SI4438 Datasheet, PDF (36/44 Pages) Silicon Laboratories – Low active power consumption

Si4438
Pin Pin Name
I/0
Description
11
nIRQ
General Microcontroller Interrupt Status Output.
When the Si4438 exhibits any one of the interrupt events, the nIRQ pin will be
O _{set low = 0. The Microcontroller can then determine the state of the interrupt}
by reading the interrupt status. No external resistor pull-up is required, but it
may be desirable if multiple interrupt lines are connected.
12
SCLK
Serial Clock Input.
I
0–VDD V digital input. This pin provides the serial data clock function for the
4-line serial data bus. Data is clocked into the Si4438 on positive edge transi-
tions.
13
SDO
O
0–VDD V Digital Output.
Provides a serial readback function of the internal control registers.
14
SDI
Serial Data Input.
I _{0–VDD V digital input. This pin provides the serial data stream for the 4-line}
serial data bus.
15
nSEL
Serial Interface Select Input.
I _{0–VDD V digital input. This pin provides the Select/Enable function for the}
4-line serial data bus.
16
XOUT
Crystal Oscillator Output.
O _{Connect to an external 25 to 32 MHz crystal, or leave floating when driving}
with an external source on XIN.
17
XIN
I
Crystal Oscillator Input.
Connect to an external 25 to 32 MHz crystal, or connect to an external source.
18
GND
GND ^{Connect to PCB ground.}
19
GPIO2
20
GPIO3
PKG PADDLE_GND
I/O
I/O
GND
General Purpose Digital I/O.
May be configured through the registers to perform various functions, including
Microcontroller Clock Output, FIFO status, POR, Wake-Up timer, Low Battery
Detect, TRSW, AntDiversity control, etc.
The exposed metal paddle on the bottom of the Si4438 supplies the RF and
circuit ground(s) for the entire chip. It is very important that a good solder con-
nection is made between this exposed metal paddle and the ground plane of
the PCB underlying the Si4438.
36
Rev 1.0