DEMO9S08QG8 Freescale Semiconductor, DEMO9S08QG8 Datasheet - Page 8

• Manufacturer Part Number: DEMO9S08QG8
• Description: BOARD EVAL FOR MC9S08QG4/8
• Manufacturer: Freescale Semiconductor

Specifications of DEMO9S08QG8

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

POWER SELECT
Power may be applied to the board through the integrated USB-BDM circuitry, a 2.0mm barrel
connector, or through connector J1. Power selection is achieved by using 2 option headers:
PWR_SEL option header and the VX_EN option header.
The PWR_SEL option header selects power input either from the integrated USB-BDM
circuitry or from the on-board voltage regulator. Power input selection, from the USB-BDM or
the on-board power supply, is mutually exclusive. This prevents power-input contention from
damaging the board. The figure below details the PWR_SEL header connections.
PWR_SEL
Figure 1: PWR_SEL Option Header
Power from the integrated BDM is drawn from the USB bus and is limited to 500mA.
Excessive current drain will violate the USB specification will cause the USB bus to disconnect.
The on-board voltage regulator (VR1) accepts power input through a 2.0mm barrel connector
(PWR). Input voltage may range from +5V to +18V. The voltage regulator (VR1) provides a
+3.3V fixed output limited to 250mA. Over-temperature and over-current limits built into the
voltage regulator protects the device from excessive stresses.
The user should consider the maximum output current limit of the selected power source when
attempting to power off-board circuitry through connector J1.
VX_EN
The VX_EN option header is a 2-pin jumper that connects the target board voltage rail to J1-1.
J1-3 is connected directly to the ground plane. Use of this feature requires a regulated +3.3V
input power source. This power input is decoupled to minimize noise input but is not
regulated. Care should be exercised when using this feature; 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-BDM or the
PWR connector; damage to the board may result.
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VB
VB
CAUTION: Violating the USB specification will cause the USB bus to disconnect. This will
PWR_SEL
PWR_SEL
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VDD
VDD
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cause the board to reset.
CONFIGURATION:
Select power input from USB-BDM
Select power input from VR1
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