LTC2433-1CMS Iloiloga Pusa
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Fa'amatalaga o oloa
Fa'amatalaga
- Product Name: Demonstration Circuit 745
- Product Type: 16-Bit Differential Input Delta Sigma ADC
- Model: LTC2433-1
Fa'atonuga o le Fa'aaogaina o Mea
Faiga Fa'atosina Amata
- Connect DC745 to a DC590 USB Serial Controller using the
supplied 14 conductor ribbon cable. - Connect DC590 to a host PC with a standard USB A/B cable.
- Run the evaluation software supplied with DC590 or download
mai linear.com/software. - Click the COLLECT button to start reading the input
voltage. - Refer to the control panel’s help menu for software features
fa'amaumauga.
Seti Meafaigaluega
Tagata osooso
J2 is the power and digital interface connector. Connect to
DC590 serial controller with supplied 14 conductor ribbon
uaea.
Connection to DC590 Serial Controller
An external conversion clock may be applied to the Fo turret to
modify the frequency rejection characteristics or data output rate
of the LTC2433-1. Be sure to remove JP4 before applying an external
clock. Refer to the LTC2433-1 data sheet for more information.
So'oga Analog
Analog signal connections are made via the row of turret posts
along the edge of the board. Use exposed ground planes along the
edges of the board for solid ground connections.
Fa'ata'ita'iga
Ulufale Pisa
Solder a short wire from the IN- turret post to the IN+ turret
post to check noise levels.
Auala masani Tete'e
Tie the two inputs together and to ground or REF+ to test common
mode rejection.
Bipolar Symmetry
To demonstrate symmetry, connect a stable, low noise, floating
voltage source with voltage less than Vref/2.
FAQ (Frequently Asked Questions)
Q: Can I use an external clock with a frequency higher than
2MHz?
A: While up to a 2MHz clock can be used, performance may be
compromised. Refer to the LTC2433-1 data sheet for more
fa'amatalaga.
Q: How do I change the reference voltage?
A: Tools are available in the software for changing reference
voltage. Refer to the software documentation for detailed
faatonuga.
Q: What is the purpose of tying the inputs to ground or REF+ in
the experiments section?
A: This is done to test common mode rejection capabilities of
the LTC2433-1.
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TA'I'ALA AMATA VAVA'E MO FA'AALIGA FA'AALIGA 745
16-BIT DIFFERENTIAL INPUT DELTA SIGMA ADC
LTC2433-1
FAAMATALAGA
Demonstration circuit 745 features the LTC2433-1, a 16-bit high performance analog-to-digital converter (ADC). The LTC2433-1 features 0.12 LSB linearity, 0.16 LSB full-scale accuracy, 5µV offset, and 1.45µV RMS noise. The inputs and reference are fully differential, with input common mode rejection of 140 dB. The LTC2433-1 is available in a 10 pin MSOP package and has an easy to use SPI interface.
DC745 is a member of Linear Technology`s QuickEvalTM family of demonstration boards. It is designed to allow easy evaluation of the LTC2433-1 and may be connected directly to the target application’s
analog signals while using the DC590 USB Serial Controller board and supplied software to measure performance. The exposed ground planes allow proper grounding to prototype circuitry. After evaluating with Linear Technology’s software, the digital signals can be connected to the end application’s processor / controller for development of the serial interface.
Fuafuaga files mo lenei laupapa matagaluega o loʻo avanoa. Valaau le falegaosimea a le LTC.
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TA'I'ALA AMATA VAVA'E MO FA'AALIGA FA'AALIGA 745
16-BIT DIFFERENTIAL INPUT DELTA SIGMA ADC
Vave Amata Taualumaga
Connect DC745 to a DC590 USB Serial Controller using the supplied 14 conductor ribbon cable. Connect DC590 to a host PC with a standard USB A/B cable. Run the evaluation software supplied with DC590 or downloaded from http://www.linear.com/software. The correct program will be loaded automatically. Click the COLLECT button to start reading the input
voltage. Details on software features are documented in the control panel’s help menu.
Tools are available for logging data, changing reference voltagu, suia le numera o togi i le siata fa'asolo ma histogram, ma suia le numera o togi averesi mo le fa'aaliga DVM.
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TA'I'ALA AMATA VAVA'E MO FA'AALIGA FA'AALIGA 745
16-BIT DIFFERENTIAL INPUT DELTA SIGMA ADC
FA'ATAU FA'ATAU
OSOUSE
JP1 Select the source for REF+, either external or 5.00 volts from the onboard LT1236 reference (default.)
JP2 Select the source for REF-, either external or Ground (0 volts, default.)
JP3 Trigger mode, either normal (default) or externally triggered.
JP4 Notch frequency. Connect to 60Hz for normal operation (Fo = GND.) The LTC2433-1 is trimmed to reject both 50Hz and 60Hz by at least 87dB when Fo is grounded. Remove this jumper when supplying an external clock to the Fo turret.
JP5 Trigger input signal. Pin 1 is a 5 volt logic signal, pin 2 is ground. When triggered mode is selected on JP3, a rising edge starts a new conversion. Note that a conversion in progress cannot be stopped, so this signal can only be used to slow down the rate at which samples are read from the LTC2433-1. When Fo is grounded, the maximum trigger frequency is 5Hz.
SO'OGA I LE DC590 SERIAL CONTROLLER
J2 is the power and digital interface connector. Connect to DC590 serial controller with supplied 14 conductor ribbon cable.
An external conversion clock may be applied to the Fo turret to modify the frequency rejection charac-
teristics or data output rate of the LTC2433-1. Be sure to remove JP4 before applying an external clock. This should be a square wave with a low level equal to ground and a high level equal to Vcc. While up to a 2MHz clock can be used, performance may be compromised. Refer to the LTC2433-1 data sheet.
SO'OGA ANALOG
Analog signal connections are made via the row of turret posts along the edge of the board. Also, when connecting the board to an existing circuit, the exposed ground planes along the edges of the board may be used to form a solid connection between grounds.
GND Ground turrets are connected directly to the internal ground planes.
VCC This is the supply for the ADC. Do not draw any power from this point.
REF+, REF- These are connected to the LTC24331 REF+ and REF- pins. If the onboard reference is being used, the reference voltage mafai ona mata'ituina mai lea tulaga. E mafai ona fa'afeso'ota'i se fa'amatalaga i fafo i nei fa'amau pe a fa'atulaga le JP1 ma le JP2 mo fa'amatalaga i fafo.
IN+, IN- These are the differential inputs to the LTC2433-1.
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TA'I'ALA AMATA VAVA'E MO FA'AALIGA FA'AALIGA 745
16-BIT DIFFERENTIAL INPUT DELTA SIGMA ADC
FAAMATALAGA
INPUT Pisa
One of the characteristics of the LTC2433-1 is that the 1.45µV input noise floor is far below the quantization level of 76uV when a 5-volt reference is used. This means that the output will be stable if the input noise level is also below 76uV. In this sense, the LTC2433-1 is a true 16 effective bit part, whereas many 16-bit SAR converters have several LSBs of noise.
Solder a short wire from the IN- turret post to the IN+ turret post. Noise should be below the quantization level of the LTC2433-1. This will result in a noise reading of zero on the control software.
Applying an external reference of 100mV results in a 1.52µV LSB, and the noise reading will be approximately 250ppm of 100mV, or 2.5µV. This is slightly higher than the 1.45µV input thermal because quantization noise is also a factor.
TULAGA MASANI TETEE
Nonoa mea e lua (o loo fesootai pea) i le eleele e ala i se uaea puupuu ma matau le vol ua faailoa maitage. Tie the inputs to REF+; the difference should be less than 1LSB due to the 130 dB CMRR of the LTC2433-1.
BIPOLAR SYMMETRY
Ina ia faʻaalia le faʻatusa o galuega faʻafeiloaʻi ADCs, faʻafesoʻotaʻi se paʻu mautu, maualalo leo, opeopea voltage puna (faatasi ai ma le voltage less than Vref/2) from
IN+ to IN- and note the indicated voltagu. Suia le polarity; o le voltage will typically be within one LSB of the first reading multiplied by 1.
One convenient voltage source for this experiment is a single alkaline battery. While a battery has fairly low noise, it is sensitive to temperature drift. It is best to use a large (D-size) battery that is insulated from air currents. A better source is a battery powered series reference such as the LT1790. This part is available with output voltages of 1.25V, 2.048V, 2.5V, 3V, 3.3V, 4.096V and 5V.
FA'ASA'I LE TULAGA FA'AVAE
The LTC2433-1’s SINC4 digital filter is trimmed to strongly reject 50 or 60Hz line noise when operated with the internal conversion clock. To measure input normal mode rejection, connect IN- to a 2.5 volt source such as an LT1790-2.5 reference or a power supply. Apply a 10Hz, 2V peak-to-peak sine wave to IN+ through a 1uF capacitor. No DC bias is required because the 2-3M input impedance of the LTC2433-1 tends to self-bias the input to midreference (see datasheet applications information for details.)
Amata ave fa'amaumauga. O le leo o lo'o i totonu o le a fai si tele, ma o le kalafi o le gaosiga ma le taimi e tatau ona fa'aalia ai suiga tetele.
Next, slowly increase the frequency to 60Hz. The noise should be almost undetectable in the graph. Note that the indicated noise in ppm may still be above that of the datasheet specification because the inputs are not connected to a DC source.
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TA'I'ALA AMATA VAVA'E MO FA'AALIGA FA'AALIGA 745
16-BIT DIFFERENTIAL INPUT DELTA SIGMA ADC
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Pepa / Punaoa
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LINEAR TECHNOLOGY LTC2433-1CMS Evaluation Kit [pdf] Taiala mo Tagata Fa'aoga DC745, DC590, LTC2433-1CMS Evaluation Kit, LTC2433-1CMS, Evaluation Kit, Kit |