Microprocessor Reset

The RESET pin is asserted whenever VCC falls below

the reset threshold voltage or if MR (manual reset) is

forced low. The reset pin remains asserted for a period

of at least 1100ms after VCC has risen above the reset

threshold voltage or MR has returned high. The reset

function ensures the microprocessor is properly reset

and powers up into a known condition after a power fail-

ure. RESET will remain valid with VCC as low as 1.4V.

VCC Transients

The MIC8115 is relatively immune to negative-going

VCC glitches below the reset threshold. Typically, a

negative-going transient 125mV below the reset

threshold with a duration of 25

µs or less will not cause

an unwanted reset.

RESET Valid to 0V

A resistor can be added from the RESET pin to ground

to ensure the RESET output remains low with VCC

down to 0V. A 100K

Ω resistor connected from RESET

to ground is recommended. The size of the resistor

should be large enough to not load the RESET output

and small enough to pull-down any stray leakage

currents.

Circuit Description

Figure 2. Reset Timing Diagram

Figure 3. RESET Valid to VCC = 0V.

VCC

MR

RESET

t1

t1

Vthr

5

VCC

RESET

µP

RESET

VCC

MIC8115

VCC

100K

MIC8115 Microprocessor Reset Circuit