MCP2150-ISLASHSS datasheet(7/52 Pages) MICROCHIP

7 / 52 page

 2002 Microchip Technology Inc.

Preliminary

DS21655B-page 7

MCP2150

2.0

DEVICE OPERATION

The MCP2150 is a cost effective, low pin count (18-

pin), easy to use device for implementing IrDA stan-

dard wireless connectivity. The MCP2150 provides

support for the IrDA standard protocol “stack” plus bit

encoding/decoding. The Serial interface and IR baud

rates are independantly selectable.

2.1

Power Up

Any time the device is powered up (parameter D003),

the Power Up Timer delay (parameter 33) occurs, fol-

lowed by an Oscillator Start-up Timer (OST) delay

(parameter 32). Once these delays complete, commu-

nication with the device may be initiated. This commu-

nication is from both the infrared transceiver’s side as

well as the controller’s UART interface.

2.2

Device Reset

The MCP2150 is forced into the reset state when the

RESET pin is in the low state. Once the RESET pin is

brought to a high state, the Device Reset sequence

occurs. Once the sequence completes, functional

operation begins.

2.3

Clock Source

The MCP2150 requires a clock source to operate. The

frequency of this clock is 11.0592 MHz (electrical spec-

ification parameter 1A). This clock can be supplied by

either a crystal/resonator or as an external clock input.

2.3.1

CRYSTAL OSCILLATOR / CERAMIC

RESONATORS

A crystal or ceramic resonator can be connected to the

OSC1 and OSC2 pins to establish oscillation

(Figure 2-1). The MCP2150 oscillator design requires

the use of a parallel cut crystal. Use of a series cut crys-

tal may give a frequency outside of the crystal

manufacturers specifications.

FIGURE 2-1:

CRYSTAL OPERATION

(OR CERAMIC

RESONATOR)

TABLE 2-1:

CAPACITOR SELECTION FOR

CERAMIC RESONATORS

TABLE 2-2:

CAPACITOR SELECTION FOR

CRYSTAL OSCILLATOR

2.3.2

EXTERNAL CLOCK IN

For applications where a clock is already available

elsewhere, users may directly drive the MCP2150 pro-

vided that this external clock source meets the AC/DC

timing requirements listed in Section 4.3. Figure 2-2

shows how an external clock circuit should be

configured.

FIGURE 2-2:

EXTERNAL CLOCK INPUT

OPERATION

See Table 2-1 and Table 2-2 for recommended values of

C1 and C2.

Note:

A series resistor may be required for AT

strip cut crystals.

XTAL

OSC2

OSC1

To internal

MCP2150

Note

logic

Freq

OSC1 (C1)

OSC2 (C2)

11.0592 MHz

10 - 22 pF

Higher capacitance increases the stability of the oscil-

lator but also increases the start-up time. These val-

ues are for design guidance only. Since each

resonator has its own characteristics, the user should

consult the resonator manufacturer for appropriate

values of external components.

Freq

OSC1 (C1)

OSC2 (C2)

11.0592 MHz

15 - 30 pF

Higher capacitance increases the stability of the oscil-

lator but also increases the start-up time. These val-

ues are for design guidance only. RS may be required

to avoid overdriving crystals with low drive level spec-

ification.

Since

each

crystal

has

its

own

characteristics, the user should consult the crystal

manufacturer for appropriate values of external

components.

Clock From

external

MCP2150

OSC1

OSC2

Open

system

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