AX5043

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8

Table 5. LOGIC

Symbol

Description

Condition

Min

Typ

Max

Units

Digital Inputs

Schmitt trigger low to high threshold point

1.9

V

Schmitt trigger high to low threshold point

1.2

V

Input voltage, low

0.8

V

Input voltage, high

2.0

V

Input leakage current

−10

10

mA

Pull−up resistors

Pins DATA, DCLK, SYSCLK, IRQ, PWRAMP,

ANTSEL

Pull−ups enabled in

the relevant pin

configuration registers

65

kW

Digital Outputs

Output Current, high

VDD_IO = 3 V

4

mA

Output Current, low

VDD_IO = 3 V

4

mA

Tri−state output leakage current

−10

10

mA

AC Characteristics

Table 6. CRYSTAL OSCILLATOR

Symbol

Description

Condition

Min

Typ

Max

Units

Crystal frequency

Note 1, 2, 3

10

16

50

MHz

Oscillator transconductance control range

Self−regulated see note 4

0.2

20

mS

Programmable tuning capacitors at pins

CLK16N and CLK16P

XTALCAP = 0x00 default

3

pF

XTALCAP = 0x01

8.5

pF

XTALCAP = 0xFF

40

pF

Programmable tuning capacitors, incre-

ment per LSB of XTALCAP

XTALCAP = 0x01 – 0xFF

0.5

pF

External clock input (TCXO)

Note 2, 3, 5

10

16

50

MHz

Input DC impedance

10

kW

1. Tolerances and start−up times depend on the crystal used. Depending on the RF frequency and channel spacing the IC must be calibrated

to the exact crystal frequency using the readings of the register TRKFREQ.

2. The choice of crystal oscillator or TCXO frequency depends on the targeted regulatory regime for TX, see separate documentation on

meeting regulatory requirements.

3. To avoid spurious emission, the crystal or TCXO reference frequency should be chosen so that the RF carrier frequency is not an integer

multiple of the crystal or TCXO frequency.

4. The oscillator transconductance is regulated for fastest start−up time during start−up and for lowest power curing steady state oscillation.

This means that values depend on the crystal used.

5. If an external clock or TCXO is used, it should be input via an AC coupling at pin CLK16P with the oscillator powered up and XTALCAP = 0x00.

For detailed TCXO network recommendations depending on the TCXO output swing refer to the AX5043 Application Note: Use with a TCXO

Reference Clock.

Table 7. LOW−POWER OSCILLATOR

Symbol

Description

Condition

Min

Typ

Max

Units

Oscillator frequency slow mode

LPOSC FAST = 0

No calibration

480

640

800

Hz

Internal calibration vs. crystal

clock has been performed

630

640

650

Oscillator frequency fast mode

LPOSC FAST = 1

No calibration

7.6

10.2

12.8

kHz

Internal calibration vs. crystal

clock has been performed

9.8

10.2

10.8