7

ATA5745C/ATA5746C [DATASHEET]

9249C–RKE–10/14

Conditions for the sensitivity measurement:

The given sensitivity values are valid for Manchester-modulated signals. For the sensitivity measurement the distance from

edge to edge must be evaluated. As can be seen in Figure 6-1 on page 22, in a Manchester-modulated data stream, the time

2.3

Sensitivity Versus Supply Voltage, Temperature and Frequency Offset

To calculate the behavior of a transmission system, it is important to know the reduction of the sensitivity due to several

influences. The most important are frequency offset due to crystal oscillator (XTO) and crystal frequency (XTAL) errors,

temperature and supply voltage dependency of the noise figure, and IF-filter bandwidth of the receiver. Figure 2-2 and

Figure 2-3 on page 8 show the typical sensitivity at 315MHz, ASK, 2.4Kbits/s and 9.6Kbits/s, Manchester, Figure 2-4 and

Figure 2-5 on page 9 show a typical sensitivity at 315MHz, FSK, 2.4Kbits/s and 9.6Kbits/s, ±38kHz, Manchester versus the

VS = VS3V_AVCC = VS5V = 2.7V, 3.0V and 3.3V.

Table 2-2.

Input Matching to 50

Ω

315

2.2

68

20

433.92

2.2

36

15

Table 2-3.

Measured Typical Sensitivity FSK,

RF Frequency

BR_Range_0

1.0Kbit/s

BR_Range_0

2.5Kbits/s

BR_Range_1

5Kbits/s

BR_Range_2

10Kbits/s

BR_Range_3

10Kbits/s

BR_Range_3

20Kbits/s

315MHz

–108dBm

–108dBm

–107dBm

–105dBm

–104dBm

–104dBm

433.92MHz

–107dBm

–107dBm

–106dBm

–104dBm

–103dBm

–103dBm

Table 2-4.

RF Frequency

BR_Range_0

1.0Kbit/s

BR_Range_0

2.5Kbits/s

BR_Range_1

5Kbits/s

BR_Range_2

10Kbits/s

BR_Range_3

10Kbits/s

315MHz

–114dBm

–114dBm

–113dBm

–111dBm

–109dBm

433.92MHz

–113dBm

–113dBm

–112dBm

–110dBm

–108dBm

Table 2-5.

Limits for Sensitivity Measurements

Bit Rate

2

2

2

1.0Kbit/s

260µs

500µs

790µs

800µs

1000µs

1340µs

2.4Kbits/s

110µs

208µs

310µs

320µs

416µs

525µs

5.0Kbits/s

55µs

100µs

155µs

160µs

200µs

260µs

9.6Kbits/s

27µs

52µs

78µs

81µs

104µs

131µs