Hardware Description
Table 2-13. User Assignable Input (Continued)
CON13 | Signal Name | Remarks |
| | |
Pin 7 | DCDC_CTL1 | Connected to MCU PTF4/TPM2CH0 |
| | |
Pin 8 | DCDC_CTL2 | Connected to MCU PTF5/TPM2CH1 |
| | |
Pin 9 | DCDC_CTL3 | Connected to MCU PTE3/TPM1CH1 |
| | |
Pin 10 | GND | — |
| | |
2.10 LED Driving Board
In general, LEDs have a nonlinear I-V behavior and current limitation is required to prevent the power dissipation to exceed a maximum limit. Therefore, the ideal source for LED driving is a constant current source. A linear type LED driver is used in this reference design and the block diagram is shown in Figure 2-4. The major advantage of linear driver is fast turn ON and OFF response times to support high frequency PWM dimming method and wide range control on dimming level. An integrated DC-to-DC boost converter (MC34063) generates the high voltage required for LED driving in series and is shared with RGB channels, but the drawback is the power loss on R channel is higher than G or B channels. Individual DC-to-DC block should be used for each channel in power sensitive applications.
LED Lighting Control using the MC9S08AW60, Rev. 1
18 | Freescale Semiconductor |
