MCP2030 datasheet(40/66 Pages) MICROCHIP

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MCP2030

DS21981A-page 40

5.20

Soft Reset

The Soft Reset is issued in the following events:

After Power-on Reset (POR),

After Inactivity timer time-out,

If an “Abort” occurs,

After receiving SPI Soft Reset command.

The “Abort” occurs if there is no positive signal

detected at the end of the AGC initialization period

(TAGC). The Soft Reset initializes internal circuits and

brings the device into a low current Standby mode

operation. The internal circuits that are initialized by the

Soft Reset include:

• Output Enable Filter

•AGC circuits

• Demodulator

• 32 kHz Internal Oscillator

The Soft Reset has no effect on the Configuration register

setup, except for some of the AFE STATUS Register 7

bits. (Register 5-8).

The circuit initialization takes one internal clock cycle

(1/32 kHz = 31.25

μs). During the initialization, the

modulation

transistors

between

each

input

and

LCCOM pins are turned-on to discharge any internal/

external parasitic charges. The modulation transistors

are turned-off immediately after the initialization time.

The Soft Reset is executed in Active mode only. It is not

valid in Standby mode.

5.21

Minimum Modulation Depth

Requirement for Input Signal

The device demodulates the modulated input signal if

the modulation depth of the input signal is greater than

the minimum requirement that is programmed in

Configuration Register 5 (Register 5-6). Figure 5-5

shows the definition of the modulation depth and

examples. MODMIN<6:5> of the Configuration Register

5 offer four options. They are 60%, 33%, 14% and 6%.

The default setting is 33%.

The purpose of this feature is to enhance the

demodulation integrity of the input signal. The 6%

setting is the best choice for the input signal with weak

modulation depth, which is typically observed near the

high-voltage base station antenna and also at far-

distance from the base station antenna. It gives the

best demodulation sensitivity, but is very susceptible to

noise spikes that can result in a bit detection error. The

60% setting can reduce the bit errors caused by noise,

but gives the least demodulation sensitivity. See

Table 5-3 for minimum modulation depth requirement

settings.

TABLE 5-3:

SETTING FOR MINIMUM

MODULATION DEPTH

REQUIREMENT

MODMIN Bits

(Config. Register 5)

Modulation Depth

Bit 6

Bit 5

33% (default)

60%

14%

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