SX8801IRXXMLTRT View Datasheet(PDF) - Semtech Corporation

Part Name

Description

MFG CO.

SX8801IRXXMLTRT

Sensing Machine Data Acquisition with 16+10 bit ZoomingADC™

Semtech Corporation 

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XE8801A – SX8801R

16.6 Programmable Gain Amplifiers

As seen in Figure 16-1, the zooming function is implemented with three programmable gain amplifiers (PGA). These

are:

•

PGA1: coarse gain tuning

•

PGA2: medium gain and offset tuning

•

PGA3: fine gain and offset tuning

All gain and offset settings are realized with ratios of capacitors. The user has control over each PGA activation and

gain, as well as the offset of stages 2 and 3. These functions are examined hereafter.

© Semtech 2005

ENABLE[3:0]

Block

xxx0

xxx1

xx0x

xx1x

x0xx

x1xx

0xxx

1xxx

ADC disabled

ADC enabled

PGA1 disabled

PGA1 enabled

PGA2 disabled

PGA2 enabled

PGA3 disabled

PGA3 enabled

Table 16-13 ADC & PGA enabling

PGA1_GAIN

0

1

PGA1 Gain

GD1 (V/V)

1

10

Table 16-14 PGA1 Gain Settings

PGA2_GAIN[1:0]

00

01

10

11

PGA2 Gain

GD2 (V/V)

1

2

5

10

Table 16-15 PGA2 gain settings

PGA2_OFFSET[3:0]

0000

0001

0010

0011

0100

0101

1001

1010

1011

1100

1101

PGA2 Offset

GDoff2 (V/V)

0

+0.2

+0.4

+0.6

+0.8

+1

-0.2

-0.4

-0.6

-0.8

-1

Table 16-16 PGA2 offset settings

16-9

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