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4694E–AUTO–08/05

ATA5282

3.9

Data Output

The wake-up signal enables the data pin that delivers the received and demodulated data

stream to the controller. Sampling and decoding has to be performed by the controller. An

example for data coding is given in the “n Bit Data” field (Figure 3-7 on page 10). This kind of

modulation requires an indication of the end of data, for example, by a burst that differs from

the other transmitted bits. As the circuit does not check the received data (except the header),

it is up to the base station which kind of modulation (pulse distance, Manchester, bi-phase...)

is used.

The data output signal is derived from the internal GAP detection. Table 3-1 describes how the

timing depends on different conditions of the applied input signal. The Q-factor of the external

LC-tank as well as the signal strength influence the pulse width of the output signal.

Figure 3-8.

Output Timing Conditions

a

c

d

b

50%

100%

Internal

NGAP

Internal

comporator

output

Coil

input

a + b = Data delay time t

ON

c + d = Data delay time t

OFF

Table 3-1.

Typical Output Timing versus Signal Strength at 3.2V Supply Voltage

Input Signal

a, c

(Figure 3-8)

b (Periods)

d (Periods)

no Q

Q

≤14

Q

≤20

no Q

Q

≤14

Q

≤20

Minimum, 2.8 mV

PP

Depends on

Q-factor

3 to 5

4 to 6

5 to 7

3 to 5

4 to 6

4 to 6

3 to 5

4 to 6

5 to 7

3 to 5

4 to 6

4 to 6

3 to 5

3 to 5

3 to 5

3 to 5

4 to 6

4 to 6