Silicon Laboratories SI4421 manual Si4421 PACKAGE PIN DEFINITIONS, Name, Type, Function

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)
6	DATA	DO		Received data output (FIFO not used)
	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)
7	CFIL	AIO		External data filter capacitor connection (Analog filter used)
	FFIT	DO		FIFO interrupt (active high). In FIFO mode, when bit ef is set in Configuration Setting Command
8	CLK	DO		Microcontroller clock output
9	XTL	AIO		Crystal connection (the other terminal of crystal to VSS) or external reference input
	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
16	nINT	DI		Interrupt input (active low)
	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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