MIC1815 datasheet(5/6 Pages) MICREL

5 / 6 page

July 2005

MIC1815

Micrel

Applications Information

Microprocessor Reset

The /RESET pin is asserted whenever VCC falls below the

reset threshold voltage. The reset pin remains asserted for a

period of tRST after VCC has risen above the reset threshold

voltage. The reset function ensures the microprocessor is

properly reset and powers up into a known condition after

a power failure. /RESET will remain valid with VCC as low

as 1V.

VCC Transients

The MIC1815 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

20µs or less will not cause an unwanted reset.

/RESET Valid at Low Voltage

A resistor can be added from the /RESET pin-to-ground to

ensure the /RESET output remains low with VCC down to

0V. A 100kΩ resistor connected from /RESET-to-ground is

recommended. The resistor should be large enough not to

load the /RESET output and small enough to pull-down any

stray leakage currents. See Figure below.

VCC

RESET

µP

RESET

VCC

MIC1815

VCC

100K

/RESET Valid to VCC = 0V

MIC1815 Datasheet(PDF) 5 Page - Micrel Semiconductor