MIC6315 datasheet(6/15 Pages) MICROCHIP

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MIC6315

DS20006450B-page 6

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2021 - 2022 Microchip Technology Inc.

3.0

APPLICATION INFORMATION

3.1

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 the

duration of the reset timeout period after VCC has risen

above the reset threshold or /MR has returned high.

The reset function ensures the microprocessor is

properly reset and powers up in a known condition after

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

low as 1V.

The /RESET output is a simple open-drain N-channel

MOSFET structure. A pull-up resistor must be used to

pull this output up to some voltage. For most

applications, this voltage will be the same power supply

that supplies VCC to the MIC6315. I

t is possible, however, to tie this resistor to some other

voltage. This will allow the MIC6315 to monitor one

voltage while level-shifting the /RESET output to some

other voltage. The pull-up voltage must be limited to

6.0V or less (absolute maximum) to avoid damage to

the MIC6315. The resistor must be small enough to

supply current to the inputs and leakage paths that are

driven by the /RESET output.

3.2

/RESET Valid at Low Voltage

As VCC drops to 0V, the MIC6315 will no longer be able

to pull the /RESET output low. At this point, the pull-up

resistor will pull the output high. The value of the pull-up

resistor and the voltage it is connected to will affect the

point at which this happens.

3.3

Wire OR’ing the /RESET Output

Because the RESET output is open-drain, several

reset sources can be wire-OR’ed, in parallel, to allow

resets from multiple sources.

3.4

VCC Transients

The MIC6315 is relatively immune to negative-going

VCC glitches below the reset threshold. Typically, a

negative-going transient 125 mV below the reset

threshold with duration of 20 μs or less will not cause

an unwanted reset. If additional transient immunity is

needed, a bypass capacitor can be placed a close as

possible to the MIC6315.

FIGURE 3-1:

MIC6315 as Used in a

Multiple Supply System.

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