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Application Notes

Receiver Control

Normal Receiver Warm Up Sequence

Receiver

Control

Line

Setting

The FLEXchip IC allows for up to six steps associated with warming up the receiver. When the FLEXchip IC turns on the receiver while decoding, it starts the warm up sequence 160 ms before it requires valid signals at the EXTS0 and EXTS1 input pins. The first step of the warm up sequence involves leaving the receiver control lines in the “Off” state for the amount of time programmed for “Warm Up Off Time”. At the end of the “Warm Up Off Time”, the first warm up setting, if enabled, is applied to the receiver control lines for the amount of time programmed for that setting. Each subsequent warm up setting is applied to the receiver control lines for their corresponding time until a disabled warm up setting is found. At the end of the last used warm up setting, the “1600 sps Sync Setting” or the “3200 sps Sync Setting” is applied to the receiver control lines depending on the current state of the FLEXchip IC. The sum total of all of the used warm up times and the “Warm Up Off Time” must not exceed 160 ms. If it exceeds 160 ms, the FLEXchip IC will execute the receiver shut down sequence at the end of the 160 ms warm up period. Figure C-1 below shows the receiver warm up sequence while decoding when all warm up settings are enabled.

 

 

 

160 ms

 

 

 

Warm Up

Warm Up

Warm Up

Warm Up

Warm Up

Warm Up

 

Off Time

Time 1

Time 2

Time 3

Time 4

Time5

 

Off

Warm Up

Warm Up

Warm Up

Warm Up

Warm Up

1600 sps or 3200 sps

Setting 1

Setting 2

Setting 3

Setting 4

Setting 5

Sync Setting

 

Possible

Possible

Possible

Possible

Possible

Possible

 

LOBAT

LOBAT

LOBAT

LOBAT

LOBAT

LOBAT

EXTS1 & EXTS0

Check

Check

Check

Check

Check

Check

signals are

 

 

 

 

 

 

expected to be

 

 

 

 

 

 

valid here.

Figure C-1 Receiver Warm Up Sequence While Decoding.

First Receiver Warm Up Sequence

When the FLEXchip IC is turned on by setting the ON bit in the Control Packet, the first warm up setting, if enabled, is applied to the receiver control lines for the amount of time programmed for that setting. Each subsequent warm up setting is applied to the receiver control lines for their corresponding time until a disabled warm up setting is found. Once a disabled warm up setting is found, the “3200 sps Sync Setting” is applied to the receiver control lines and the decoder does not expect valid signal until after the “3200 sps Sync Warm Up Time” has expired. Figure C-2 on page C-3 below shows the receiver warm up sequence when the FLEXchip IC is first turned on and when all warm up settings are enabled.

C-2

MC68175/D, Preliminary

MOTOROLA

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