LTC693 LINER [Linear Technology], LTC693 Datasheet - Page 14

• Manufacturer Part Number: LTC693
• Description: Microprocessor Supervisory Circuits
• Manufacturer: LINER [Linear Technology]

LTC692/LTC693
Table 2. LTC693 Reset Active Time and Watchdog Time-Out Selections
Pushbutton Reset
The LTC692/LTC693 do not provide a logic input for direct
connection to a pushbutton. However, a pushbutton in
series with a 100 resistor connected to the RESET output
pin (Figure 13) provides an alternative for manual reset.
Connecting a 0.1 F capacitor to the RESET pin debounces
the pushbutton input.
The 100
quired to prevent the ringing, due to the capacitance and
lead inductance, from pulling the RESET pins of the MPU
and LTC692/LT693 below ground.
14
TYPICAL
A
*The nominal internal frequency is 10.24kHz. The nominal oscillator frequency with external capacitor is F
PPLICATI
Floating or High
Floating or High
OSC SEL
Low
Low
resistor in series with the pushbutton is re-
A
PPLICATI
O
U
S
I FOR ATIO
U
External Clock Input
External Capacitor*
Floating or High
O
R1
10k
R2
30k
OSC IN
Low
U
S
W
1
Capacitor Backup with 74HC4016 Switch
74HC4016
10
7
11
U
12
13
14
(Short Period)
5V
2
400ms
NORMAL
1024 clks
47pF
+
1.6 sec
100ms
WATCHDOG TIME-OUT PERIOD
100 F
0.1 F
C
5V
V
V
CC
BATT
V
CC
Figure 13. The External Pushbutton Reset
LTC693
LTC692
LTC693
GND
GND
LOW LINE
RESET
IMMEDIATELY
AFTER RESET
(Long Period)
1.6 sec
V
4096 clks
47pF
OUT
1.6 sec
1.6 sec
OSC
LTC692/3 • TA3
(Hz) =
C
0.1 F
184,000
C(pF)
0.1 F
RESET ACTIVE TIME
800ms
100
2048 clks
47pF
LTC693
200ms
200ms
RESET
(e.g. 6805)
C
MPU
LTC692/3 • F13