MCP111 datasheet(12/26 Pages) MICROCHIP

12 / 26 page

MCP111/112

DS21889D-page 12

4.2

Negative Going VDD Transients

The minimum pulse width (time) required to cause a

reset may be an important criteria in the implementa-

tion of a Power-on Reset (POR) circuit. This time is

referred to as transient duration, defined as the amount

of time needed for these supervisory devices to

respond to a drop in VDD. The transient duration time is

dependant on the magnitude of VTRIP – VDD. Generally

speaking, the transient duration decreases with

increases in VTRIP – VDD.

Figure 4-3 shows a typical transient duration vs. reset

comparator overdrive for which the MCP111/112 will

not generate a reset pulse. It shows that the farther

below the trip point the transient pulse goes, the

duration of the pulse required to cause a reset gets

shorter. Figure 2-18 shows the transient response

characteristics for the MCP111/112.

A 0.1 µF bypass capacitor, mounted as close as

possible to the VDD pin, provides additional transient

immunity (refer to Figure 4-1).

FIGURE 4-3:

Example of Typical

Transient Duration Waveform.

4.3

Effect of Temperature on Time-out

Period (tRPU)

The time-out period (t

RPU) determines how long the

device remains in the reset condition. This is affected

by both V

DD and temperature. The graph shown in

Figures 2-22, 2-23 and 2-24 show the typical response

for different V

DD values and temperatures.

4.4

Using in PICmicro®

Microcontroller ICSP™

Applications (MCP111 only)

Figure 4-4 shows the typical application circuit for using

the MCP111 for voltage supervisory function when the

PICmicro microcontroller will be programmed via the

In-Circuit

Serial

Programming™

(ICSP)

feature. Additional information is available in TB087,

“Using Voltage Supervisors with PICmicro® Microcon-

troller Systems which Implement In-Circuit Serial

Programming™”, DS91087.

FIGURE 4-4:

Typical Application Circuit

for PICmicro® Microcontroller with the ICSP™

feature.

Time (µs)

VTRIP(MIN) - VDD

tTRANS

VTRIP(MAX)

VTRIP(MIN)

Note:

It is recommended that the current into the

RST pin be current limited by a 1 k

resistor.

VDD/VPP

VDD

MCLR

(reset input)

(Active-Low)

VSS

PICmicro®

MCU

RPU

0.1 µF

MCP111

VDD

RST

VSS

MCP111 数据表(PDF) 12 Page - Microchip Technology

MCP111 数据表(HTML) 12 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

数据表下载