V
C
amb
CC
T
= 0.1 F
= 5.0 V
= 25 C
100
100
R
1
2
2
, EXTERNAL PIN 7 TO GROUND RESISTOR (k )
from Pin 7 to V
from Pin 7 to ground, as shown in Figure 21.
R
1
, EXTERNAL PIN 7 TO V
200
200
300
300
CC
V
V
SL
SH
, as shown in Figure 19. See
400
400
CC
NE56605-42
V
V
SH
SL
RESISTOR (k )
500
500
1
to use.
T
V
C
amb
CC
T
2
= 0.1 F
600
600
Product data
= 5.0 V
= 25 C
to use.
SL01289
SL01288
1
2
700
700
.
.