Why should I use a standalone reset IC if one is already integrated in the microcontroller?

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Why should I use a standalone reset IC if one is

already integrated in the microcontroller?

1.

A standalone reset IC has the following advantages over a microcontroller-integrated

POR or LVD:

a)

A reset IC functions while the microcontroller is in low power mode.

b)

A reset IC has a much lower consumption (10

μA) than a POR/LVD (100 μA).

c)

d)

The accuracy of the reset voltage threshold, across the temperature range -40 °C

to 85 °C, is good for a reset IC (250 mV) whereas it is poor for a POR/LVD

(400 mV).

e)

For a reset IC, a brownout detect cannot be disabled by software.

2.

A standalone reset IC can monitor dedicated peripheral voltages

3.

Standalone reset ICs can be put in parallel

Example: in an application with a mixture of 1.8 V and 3 V components, including

1.8 V and 3.3 V processors, both processors must be reset even if only one

supply drops out of tolerance.

4.

the microcontroller and any peripherals work at power-up.

5

What are the following core features of reset and

supervisor ICs used for?

5.1

Power-on reset (POR)

After system startup, a certain period of time is required for the power supply voltage to

stabilize. Consequently, ST supervisor devices usually generate a reset pulse after power-

asserted, the clock is stabilized and the registers are set to their default values. This

function is called POR.

5.2

Low-voltage detect (LVD)

Another major function of reset and supervisor ICs is low voltage detection (LVD), which

Also, if the triggering event is a narrow glitch, an RC circuit only generates a poor reset,

which may lead to malfunctioning of the microprocessor (example, failure to load registers

correctly, execution of invalid instructions, processing incorrect data). In contrast, reset and

supervisor ICs are safe and robust by design.