DEMO908QC16 Freescale Semiconductor, DEMO908QC16 Datasheet - Page 12

• Manufacturer Part Number: DEMO908QC16
• Description: BOARD DEMO FOR MC908QC16
• Manufacturer: Freescale Semiconductor
• Type: MCUr

Specifications of DEMO908QC16

• Contents: Board, Cable, CD
• Processor To Be Evaluated: MC908QC16
• Data Bus Width: 8 bit
• Interface Type: RS-232, USB
• Silicon Manufacturer: Freescale
• Core Architecture: HC08
• Core Sub-architecture: HC08
• Silicon Core Number: MC68HC908
• Silicon Family Name: HC08Q
• Kit Contents: Board
• Rohs Compliant: No
• For Use With/related Products: MC908QC16
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

D E M O 9 0 8 Q C 1 6
tempting to power off-board circuitry through connector J1 or when connecting external cir-
cuitry. Drawing excessive current will lead to VR1 shutdown.
Figure 3: PWR_SEL Option Header
VX_EN
The VX_EN option header is a 2-pin jumper that connects input J1-1 directly to the target
board +5V voltage rail. J1-3 is hard-wired to the ground plane. Use of this feature requires a
regulated +5V input power source. This power input is decoupled to minimize noise input but
is not regulated. Care should be exercised when using this feature as no protection is applied
on this input and damage to the target board may result if over-driven. Also, do not attempt to
power the target board through this connector while also applying power through the USB-
MON08 or the PWR connector; damage to the board may result.
The VX_EN option header also allows the user to supply power to off-board circuitry through
connector J1. Current limitation of the USB bus or the on-board regulator must be considered
when attempting to source power to external circuitry. Excessive current drain may damage
the target board, the host PC USB hub, or the on-board regulator. The figure below details the
VX_EN header connections.
Figure 4. VX_EN Option Header
RESET SWITCH
The RESET switch provides a method to apply an asynchronous RESET to the MCU. The
RESET switch is connected directly to the RST* input on the MCU. Pressing the RESET
switch applies a low voltage level to the RST* input. A pull-up bias resistor on the RST* input
allows normal MCU operation. Shunt capacitance ensures an adequate input pulse width.
NOTE: Do not exceed available current supply from USB-MON08 cable or on-board regulator
NOTE: This header is not installed in default configuration.
VX_EN
PWR_SEL
1
1
1
2
2
2
when sourcing power through connector J1 to external circuitry.
3
3
Enabled
ON
Disabled
OFF
CONFIGURATION:
Select power input from
Select power input from on-board regulator
12
USB-MON08
J U N E
2 0 ,
2 0 0 5