Справочник Пользователя для Freescale Semiconductor Demonstration Board for Freescale MC9S12XHY256 Microcontroller DEMO9S12XHY256 DEMO9S12XHY256
Модели
DEMO9S12XHY256
D E M O 9 S 1 2 X H Y 2 5 6
J U L Y 1 5 , 2 0 1 0
U S E R G U I D E
9
Figure 3: V_SEL Option Header
PWR_SEL
Enable power to board from on-board regulator
VR1 USB
PWR_SEL
Enable power to board from integrated USB-BDM
VR1 USB
Power from the integrated BDM is drawn from the USB bus and is limited to 500 mA. This
current limit accounts for the total current supplied over the USB cable to the BDM circuit, the
target board, and any connected circuitry. Current drain in excess of 500 mA will violate the
USB specification and will cause the USB bus to disconnect. This will cause the board to
exhibit power cycling where the board appears to turn-on then off continually. Damage to the
host PC or the target board may also result.
current limit accounts for the total current supplied over the USB cable to the BDM circuit, the
target board, and any connected circuitry. Current drain in excess of 500 mA will violate the
USB specification and will cause the USB bus to disconnect. This will cause the board to
exhibit power cycling where the board appears to turn-on then off continually. Damage to the
host PC or the target board may also result.
CAUTION:
When powered from the USB bus, do not exceed the 500mA
maximum allowable current drain. Damage to the target board or host
PC may result
VX_EN
The VX_EN (JP10) option header is a 2-pin jumper that connects or disconnects input J1-1
directly to the target board voltage rail. J1-3 connects directly to the target board ground
plane. Use of this feature requires a regulated input power source. This power input is
decoupled to minimize noise but is not regulated or protected. Care should be exercised when
using this feature; no protection is applied on this input and damage to the target board may
result if excessive voltage is applied. Also, do not attempt to power the target board through
this connector while also applying power through the USB-Multilink BDM or the PWR
connector; damage to the board may result.
directly to the target board voltage rail. J1-3 connects directly to the target board ground
plane. Use of this feature requires a regulated input power source. This power input is
decoupled to minimize noise but is not regulated or protected. Care should be exercised when
using this feature; no protection is applied on this input and damage to the target board may
result if excessive voltage is applied. Also, do not attempt to power the target board through
this connector while also applying power through the USB-Multilink BDM or the PWR
connector; damage to the board may result.
CAUTION:
Damage to the board may result if voltages greater than +5.5V are
applied at the connector J1 input. Using the J1-1 and J1-3 input
connects input voltage directly to the target board voltage rails.
Power may also be sourced to off-board circuitry through the J1 connector. The current
supplied from the USB bus or the on-board regulator limits current available to external
circuitry. Excessive current drain may damage the target board, the host PC USB hub, or the
on-board regulator. Figure 4 below shows the VX_EN header option settings.
supplied from the USB bus or the on-board regulator limits current available to external
circuitry. Excessive current drain may damage the target board, the host PC USB hub, or the
on-board regulator. Figure 4 below shows the VX_EN header option settings.