Datasheet

14
6.13. FET
A Renesas N-channel power switching MOSFET (part number: RQKD609CQDQS) Q7 with low on resistance (Rds(ON)
= 78mOHM typ.) is included on the RDK. The MOSFET will switch a load (ON/OFF) connected between header J2-5&6
and J2-3&4. The power to the MOSFET is supplied from external source from header J2-1&2 (ground or negative) to
J2-5&6 (positive, up to 60V max). The MOSFET will switch the load ON or OFF by PWM waveform output from the RL78
timer channel TO05 on CPU pin 31. LED7 will Turn ON when the MOSFET is ON.
A schottky flywheel diode which matches with the MOSFET ratings (2A at 60V) is added to catch flyback currents when
using inductive loads such as small motors. The below is an example of connection diagram when external motor or
lamp is connected to the MOSFET. Using PWM can vary the motor speed.
6.14.Oscillator Sources
All crystals are provided by NDK. The RDK supplies the RL78 with an external main system clock crystal unit (X1), part
number NX3225GA, and subsystem clock crystal unit (X2), part number NX3215SA. The TK debugger has a USB clock
crystal unit (X3), part number NX3225SA. Table 6-5 details the crystals that are fitted on the RL78 RDK.
Component Function Frequency
Crystal (X1) Main System Clock (X1) 12 MHz
Crystal (X2) Subsystem Clock (XT1) 32.768 KHz
Crystal (X3) Debugger USB Clock 16 MHz
Table 6-5: Oscillators / Resonators