RFM219SW

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1.4 Crystal Oscillator

Table 5. Crystal Oscillator Specifications

Parameter

Symbol

Conditions

Min

Typ

Max

Unit

Crystal Frequency

[1]

26

26

26

MHz

Crystal Tolerance

[2]

±20

ppm

Load Capacitance

10

15

20

pF

Crystal ESR

Rm

60

Ω

XTAL Startup Time

[3]

400

us

Notes:

[1]. The RFM219SW can directly work with external 26 MHz reference clock input to XIN pin (a coupling capacitor is required)

with peak-to-peak amplitude of 0.3 to 0.7 V.

[2]. This is the total tolerance including (1) initial tolerance, (2) crystal loading, (3) aging, and (4) temperature dependence.

The acceptable crystal tolerance depends on RF frequency and channel spacing/bandwidth.

[3]. This parameter is to a large degree crystal dependent.

1.5 LPOSC

Table 6. LPOSC Specifications

Parameter

Symbol

Conditions

Min

Typ

Max

Unit

Calibrated Frequency

[1]

1

kHz

Frequency Accuracy

After calibration

1

%

Temperature Coefficient

[2]

-0.02

%/°C

Supply Voltage Coefficient

[3]

+0.5

%/V

Initial Calibration Time

4

ms

Notes:

[1]. The LPOSC is automatically calibrated to the crystal oscillator during the PUP state, and is periodically calibrated since

then.

[2]. Frequency drifts when temperature changes after calibration.

[3]. Frequency drifts when supply voltage changes after calibration.