MIC2775 Micrel Semiconductor, MIC2775 Datasheet - Page 5

• Manufacturer Part Number: MIC2775
• Description: Micro-Power Voltage Supervisor Advance Information
• Manufacturer: Micrel Semiconductor

Functional Diagram
Functional Description
V
The V
tored input voltage. The voltage at this pin is continually
compared against the internal reference. The trip-point at
which a reset occurs is factory programmed. A reset is
triggered if and when V
esis is employed to prevent chattering due to noise. The
comparator on the V
negative-going transients.
RST, /RST Reset Outputs
Typically, the MIC2775 is used to monitor the power supply
of intelligent circuits such as microcontrollers and micropro-
cessors. By connecting the appropriate reset output of a
MIC2775 to the reset input of a µC or µP, the processor will
be properly reset at power-on and during power-down and
brown-out conditions. In addition, asserting /MR, the manual
reset input, will activate the reset function.
September 29, 2000
MIC2775
DD
Input
DD
pin is both the power supply terminal and a moni-
/MR
DD
V
DD
input is relatively immune to very brief
DD
V
falls below the trip-point. Hyster-
DD
I
PU
GND
V
REF
5
The reset outputs are asserted any time /MR is asserted or if
V
remain asserted for t
above the threshold boundary and/or /MR is released. A reset
pulse is also generated at power-on. Hysteresis is included in
the comparator to prevent chattering of the outputs due to
noise.
/MR, Manual Reset Input
The ability to initiate a reset via external logic or a manual
switch is provided in addition to the MIC2775’s automatic
supervisory functions. Driving the /MR input to a logic low
causes an immediate and unconditional reset to occur.
Assuming V
(returns high), the reset outputs will be de-asserted no less
than t
mechanical switch. Typically, a momentary push-button switch
is connected such that /MR is shorted to ground when the
switch contacts close. The switch may be connected directly
between /MR and GND. /MR has an internal 100nA pull-up
current to V
DD
Delay
Line
drops below the threshold voltage. The reset outputs
RST
One Shot
later. /MR may be driven by a logic signal or
DD
DD
and may be left open if unused.
is within tolerance when /MR is released
RST
R
S
MIC2775
(min) after V
/Q
Q
/RST
DD
RST
subsequently returns
MIC2775
Micrel