LTC695C-3.3 데이터 시트보기 (PDF) - Linear Technology
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LTC695C-3.3 Datasheet PDF : 20 Pages
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LTC694-3.3/LTC695-3.3
TYPICAL APPLICATION
Table 2. LTC695-3.3 Reset Active Time and Watchdog Timeout Selections
WATCHDOG TIMEOUT PERIOD
OSC SEL
OSC IN
IMMEDIATELY AFTER
NORMAL (SHORT PERIOD) RESET (LONG PERIOD)
Low
External Clock Input
1024 CLKs
4096 CLKs
Low
External Capacitor*
400ms
70pF
•
C
1.6s
70pF
•
C
RESET ACTIVE TIME
LTC695-3.3
2048 CLKs
800ms
70pF
•
C
Floating or High
Floating or High
Low
Floating or High
100ms
1.6 sec
1.6 sec
1.6 sec
*The nominal internal frequency is 10.24kHz. The nominal oscillator frequency with external capacitor is fOSC (Hz) =
184,000
C(pF) • 1025
200ms
200ms
the internal oscillator is enabled and the reset active time
is fixed at 140ms minimum for the LTC695-3.3. OSC IN
selects between the 1 second and 70ms minimum normal
watchdog timeout periods. In both cases, the timeout period
immediately after a reset is at least 1 second.
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 100Ω resistor connected to the
RESET output pin (Figure 13) provides an alternative for
manual reset. Connecting a 0.1μF capacitor to the RESET
pin debounces the push-button input.
The 100Ω resistor in series with the push-button is re-
quired to prevent the ringing, due to the capacitance and
lead inductance, from pulling the RESET pins of the MPU
and LTC69X below ground.
3.3V
VCC
RESET
LTC694-3.3
LTC695-3.3
0.1μF
100Ω
RESET
MPU
(e.g. 68HC05)
GND
694/5-3.3 F13
Figure 13. The External Push-Button Reset
TYPICAL APPLICATION
Capacitor Back-Up with 74HC4016 Switch
3.3V
0.1μF
R1
10k
10 11 12 14
1
74HC4016
2
VCC
VOUT
LTC695-3.3
VBATT LOW LINE
R2
30k
7
13 +
100μF
GND
0.1μF
694/5-3.3 TA03
69453fb
15
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