NXP Semiconductors FRDMKW36UG, Руководство пользователя, Страница: 13 / 28

• 32 MHz Reference Oscillator
— Figure 12 shows the 32 MHz external crystal Y1. The Bluetooth LE specification requires the frequency to be
accurate less than ±50 ppm. The FRDM-KW36 is equipped with a ±10 ppm oscillator.
— Internal load capacitors provide the crystal load capacitance. The internal load capacitors are adjustable which
allows the center frequency of the crystal to be tuned.
— To measure the 32 MHz oscillator frequency, program the CLKOUT (PTB0) signal to provide buffered output clock
signal.
Figure 13. FRDM-KW36 32.786 kHz oscillator circuit
• 32.768 kHz Crystal Oscillator (required to support radio deep sleep mode)
— 32.768 kHz crystal Y2 is provided (see Figure 13 ).
— Internal load capacitors provide the entire crystal load capacitance.
3.3 Power management
There are several ways to power and measure current on the FRDM-KW36 board. Figure 14 shows the FRDM-KW36 power-
management circuit.
Figure 14. FRDM-KW36 power management circuit
The FRDM-KW36 can be powered by the following means:
• Through the micro USB type B connector (J11), which provides 5 V to the P5V_SDA_PSW signal into the 3V3 LDO (U16).
NXP Semiconductors
Functional description
FRDM-KW36 Freedom Development Board User’s Guide, Rev. 4, 01/2020
User's Guide 13 / 28