Silicon Laboratories SI4421 - Manual (Page 4)

Si4421
PACKAGE PIN DEFINITIONS
Pin type key: D=digital, A=analog, S=supply, I=input, O=output, IO=input/output
Pin Name Type Function
1 SDI DI Data input of the serial control interface
2 SCK DI Clock input of the serial control interface
3 nSEL DI Chip select input of the serial control interface (active low)
4 SDO DO Serial data output with bus hold
5 nIRQ DO Interrupt request output (active low)
FSK DI Transmit FSK data input (internal pull up resistor 133 k)
DATA DO Received data output (FIFO not used)
6
nFFS DI
FIFO select input (active low). In FIFO mode, when bit ef is set in Configuration Setting Command,
page 15 (internal pull up resistor 133 k)
DLCK DO Received data clock output (Digital filter used, FIFO not used)
CFIL AIO External data filter capacitor connection (Analog filter used) 7
FFIT DO FIFO interrupt (active high). In FIFO mode, when bit ef is set in Configuration Setting Command
8 CLK DO Microcontroller clock output
XTL AIO Crystal connection (the other terminal of crystal to VSS) or external reference input
9
REF AIO External reference input. Use 33 pF series coupling capacitor
10 nRES DIO Open drain reset output with internal pull-up and input buffer (active low)
11 VSS S Ground reference voltage
12 RF2 AIO RF differential signal input/output
13 RF1 AIO RF differential signal input/output
14 VDD S Positive supply voltage
15 ARSSI AO Analog RSSI output
nINT DI Interrupt input (active low)
16
VDI DO Valid data indicator output
Note: The actual mode of the multipurpose pins (pin 6 and 7) is determined by the TX/RX data I/O settings of the transceiver.
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