AD7705BR Analog Devices Inc, AD7705BR Datasheet - Page 41

• Manufacturer Part Number: AD7705BR
• Description: A/D Converter (A-D) IC
• Manufacturer: Analog Devices Inc

Specifications of AD7705BR

• Mounting Type: Surface Mount
• No. Of Channels: 2
• Peak Reflow Compatible (260 C): No
• Supply Voltage: 3.3V
• No. Of Bits: 16 Bit
• Leaded Process Compatible: No
• Features: 3V/5V, 1mW, 2?Channel, 16?Bit
• Rohs Status: RoHS non-compliant
• Number Of Bits: 16
• Sampling Rate (per Second): 500
• Data Interface: DSP, MICROWIRE™, QSPI™, Serial, SPI™
• Number Of Converters: 1
• Power Dissipation (max): 1mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 16-SOIC (0.300", 7.50mm Width)
• Number Of Elements: 1
• Resolution: 16Bit
• Architecture: Delta-Sigma
• Sample Rate: 0.5KSPS
• Input Polarity: Unipolar/Bipolar
• Input Type: Voltage
• Differential Input: Yes
• Power Supply Requirement: Single
• Single Supply Voltage (typ): 3/5V
• Single Supply Voltage (min): 2.7V
• Single Supply Voltage (max): 5.25V
• Dual Supply Voltage (typ): Not RequiredV
• Dual Supply Voltage (min): Not RequiredV
• Dual Supply Voltage (max): Not RequiredV
• Power Dissipation: 1mW
• Integral Nonlinearity Error: ±0.003%FSR
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 16
• Package Type: SOIC W
• Input Signal Type: Differential
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With: EVAL-AD7705EBZ - BOARD EVALUATION FOR AD7705
• Lead Free Status / Rohs Status: Not Compliant

BATTERY MONITORING
An application where the low power, single-supply operation is
required is battery monitoring in portable equipment applications.
Figure 29 shows a block diagram of a battery monitor using the
AD7705 and an external multiplexer to measure differentially
the voltage across a single cell.
The second channel on the AD7705 is used to monitor current
drain from the battery. The AD7705, with its dual-input
channel, is ideally suited for measurement systems requiring
two input channels, as in this case, to monitor voltage and
current.
DC BATTERY
CHARGING
SOURCE
GND
R
SENSE
VCELL 1
VCELL 2
VCELL 3
VCELL 4
Figure 29. Battery Monitoring Using the AD7705
VDIFF1
VDIFF2
VDIFF3
VDIFF4
Rev. C | Page 41 of 44
4-TO-1
DIFFERENTIAL
MULTIPLEXER
Because the AD7705 can accommodate very low input signals,
R
Operating with a gain of 128, a ±9.57 mV full-scale signal can
be measured with a resolution of 2 μV, giving 13.5 bits of flicker-
free performance in such a system.
To obtain specified performance in unbuffered mode, the
common-mode range of the input is GND to V
the absolute value of the analog input voltage lies between
GND − 100 mV and V
GND − 200 mV can be accommodated on the AD7705 at 25°C
without any degradation in performance, but with significantly
increased leakage at elevated temperatures.
AIN1(+)
AIN1(–)
AIN2(+)
AIN2(–)
SENSE
ON/OFF SWITCH
V
DD
can be kept low, reducing undesired power dissipation.
AD7705
REF IN(+)
REF IN(–)
1.225V
REF
3V
DD
REGULATORS
+ 30 mV. Absolute voltages of
VOLTAGE
LOAD
5V
AD7705/AD7706
DD
, provided that