Linear Technology DC861A-A Quick Start Manual page 2

DC861 QUICK START GUIDE
DESCRIPTION
DC861A-A or -B demonstration circuit f eatures a dual digitally pro-
grammable gain amplif ier (PG A) I C, LTC6912-1 (DC861A-A) or
LTC6912-2 (DC861A-B). The LTC® 6912 is a f amily of dual chan-
nel, low noise, digitally programmable gain amplif iers (PG A) that
are easy to use and occupy very little PC board space. The gains
f or both channels are independently programmable using a 3-
wire SPI interf ace to select voltage gains of 0, 1, 2, 5, 10, 20, 50,
and 100V/ V (LTC6912-1); and 0, 1, 2, 4, 8, 16, 32, and 64V/ V
(LTC6912-2). All gains are inverting. The LTC6912 consists of 2
matched amplif iers with rail-to-rail outputs. O perating f rom sin-
gle or split supplies f rom 2.7V to 10.5V total, the LTC6912-X is
of f ered in tiny SSO P-16 and DFN -12 Packages (the DC861 board
contains an LTC6912 in the SSO P-16).
Figure 1. Demonstration Circuit DC861A-A (LTC6912-1).
DEMO CIRCUIT 861A
QUICK START GUIDE
DUAL, SPI PROGRAMABLE GAIN AMPLIFIER R,
LTC6912-1 AND LTC6912-2
The demo board highlights the f ollowing:
1. Two independent digitally programmable gain amplif iers.
2. A 2:1 Analog M UX with a dual PG A.
3. Daisy chain of two dual PG As (must use two DC861boards).
4. A 4:1 Analog M UX with quad PG As (must use two DC861boards).
On board switches and a 4-Digit LED display provide the user with the
means to input PG A settings to a PI C (micro-controller). The PI C
sends the settings to the PG A using a 3-wire SPI interf ace. Jumpers
on board conf igure the demonstration circuit as a dual PG A or a 2:1
analog M UX. A f lat ribbon cable and a connector are provided f or the
daisy-chain connection of two DC861 boards.
The DC861 demonstration circuit is a stand-alone board (computer
control is not required).
Figure 2. Bl ock Diagram, LTC6912-1/ 2, SSOP -16 Package.
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