Linear Technology LTC6912-1, Быстрый старт, Страница: 5 / 9

DC861 QUICK START GUIDE
4
Table 3. Hex and D ecimal Digits and PGA Settings.
Hex (
N ote 1)
LTC6912-1 Gain Decimal LTC6912-2 Gain Decimal
0 (-120dB) (
N ote 2)
0 (-120dB) (
N ote 2)
-1 -1
-2 -2
-5 -4
-10 -8
-20 -16
-50 -32
-100 -64
0 (-120dB) (
N ote 3)
0 (-120dB) (
N ote 3)
0 (-120dB) (
N ote 3)
0 (-120dB) (
N ote 3)
0 (-120dB) (
N ote 3)
0 (-120dB) (
N ote 3)
0 (-120dB) (
N ote 3)
0 (-120dB) (
N ote 3)
0000
1111
2222
3333
4444
5555
6666
7777
8888
9999
Α
Α Α
Α
ββββ
00000000
00001111
02 02 02 02
05 05 05 05
10 10 10 10
20 20 20 20
50 50 50 50
1Η 1Η 1Η 1Η
Η1 Η1 Η1 Η1
Η1 Η1 Η1 Η1
Η1 Η1 Η1 Η1
Η1 Η1 Η1 Η1
Note 1: The hex digits C,
D, E and F are not used.
00000000
01
01 01
01
02
02 02
02
04
04 04
04
08
08 08
08
16
16 16
16
32
32 32
32
64
64 64
64
Η1
Η1 Η1
Η1
Η1
Η1 Η1
Η1
Η1
Η1 Η1
Η1
Η1
Η1 Η1
Η1
Note 2: The input is high impedance and
the output is low impedance.
Note 3: The input and output
are high impedance.
Initial Setup Procedure:
The following is an initial set-up guide to the function of the board’s jum pers, switches and connectors (see Figure 4).
A. D ual PG A (one D C861)
1. Connect a DC861 board as shown in Figure 5.
(J2-Dual, J6-DUAL, SW 1-D-O N , SW 2-O FF, SW 3-EN BL).
2. Set the power supply to ±5V and turn it on.
3. Turn on the sinewave generator and set it to a 1Vp-p, 1kH z sinewave
(refer to Tables 1 or 2 for the nominal PG A A and B input impedance).
4. O n power up the 4-digit LED display shows the LTC6912 gain settings in hex
(The gain setting shown on power up is the last stored setting).
H olding the SELECT sw for more than three seconds changes the display to show decimal digits
The correspondence between a hex number and a PG A setting is shown on Table 3.
(See Figure 6 for display examples in hex and decimal digits).
6. Use the SELECT and UP and DO W N switches to select the gain and press the SEN D switch to send the data to
the LTC6912 (for a quick board test, set the PG A A and B gain to one (0dB) and the oscilloscope channels #1
and #2 connected to O UT A and O UT B respectively should show a 1Vp-p, 1kH z sinewave (1Vp-p input times
one).