The AX5243 is a miniaturized version of the AX5043.
The AX5043 comes in a QFN28 5x5 mm2 package, while the AX5243 comes in a QFN20 4x4 mm2, thus enclosing the same RF performance of the AX5043 in a 35% smaller package.
In order to fit the silicon chip in the AX5243 smaller package, some of the peripherals are not pinned out such as (differences highlighted in yellow):
- ANTP1: single ended output of the transmitter Power Amplifier.
- DATA and DCLK: general purpose I/O also connected to the encoder block allowing for Wire Mode, wired bidirectional communication via the data (DATA) and clock (DCLK) lines.
- ANTSEL: general purpose I/O that can be used to control an external power amplifier.
Another difference is the naming of PWRAMP (pin 20 of AX5043) and TCXO_EN (pin 15 of AX5243) which are labelled differently, but are the same GPIO pad on the silicon.
The AX5043 has five available GPIOs: DATA, DCLK, SYSCLK, IRQ, ANTSEL, PWRAMP. They can be used as general purpose I/O pins by programming pin configuration registers PINFUNCSYSCLK, PINFUNCDCLK, PINFUNCDATA, PINFUNCIRQ, PINFUNCANTSEL, PINFUNCPWRAMP.
The AX5243 has three available GPIOs: SYSCLK, IRQ, TCXO_EN (a.k.a PWRAMP). They can be used as general purpose I/O pins by programming pin configuration registers PINFUNCSYSCLK, PINFUNCIRQ, PINFUNCPWRAMP.
More information on these devices can be found in the datasheets: