ADS7852YB Burr-Brown Corporation, ADS7852YB Datasheet - Page 9

• Manufacturer Part Number: ADS7852YB
• Description: 12-Bit/ 8-Channel/ Parallel Output ANALOG-TO-DIGITAL CONVERTER
• Manufacturer: Burr-Brown Corporation

THEORY OF OPERATION
The ADS7852 is a high-speed successive approximation
register (SAR) analog-to-digital converter (A/D) with an
internal 2.5V bandgap reference. The architecture is based
on capacitive redistribution which inherently includes a
sample/hold function. The converter is fabricated on a 0.6mi-
cron CMOS process. See Figure 1 for the basic operating
circuit for the ADS7852.
The ADS7852 requires an external clock to run the conver-
sion process. This clock can vary between 200kHz (12.5Hz
throughput) and 8MHz (500kHz throughput). The duty cycle
of the clock is unimportant as long as the minimum HIGH
and LOW times are at least 50ns and the clock period is at
least 125ns. The minimum clock frequency is governed by
the parasitic leakage of the Capacitive Digital-to-Analog
(CDAC) capacitors internal to the ADS7852.
FIGURE 1. Typical Circuit Configuration.
Analog Supply
+5V
0V to 5V
+
10 F
+
0.1 F
0.1 F
1
2
3
4
5
6
7
8
AIN0
AIN1
AIN2
AIN3
AIN4
AIN5
AIN6
AIN7
+
2.2 F
+
9
ADS7852Y
The front-end input multiplexer of the ADS7852 features
eight single-ended analog inputs. Channel selection is per-
formed using the address pins A0 (pin 14), A1 (pin 13), and
A2 (pin 12). When a conversion is initiated, the input
voltage is sampled on the internal capacitor array. While a
conversion is in progress, all channel inputs are discon-
nected from any internal function (see Truth Table for
addressing).
The range of the analog input is set by the voltage on the
V
is 0V to 5V. An external reference voltage can be placed on
V
external voltage is 2.0V to 2.55V, giving an input voltage
range of 4.0V to 5.1V.
REF
REF
, overdriving the internal voltage. The range for the
pin. With the internal 2.5V reference, the input range
DB2
DB3
DB4
DB5
DB6
DB7
DB8
DB9
24
23
22
21
20
19
18
17
ADS7852
®