MCP37D11-80ESLASHTE datasheet(36/136 Pages) MICROCHIP

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MCP37D11-80: 80 MSPS 12-BIT PIPELINED ADC

DS20006381A-page 36

 2020 Microchip Technology Inc.

4.5.1.2

Single-Ended Input Configuration

Figure 4-5 shows an example of a single-ended input

configuration. This single-ended input configuration is

not recommended for the best performance. SNR and

SFDR performance degrades significantly when the

device is operated in a single-ended configuration. The

unused negative side of the input should be

AC-coupled to ground using a capacitor.

FIGURE 4-5:

Singled-Ended Input

Configuration.

4.5.2

SENSE VOLTAGE AND INPUT

FULL-SCALE RANGE

The device has a bandgap-based differential internal

reference voltage. The SENSE pin voltage is used to

select the reference voltage source and configure the

input full-scale range. A comparator detects the

SENSE pin voltage and configures the full-scale input

range into one of the three possible modes which are

summarized in Table 4-2. Figure 4-6 shows an

example of how the SENSE pin should be driven.

The SENSE pin can sink or source currents as high as

500 µA across all operational conditions. Therefore, it

may require a driver circuit, unless the SENSE

reference source provides sufficient output current.

FIGURE 4-6:

SENSE Pin Voltage Setup.

AIN+

AIN-

VCM



Analog



10 µF

0.1 µF

10 µF

0.1 µF



VCM

Input

Note 1:

This voltage buffer can be removed if the SENSE

reference is coming from a stable source (such as

MCP1700) which can provide a sufficient output

current to the SENSE pin.

SENSE

0.1 µF

MCP1700

0.1 µF

(Note 1)

TABLE 4-2:

SENSE PIN VOLTAGE AND INPUT FULL-SCALE RANGE

SENSE Pin

Voltage

(VSENSE)

Selected

Reference Voltage

(VREF)

Full-Scale Input Voltage

Range (AFS)

LSb Size

(Calculated with AFS)

Condition

Tied to GND

0.7V

1.4875 VP-P(1)

363.16 µV

Low-Reference

Mode(4)

0.4V – 0.8V

0.7V – 1.4V

1.4875 VP-P to 2.975 VP-P(2)

Adjustable

Sense Mode(5)

Tied to AVDD12

1.4875V

2.975 VP-P(3)

726.32 µV

High-Reference

Mode(4)

Note 1: AFS = (17/16) x 1.4 VP-P =1.487 VP-P.

2: AFS = (17/16) x 2.8 VP-P x(VSENSE)/0.8 = 1.4875 VP-P to 2.975 VP-P.

3: AFS = (17/16) x 2.8 VP-P =2.975 VP-P.

4: Based on internal bandgap voltage.

5: Based on VSENSE.

MCP37D11-80E/TE Datasheet(PDF) 36 Page - Microchip Technology

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