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Engineering a More Sustainable Future | ADI
AD7380 / MAX11198
MAX11195
AD7760
ADC
AD7866 / MAX11192
24
Bits
16
14
12
Table 1: ADC Options
Resolver Encoders
Optical and Magnetic Encoders
Robust Connectivity Power Management
AMP
AMP
AMP
AMP
AMP
AMP
AMP
AMP
AMP
AMP
AMP
AMP
5 V
3.3 V 3.3 V
> 5.5 V
RESOLVER
TO DIGITAL
CONVERTER
RESOLVER
SPI
EXTENDER
MEMS
LDO
TEMP
Sensor
AD2S1210
AD8694 / AD8692 / AD8397
LTC4332
Excitation Freq & Complement
+/- COS Differential Pair
+/- SIN Differential Pair
For reliable data transmission at high data rates over long
cables, jitter and skew performance are critical. The
ADM3066E/ADM3067E half/full duplex RS-485 transceivers
are suitable for use with common motor encoding
protocols such as SSI, BiSS, EnDat 2.2 and Hiperface DSL.
With ultra low transmitter and receiver skew performance,
and high common mode transient immunity (CMTI), they are
ideal for use in harsh industrial environments.
Next Generation Functionality
Position encoders are integrating new functionality to enable more advanced features and increase productivity. MEMS
vibration sensors, such as the ADXL371, are being integrated into encoders to enable motor health monitoring by sensing
vibration signatures that can then be used for condition-based monitoring or predictive maintenance features. Adjacent motor
faults are often monitored using the industry leading low noise ADXL359 MEMS accelerometer. In some applications, such as
CNC machines, the MEMS vibration data sent from the encoder to the servo drive can be used to optimize the performance of
the system in real time.
With the increasing deployment of more advanced
manufacturing capabilities that utilize more motors with
encoders, there is a need for a reduction in encoder form
factor. Highly integrated power management solutions,
supporting multiple voltage rails in compact footprint ICs,
with high ambient temperature operation and high efficiency,
help to reduce the thermal challenge within the encoder.
For resolver encoders, the AD2S1210 is a complete monolithic
resolver-to-digital converter with a wide temperature range
(-40
o
C to 125
o
C). AD8694 amplifiers are used to create a
third-order Butterworth low pass filter to pass the resolver
signals to the AD2S1210. The LTC4332 SPI extender enables
system partitioning, providing the option of placing the
microcontroller at the servo drive, rather than at the encoder,
saving space and reducing design complexity.
Multi-rail low noise LDOs such as the ADP320, LT3023, and LT3029 are used to power all components
in optical and magnetic encoder signal chains. The ADM3066E RS-485 transceiver features ultra low
transmitter and receiver skew performance, making these devices ideal for transmission of a precision
clock. The high throughput rate and simultaneous sampling capabilities of the AD7380 4 MSPS SAR
ADC enable on-chip oversampling, resulting in higher angular position accuracy. Depending on the
needs of the application, alternative ADC options are shown in Table 1. For applications requiring
resolutions of 12 bits or less, the MAX32672 ultra-low-power Arm Cortex-M4F microcontroller includes
a 12-bit 1 MSPS ADC with enhanced security, peripherals, and power management interfaces.
The ADA4622-4 quad rail-to-rail op-amp with input EMI filters
for increased signal robustness is ideally suited to optical
encoders. It includes a strong output drive to improve settling
time performance and enable direct drive of the AD7380 SAR
ADC inputs.
For magnetic encoders, the ADA4571 - an anisotropic
magnetoresistive (AMR) sensor – integrates signal conditioning
amplifiers and ADC drivers improving reliability, in addition to
reducing size and weight. Angular accuracy of 0.1
o
typical
angular error enhances closed loop control, and reduces motor
torque ripple and noise.
ADM3066E
Half Duplex
RS-485 Transceiver
ADM3067E
Full Duplex
RS-485 Transceiver
AMR
ADC
ASIC
or
MCU
AMR
MEMS
LDO
TEMP
Sensor
RS-485/
RS-422
AMP
AMP
COMP
SIN
3.3 V
2.5 V
1.8 V
5 V
COS
MAGNETIC
FIELD
+
-
ADA4570
ADA4571
ADA4571-2
LTC6702
ADT7320
ADM3066E
ADXL371
ADP320
AD7380
ADP120/ADP220/ADP320
LT3023/LT3027
LT3024/LT3029
Photo
Diode
ADC
ASIC
or
MCU
Photo
Diode
MEMS
LDO
TEMP
Sensor
RS-485/
RS-422
AMP
AMP
COMP
SIN
3.3 V
2.5 V
1.8 V
5 V
COS
LIGHT
LTC6702
ADA4622-4
ADT7320
AD7380
ADM3066E
ADXL371
ADP320
Single/Dual/Triple 200mA
Dual 100 mA
Dual 500 mA
Low Noise Voltage Regulators
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