 2018-2019 Microchip Technology Inc.

DS00002838B-page 15

UPD301A

3.3.3

BOOT_SEL CONFIGURATION STRAP

The BOOT_SEL configuration strap is used to select the UPD301A boot mode between a normal boot or a boot ROM

boot, and is implemented using a weak pull-up/pull-down of 200 kΩ, as shown in Table 3-5.

3.3.4

DC_DC_SEL CONFIGURATION STRAP

The DC_DC_SEL configuration strap is used to specify which DC/DC converter the DAC output is configured for.

The DC_DC_SEL configuration strap is encoded to one of three possible values determined by external resistors, as

detailed in Table 3-6.

TABLE 3-5:

BOOT_SEL RESISTOR ENCODING

BOOT_SEL Resistor Value

Setting

200 kΩ Pull-Down

Boot from boot ROM

200 kΩ Pull-Up

Normal operation

TABLE 3-6:

DC_DC_SEL RESISTOR ENCODING

DC_DC_SEL Resistor Value

DAC Output

200 kΩ Pull-Down

General linear DAC operation.

The DAC output range is defined as:

• 0V - 0V on VBUS

• 2.5V = 20V on VBUS

This output is linear for the range in between.

200 kΩ Pull-Up

Reserved for future use.

4.7 kΩ Pull-Down

Reserved for future use.