AD7730LBRU Analog Devices Inc, AD7730LBRU Datasheet - Page 44

• Manufacturer Part Number: AD7730LBRU
• Description: IC ADC TRANSDUCER BRIDGE 24TSSOP
• Manufacturer: Analog Devices Inc

Specifications of AD7730LBRU

• Rohs Status: RoHS non-compliant
• Number Of Bits: 24
• Sampling Rate (per Second): 600
• Data Interface: DSP, Serial, SPI™
• Number Of Converters: 1
• Power Dissipation (max): 125mW
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP (0.173", 4.40mm Width)
• For Use With: EVAL-AD7730LEBZ - BOARD EVALUATION FOR AD7730EVAL-AD7730EBZ - BOARD EVAL FOR AD7730

a
LOW POWER
BRIDGE TRANSDUCER ADC
KEY FEATURES
Resolution of 110,000 Counts (Peak-to-Peak)
Power Consumption: 15 mW typ
Offset Drift: < 1 ppm/ C
Gain Drift: 3 ppm/ C
Line Frequency Rejection: >150 dB
Buffered Differential Inputs
Programmable Filter Cutoffs
Specified for Drift Over Time
Operates with Reference Voltages of 1 V to 5 V
ADDITIONAL FEATURES
Two-Channel Programmable Gain Front End
On-Chip DAC for Offset/TARE Removal
FAST Step Mode
AC or DC Excitation
Single Supply Operation
APPLICATIONS
Portable Weigh Scales
*Protected by U.S. Patent No: 5, 134, 401. Other Patent Applications Filed.
AIN2(+)/D1
AIN2(–)/D0
AIN1(+)
AIN1(–)
VBIAS
ACX
ACX
AV
MUX
EXCITATION
DD
CLOCK
AC
100nA
100nA
DV
AGND
AV
DD
FUNCTIONAL BLOCK DIAGRAM
DD
AGND
BUFFER
6-BIT
DAC
REF IN(–) REF IN(+)
REFERENCE DETECT
+
–
DGND
PGA
–44–
AND CONTROL LOGIC
SERIAL INTERFACE
POL
GENERAL DESCRIPTION
The AD7730L is a complete low power analog front-end for
weigh-scale and pressure measurement applications. The device
accepts low level signals directly from a transducer and outputs
a serial digital word. The input signal is applied to a proprietary
programmable gain front end based around an analog modula-
tor. The modulator output is processed by a low pass program-
mable digital filter, allowing adjustment of filter cutoff, output
rate and settling-time.
The part features two buffered differential programmable gain
analog inputs as well as a differential reference input. The part
operates from a single +5 V supply and typically consumes less
than 3 mA. It accepts four unipolar analog input ranges: 0 mV
to +10 mV, +20 mV, +40 mV and +80 mV and four bipolar
ranges 10 mV, 20 mV, 40 mV and 80 mV. The peak-to-
peak resolution achievable directly from the part is 1 in 110,000
counts. An on-chip 6-bit DAC allows the removal of TARE
voltages. Clock signals for synchronizing ac excitation of the
bridge are also provided.
The serial interface on the part can be configured for three-wire
operation and is compatible with microcontrollers and digital
signal processors. The AD7730L contains self-calibration and
system calibration options and features an offset drift of less
than 5 nV/ C and a gain drift of less than 3 ppm/ C.
The part is available in a 24-lead SOIC and 24-lead TSSOP
package.
MODULATOR
SIGMA-DELTA A/D CONVERTER
REGISTER BANK
SIGMA-
DELTA
RDY
AD7730L
PROGRAMMABLE
GENERATION
DIGITAL
FILTER
CLOCK
RESET
APPENDIX–AD7730L*
STANDBY
SYNC
MCLK IN
MCLK OUT
SCLK
CS
DIN
DOUT
REV. A