cs5520-bp Cirrus Logic, Inc., cs5520-bp Datasheet - Page 33

• Manufacturer Part Number: cs5520-bp
• Description: 16/20-bit Bridge Transducer A/d Converters
• Manufacturer: Cirrus Logic, Inc.

A bridge driver, composed of a Siliconix TP0610
transistor and a Micrel MIC4428 dual CMOS
driver, is provided which allows the BX2 output
from the CS5516 or CS5520 to provide either dc
or ac excitation to the bridge.
The digital interface pins of the A/D converter
connect to the microcontroller, or alternatively,
these connections can be cut, or the on-board
microcontroller can be removed, and the user’s
own microcontroller can be interfaced to J1
header connector.
Figure 2 illustrates the Motorola 68HC705C8
microcontroller which reads or writes data into
the A/D converter and communicates with the
DS74DB4
DS74DB3
From
Figure 1
10k
+5VD
SMODE
OSCLK
DRDY
SCLK
10k
R20
SOD
RST
SID
CS
38
39
10
31
32
33
36
11
12
13
14
15
16
17
18
19
3
2
9
Vpp
IRQ
OSC2
OSC1
PA1
PD2
PD3
PD4
PD7
PA0
PA2
PB0
PB1
PB2
PB3
PB4
PB5
PB6
PB7
V DD
40
+
68HC705C8
C23
47 F
20
Vss
U2
Figure 2. Microcontroller and RS-232 Interface
RESET
TCMP
TCAP
0.1 F
C22
PD0
PD1
PA3
PA4
PA5
PA6
PA7
PC0 28
PC1 27
PC2 26
PC3 25
PC4 24
PC5 23
PC6 22
PC7 21
PD5
29
30
34
35
37
1
8
7
6
5
4
470
D1
10k
1 F
C24
+5VD
470
PC-compatible computer via the RS-232 inter-
face. The microcontroller derives its 4 MHz
clock from the A/D converter clock. The micro-
controller is configured to communicate over the
RS-232 link at 4800 baud, no parity, 8-bit data,
and 1 stop bit. A Motorola MC145407 RS-232
interface chip is used to send and recieve data to
the PC-compatible computer via the 25-pin Sub-
D connector.
Table 1 lists the commands sent to the microcon-
troller to write to or to read from the registers in
the A/D converter. If software other than that
provided with the evaluation board is used, the
format of the data transmitted over the RS232
line is as follow: Write commands are com-
RESET
RXD
TXD
470
D2
10 F
C28
+
16
15
14
13
12
11
3
1
+5VD
CDB5516/CDB5520
C2-
C2+
Vcc
GND
2
19
MC145407
U4
10 F
C26
+
C1+
V DD
Vss
C1-
4
17
10 F
C25
18
20
10
5
6
7
8
9
+
C27
10 F
DCD
RXD
DSR
TXD
RTS
CTS
DTR
R28
10k
RI
Sub-D
25 Pin
20
22
2
3
4
5
6
8
7
33
33