Chapter 3 — Theory of Operation
CV30 Fixed Mount Computer Service Manual 51
DSUB_PWR_EN. The CPU exerted this signal; Logic “H” will enable
both switches to channel individual V5P0_COM1 and V5P0_COM2
through a ferrite bead to the serial COM port. These two switches have a
current limit minimum of 800 mA for each individual V5P0_COM1 and
V5P0_COM2.
V5P0_USB1, V5P0_USB2, and V5P0_USBH
V5P0_MAIN To V5P0_USB1 and V5P0_USB2
Both the V5P0_USB1 and V5P0_USB2 are output from the V5P0_MAIN
through a dual channel power distribution switch MIC2026. This switch
has a current limit minimum of 500mA for each channel. Each channel will
monitor the current consumption individually. Should any of the channel
current exceed 500mA, a fault status output flag signal nUSBOC will be
exerted to the USB hub to instruct the hub to exert a nUSB_PSW signal to
off the switch.
V5P0_MAIN To V5P0_USBH
The V5P0_USBH is the PFET controlled version of V5P0_MAIN by the
signal USBH_PWR_EN. The CPU asserted this signal to allow the
V5P0_USBH power to the USB hub ISP1520.
SYS_PWR
V12P0 To SYS_PWR
The SYS_PWR originates from the V12P0 power source through a
schottky diode. This power source supplies power to the battery charging
system and main power buck MAX1745 to MAIN_PWR.
MAIN_PWR
SYS_PWR to MAIN_PWR
The MAIN_PWR is available through two main sources: the voltage 4.5 V
voltage bucked through MAX1745 from SYS_PWR and the BK_PWR
source from backup battery. With the external source attached,
MAIN_PWR will always source from the buck converter. The BK_PWR
will take charge as the source to the MAIN_PWR once the external power
source is removed. The switching occurs when voltage detection IC S-
80830C detects SYS_PWR drops below 8V.
BK_PWR
BK_PWR is the power source from the backup battery that supplies power
to MAIN_PWR if the external power source is removed. The voltage range
is defined between maximum of 4.2 V at full charge to minimum of 3.0 V
at end of charge.
VCC_CORE, VCC_PLL, VCC_SRAM, V2P5, V1P8
MAIN_PWR To VCC_CORE, VCC_PLL, VCC_SRAM, V2P5, V1P8
To Next Page
Loading...
