MIC826 datasheet(9/22 Pages) MICROCHIP

9 / 22 page



2022 Microchip Technology Inc. and its subsidiaries

DS20006668A-page 9

MIC826

4.0

FUNCTIONAL DESCRIPTION

4.1

Design and Product Advantages

The MIC826 is a voltage supervisor reset IC with a

manual reset input, watchdog input, and dual reset

outputs. The MIC826 asserts and holds a reset when

the supply voltage falls below the factory-programmed

threshold voltage, when /MR is at low logic level, or

when watchdog input times out. Reset is asserted for a

fixed reset timeout period after the supply voltage

increases above the rising threshold voltage or when

the manual reset input is asserted high.

The MIC826 features an active-low, push-pull reset

output (/RESET) and an active-high, push-pull reset

output (RESET). It also contains 52 kΩ pull-up

resistors on the /MR input to make it easy to connect to

pushbutton inputs. The MIC826 also features a

watchdog (WDI) input.

4.2

Manual Reset Input (/MR)

The /MR input pin has integrated pull-up resistors to

keep the current consumption low when the pushbutton

switch is pressed.

4.3

Reset Outputs (/RESET and

RESET)

There are two reset outputs: /RESET and RESET. Both

outputs are push-pull, which eliminates the need for

pull-up resistors. The RESET output is the inverse of

the /RESET output.

4.4

Asserting /RESET and RESET

Outputs

4.4.1

WHEN FUNCTIONING AS A

MANUAL RESET

The reset outputs /RESET and RESET are asserted

while the /MR pin is driven low. Both reset outputs

remain asserted for a factory-programmed reset

timeout delay time, tRP. The typical value of a reset

timeout period is 200 ms. The /RESET pin is driven low

while the RESET pin is driven high whenever /MR is

pulled low.

FIGURE 4-1:

Manual Reset Function.

4.4.2

WHEN FUNCTIONING AS A

VOLTAGE SUPERVISOR

The /RESET pin is asserted whenever VCC falls below

the reset threshold voltage, VRST (VCC < VRST). The

VCC pin circuitry includes hysteresis to prevent

/RESET or RESET pin chattering due to noise. The

/RESET pin remains asserted for the duration of the

reset timeout delay (tRP) after VCC has risen above the

reset threshold voltage plus the hysteresis. The reset

function ensures that a microprocessor is properly

reset and powers up in a known condition after a power

failure. The /RESET remains valid with VCC as low as

1V. The RESET output is a complement of the /RESET

output.

FIGURE 4-2:

Voltage Supervisor

Function.

4.4.3

WATCHDOG INPUT

The MIC826 has an on-chip watchdog timer that can

reset the microprocessor if it fails to strobe the WDI

input within a preset timeout period (tWD). If the WDI pin

is left unconnected, this function is disabled. The

watchdog timeout period starts when either of the reset

outputs becomes inactive and either a high-to-low or

low-to-high transition occurs before the watchdog

timeout period (tWD). If the watchdog timer times out,

then the reset outputs will assert and stay asserted for

a reset timeout period (tRP). The watchdog timer is also

cleared whenever the reset outputs are asserted by

MIC826 Datasheet(PDF) 9 Page - Microchip Technology

MIC826 Datasheet(HTML) 9 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Datasheet Download

Link URL