0

50

100

150

200

250

300

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

DAC CODE

VDD = 3.3V

G = 1002 V/V

G = 2004 V/V

G = 4003 V/V

G = 7986 V/V

0

50

100

150

200

250

300

-0.50

0.25

1.00

1.75

2.50

3.25

4.00

4.75

5.50

DAC CODE

VDD = 5V

G = 1002 V/V

G = 2004 V/V

G = 4003 V/V

G = 7986 V/V

10k

100k

1M

10M

0

10

20

30

40

FREQUENCY (Hz)

G = 32 V/V

G = 16 V/V

G = 8 V/V

G = 4 V/V

10

100

1k

60

70

80

90

100

110

120

FREQUENCY (Hz)

G = 7986 V/V

G = 4003 V/V

G = 2004 V/V

G = 1002 V/V

2.5

3.0

3.5

4.0

4.5

5.0

5.5

50

55

60

65

70

VDD (V)

G = 1002 V/V

1k

10k

100k

1M

0

10

20

30

40

50

60

FREQUENCY (Hz)

G = 250 V/V

G = 42 V/V

LMP91051

SNAS581A – MARCH 2012 – REVISED NOVEMBER 2012

www.ti.com

Typical Performance Characteristics (continued)

Output Offset

vs.

Supply Voltage

PGA1 Small Signal Bandwidth

Power Supply Rejection Ratio

vs.

PGA2 Small Signal Bandwidth

Frequency

DAC DC Sweep

DAC DC Sweep

Functional Description

PROGRAMMABLE GAIN AMPLIFIER

The LMP91051 offers two programmable gain modes (low/high) with four programmable gain settings each. The

purpose of the gain mode is to enable thermopiles with larger dark voltage levels. All gain settings are accessible

through bits GAIN1 and GAIN2[1:0]. The low gain mode has a range of 167 V/V to 1335 V/V while the high gain

mode has a range of 1002 V/V to 7986 V/V. The PGA is referenced to the internally generated VCM. Input

signal, referenced to this VCM voltage, should be within +/-2mV (see VINMAX_HGM specification) in high gain

mode. In the low gain mode the first stage will provide a gain of 42 V/V instead of 250 V/V, thus allowing a larger

maximum input signal up to +/-12mV (VINMAX_LGM).

14

Copyright © 2012, Texas Instruments Incorporated

Product Folder Links: LMP91051