Product Info

Table Of Contents

ABLUE TECHNOLOGY

Configurations summary for reference circuit 5

Config no.

Main Supply

EXT Supply Output

USB

VDDH

VDD

Config.5

USB(VDDH = VBUS)

N/A

Yes

Explanation of symbols in reference circuit 5 schematic

Symbol

Parameter

Min.

Typ.

Max.

Units

BUS

Supply voltage on VBUS pin

4.35

5.5

EXT

Voltage output on VDD when supplied from internal

regulator (REG0). V

BUS

is the input to REG0.

1.8

3.3

Some general guidance is summarized here:

 Main supply voltage is connected to VDD/VDDH. The system will enter one of two supply voltage

modes, normal or high voltage mode, depending on how the supply voltage is connected to these

pins. Normal voltage mode is entered when the supply voltage is connected to both the VDD and

VDDH pins (so that VDD equals VDDH).High voltage mode is entered when the supply voltage is

only connected to the VDDH pin and the VDD pin is not connected to any voltage supply.

 By default, the LDO regulators in the chip are enabled and the DC/DC regulator of REG1 stage is

disabled. Register DCDCEN is used to enable the DC/DC regulator for REG1 stage. External LC

filters has been connected in the Module for DC/DC regulators being used.

 The GPIO high reference voltage always equals the level on the VDD pin. In normal voltage

mode, the GPIO high level equals the voltage supplied to the VDD pin, and in high voltage mode

it equals the level specified in the register REGOUT0 UICR registers.

 When the power is supplied to VDDH, the output from the VDD pin could be used to supply

ht t p: // www. abl uet ech. com