AT86RF230_09 ATMEL [ATMEL Corporation], AT86RF230_09 Datasheet - Page 6

• Manufacturer Part Number: AT86RF230_09
• Description: Low Power 2.4 GHz Transceiver for ZigBee, IEEE 802.15.4, 6LoWPAN, RF4CE and ISM
• Manufacturer: ATMEL [ATMEL Corporation]

Table 4-2. Comments on Analog and RF Pins
4.3 Digital Pins
4.3.1 Driver Strength Settings of Digital Output Pins
6
Pin
RFP/RFN
XTAL1/XTAL2
AT86RF230
Condition
VDC = 0.9V (TX)
VDC = 20 mV (RX) at both pins
CPAR = 3 pF
VDC = 0.9V at both pins
In receive mode, the RF input provides a low-impedance path to ground when transistor
M0 (see Figure 4-1) pulls the inductor center tap to ground. A DC voltage drop of 20 mV
across the on-chip inductor can be measured at the RF pins.
In transmit mode, a control loop provides a common-mode voltage of 0.9V. Transistor
M0 is off, allowing the PA to set the common-mode voltage. The common-mode
capacitance at each pin to ground shall be < 30 pF to ensure the stability of this
common-mode feedback loop.
XTAL1, XTAL2
The pin XTAL1 is the input of the reference oscillator amplifier (XOSC), XTAL2 is the
output. A detailed description of the crystal oscillator setup and the related
XTAL1/XTAL2 pin configuration can be found in section 9.6.
When using an external clock reference signal, XTAL1 shall be used as input pin. For
further details refer to section 9.6.3.
The digital interface of the AT86RF230 compromises pins SEL , SCLK, MOSI and
MISO forming the serial peripheral interface (SPI) and pins CLKM, IRQ, SLP_TR and
The digital radio transceiver interface is described in detail in section 6.
The driver strength of the digital output pins (MISO, IRQ) and CLKM pin can be
configured by register 0x03 (TRX_CTRL_0) as described in Table 4-3.
The capacitive load should be as small as possible and not larger than 50 pF when
using the 2 mA minimum driver strength setting. Generally, the output driver strength
should be adjusted to the lowest possible value in order to keep the current
consumption and the emission of digital signal harmonics low.
Table 4-3. Digital Output Driver Configuration
RST used as additional control signal between radio transceiver and microcontroller.
Pin
MISO, IRQ
CLKM
Default Driver Strength
2 mA
4 mA
Recommendation/Comment
AC-coupling is required if an antenna with a DC path to ground is used.
Serial capacitance must be < 30 pF.
Parasitic capacitance (CPAR) of the pins must be considered as additional
load capacitance to the crystal.
Comment
Adjustable to 2 mA, 4 mA, 6 mA and 8 mA
Adjustable to 2 mA, 4 mA, 6 mA and 8 mA
5131E-MCU Wireless-02/09