TCM810 Microchip Technology Inc., TCM810 Datasheet - Page 5

• Manufacturer Part Number: TCM810
• Description: 3-pin Microcontroller Reset Monitors
• Manufacturer: Microchip Technology Inc.

4.0
4.1
The TCM809/TCM810 provides accurate V
ing and reset timing during power-up, power-down and
brown-out/sag conditions. These devices also reject
negative-going transients (glitches) on the power
supply line. Figure 4-1 shows the maximum transient
duration vs. maximum negative excursion (overdrive)
for glitch rejection. Any combination of duration and
overdrive that lies under the curve will not generate a
reset signal.
FIGURE 4-1:
Duration vs. Overdrive for Glitch Rejection at
+25°C.
© 2005 Microchip Technology Inc.
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120
110
100
90
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60
50
40
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1
APPLICATIONS INFORMATION
V
400
320
240
160
80
DD
0
V
1
TCM8XXZ/R/S/T
Reset Comparator Overdrive (mV)
(SOT-23)
Transient Rejection
DD
T
A
Reset Comparator Overdrive
= +25°C
[V
10
Maximum Transient
Duration
TH
[V
5
TCM8XXL/M/J (SOT-23)
TH
– V
– V
DD
TCM8XXZ/R/S/T (SC-70)
] (mv)
DD
TCM8XXL/M/J (SC-70)
Overdrive
] (mv)
V
100
TH
100
DD
1000
monitor-
1000
Combinations above the curve are detected as a
brown-out
immunity can be improved by adding a capacitor in
close proximity to the V
4.2
The TCM809 RESET output is valid to V
Below this voltage the output becomes an "open cir-
cuit" and does not sink current. This means CMOS
logic inputs to the microcontroller will be floating at an
undetermined voltage. Most digital systems are
completely shut down well above this voltage.
However, in situations where RESET must be main-
tained valid to V
connected from RESET to ground to discharge stray
capacitances and hold the output low (Figure 4-2). This
resistor value, though not critical, should be chosen
such that it does not appreciably load RESET under
normal operation (100 k
applications). Similarly, a pull-up resistor to V
required for the TCM810 to ensure a valid high RESET
for V
FIGURE 4-2:
RESET output of the TCM809 ensures that the
RESET output is valid to V
DD
below 1.0V.
RESET Signal Integrity During
Power-Down
TCM809/TCM810
or
TCM809
DD
power-down
GND
V
V
= 0V, a pull-down resistor must be
DD
DD
RESET
The addition of R
DD
pin of the TCM809/TCM810.
will be suitable for most
DD
condition.
= 0V.
R
100 k
1
DS21661D-page 5
1
DD
at the
Transient
= 1.0V.
DD
is