Datasheet MCP4802, MCP4812, MCP4822 (Microchip) - 26

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MCP4802/4812/4822 6.5 Single-Supply Operation
6.5.1.1 Decreasing Output Step Size The MCP4802/4812/4822 family of devices are rail-to- If the application is calibrating the bias voltage of a rail voltage output DAC devices designed to operate diode or transistor, a bias voltage range of 0.8V may be with a V desired with about 200 µV resolution per step. Two DD range of 2.7V to 5.5V. Its output amplifier is robust enough to drive small-signal loads directly. common methods to achieve a 0.8V range are to either Therefore, it does not require any external output buffer reduce VREF to 0.82V (using the MCP49XX family for most applications. device that uses external reference) or use a voltage divider on the DAC’s output. 6.5.1 DC SET POINT OR CALIBRATION Using a VREF is an option if the VREF is available with A common application for the devices is a digitally- the desired output voltage range. However, controlled set point and/or calibration of variable occasionally, when using a low-voltage VREF, the noise parameters, such as sensor offset or slope. For floor causes SNR error that is intolerable. Using a example, the MCP4822 provides 4096 output steps. If voltage divider method is another option and provides G = 1 is selected, the internal 2.048V V some advantages when V REF would REF needs to be very low or produce 500 µV of resolution. If G = 2 is selected, the when the desired output voltage is not available. In this internal 2.048 V case, a larger value V REF would produce 1 mV of resolution. REF is used while two resistors scale the output range down to the precise desired level. Example 6-1 illustrates this concept. Note that the bypass capacitor on the output of the voltage divider plays a critical function in attenuating the output noise of the DAC and the induced noise from the environ- ment.
EXAMPLE 6-1: EXAMPLE CIRCUIT OF SET POINT OR THRESHOLD CALIBRATION
VDD
(a) Single Output DAC:
MCP4801 MCP4811 MCP4821 VCC+
(b) Dual Output DAC:
RSENSE VDD MCP4802 MCP4812 Comparator R MCP4822 1 V V TRIP OUT
DAC
V R 0.1 µF CC– 2 SPI 3-wire Dn V = 2.048  G  --- G = Gain selection (1x or 2x) OUT N 2 Dn = Digital value of DAC (0-255) for MCP4801/MCP4802 = Digital value of DAC (0-1023) for MCP4811/MCP4812 R  2  = Digital value of DAC (0-4095) for MCP4821/MCP4822 V = V ----------  trip OUT R + R  1 2 N = DAC bit resolution DS20002249B-page 26  2010-2015 Microchip Technology Inc. Document Outline 1.0 Electrical Characteristics FIGURE 1-1: SPI Input Timing Data. 2.0 Typical Performance Curves FIGURE 2-1: DNL vs. Code (MCP4822). FIGURE 2-2: DNL vs. Code and Temperature (MCP4822). FIGURE 2-3: Absolute DNL vs. Temperature (MCP4822). FIGURE 2-4: INL vs. Code and Temperature (MCP4822). FIGURE 2-5: Absolute INL vs. Temperature (MCP4822). FIGURE 2-6: INL vs. Code (MCP4822). FIGURE 2-7: DNL vs. Code and Temperature (MCP4812). FIGURE 2-8: INL vs. Code and Temperature (MCP4812). FIGURE 2-9: DNL vs. Code and Temperature (MCP4802). FIGURE 2-10: INL vs. Code and Temperature (MCP4802). FIGURE 2-11: Full-Scale VOUTA vs. Ambient Temperature and VDD. Gain = 1x. FIGURE 2-12: Full-Scale VOUTA vs. Ambient Temperature and VDD. Gain = 2x. FIGURE 2-13: Output Noise Voltage Density (VREF Noise Density) vs. Frequency. Gain = 1x. FIGURE 2-14: Output Noise Voltage (VREF Noise Voltage) vs. Bandwidth. Gain = 1x. FIGURE 2-15: IDD vs. Temperature and VDD. FIGURE 2-16: IDD Histogram (VDD = 2.7V). FIGURE 2-17: IDD Histogram (VDD = 5.0V). FIGURE 2-18: Software Shutdown Current vs. Temperature and VDD. FIGURE 2-19: Offset Error vs. Temperature and VDD. FIGURE 2-20: Gain Error vs. Temperature and VDD. FIGURE 2-21: VIN High Threshold vs. Temperature and VDD. FIGURE 2-22: VIN Low Threshold vs. Temperature and VDD. FIGURE 2-23: Input Hysteresis vs. Temperature and VDD. FIGURE 2-24: VOUT High Limit vs.Temperature and VDD. FIGURE 2-25: VOUT Low Limit vs. Temperature and VDD. FIGURE 2-26: IOUT High Short vs. Temperature and VDD. FIGURE 2-27: IOUT vs. VOUT. Gain = 2x. FIGURE 2-28: VOUT Rise Time. FIGURE 2-29: VOUT Fall Time. FIGURE 2-30: VOUT Rise Time. FIGURE 2-31: VOUT Rise Time. FIGURE 2-32: VOUT Rise Time Exit Shutdown. FIGURE 2-33: PSRR vs. Frequency. 3.0 Pin descriptions TABLE 3-1: Pin Function Table for MCP4802/4812/4822 3.1 Supply Voltage Pins (VDD, VSS) 3.2 Chip Select (CS) 3.3 Serial Clock Input (SCK) 3.4 Serial Data Input (SDI) 3.5 Latch DAC Input (LDAC) 3.6 Analog Outputs (VOUTA, VOUTB) 4.0 General Overview TABLE 4-1: LSb of each device FIGURE 4-1: Example for INL Error. FIGURE 4-2: Example for DNL Error. 4.1 Circuit Descriptions FIGURE 4-3: Typical Transient Response. FIGURE 4-4: Output Stage for Shutdown Mode. 5.0 Serial Interface 5.1 Overview 5.2 Write Command FIGURE 5-1: Write Command for MCP4822 (12-bit DAC). FIGURE 5-2: Write Command for MCP4812 (10-bit DAC). FIGURE 5-3: Write Command for MCP4802 (8-bit DAC). 6.0 Typical Applications 6.1 Digital Interface 6.2 Power Supply Considerations 6.3 Output Noise Considerations FIGURE 6-1: Typical Connection Diagram. 6.4 Layout Considerations 6.5 Single-Supply Operation 6.6 Bipolar Operation 6.7 Selectable Gain and Offset Bipolar Voltage Output Using a Dual Output DAC 6.8 Designing a Double-Precision DAC Using a Dual DAC 6.9 Building Programmable Current Source 7.0 Development support 7.1 Evaluation and Demonstration Boards 8.0 Packaging Information 8.1 Package Marking Information AMERICAS Corporate Office Atlanta Austin, TX Boston Chicago Cleveland Dallas Detroit Houston, TX Indianapolis Los Angeles New York, NY San Jose, CA Canada - Toronto ASIA/PACIFIC Asia Pacific Office Hong Kong Australia - Sydney China - Beijing China - Chengdu China - Chongqing China - Dongguan China - Hangzhou China - Hong Kong SAR China - Nanjing China - Qingdao China - Shanghai China - Shenyang China - Shenzhen China - Wuhan China - Xian ASIA/PACIFIC China - Xiamen China - Zhuhai India - Bangalore India - New Delhi India - Pune Japan - Osaka Japan - Tokyo Korea - Daegu Korea - Seoul Malaysia - Kuala Lumpur Malaysia - Penang Philippines - Manila Singapore Taiwan - Hsin Chu Taiwan - Kaohsiung Taiwan - Taipei Thailand - Bangkok EUROPE Austria - Wels Denmark - Copenhagen France - Paris Germany - Dusseldorf Germany - Munich Germany - Pforzheim Italy - Milan Italy - Venice Netherlands - Drunen Poland - Warsaw Spain - Madrid Sweden - Stockholm UK - Wokingham Worldwide Sales and Service