TC3403 MICROCHIP [Microchip Technology], TC3403 Datasheet - Page 10

• Manufacturer Part Number: TC3403
• Description: +1.8V Low Power, Quad Input, 16-Bit Sigma-Delta A/D Converter with a Power Fault Monitor and Microprocessor Reset Circuit
• Manufacturer: MICROCHIP [Microchip Technology]

TC3403
3.3
The TC3403 RESET output is high impedance pro-
vided the voltage at V
voltage reference. This reference is approximately the
same value as the voltage appearing at REF
V
low. When V
voltage again, RESET is held low for the reset active
timeout period, t
output is ensured to be valid for V
When used to generate a Power-on or Brown-out
Reset, an external resistor network is required to divide
the appropriate V
V
example, to generate a POR for a V
the values of R1 and R2 should be 137kΩ and 115kΩ
respectively.
Since RESET is an open drain, it can be wired-OR’ed
with another open drain or external switch if desired.
DS21412B-page 10
TH
TH
is less than the internal reference, RESET is pulled
input, (See the Typical Application circuit). For
V
DD
TH
Monitor
9
, before being released. The RESET
rises above the internal reference
DD
threshold down to 1.23V at the
TH
is greater than the internal
DD
DD
= 1.3V to 5.5V.
at 3V- 10%, then
OUT
. When
3.4
The Power Fail detector is a comparator in which the
inverting input is connected to the internal voltage
reference. The non-inverting input is the PFI pin of the
TC3403 and the PFO pin is the active low, open drain
output. This comparator is suitable as an early warning
fail or low battery indicator. In a typical application,
where a voltage regulator is being used to supply
power to a system, the Power Fail comparator would
monitor the input voltage to the regulator while the V
monitor would measure the output voltage of the
regulator. Both PFO and RESET would drive interrupt
pins of a microcontroller.
The Power Fail detector may be used as a Wake-up or
Watchdog Timer. The Typical Application circuit shows
an RC network on PFI with the capacitor tied to a
tristated µC I/O pin. If R4 is 1 MΩ and C2 is 10µF, the
time constant is roughly ten seconds. The µC resets
the RC network by driving the I/O tied to PFI low and
then tristating it. The RC network will ramp to 1.23V in
roughly 9 seconds, assuming a V
PFO tied to a µC input or interrupt, the µC will see a low
to high transition on PFO when the voltage on PFI
exceeds 1.23V. The PFO output is specified to be valid
for V
DD
= 1.3 to 5.5V.
Power Fail Detector
©
2002 Microchip Technology Inc.
BATT
of 3.0V. With
DD