MCP2221 datasheet(20/80 Pages) MICROCHIP

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MCP2221

DS20005292B-page 20

 2015 Microchip Technology Inc.

1.8

GPIO/ADC/DAC Module

This module communicates with the USB HID

sub-module through the Bus Matrix module. It allows

the manipulation of GPIOs, retrieving the ADC data

and setting the DAC value.

1.8.1

GPIO

When the GPs are configured for GPIO operation,

those configured GPs can be used as digital inputs or

outputs.

When working as outputs, the GPs output logic levels

(logic 0 or 1).

1.8.1.1

VRM

The ADC and DAC sub-modules each have a voltage

reference module (VRM). Each VRM can be configured

(at Power-Up and run time) to output one of the four

voltage choices available.

The VRM can provide the following voltages as a

reference:

•VDD – the VRM output is exactly the voltage

present at the VDD pin of the MCP2221. It can

take any value from 3.3 to 5V.

• 1.024V – the VRM output of 1.024V is obtained

from an internal voltage reference

• 2.048V – the VRM output of 2.048V is obtained

from an internal voltage reference

• 4.096V – the VRM output of 4.096V is obtained

from an internal voltage reference. If the VDD is

lower than 4.096V, the VRM output will have the

value of VDD.

1.8.2

ADC CONVERTER

The ADC converter is producing 10-bit values and it

uses its own VRM module.

It features three external channels (connected to

GP1/2/3 if configured for ADC operation).

The sampling rate of the ADC is around 1000 sps.

FIGURE 1-6:

ADC SUB-MODULE

DETAILS

1.8.3

DAC CONVERTER

The DAC is 5-bit wide, has a single analog output and

it uses its own VRM module.

The DAC output voltage can be routed to GP2/3 (if

GP2/3 are configured for DAC operation).

If the GP2 and GP3 are configured for DAC operation,

they will present the same analog voltage value

because they are connected to the same DAC output.

FIGURE 1-7:

DAC SUB-MODULE

DETAILS

10-bit ADC

3 Ext. Channels

VRM

OFF

1.024V

2.048V

4.096V

10-Bit

VDD

CHIPSETTING3<2>

CHIPSETTING3<4:3>

Analog Mux

Value

5-Bit DAC

5-Bit Value

VRM

OFF

1.024V

2.048V

4.096V

Analog

VDD

CHIPSETTING2<5>

CHIPSETTING2<7:6>

Analog Mux

Output

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