RNA51957A_15 Datasheet, PDF (7/14 Pages) Renesas Technology Corp – Voltage Detecting, System Resetting IC Series

RNA51957A, B
Example of Application Circuit
Reset Circuit of RNA51957
R₁
Input
R₂
Power-
supply
R_L
Output
RNA51957x
GND
Delay capacitor
Cd
Preliminary
V_CC
Power-
supply
RESET
Logic circuit
GND
Figure 1 Reset Circuit of RNA51957
Notes: 1. The detecting supply voltage is V_S  (R₁ +R₂)/R₂ (V) approximately. V_S = 1.25 V (Typ)
The detecting supply voltage can be set between 2 V and 15 V.
2. The delay time is about 0.34  Cd (pF) s.
3. If the RNA51957 and the logic circuit share a common power source, type A (built-in load type) can be used
whether a pull-up resistor is included in the logic circuit or not.
4. The logic circuit preferably should not have a pull-down resistor, but if one is present, add load resistor R_L to
overcome the pull-down resistor.
5. When a negative supply voltage is used, the supply voltage side of RNA51957 and the GND side are
connected to negative supply voltage respectively.
Case of Using Reset Signal except Supply Voltage in the RNA51957
(a) Reset at ON
(b) Reset at transistor ON
R₁
Input
Power-
supply
Out
R_L
put
RNA51957x
V_CC
Power-
supply
RESET
Logic circuit
R₁
Input
Power-
supply
Out
R_L
put
RNA51957x
V_CC
Power-
supply
RESET
Logic circuit
R₂
GND
Delay capacitor
GND
R₂
GND
Delay capacitor
GND
Cd
Cd
Control
signal
Figure 2 Case of Using Reset Signal except Supply Voltage in the RNA51957
R03DS0010EJ0500 Rev.5.00
Jun 19, 2012
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