TWR-KL28Z Hardware Description
TWR-
KL28Z User’s Guide, Rev. 0, 06/2016
NXP Semiconductors
11
4.6. LED
Four PWM-capable KL28Z signals are connected to four LEDs.
Figure 9. LED schematic diagram
4.7. Analog reference voltage
The onboard ADC of the TWR KL28Z uses the Reference Voltage High (VREFH) and Reference
Voltage Low (VREFL) pins to set high and low voltage references for the analog modules. By default
VREFH is attached to P3V3_KL28Z (3.3 V Supply). VREFL is connected to GND.
Figure 10. VREFH circuit schematic
If desired, VREFH can use a VDDA independent reference by cut J35 jumper.
