LTC695-3.3 LINER [Linear Technology], LTC695-3.3 Datasheet - Page 14

• Manufacturer Part Number: LTC695-3.3
• Description: 3.3V Microprocessor Supervisory Circuits
• Manufacturer: LINER [Linear Technology]

LTC694-3.3/LTC695-3.3
A
Table 2. LTC695-3.3 Reset Active Time and Watchdog Time-Out Selections
Push-Button Reset
The LTC694-3.3/LTC695-3.3 do not provide a logic input
for direct connection to a push-button. However, a push-
button 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 push-button input.
The 100
required to prevent the ringing, due to the capacitance and
lead inductance, from pulling the RESET pins of the MPU
and LTC69X below ground.
14
TYPICAL
OSC SEL
Low
Low
Floating or High
Floating or High
*The nominal internal frequency is 10.24kHz. The nominal oscillator frequency with external capacitor is f
PPLICATI
resistor in series with the push-button is
A
O
PPLICATI
U
S
I FOR ATIO
U
External Clock Input
External Capacitor*
Floating or High
O
OSC IN
R1
10k
R2
30k
U
Low
W
Capacitor Back-Up with 74HC4016 Switch
1
10
7
74HC4016
11
U
12
13
14
100 F
0.1 F
(Short Period)
3.3V
2
400ms
1024 CLKs
NORMAL
70pF
+
100ms
1.6 sec
WATCHDOG TIME-OUT PERIOD
• C
V
V
3.3V
CC
BATT
LTC695-3.3
GND
LOW LINE
Figure 13. The External Push-Button Reset
V
CC
LTC694-3.3
LTC695-3.3
V
OUT
GND
IMMEDIATELY
AFTER RESET
(Long Period)
RESET
4096 CLKs
1.6 sec
70pF
OSC
1.6 sec
1.6 sec
694/5-3.3 TA03
0.1 F
(Hz) =
• C
0.1 F
C(pF) • 1025
184,000
100
RESET ACTIVE TIME
LTC695-3.3
800ms
2048 CLKs
RESET
(e.g. 68HC05)
70pF
200ms
200ms
MPU
694/5-3.3 F13
• C