Silicon Laboratories SI4421 Si4421, AC Characteristics Transmitter, AC Characteristics Others

Si4421

AC Characteristics (Transmitter)

Symbol

Parameter

Conditions/Notes

Min

Typ

Max

Units

IOUT

Open collector output DC current

Programmable

0.5

6

mA

Pmax_50

Max. output power delivered to 50

In 433 MHz band

7

dBm

Ohm load over a suitable matching

In 868 MHz / 915 MHz bands

5

network (Note 4)

Max. EIRP with suitable selected

In 433 MHz band with monopole antenna

7

Pmax_ant

with matching network (Note 4)

dBm

PCB antenna (Note 6)

In 868 MHz / 915 MHz bands (Note 5)

7

Pout

Typical output power

Selectable in 2.5 dB steps (Note 7)

Pmax -17.5

Pmax

dBm

Psp

Spurious emission

At max power 50 Ohm load (Note 4)

-55

dBc

l f-fspl > 1 MHz

With PCB antenna (Note 5)

-60

Pharm

Harmonic suppression

At max power 50 Ohm load (Note 4)

-35

dBc

With PCB antenna (Note 5)

-42

Co

Output capacitance (set by the

In 433 MHz band

2

2.6

3.2

pF

automatic antenna tuning circuit)

In 868 MHz / 915 MHz bands

2.1

2.7

3.3

Qo

Quality factor of the output

In 433 MHz band

13

15

17

capacitance

In 868 MHz / 915 MHz bands

8

10

12

Lout

Output phase noise

100 kHz from carrier, in 868 MHz band

-80

dBc/Hz

1 MHz from carrier, in 868 MHz band

-103

BRTX

FSK bit rate

Via internal TX data register

172

kbps

BRATX

FSK bit rate

TX data connected to the FSK input

256

kbps

dffsk

FSK frequency deviation

Programmable in 15 kHz steps

15

240

kHz

AC Characteristics (Turn-on/Turnaround timings)

Symbol

Parameter

Conditions/Notes

Min

Typ

Max

Units

tsx

Crystal oscillator startup time

Default capacitance bank setting, crystal

2

7

ms

ESR < 50 Ohm (Note 9). Crystal load

capacitance = 16 pF.

Ttx_XTAL_ON

Transmitter turn-on time

Synthesizer off, crystal oscillator on with

250

µs

10 MHz step

Trx_XTAL_ON

Receiver turn-on time

Synthesizer off, crystal oscillator on with

250

µs

10 MHz step

Ttx_rx_SYNT_ON

Transmitter – Receiver turnover time

Synthesizer and crystal oscillator on

150

µs

during TX/RX change with 10 MHz step

Trx_tx_SYNT_ON

Receiver – Transmitter turnover time

Synthesizer and crystal oscillator on

150

µs

during RX/TX change with 10 MHz step

AC Characteristics (Others)

Symbol

Parameter

Conditions/Notes

Min

Typ

Max

Units

Cxl

Crystal load capacitance,

Programmable in 0.5 pF steps, tolerance

8.5

16

pF

see crystal selection guide

± 10%

tPOR

Internal POR timeout

After Vdd has reached 90% of final value

100

ms

(Note 8)

Crystal oscillator must be enabled to

tPBt

Wake-up timer clock accuracy

ensure proper calibration at the start up.

± 10

%

(Note 9)

CinD

Digital input capacitance

2

pF

tr , tf

Digital output rise/fall time

15 pF pure capacitive load

10

ns

Notes are on page 12.

11