CXAS42302 is a high-precision A/D converter that integrates multiplexed BCD outputs and digital driver circuits. Its biggest feature is that it supports a measurement range of ± 20000 counts and ensures that the error does not exceed ± 1 word at full range of 2.0000V. This chip has true proportional computing capability, automatic zero adjustment function, and extremely low zero point error（10μV）， Suitable for situations that require extremely high precision.
-
[ CXAS42302 ]"
CXAS42302 High Precision Four and a Half Bit A/D Converter: Performance, Applications, and Interface Explanation
In today's high-precision measurement and data acquisition systems, the conversion of analog signals to digital signals is a key step in achieving intelligence and digitization. CXAS42302, as a high-performance four and a half bit A/D converter, is an ideal choice for industrial control, instrumentation, and embedded systems due to its excellent accuracy, rich interface configuration, and wide application adaptability. This article will delve into the core features, working principles, typical applications, and interface design with microprocessors of CXAS42302, helping engineers better understand and apply the chip.
1、 Product Overview and Core Features
CXAS42302 is a high-precision A/D converter that integrates multiplexed BCD outputs and digital driver circuits. Its biggest feature is its support for± A measurement range of 20000 counts, and ensuring that the error does not exceed± at a full range of 2.0000V; One word. This chip has true proportional computing capability, automatic zero adjustment function, and extremely low zero point error (<10μ V), making it suitable for applications with extremely high precision requirements.
Its main characteristics include:
· High impedance differential input, input bias current below 10pA;
· Multiplexing BCD output (B1– B8) and bit select signal (D1– D5), compatible with TTL levels;
· Supports over range (OR) and under range (UR) indication, facilitating automatic range switching;
· Built in polarity judgment function, stable reading at zero input;
· Provide STROBE, BUSY, R/H and other control signals for easy interface with microprocessors or UART devices.
2、 Internal structure and pin function
CXAS42302 integrates internal modules such as buffer, integrator, comparator, auto zero circuit, control logic, and multiplexer. Its integral architecture ensures high linearity and anti-interference ability. The chip offers two packaging forms, 28 pin DIP and SOP, suitable for different installation environments.
The key pins include:
· IN+ / IN-Differential analog input;
· REFReference voltage input;
· B1– B8BCD data output;
· D1– D5: Select output;
· BUSYConversion status indication;
· STROBEData output gating pulse;
· R/HRun/maintain control.
3、 Electrical characteristics and working conditions
CXAS42302 in± Working under 5V dual power supply, typical clock frequency is 100– 200kHz。 Its electrical performance is as follows:
· Linear error:≤ 1 word;
· Flip error:≤ 1 word;
· Input leakage current:<10pA;
· Zero drift:<0.5μ V/℃；
· Noise level: Typical 15μ V.
To ensure stable operation, it is recommended that the power supply voltage range be: V+=+4V to+6V, V -=-3V to -8V. The operating temperature range of the chip is 0 ℃ to 70 ℃, and the storage temperature range is -65 ℃ to+160 ℃.
4、 Key points of peripheral circuit design
When designing the peripheral circuit of CXAS42302, the following points should be noted:
4.1. Integral resistor and capacitor：
· RINT=V full range/20μ A, for example, 2V range corresponds to 100kΩ;
· CINT ≈ 10000 × TCLK/V full range, with a typical value of 0.47 μ F.
4.2. Automatic zeroing and reference capacitor：
· The recommended values for CAZ and CREF are 1μ F, and low dielectric absorption capacitance is selected to reduce errors.
4.3. reference voltage：
· The VREF should be half of the full-scale voltage. For example, if the 2V range corresponds to 1.000V, a reference source such as MC1403 can be used.
4.4. Clock and anti-interference：
· The clock frequency should be selected as an integer multiple of the 50/60Hz power frequency, such as 100kHz, 125kHz, etc;
· The integration time is set to an integer multiple of the power frequency cycle to suppress power frequency interference.
4.5. Grounding strategy：
· Analog ground (ANLG COM) and digital ground (DGTL GND) should be wired separately to avoid digital noise interference with analog signals.
5、 Typical Application Circuit
5.1 LCD display digital voltmeter
Using ICM7211A as the LCD decoding driver, combined with CD4050A to display polarity, overrange, and other information, a complete 2V range voltmeter is constructed.
5.2 LED display voltmeter
By using a common anode LED and a 7447 decoder, and driving the bit selection signal through NPN transistors, high brightness display is achieved.
5.3 Parallel interface with 8031 microcontroller
By using the 74LS157 multiplexer, the BCD code and flag signal are multiplexed onto the P1 port of the 8031, and the STROBE signal is used to synchronously read data, saving I/O resources.
5.4 Serial interface with 8031 microcontroller
Using BUSY signal and microcontroller timer to achieve serial counting mode conversion greatly simplifies hardware connection and improves the system's anti-interference ability.
VI. Summary
CXAS42302 is widely used in measurement systems for various physical quantities such as voltage, current, temperature, pressure, and speed due to its high precision, low power consumption, flexible interface design, and good anti-interference ability. Whether it is traditional instruments or modern embedded data acquisition devices, CXAS42302 can provide stable and reliable analog-to-digital conversion solutions.
As JTM-IC（jtm-ic.com）The recommended high-performance ADC chip, CXAS42302, has been validated for its outstanding performance in multiple industrial and consumer projects. For more technical details, samples, or design support, please visit our official websitejtm-ic.comOr contact our technical support team.
7、 Download the relevant chip selection guide; ►More similar products ...
