EVAL-AD7706EB Analog Devices Inc, EVAL-AD7706EB Datasheet - Page 31

• Manufacturer Part Number: EVAL-AD7706EB
• Description: BOARD EVAL FOR AD7706
• Manufacturer: Analog Devices Inc

Specifications of EVAL-AD7706EB

• Number Of Adc's: 1
• Number Of Bits: 16
• Sampling Rate (per Second): 500
• Data Interface: Serial
• Inputs Per Adc: 3 Differential
• Input Range: 0 ~ 5.25 V
• Power (typ) @ Conditions: 6.5mW @ 500SPS
• Voltage Supply Source: Single
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: AD7706
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Battery Monitoring
Another area where the low power, single supply operation is a
requirement is battery monitoring in portable equipment appli-
cations. Figure 26 shows a block diagram of a battery monitor
that includes the AD7705 and an external multiplexer used to
differentially measure the voltage across a single cell. The sec-
ond channel on the AD7705 is used to monitor current drain
from the battery. The AD7705 with its dual input channel is
ideally suited to measurement systems requiring two input chan-
nels, as in this case, to monitor voltage and current. Since the
AD7705 can accommodate very low input signals the R
REV. A
DC BATTERY
CHARGING
SOURCE
GND
R
SENSE
Figure 26. Battery Monitoring Using the AD7705
VCELL 1
VCELL 2
VCELL 3
VCELL 4
VDIFF1
VDIFF2
VDIFF3
VDIFF4
SENSE
4-TO-1
DIFFERENTIAL
MULTIPLEXER
–31–
can be kept low reducing undesired power dissipation. Operat-
ing with a gain of 128, a 9.57 mV full-scale signal can be
measured with a resolution of 2 V, giving 13.5 bits of flicker-
free performance in such a system. In order to obtain specified
performance in unbuffered mode, the common mode range of
the input is from GND to V
of the analog input voltage lies between GND – 30 mV and
V
accommodated on the AD7705 at 25 C without any degrada-
tion in performance, but leakage current increases significantly
at elevated temperatures.
DD
AIN1(–)
AIN2(+)
AIN2(–)
AIN1(+)
+ 30 mV. Absolute voltages of GND – 200 mV can be
ON/OFF SWITCH
V
DD
REF IN(+)
AD7705
REF IN(–)
1.225V
REF
+3V
REGULATORS
VOLTAGE
DD
provided that the absolute value
AD7705/AD7706
LOAD
+5V