Linear Technology DC861A-A Quick Start Manual page 6

DC861 QUICK START GUIDE
B. 2:1 Anal og M U X
1. Connect a DC861 board as shown in Figure 5.
(J2-Dual, J6-M UX' D, 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
(ref er to Tables 1 or 2 f or the nominal PG A A and B input impedance).
4. Connect one oscilloscope channel to an output (in a M UX operation O UT A and B are shorted).
5. Use the SELECT and UP and DO W N switches to set the gain to one (0dB) f or PG A A and two (6dB) f or PG A B
and press the SEN D switch to send the data to the LTC6912.
6. Pressing the SEN D switch repeatedly will show on the LED display an 01 or an 02 (the 2:1 M UX gain switches
f rom one to two) and the output between O UT A or O UT B (the oscilloscope display should alternately show a
1Vp-p and a 2Vp-p, 1kH z sinewave (the 2:1 M UX switches between amplif ier gains one and two).
C. Q U AD PG A (D aisy Chain O peration of tw o D C861)
Not e: I n a dai sy cha i n m ode, t he PGA set t i ngs ar e set i n hex and on SEND t he set t i ngs ar e shown i n deci m a l.
1. Connect two DC861 boards as shown in Figure 7.
(j umpers and switches on master and slave boards, J2-Dual, J6-DUAL, SW 1-D-O N , SW 3-EN BL).
2. O n the master board set SW 2 to O N and on the slave board set SW 2 to O FF.
3. Set the power supply to ±5V and turn it on.
4. Turn on the sinewave generator and set it to a 0.1V p-p (100mV), 1kH z sinewave
(ref er to Tables 1 or 2 f or the nominal PG A A and B input impedance).
5. The 4-digit display on the slave board should be blank and the gain settings f or all f our PG As shown in hex digits on
the master board' s 4-digit LED display.
6. Use the SELECT and UP and DO W N switches to set on the master' s display the gains in hex of the f our PG As
as f ollows: #1 digit to 4, #2 digit to 3, #3 digit to 2 and #1 digit to 1.
Not e: Bef or e t he SEND sw i s pr essed, t he m a st er di spla y shows t he PGA ga i n f r om lef t t o r i ght i n t he sa m e sequenc e of t he
16-bi t SPI wor d ( t he set t i ng f or t he sla v e PGA B i s sent f i r st t hen t he set t i ng f or t he sla v e PGA A, t hen t he set t i ng f or t he
m a st er PGA B a nd la st t he set t i ng f or t he m a st er PGA A) .
7. Press the SEN D switch to send the data to the LTC6912 on the master and slave boards.
8. The master and slave display and oscilloscope display should show:
a. M aster display digits #1 and 2, PG A B gain=02 and on oscilloscope channel #2 a 0.2Vp-p, 1kH z sinewave.
b. M aster display digits #3 and 4, PG A A gain=01 and on oscilloscope channel #1 a 0.1Vp-p, 1kH z sinewave.
c. Slave display digits #1 and 2, PG A B gain=10 (LTC6912-1) or PG A B gain=08 (LTC6912-2) and on
oscilloscope channel #4 a 1.0Vp-p, 1kH z sinewave (LTC6912-1) or a 0.8Vp-p, 1kH z sinewave (LTC6912-2).
d. Slave display digits #3 and 4, PG A A gain=05 (LTC6912-1) or PG A B gain=04 (LTC6912-2) and on
oscilloscope channel #3 a 0.5Vp-p, 1kH z sinewave (LTC6912-1) or a 0.5Vp-p, 1kH z sinewave (LTC6912-2).
(See Figure 7 example).
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