ANSELA datasheet(84/222 Pages) MICROCHIP

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MCP19111

DS22331A-page 84

 2013 Microchip Technology Inc.

14.1

Power-on Reset (POR)

The on-chip POR circuit holds the chip in Reset until

VDD has reached a high enough level for proper

operation. To take advantage of the POR, simply

connect the MCLR pin through a resistor to VDD. This

will eliminate external RC components usually needed

to create Power-on Reset.

When the device starts normal operation (exits the

Reset condition), device operating parameters (i.e.,

voltage, frequency, temperature, etc.) must be met to

ensure proper operation. If these conditions are not

met, the device must be held in Reset until the

operating conditions are met.

14.2

MCLR

MCP19111 has a noise filter in the MCLR Reset path.

The filter will detect and ignore small pulses.

It should be noted that a WDT Reset does not drive

MCLR pin low.

Voltages applied to the MCLR pin that exceed its

specification can result in both MCLR Resets and

excessive current beyond the device specification

during the ESD event. For this reason, Microchip

recommends that the MCLR pin no longer be tied

directly to VDD. The use of an RC network, as shown in

Figure 14-2, is suggested.

An internal MCLR option is enabled by clearing the

MCLRE bit in the Configuration Word register. When

MCLRE = 0, the Reset signal to the chip is generated

internally. When the MCLRE = 1, the MCLR pin

becomes an external Reset input. In this mode, the

MCLR pin has a weak pull-up to VDD.

FIGURE 14-2:

RECOMMENDED MCLR

CIRCUIT

TABLE 14-2:

STATUS/PCON BITS AND THEIR SIGNIFICANCE

POR

Condition

011

Power-on Reset

u0u

WDT Reset

u00

WDT Wake-up

uuu

MCLR Reset during normal operation

u10

MCLR Reset during Sleep

Legend: u = unchanged, x = unknown

Note:

The POR circuit does not produce an

internal Reset when VDD declines. To

re-enable the POR, VDD must reach VSS

for a minimum of 100 µs.

VDD

MCLR

 (or greater)

0.1 µF

(optional, not critical)

100



(needed with

SW1

(optional)

MCP19111

capacitor)

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