APR3101/2/3
Application Information
VCC Transient Rejection
the IC is shutdown, and the output becomes a floating
state. If it is a trouble, a resistor should be connected
from reset output to ground to keep the reset output
low (see Figure 1). For The APR3102, a pull-up resis-
tor to VCC is required to keep the valid reset output for
VCC below 1.2V.¡@
The APR3101/2/3 have the function to reject the tran-
sient glitches from the power line. The Maximum Tran-
sient Duration vs. Reset Threshold Overdrive shows
at Typical Characteristics. The transient voltage with
the duration under the curve will not generate a reset
signal, e.g. a transient of 100mV below the reset
threshold voltage have the duration more than 35us, it
will generate a reset signal. Connect a 0.1uF bypass
capacitor to the VCC pin can improve the transient
immunity.
VCC
VCC
Manual Reset Input
RESET
Force the MR low asserts the reset signal, asserted
reset continues as long as MR is low and after the
MR goes high the reset signal is maintained for a fixed
timeout period. The MR is internally connected a 47kΩ
resistor to VCC, so it can be floating if MR is not used.
The MR input also has a debounce time 500ns to avoid
the glitches. It allows use of a mechanical switch or a
TTL, and CMOS logic signal.
100K
GND
Figure 1. Ensuring RESET Valid to VCC = 0 V
+3.3V
+5.0V
Reset Output
VCC
VCC
The APR3101/2/3 have 3 output stage versions:
APR3101 is an active low push-pull output,when the
VCC drops below the reset threshold or MR goes low,
the RESET output generates a low signal. APR3102
is an active high push-pull output, when the VCC drops
below the reset threshold or MR goes low; the RE-
SET output generates a high signal (see Timing Chart).
APR3103 is an active low open drain output, the RE-
SET output must be connected a pull-up resistor to a
supply voltage that is lower than 6V, it suits to use in
multiple voltage systems (see Figure 2). The APR3101
RESET output is valid until the VCC=1.2V, below 1.2V
APR3103
100k
RESET
5V
INPUT System
MR
RESET
GND
GND
Figure 2. APR3103 Open Drain Output with Multiple
Supplies
Copyright ANPEC Electronics Corp.
Rev. A.3 - Feb., 2004
10
www.anpec.com.tw
ANPEC [ ANPEC ELECTRONICS COROPRATION ]
