MCP4802/4812/4822 8/10/12-Bit Dual Voltage Output Digital-to-Analog Converter with Internal VREF and SPI Interface Features Description • • • • • • The MCP4802/4812/4822 devices are dual 8-bit, 10-bit and 12-bit buffered voltage output Digital-to-Analog Converters (DACs), respectively. The devices operate from a single 2.7V to 5.5V supply with SPI compatible Serial Peripheral Interface. The devices have a high precision internal voltage reference (VREF = 2.048V). The user can configure the full-scale range of the device to be 2.048V or 4.096V by setting the Gain Selection Option bit (gain of 1 of 2). Each DAC channel can be operated in Active or Shutdown mode individually by setting the Configuration register bits. In Shutdown mode, most of the internal circuits in the shutdown channel are turned off for power savings and the output amplifier is configured to present a known high resistance output load (500 k typical. The devices include double-buffered registers, allowing synchronous updates of two DAC outputs using the LDAC pin. These devices also incorporate a Power-on Reset (POR) circuit to ensure reliable powerup. The devices utilize a resistive string architecture, with its inherent advantages of low DNL error, low ratio metric temperature coefficient and fast settling time. These devices are specified over the extended temperature range (+125°C). The devices provide high accuracy and low noise performance for consumer and industrial applications where calibration or compensation of signals (such as temperature, pressure and humidity) are required. The MCP4802/4812/4822 devices are available in the PDIP, SOIC and MSOP packages. Applications • • • • • Set Point or Offset Trimming Sensor Calibration Precision Selectable Voltage Reference Portable Instrumentation (Battery-Powered) Calibration of Optical Communication Devices Related Products(1) P/N DAC Resolution No. of Channels MCP4801 8 1 Voltage Reference (VREF) MCP4811 10 1 MCP4821 12 1 MCP4802 8 2 MCP4812 10 2 MCP4822 12 2 MCP4901 8 1 CS 2 MCP4911 10 1 SCK 3 MCP4921 12 1 MCP4902 8 2 MCP4912 10 2 MCP4922 12 2 Internal (2.048V) Package Types 8-Pin PDIP, SOIC, MSOP VDD 1 External SDI 4 MCP48X2 • • • • • • MCP4802: Dual 8-Bit Voltage Output DAC MCP4812: Dual 10-Bit Voltage Output DAC MCP4822: Dual 12-Bit Voltage Output DAC Rail-to-Rail Output SPI Interface with 20 MHz Clock Support Simultaneous Latching of the Dual DACs with LDAC pin Fast Settling Time of 4.5 µs Selectable Unity or 2x Gain Output 2.048V Internal Voltage Reference 50 ppm/°C VREF Temperature Coefficient 2.7V to 5.5V Single-Supply Operation Extended Temperature Range: -40°C to +125°C 8 VOUTA 7 VSS 6 VOUTB 5 LDAC MCP4802: 8-bit dual DAC MCP4812: 10-bit dual DAC MCP4822: 12-bit dual DAC Note 1: The products listed here have similar AC/DC performances. 2010-2015 Microchip Technology Inc. DS20002249B-page 1 MCP4802/4812/4822 Block Diagram CS SDI SCK LDAC Power-on Reset Interface Logic VDD VSS Input Input Register A Register B 2.048V VREF DACA Register DACB Register String DACA String DACB Gain Logic Gain Logic Output Op Amps Output Logic VOUTA DS20002249B-page 2 VOUTB 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 1.0 ELECTRICAL CHARACTERISTICS † Notice: Stresses above those listed under “Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operational listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. Absolute Maximum Ratings † VDD....................................................................... 6.5V All inputs and outputs .......... VSS – 0.3V to VDD + 0.3V Current at Input Pins ......................................... ±2 mA Current at Supply Pins .................................... ±50 mA Current at Output Pins .................................... ±25 mA Storage temperature .......................... -65°C to +150°C Ambient temp. with power applied ..... -55°C to +125°C ESD protection on all pins 4 kV (HBM), 400V (MM) Maximum Junction Temperature (TJ)................+150°C ELECTRICAL CHARACTERISTICS Electrical Specifications: Unless otherwise indicated, VDD = 5V, VSS = 0V, VREF = 2.048V, Output Buffer Gain (G) = 2x, RL = 5 k to GND, CL = 100 pF, TA = -40 to +85°C. Typical values are at +25°C. Parameters Sym Min Typ Max Units Input Voltage VDD 2.7 — 5.5 V Input Current IDD — 415 750 µA Software Shutdown Current ISHDN_SW — 3.3 6 µA Power-on Reset Threshold VPOR — 2.0 — V Conditions Power Requirements All digital inputs are grounded, all analog outputs (VOUT) are unloaded. Code = 0x000h DC Accuracy MCP4802 Resolution n 8 — — Bits INL Error INL -1 ±0.125 1 LSb DNL DNL -0.5 ±0.1 +0.5 LSb Note 1 MCP4812 Resolution n 10 — — Bits INL Error INL -3.5 ±0.5 3.5 LSb DNL DNL -0.5 ±0.1 +0.5 LSb Note 1 MCP4822 Resolution n 12 — — Bits INL Error INL -12 ±2 12 LSb DNL DNL -0.75 ±0.2 +0.75 VOS -1 ±0.02 1 Offset Error Offset Error Temperature Coefficient Gain Error Gain Error Temperature Coefficient Note 1: 2: VOS/°C LSb Note 1 % of FSR Code = 0x000h — 0.16 — ppm/°C -45°C to +25°C — -0.44 — ppm/°C +25°C to +85°C gE -2 -0.10 2 G/°C — -3 — % of FSR Code = 0xFFFh, not including offset error ppm/°C Guaranteed monotonic by design over all codes. This parameter is ensured by design, and not 100% tested. 2010-2015 Microchip Technology Inc. DS20002249B-page 3 MCP4802/4812/4822 ELECTRICAL CHARACTERISTICS (CONTINUED) Electrical Specifications: Unless otherwise indicated, VDD = 5V, VSS = 0V, VREF = 2.048V, Output Buffer Gain (G) = 2x, RL = 5 k to GND, CL = 100 pF, TA = -40 to +85°C. Typical values are at +25°C. Parameters Sym Min Typ Max Units Conditions VREF 2.008 2.048 2.088 V VREF/°C — 125 325 ppm/°C -40°C to 0°C — 0.25 0.65 LSb/°C -40°C to 0°C — 45 160 ppm/°C 0°C to +85°C 0°C to +85°C Internal Voltage Reference (VREF) Internal Reference Voltage Temperature Coefficient (Note 2) VOUTA when G = 1x and Code = 0xFFFh — 0.09 0.32 LSb/°C Output Noise (VREF Noise) ENREF (0.110 Hz) — 290 — µVp-p Code = 0xFFFh, G = 1x Output Noise Density eNREF (1 kHz) — 1.2 — µV/Hz Code = 0xFFFh, G = 1x eNREF (10 kHz) — 1.0 — µV/Hz Code = 0xFFFh, G = 1x fCORNER — 400 — Hz Output Swing VOUT — 0.01 to VDD – 0.04 — V Phase Margin PM — 66 — Degree (°) Slew Rate SR — 0.55 — V/µs ISC — 15 24 mA tSETTLING — 4.5 — µs DAC-to-DAC Crosstalk — <10 — nV-s Major Code Transition Glitch — 45 — nV-s 1/f Corner Frequency Output Amplifier Short Circuit Current Settling Time Accuracy is better than 1 LSb for VOUT = 10 mV to (VDD–40 mV) CL= 400 pF, RL = Within 1/2 LSb of final value from 1/4 to 3/4 full-scale range Dynamic Performance (Note 2) Digital Feedthrough — <10 — nV-s Analog Crosstalk — <10 — nV-s Note 1: 2: 1 LSb change around major carry (0111...1111 to 1000...0000) Guaranteed monotonic by design over all codes. This parameter is ensured by design, and not 100% tested. DS20002249B-page 4 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 ELECTRICAL CHARACTERISTIC WITH EXTENDED TEMPERATURE Electrical Specifications: Unless otherwise indicated, VDD = 5V, VSS = 0V, VREF = 2.048V, Output Buffer Gain (G) = 2x, RL = 5 k to GND, CL = 100 pF. Typical values are at +125°C by characterization or simulation. Parameters Sym Min Typ Max VDD Units 2.7 — 5.5 V IDD — 440 — µA Software Shutdown Current ISHDN_SW — 5 — µA Power-On Reset threshold VPOR — 1.85 — V Conditions Power Requirements Input Voltage Input Current Input Curren All digital inputs are grounded, all analog outputs (VOUT) are unloaded. Code = 0x000h. DC Accuracy MCP4802 Resolution n 8 — — Bits INL Error INL — ±0.25 — LSb DNL DNL — ±0.2 — LSb Note 1 MCP4812 Resolution n 10 — — Bits INL Error INL — ±1 — LSb DNL DNL — ±0.2 — LSb n 12 — — Bits INL Error INL — ±4 — LSb DNL DNL — ±0.25 — LSb VOS — ±0.02 — % of FSR VOS/°C — -5 — ppm/°C gE — -0.10 — % of FSR G/°C — -3 — ppm/°C VREF — 2.048 — V VREF/°C — 125 — ppm/°C — 0.25 — LSb/°C -40°C to 0°C — 45 — ppm/°C 0°C to +85°C 0°C to +85°C Note 1 MCP4822 Resolution Offset Error Offset Error Temperature Coefficient Gain Error Gain Error Temperature Coefficient Note 1 Code = 0x000h +25°C to +125°C Code = 0xFFFh, not including offset error Internal Voltage Reference (VREF) Internal Reference Voltage Temperature Coefficient (Note 2) Output Noise (VREF Noise) Output Noise Density 1/f Corner Frequency Note 1: 2: VOUTA when G = 1x and Code = 0xFFFh -40°C to 0°C — 0.09 — LSb/°C ENREF (0.1 – 10 Hz) — 290 — µVp-p Code = 0xFFFh, G = 1x eNREF (1 kHz) — 1.2 — µV/Hz Code = 0xFFFh, G = 1x eNREF (10 kHz) — 1.0 — µV/Hz Code = 0xFFFh, G = 1x fCORNER — 400 — Hz Guaranteed monotonic by design over all codes. This parameter is ensured by design, and not 100% tested. 2010-2015 Microchip Technology Inc. DS20002249B-page 5 MCP4802/4812/4822 ELECTRICAL CHARACTERISTIC WITH EXTENDED TEMPERATURE (CONTINUED) Electrical Specifications: Unless otherwise indicated, VDD = 5V, VSS = 0V, VREF = 2.048V, Output Buffer Gain (G) = 2x, RL = 5 k to GND, CL = 100 pF. Typical values are at +125°C by characterization or simulation. Parameters Sym Min Typ Max Units Conditions Output Swing VOUT — 0.01 to VDD – 0.04 — V Accuracy is better than 1 LSb for VOUT = 10 mV to (VDD – 40 mV) Phase Margin PM — 66 — Slew Rate SR — 0.55 — V/µs ISC — 17 — mA tSETTLING — 4.5 — µs DAC-to-DAC Crosstalk — <10 — nV-s Major Code Transition Glitch — 45 — nV-s Digital Feedthrough — <10 — nV-s Analog Crosstalk — <10 — nV-s Output Amplifier Short Circuit Current Settling Time Degree (°) CL= 400 pF, RL = Within 1/2 LSb of final value from 1/4 to 3/4 full-scale range Dynamic Performance (Note 2) Note 1: 2: 1 LSb change around major carry (0111...1111 to 1000...0000) Guaranteed monotonic by design over all codes. This parameter is ensured by design, and not 100% tested. AC CHARACTERISTICS (SPI TIMING SPECIFICATIONS) Electrical Specifications: Unless otherwise indicated, VDD = 2.7V – 5.5V, TA= -40 to +125°C. Typical values are at +25°C. Parameters Sym Min Typ Max Units Schmitt Trigger High-Level Input Voltage (All digital input pins) VIH 0.7 VDD — — V Schmitt Trigger Low-Level Input Voltage (All digital input pins) VIL — — 0.2 VDD V VHYS — 0.05 VDD — V Input Leakage Current ILEAKAGE -1 — 1 A LDAC = CS = SDI = SCK = VDD or VSS Digital Pin Capacitance (All inputs/outputs) CIN, COUT — 10 — pF VDD = 5.0V, TA = +25°C, fCLK = 1 MHz (Note 1) Clock Frequency FCLK — — 20 MHz Clock High Time tHI 15 — — ns Hysteresis of Schmitt Trigger Inputs Clock Low Time Conditions TA = +25°C (Note 1) Note 1 tLO 15 — — ns Note 1 tCSSR 40 — — ns Applies only when CS falls with CLK high. (Note 1) Data Input Setup Time tSU 15 — — ns Note 1 Data Input Hold Time tHD 10 — — ns Note 1 SCK Rise to CS Rise Hold Time tCHS 15 — — ns Note 1 CS Fall to First Rising CLK Edge Note 1: This parameter is ensured by design and not 100% tested. DS20002249B-page 6 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 AC CHARACTERISTICS (SPI TIMING SPECIFICATIONS) Electrical Specifications: Unless otherwise indicated, VDD = 2.7V – 5.5V, TA= -40 to +125°C. Typical values are at +25°C. Parameters Sym Min Typ Max Units tCSH 15 — — ns Note 1 LDAC Pulse Width tLD 100 — — ns Note 1 LDAC Setup Time tLS 40 — — ns Note 1 tIDLE 40 — — ns Note 1 CS High Time SCK Idle Time before CS Fall Note 1: Conditions This parameter is ensured by design and not 100% tested. tCSH CS tIDLE tCSSR Mode 1,1 tHI tLO tCHS SCK Mode 0,0 tSU tHD SDI MSb in LSb in LDAC tLS FIGURE 1-1: tLD SPI Input Timing Data. TEMPERATURE CHARACTERISTICS Electrical Specifications: Unless otherwise indicated, VDD = +2.7V to +5.5V, VSS = GND. Parameters Sym Min Typ Max Units Specified Temperature Range TA -40 — +125 °C Operating Temperature Range TA -40 — +125 °C Storage Temperature Range TA -65 — +150 °C Thermal Resistance, 8L-MSOP JA — 211 — °C/W Thermal Resistance, 8L-PDIP JA — 90 — °C/W Thermal Resistance, 8L-SOIC JA — 150 — °C/W Conditions Temperature Ranges Note 1 Thermal Package Resistances Note 1: The MCP4802/4812/4822 devices operate over this extended temperature range, but with reduced performance. Operation in this range must not cause TJ to exceed the maximum junction temperature of +150°C. 2010-2015 Microchip Technology Inc. DS20002249B-page 7 MCP4802/4812/4822 NOTES: DS20002249B-page 8 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 2.0 TYPICAL PERFORMANCE CURVES Note: The graphs and tables provided following this note are a statistical summary based on a limited number of samples and are provided for informational purposes only. The performance characteristics listed herein are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified operating range (e.g., outside specified power supply range) and therefore outside the warranted range. Note: Unless otherwise indicated, TA = +25°C, VDD = 5V, VSS = 0V, VREF = 2.048V, Gain = 2x, RL = 5 k, CL = 100 pF. 0.3 0.2 INL (LSB) DNL (LSB) 0.1 0 -0.1 -0.2 -0.3 0 1024 2048 3072 5 4 3 2 1 0 -1 -2 -3 -4 -5 Ambient Temperature 125C 4096 0 1024 DNL vs. Code (MCP4822). 2.5 Absolute INL (LSB) 0.1 DNL (LSB) 4096 FIGURE 2-4: INL vs. Code and Temperature (MCP4822). 0.2 0 -0.1 2 1.5 1 0.5 0 -0.2 0 1024 2048 3072 Code (Decimal) -40 4096 125C 85C -20 0 20 40 60 80 100 120 Ambient Temperature (ºC) 25C FIGURE 2-2: DNL vs. Code and Temperature (MCP4822). FIGURE 2-5: Absolute INL vs. Temperature (MCP4822). 0.0766 2 0.0764 0.0762 0 INL (LSB) Absolute DNL (LSB) 3072 25 Code (Decimal) Code (Decimal) FIGURE 2-1: 2048 85 0.076 0.0758 0.0756 0.0754 -2 -4 0.0752 0.075 -6 -40 -20 0 20 40 60 80 0 100 120 1024 FIGURE 2-6: Note: 2010-2015 Microchip Technology Inc. 3072 4096 Code (Decimal) Ambient Temperature (ºC) FIGURE 2-3: Absolute DNL vs. Temperature (MCP4822). 2048 INL vs. Code (MCP4822). Single device graph for illustration of 64 code effect. DS20002249B-page 9 MCP4802/4812/4822 Note: Unless otherwise indicated, TA = +25°C, VDD = 5V, VSS = 0V, VREF = 2.048V, Gain = 2x, RL = 5 k, CL = 100 pF. 0.3 0.6 o - 40 C 0.4 0.1 INL (LSB) DNL (LSB) - 40oC 0.5 0.2 0 -0.1 o 85 C 0.3 0.2 0.1 0 125oC -0.1 -0.2 -0.3 -0.3 0 128 256 384 512 640 768 25oC -0.2 +25oC to +125oC 0 896 1024 32 64 96 FIGURE 2-7: DNL vs. Code and Temperature (MCP4812). Full Scale VOUT (V) 1 INL (LSB) 85oC 0 -0.5 -1 -1.5 25oC -2 o - 40 C -2.5 2.050 2.049 2.048 2.047 2.046 2.045 2.044 2.043 2.042 2.041 2.040 o -20 -3 128 256 384 512 640 768 o 256 0 20 40 60 80 100 120 FIGURE 2-11: Full-Scale VOUTA vs. Ambient Temperature and VDD. Gain = 1x. FIGURE 2-8: INL vs. Code and Temperature (MCP4812). 0.15 224 Ambient Temperature (°C) 896 1024 Code 192 VDD: 4V VDD: 3V VDD: 2.7V -40 125 C 0 160 FIGURE 2-10: INL vs. Code and Temperature (MCP4802). 1.5 0.5 128 Code Code 4.100 o DNL (LSB) 0.1 0.05 0 34 -0.05 -0.1 Full Scale VOUT (V) Temperature: - 40 C to +125 C 4.096 4.092 VDD: 5.5V 4.088 VDD: 5V 4.084 4.080 -0.15 4.076 0 32 64 96 128 160 192 224 256 Code FIGURE 2-9: DNL vs. Code and Temperature (MCP4802). DS20002249B-page 10 -40 -20 0 20 40 60 80 100 120 Ambient Temperature (°C) FIGURE 2-12: Full-Scale VOUTA vs. Ambient Temperature and VDD. Gain = 2x. 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 Note: Unless otherwise indicated, TA = +25°C, VDD = 5V, VSS = 0V, VREF = 2.048V, Gain = 2x, RL = 5 k, CL = 100 pF. 25 Output Noise Voltage Density (µV/Hz) 100 1.E-04 Occurrence 20 1.E-05 10 1 1.E-06 15 10 5 FIGURE 2-16: FIGURE 2-14: Output Noise Voltage (VREF Noise Voltage) vs. Bandwidth. Gain = 1x. 340 440 435 430 425 420 435 430 IDD (µA) FIGURE 2-17: IDD Histogram (VDD = 5.0V). 5.5V 5.0V 4.0V 3.0V 2.7V VDD 320 300 IDD (µA) 425 1M 1E+6 420 10k 100k 1E+4 1E+5 Bandwidth (Hz) 415 1k 1E+3 410 Maximum Measurement Time = 10s 405 Eni (in VRMS) 400 0.10 1.E-04 395 Eni (in VP-P) IDD Histogram (VDD = 2.7V). 22 20 18 16 14 12 10 8 6 4 2 0 385 Occurrence Output Noise Voltage (mV) 1.E-02 10.0 390 FIGURE 2-13: Output Noise Voltage Density (VREF Noise Density) vs. Frequency. Gain = 1x. 0.01 1.E-05 100 1E+2 415 IDD (µA) Frequency (Hz) 1.E-03 1.00 410 100k 1E+5 405 10k 1E+4 400 1k 1E+3 395 100 1E+2 390 10 1E+1 385 0 1 1E+0 380 0.1 1.E-07 0.1 1E-1 280 260 240 220 200 180 -40 -20 0 20 40 60 80 100 120 Ambient Temperature (°C) FIGURE 2-15: IDD vs. Temperature and VDD. 2010-2015 Microchip Technology Inc. DS20002249B-page 11 MCP4802/4812/4822 Note: Unless otherwise indicated, TA = +25°C, VDD = 5V, VSS = 0V, VREF = 2.048V, Gain = 2x, RL = 5 k, CL = 100 pF. 5.5V 4 5.0V 3.5 ISHDN_SW (µA) 3.5 3 4.0V 2.5 3.0V 2.7V 2 V DD 1.5 VIN Hi Threshold (V) 4 VDD 5.5V 5.0V 3 4.0V 2.5 2 3.0V 2.7V 1.5 1 1 -40 -20 0 20 40 60 80 100 -40 120 -20 FIGURE 2-18: Software Shutdown Current vs. Temperature and VDD. 20 40 60 80 100 120 FIGURE 2-21: VIN High Threshold vs. Temperature and VDD. 1.6 0.09 0.07 0.05 5.5V 0.03 VDD 0.01 5.0V 4.0V 3.0V 2.7V -0.01 -0.03 -40 -20 0 20 40 60 80 100 120 VDD 1.5 5.5V 1.4 5.0V 1.3 1.2 4.0V 1.1 1 3.0V 2.7V 0.9 0.8 -40 -20 0 20 40 60 80 100 120 Ambient Temperature (ºC) Ambient Temperature (ºC) FIGURE 2-19: and VDD. VIN Low Threshold (V) 0.11 Offset Error (%) 0 Ambient Temperature (ºC) Ambient Temperature (ºC) Offset Error vs. Temperature FIGURE 2-22: VIN Low Threshold vs. Temperature and VDD. -0.05 -0.1 VDD Gain Error (%) -0.15 5.5V 5.0V 4.0V 3.0V 2.7V -0.2 -0.25 -0.3 -0.35 -0.4 -0.45 -0.5 -40 -20 0 20 40 60 80 100 120 Ambient Temperature (ºC) FIGURE 2-20: and VDD. DS20002249B-page 12 Gain Error vs. Temperature 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 Note: Unless otherwise indicated, TA = +25°C, VDD = 5V, VSS = 0V, VREF = 2.048V, Gain = 2x, RL = 5 k, CL = 100 pF. 16 2.5 5.5V 2 5.0V 1.75 1.5 4.0V 1.25 1 3.0V 2.7V 0.75 0.5 15 IOUT_HI_SHORTED (mA) VIN_SPI Hysteresis (V) 5.5V 5.0V 4.0V 3.0V 2.7V VDD 2.25 14 VDD 13 12 11 0.25 10 0 -40 -20 0 20 40 60 80 -40 100 120 -20 Ambient Temperature (ºC) FIGURE 2-23: Input Hysteresis vs. Temperature and VDD. 40 60 80 100 120 6.0 4.0V 0.033 0.031 5.0 0.029 4.0 VREF = 4.096V 0.027 0.025 3.0V 0.023 2.7V 0.021 VDD 0.019 VOUT (V) VOUT_HI Limit (VDD-Y)(V) 20 FIGURE 2-26: IOUT High Short vs. Temperature and VDD. 0.035 Output Shorted to VDD 3.0 2.0 1.0 Output Shorted to VSS 0.017 0.0 0.015 -40 -20 0 20 40 60 80 0 100 120 2 Ambient Temperature (ºC) FIGURE 2-24: VOUT High Limit vs.Temperature and VDD. 0.0028 VOUT_LOW Limit (Y-AVSS)(V) 0 Ambient Temperature (ºC) FIGURE 2-27: 4 6 8 10 IOUT (mA) 12 14 16 IOUT vs. VOUT. Gain = 2x. VDD 0.0026 0.0024 5.5V 0.0022 5.0V 0.0020 4.0V 3.0V 2.7V 0.0018 0.0016 0.0014 0.0012 0.0010 -40 -20 0 20 40 60 80 100 120 Ambient Temperature (ºC) FIGURE 2-25: VOUT Low Limit vs. Temperature and VDD. 2010-2015 Microchip Technology Inc. DS20002249B-page 13 MCP4802/4812/4822 Note: Unless otherwise indicated, TA = +25°C, VDD = 5V, VSS = 0V, VREF = 2.048V, Gain = 2x, RL = 5 k, CL = 100 pF. VOUT VOUT SCK LDAC LDAC Time (1 µs/div) FIGURE 2-28: VOUT Rise Time. Time (1 µs/div) FIGURE 2-31: VOUT Rise Time. VOUT VOUT SCK SCK LDAC LDAC Time (1 µs/div) VOUT Fall Time. FIGURE 2-32: Shutdown. VOUT Rise Time Exit Ripple Rejection (dB) FIGURE 2-29: Time (1 µs/div) VOUT SCK LDAC Time (1 µs/div) FIGURE 2-30: DS20002249B-page 14 VOUT Rise Time. Frequency (Hz) FIGURE 2-33: PSRR vs. Frequency. 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 3.0 PIN DESCRIPTIONS The descriptions of the pins are listed in Table 3-1. TABLE 3-1: PIN FUNCTION TABLE FOR MCP4802/4812/4822 MCP4802/4812/4822 Symbol Description MSOP, PDIP, SOIC 3.1 1 VDD Supply Voltage Input (2.7V to 5.5V) 2 CS Chip Select Input 3 SCK Serial Clock Input 4 SDI Serial Data Input 5 LDAC Synchronization Input. This pin is used to transfer DAC settings (Input Registers) to the output registers (VOUT) 6 VOUTB DACB Output 7 VSS 8 VOUTA Ground reference point for all circuitry on the device DACA Output Supply Voltage Pins (VDD, VSS) VDD is the positive supply voltage input pin. The input supply voltage is relative to VSS and can range from 2.7V to 5.5V. The power supply at the VDD pin should be as clean as possible for a good DAC performance. It is recommended to use an appropriate bypass capacitor of about 0.1 µF (ceramic) to ground. An additional 10 µF capacitor (tantalum) in parallel is also recommended to further attenuate high-frequency noise present in application boards. VSS is the analog ground pin and the current return path of the device. The user must connect the VSS pin to a ground plane through a low-impedance connection. If an analog ground path is available in the application Printed Circuit Board (PCB), it is highly recommended that the VSS pin be tied to the analog ground path or isolated within an analog ground plane of the circuit board. 3.2 Chip Select (CS) CS is the Chip Select input pin, which requires an active-low to enable serial clock and data functions. 3.3 3.4 Serial Data Input (SDI) SDI is the SPI compatible serial data input pin. 3.5 Latch DAC Input (LDAC) LDAC (latch DAC synchronization input) pin is used to transfer the input latch registers to their corresponding DAC registers (output latches, VOUT). When this pin is low, both VOUTA and VOUTB are updated at the same time with their input register contents. This pin can be tied to low (VSS) if the VOUT update is desired at the rising edge of the CS pin. This pin can be driven by an external control device such as an MCU I/O pin. 3.6 Analog Outputs (VOUTA, VOUTB) VOUTA is the DAC A output pin, and VOUTB is the DAC B output pin. Each output has its own output amplifier. The full-scale range of the DAC output is from VSS to G* VREF, where G is the gain selection option (1x or 2x). The DAC analog output cannot go higher than the supply voltage (VDD). Serial Clock Input (SCK) SCK is the SPI compatible serial clock input pin. 2010-2015 Microchip Technology Inc. DS20002249B-page 15 MCP4802/4812/4822 NOTES: DS20002249B-page 16 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 4.0 GENERAL OVERVIEW The MCP4802, MCP4812 and MCP4822 are dual voltage output 8-bit, 10-bit and 12-bit DAC devices, respectively. These devices include rail-to-rail output amplifiers, internal voltage reference, shutdown and reset-management circuitry. The devices use an SPI serial communication interface and operate with a single supply voltage from 2.7V to 5.5V. The DAC input coding of these devices is straight binary. Equation 4-1 shows the DAC analog output voltage calculation. EQUATION 4-1: V OUT ANALOG OUTPUT VOLTAGE (VOUT) 2.048V Dn = ----------------------------------G n 2 Where: 2.048V = Internal voltage reference Dn = DAC input code G n = Gain selection = 2 for <GA> bit = 0 = 1 for <GA> bit = 1 = DAC Resolution = 8 for MCP4802 = 10 for MCP4812 = 12 for MCP4822 1 LSb is the ideal voltage difference between two successive codes. Table 4-1 illustrates the LSb calculation of each device. TABLE 4-1: MCP4802 (n = 8) MCP4812 (n = 10) MCP4822 (n = 12) (a) 0.0V to 255/256 * 2.048V when gain setting = 1x. 1x 2x 1x 2x 1x 2x LSb Size 2.048V/256 = 8 mV 4.096V/256 = 16 mV 2.048V/1024 = 2 mV 4.096V/1024 = 4 mV 2.048V/4096 = 0.5 mV 4.096V/4096 = 1 mV INL ACCURACY Integral Non-Linearity (INL) error for these devices is the maximum deviation between an actual code transition point and its corresponding ideal transition point once offset and gain errors have been removed. The two end points method (from 0x000 to 0xFFF) is used for the calculation. Figure 4-1 shows the details. A positive INL error represents transition(s) later than ideal. A negative INL error represents transition(s) earlier than ideal. INL < 0 111 110 Actual Transfer Function 101 The ideal output range of each device is: • MCP4802 (n = 8) Gain Selection Device 4.0.1 LSb OF EACH DEVICE Digital Input Code 100 011 Ideal Transfer Function (b) 0.0V to 255/256 * 4.096V when gain setting = 2x. • MCP4812 (n = 10) 010 (a) 0.0V to 1023/1024 * 2.048V when gain setting = 1x. 001 (b) 0.0V to 1023/1024 * 4.096V when gain setting = 2x. • MCP4822 (n = 12) 000 INL < 0 (a) 0.0V to 4095/4096 * 2.048V when gain setting = 1x. DAC Output (b) 0.0V to 4095/4096 * 4.096V when gain setting = 2x. Note: See the output swing voltage specification in Section 1.0 “Electrical Characteristics”. 2010-2015 Microchip Technology Inc. FIGURE 4-1: Example for INL Error. DS20002249B-page 17 MCP4802/4812/4822 4.0.2 DNL ACCURACY 4.1 A Differential Non-Linearity (DNL) error is the measure of variations in code widths from the ideal code width. A DNL error of zero indicates that every code is exactly 1 LSb wide. 111 110 Actual Transfer Function 101 Digital Input Code 100 Ideal Transfer Function 011 001 Wide Code, >1 LSb 000 Narrow Code, <1 LSb DAC Output 4.0.3 Example for DNL Error. OFFSET ERROR An offset error is the deviation from zero voltage output when the digital input code is zero. 4.0.4 OUTPUT AMPLIFIERS The DAC’s outputs are buffered with a low-power, precision CMOS amplifier. This amplifier provides low offset voltage and low noise. The output stage enables the device to operate with output voltages close to the power supply rails. Refer to Section 1.0 “Electrical Characteristics” for the analog output voltage range and load conditions. In addition to resistive load-driving capability, the amplifier will also drive high capacitive loads without oscillation. The amplifier’s strong outputs allow VOUT to be used as a programmable voltage reference in a system. 4.1.1.1 010 FIGURE 4-2: 4.1.1 Circuit Descriptions Programmable Gain Block The rail-to-rail output amplifier has two configurable gain options: a gain of 1x (<GA> = 1) or a gain of 2x (<GA> = 0). The default value for this bit is a gain of 2 (<GA> = 0). This results in an ideal full-scale output of 0.000V to 4.096V due to the internal reference (VREF = 2.048V). 4.1.2 VOLTAGE REFERENCE The MCP4802/4812/4822 devices utilize internal 2.048V voltage reference. The voltage reference has a low temperature coefficient and low noise characteristics. Refer to Section 1.0 “Electrical Characteristics” for the voltage reference specifications. GAIN ERROR A gain error is the deviation from the ideal output, VREF – 1 LSb, excluding the effects of offset error. DS20002249B-page 18 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 4.1.3 POWER-ON RESET CIRCUIT The internal Power-on Reset (POR) circuit monitors the power supply voltage (VDD) during the device operation. The circuit also ensures that the DAC powers up with high output impedance (<SHDN> = 0, typically 500 k. The devices will continue to have a high-impedance output until a valid write command is received and the LDAC pin meets the input low threshold. If the power supply voltage is less than the POR threshold (VPOR = 2.0V, typical), the DACs will be held in their Reset state. The DACs will remain in that state until VDD > VPOR and a subsequent write command is received. Figure 4-3 shows a typical power supply transient pulse and the duration required to cause a reset to occur, as well as the relationship between the duration and trip voltage. A 0.1 µF decoupling capacitor, mounted as close as possible to the VDD pin, can provide additional transient immunity. 4.1.4 SHUTDOWN MODE The user can shut down each DAC channel selectively using a software command (<SHDN> = 0). During Shutdown mode, most of the internal circuits in the channel that was shut down are turned off for power savings. The internal reference is not affected by the shutdown command. The serial interface also remains active, thus allowing a write command to bring the device out of the Shutdown mode. There will be no analog output at the channel that was shut down and the VOUT pin is internally switched to a known resistive load (500 k typical. Figure 4-4 shows the analog output stage during the Shutdown mode. The device will remain in Shutdown mode until the <SHDN> bit = 1 is latched into the device. When a DAC channel is changed from Shutdown to Active mode, the output settling time takes < 10 µs, but greater than the standard active mode settling time (4.5 µs). VOUT Supply Voltages Op Amp 5V VPOR VDD - VPOR Power-Down Control Circuit Resistive Load Transient Duration 500 k Resistive String DAC Transient Duration (µs) Time 10 FIGURE 4-4: Mode. TA = +25°C 8 Output Stage for Shutdown 6 4 Transients above the curve will cause a reset 2 0 FIGURE 4-3: Transients below the curve will NOT cause a reset 1 2 3 4 VDD - VPOR (V) 5 Typical Transient Response. 2010-2015 Microchip Technology Inc. DS20002249B-page 19 MCP4802/4812/4822 NOTES: DS20002249B-page 20 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 5.0 SERIAL INTERFACE 5.1 Overview The MCP4802/4812/4822 devices are designed to interface directly with the Serial Peripheral Interface (SPI) port, available on many microcontrollers, and supports Mode 0,0 and Mode 1,1. Commands and data are sent to the device via the SDI pin, with data being clocked-in on the rising edge of SCK. The communications are unidirectional and, thus, data cannot be read out of the MCP4802/4812/4822 devices. The CS pin must be held low for the duration of a write command. The write command consists of 16 bits and is used to configure the DAC’s control and data latches. Register 5-1 to Register 5-3 detail the input register that is used to configure and load the DACA and DACB registers for each device. Figure 5-1 to Figure 5-3 show the write command for each device. Refer to Figure 1-1 and SPI Timing Specifications Table for detailed input and output timing specifications for both Mode 0,0 and Mode 1,1 operation. 2010-2015 Microchip Technology Inc. 5.2 Write Command The write command is initiated by driving the CS pin low, followed by clocking the four Configuration bits and the 12 data bits into the SDI pin on the rising edge of SCK. The CS pin is then raised, causing the data to be latched into the selected DAC’s input registers. The MCP4802/4812/4822 devices utilize a doublebuffered latch structure to allow both DACA’s and DACB’s outputs to be synchronized with the LDAC pin, if desired. By bringing down the LDAC pin to a low state, the contents stored in the DAC’s input registers are transferred into the DAC’s output registers (VOUT), and both VOUTA and VOUTB are updated at the same time. All writes to the MCP4802/4812/4822 devices are 16-bit words. Any clocks after the first 16th clock will be ignored. The Most Significant four bits are Configuration bits. The remaining 12 bits are data bits. No data can be transferred into the device with CS high. The data transfer will only occur if 16 clocks have been transferred into the device. If the rising edge of CS occurs prior, shifting of data into the input registers will be aborted. DS20002249B-page 21 MCP4802/4812/4822 REGISTER 5-1: WRITE COMMAND REGISTER FOR MCP4822 (12-BIT DAC) W-x W-x W-x W-0 W-x W-x W-x W-x W-x W-x W-x W-x W-x W-x W-x W-x A/B — GA SHDN D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 bit 15 bit 0 REGISTER 5-2: WRITE COMMAND REGISTER FOR MCP4812 (10-BIT DAC) W-x W-x W-x W-0 W-x W-x W-x W-x W-x W-x W-x W-x W-x W-x W-x A/B — GA SHDN D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 x bit 15 W-x x bit 0 REGISTER 5-3: WRITE COMMAND REGISTER FOR MCP4802 (8-BIT DAC) W-x W-x W-x W-0 W-x W-x W-x W-x W-x W-x W-x W-x W-x W-x W-x W-x A/B — GA SHDN D7 D6 D5 D4 D3 D2 D1 D0 x x x x bit 15 bit 0 Where: bit 15 bit 14 bit 13 bit 12 A/B: DACA or DACB Selection bit 1 = Write to DACB 0 = Write to DACA — Don’t Care GA: Output Gain Selection bit 1 = 1x (VOUT = VREF * D/4096) 0 = 2x (VOUT = 2 * VREF * D/4096), where internal VREF = 2.048V. SHDN: Output Shutdown Control bit Active mode operation. VOUT is available. Shutdown the selected DAC channel. Analog output is not available at the channel that was shut down. VOUT pin is connected to 500 ktypical) 1= 0= bit 11-0 D11:D0: DAC Input Data bits. Bit x is ignored. Legend R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ -n = Value at POR 1 = bit is set 0 = bit is cleared DS20002249B-page 22 x = bit is unknown 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 CS 0 1 2 3 4 5 6 7 8 9 10 11 12 (Mode 1,1) 13 14 15 SCK (Mode 0,0) config bits A/B SDI 12 data bits — GA SHDN D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 LDAC VOUT FIGURE 5-1: Write Command for MCP4822 (12-bit DAC). CS 0 1 2 3 4 5 6 7 8 9 10 11 12 (Mode 1,1) 13 14 15 SCK (Mode 0,0) config bits A/B SDI 12 data bits — GA SHDN D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 X X LDAC VOUT Note: X = “don’t care” bits. FIGURE 5-2: Write Command for MCP4812 (10-bit DAC). CS 0 1 2 3 4 5 6 7 8 9 10 11 12 (Mode 1,1) 13 14 15 SCK (Mode 0,0) config bits A/B SDI 12 data bits — GA SHDN D7 D6 D5 D4 D3 D2 D1 D0 X X X X LDAC VOUT Note: FIGURE 5-3: X = “don’t care” bits. Write Command for MCP4802 (8-bit DAC). 2010-2015 Microchip Technology Inc. DS20002249B-page 23 MCP4802/4812/4822 NOTES: DS20002249B-page 24 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 6.0 TYPICAL APPLICATIONS 6.3 Output Noise Considerations The MCP4802/4812/4822 family of devices are general purpose DACs for various applications where a precision operation with low-power and internal voltage reference is required. The voltage noise density (in µV/Hz) is illustrated in Figure 2-13. This noise appears at VOUTX, and is primarily a result of the internal reference voltage. Its 1/f corner (fCORNER) is approximately 400 Hz. Applications generally suited for the devices are: Figure 2-14 illustrates the voltage noise (in mVRMS or mVP-P). A small bypass capacitor on VOUTX is an effective method to produce a single-pole Low-Pass Filter (LPF) that will reduce this noise. For instance, a bypass capacitor sized to produce a 1 kHz LPF would result in an ENREF of about 100 µVRMS. This would be necessary when trying to achieve the low DNL error performance (at G = 1) that the MCP4802/4812/4822 devices are capable of. The tested range for stability is .001µF through 4.7 µF. Digital Interface The MCP4802/4812/4822 devices utilize a 3-wire synchronous serial protocol to transfer the DAC’s setup and input codes from the digital devices. The serial protocol can be interfaced to SPI or Microwire peripherals that is common on many microcontroller units (MCUs), including Microchip’s PIC® MCUs and dsPIC® DSCs. In addition to the three serial connections (CS, SCK and SDI), the LDAC signal synchronizes the two DAC outputs. By bringing down the LDAC pin to “low”, all DAC input codes and settings in the two DAC input registers are latched into their DAC output registers at the same time. Therefore, both DACA and DACB outputs are updated at the same time. Figure 6-1 shows an example of the pin connections. Note that the LDAC pin can be tied low (VSS) to reduce the required connections from four to three I/O pins. In this case, the DAC output can be immediately updated when a valid 16 clock transmission has been received and the CS pin has been raised. VDD C1 = 10 µF C2 = 0.1 µF VDD 1 µF SDI CS1 SDI AVSS SDO SCK LDAC VOUTB C2 C1 VOUTA VOUTB VOUTA C2 C1 1 µF C2 C1 VDD PIC® Microcontroller 6.1 MCP48x2 Set Point or Offset Trimming Sensor Calibration Precision Selectable Voltage Reference Portable Instrumentation (Battery-Powered) Calibration of Optical Communication Devices MCP48x2 • • • • • CS0 6.2 Power Supply Considerations The typical application will require a bypass capacitor in order to filter out the noise in the power supply traces. The noise can be induced onto the power supply's traces from various events such as digital switching or as a result of changes on the DAC's output. The bypass capacitor helps to minimize the effect of these noise sources. Figure 6-1 illustrates an appropriate bypass strategy. In this example, two bypass capacitors are used in parallel: (a) 0.1 µF (ceramic) and (b)10 µF (tantalum). These capacitors should be placed as close to the device power pin (VDD) as possible (within 4 mm). The power source supplying these devices should be as clean as possible. If the application circuit has separate digital and analog power supplies, VDD and VSS of the device should reside on the analog plane. AVSS FIGURE 6-1: Diagram. 6.4 VSS Typical Connection Layout Considerations Inductively-coupled AC transients and digital switching noises can degrade the output signal integrity, and potentially reduce the device performance. Careful board layout will minimize these effects and increase the Signal-to-Noise Ratio (SNR). Bench testing has shown that a multi-layer board utilizing a low-inductance ground plane, isolated inputs and isolated outputs with proper decoupling, is critical for the best performance. Particularly harsh environments may require shielding of critical signals. Breadboards and wire-wrapped boards are not recommended if low noise is desired. 2010-2015 Microchip Technology Inc. DS20002249B-page 25 MCP4802/4812/4822 6.5 6.5.1.1 Single-Supply Operation Decreasing Output Step Size The MCP4802/4812/4822 family of devices are rail-torail voltage output DAC devices designed to operate with a VDD range of 2.7V to 5.5V. Its output amplifier is robust enough to drive small-signal loads directly. Therefore, it does not require any external output buffer for most applications. If the application is calibrating the bias voltage of a diode or transistor, a bias voltage range of 0.8V may be desired with about 200 µV resolution per step. Two common methods to achieve a 0.8V range are to either reduce VREF to 0.82V (using the MCP49XX family device that uses external reference) or use a voltage divider on the DAC’s output. 6.5.1 Using a VREF is an option if the VREF is available with the desired output voltage range. However, occasionally, when using a low-voltage VREF, the noise floor causes SNR error that is intolerable. Using a voltage divider method is another option and provides some advantages when VREF needs to be very low or when the desired output voltage is not available. In this case, a larger value VREF is used while two resistors scale the output range down to the precise desired level. DC SET POINT OR CALIBRATION A common application for the devices is a digitallycontrolled set point and/or calibration of variable parameters, such as sensor offset or slope. For example, the MCP4822 provides 4096 output steps. If G = 1 is selected, the internal 2.048V VREF would produce 500 µV of resolution. If G = 2 is selected, the internal 2.048 VREF would produce 1 mV of resolution. 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 environment. EXAMPLE 6-1: EXAMPLE CIRCUIT OF SET POINT OR THRESHOLD CALIBRATION VDD (a) Single Output DAC: MCP4801 MCP4811 MCP4821 (b) Dual Output DAC: MCP4802 VCC+ RSENSE VDD MCP4812 MCP4822 DAC Comparator R1 VOUT VTRIP R2 0.1 µF VCC– SPI 3-wire Dn VOUT = 2.048 G -----N 2 R2 V trip = VOUT -------------------- R 1 + R 2 DS20002249B-page 26 G = Dn = Digital value of DAC (0-255) for MCP4801/MCP4802 = Digital value of DAC (0-1023) for MCP4811/MCP4812 N Gain selection (1x or 2x) = Digital value of DAC (0-4095) for MCP4821/MCP4822 = DAC bit resolution 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 6.5.1.2 Building a “Window” DAC If the threshold is not near VREF, 2VREF or VSS, then creating a “window” around the threshold has several advantages. One simple method to create this “window” is to use a voltage divider network with a pullup and pull-down resistor. Example 6-2 shows this concept. When calibrating a set point or threshold of a sensor, typically only a small portion of the DAC output range is utilized. If the LSb size is adequate enough to meet the application’s accuracy needs, the unused range is sacrificed without consequences. If greater accuracy is needed, then the output range will need to be reduced to increase the resolution around the desired threshold. EXAMPLE 6-2: SINGLE-SUPPLY “WINDOW” DAC (a) Single Output DAC: MCP4801 MCP4811 MCP4821 (b) Dual Output DAC: MCP4802 MCP4812 VCC+ MCP4822 VDD DAC VCC+ RSENSE R3 VOUT Comparator R1 VTRIP 0.1 µF R2 VCC- SPI 3-wire VCC- Dn VOUT = 2.048 G -----N 2 G = Gain selection (1x or 2x) Dn = Digital value of DAC (0-255) for MCP4801/MCP4802 = Digital value of DAC (0-1023) for MCP4811/MCP4812 N = Digital value of DAC (0-4095) for MCP4821/MCP4822 = DAC bit resolution Thevenin Equivalent R2 R3 R 23 = ------------------R2 + R3 R1 VOUT VO V CC+ R 2 + V CC- R 3 V 23 = -----------------------------------------------------R2 + R3 V OUT R23 + V 23 R1 V trip = --------------------------------------------R 1 + R23 2010-2015 Microchip Technology Inc. R23 V23 DS20002249B-page 27 MCP4802/4812/4822 6.6 Bipolar Operation Example 6-3 illustrates a simple bipolar voltage source configuration. R1 and R2 allow the gain to be selected, while R3 and R4 shift the DAC's output to a selected offset. Note that R4 can be tied to VDD, instead of VSS, if a higher offset is desired. Also note that a pull-up to VDD could be used instead of R4, or in addition to R4, if a higher offset is desired. Bipolar operation is achievable using the MCP4802/4812/4822 family of devices by utilizing an external operational amplifier (op amp). This configuration is desirable due to the wide variety and availability of op amps. This allows a general purpose DAC, with its cost and availability advantages, to meet almost any desired output voltage range, power and noise performance. EXAMPLE 6-3: DIGITALLY-CONTROLLED BIPOLAR VOLTAGE SOURCE R2 (a) Single Output DAC: VDD MCP4801 VDD MCP4811 R1 MCP4821 VOUT (b) Dual Output DAC: VO R3 DAC VIN+ MCP4802 MCP4812 MCP4822 VCC+ R4 VCC– 0.1 µF SPI 3-wire Dn VOUT = 2.048 G -----N 2 VOUT R 4 VIN+ = -------------------R 3 + R4 R2 R2 V O = V IN+ 1 + ------ – V DD ------ R1 R 1 6.6.1 G = Gain selection (1x or 2x) Dn = Digital value of DAC (0-255) for MCP4801/MCP4802 = Digital value of DAC (0-1023) for MCP4811/MCP4812 = Digital value of DAC (0-4095) for MCP4821/MCP4822 = DAC bit resolution N DESIGN EXAMPLE: DESIGN A BIPOLAR DAC USING Example 6-3 WITH 12-BIT MCP4822 OR MCP4821 An output step magnitude of 1 mV, with an output range of ±2.05V, is desired for a particular application. The equation can be simplified to: – R2 – 2.05 --------- = ----------------R1 4.096V R2 1 ------ = --R1 2 If R1 = 20 k and R2 = 10 k, the gain will be 0.5. Step 1: Calculate the range: +2.05V – (-2.05V) = 4.1V. Step 2: Calculate the resolution needed: 4.1V/1 mV = 4100 Since 212 = 4096, 12-bit resolution is desired. Step 3:The amplifier gain (R2/R1), multiplied by fullscale VOUT (4.096V), must be equal to the desired minimum output to achieve bipolar operation. Since any gain can be realized by choosing resistor values (R1+R2), the VREF value must be selected first. If a VREF of 4.096V is used (G=2), solve for the amplifier’s gain by setting the DAC to 0, knowing that the output needs to be -2.05V. DS20002249B-page 28 Step 4: Next, solve for R3 and R4 by setting the DAC to 4096, knowing that the output needs to be +2.05V. R4 2 2.05V + 0.5 4.096V ------------------------ = ------------------------------------------------------- = -- R3 + R4 1.5 4.096V 3 If R4 = 20 k, then R3 = 10 k 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 6.7 Selectable Gain and Offset Bipolar Voltage Output Using a Dual Output DAC This circuit is typically used for linearizing a sensor whose slope and offset varies. The equation to design a bipolar “window” DAC would be utilized if R3, R4 and R5 are populated. In some applications, precision digital control of the output range is desirable. Example 6-4 illustrates how to use the MCP4802/4812/4822 family of devices to achieve this in a bipolar or single-supply application. EXAMPLE 6-4: BIPOLAR VOLTAGE SOURCE WITH SELECTABLE GAIN AND OFFSET R2 VDD VCC+ VOUTA R1 DACA Dual Output DAC: (DACA for Gain Adjust) VDD MCP4802 VCC+ MCP4812 MCP4822 VOUTB VO R5 R3 VIN+ DACB (DACB for Offset Adjust) SPI R4 3 VCC– VCC– Dn V OUTA = 2.048 G A -----N 2 Dn VOUTB = 2.048 G B -----N 2 VIN+ 0.1 µF VOUTB R 4 + V CC- R 3 = ------------------------------------------------R 3 + R4 G = Gain selection (1x or 2x) N = DAC bit resolution DA , DB = Digital value of DAC (0-255) for MCP4802 = Digital value of DAC (0-1023) for MCP4812 = Digital value of DAC (0-4095) for MCP4822 R2 R2 V O = V IN+ 1 + ------ – V OUTA ------ R1 R1 Offset Adjust Gain Adjust Bipolar “Window” DAC using R4 and R5 Thevenin Equivalent VCC+ R4 + V CC- R 5 V45 = --------------------------------------------R4 + R 5 V OUTB R 45 + V45 R 3 V IN+ = -----------------------------------------------R 3 + R 45 R4R5 R45 = ------------------R4 + R5 R2 R2 V O = V IN+ 1 + ------ – V OUTA ------ R 1 R 1 Offset Adjust Gain Adjust 2010-2015 Microchip Technology Inc. DS20002249B-page 29 MCP4802/4812/4822 6.8 Designing a Double-Precision DAC Using a Dual DAC Step 1: Calculate the resolution needed: Example 6-5 illustrates how to design a single-supply voltage output capable of up to 24-bit resolution from a dual 12-bit DAC (MCP4822). This design is simply a voltage divider with a buffered output. As an example, if an application similar to the one developed in Section 6.6.1 “Design Example: Design a Bipolar DAC Using Example 6-3 with 12bit MCP4822 or MCP4821” required a resolution of 1 µV instead of 1 mV, and a range of 0V to 4.1V, then 12-bit resolution would not be adequate. EXAMPLE 6-5: 4.1V/1 µV = 4.1 x 106. Since 222 = 4.2 x 106, 22-bit resolution is desired. Since DNL = ±0.75 LSb, this design can be done with the 12-bit MCP4822 DAC. Step 2: Since DACB’s VOUTB has a resolution of 1 mV, its output only needs to be “pulled” 1/1000 to meet the 1 µV target. Dividing VOUTA by 1000 would allow the application to compensate for DACB’s DNL error. Step 3: If R2 is 100, then R1 needs to be 100 k. Step 4: The resulting transfer function is shown in the equation of Example 6-5. SIMPLE, DOUBLE-PRECISION DAC WITH MCP4822 VDD MCP4822 VCC+ VOUTA (DACA for Fine Adjustment) VO R1 R1 >> R2 VDD MCP4822 VOUTB R2 0.1 µF VCC– (DACB for Course Adjustment) SPI 3-wire DA VOUTA = 2.048 G A ------12 2 DB V OUTB = 2.048 GB ------12 2 Gx = Gain selection (1x or 2x) Dn = Digital value of DAC (0-4096) V OUTA R 2 + VOUTB R 1 VO = -----------------------------------------------------R 1 + R2 DS20002249B-page 30 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 6.9 Building Programmable Current Source However, this also reduces the resolution that the current can be controlled with. The voltage divider, or “window”, DAC configuration would allow the range to be reduced, thus increasing resolution around the range of interest. When working with very small sensor voltages, plan on eliminating the amplifier’s offset error by storing the DAC’s setting under known sensor conditions. Example 6-6 shows an example of building a programmable current source using a voltage follower. The current sensor (sensor resistor) is used to convert the DAC voltage output into a digitally-selectable current source. Adding the resistor network from Example 6-2 would be advantageous in this application. The smaller RSENSE is, the less power dissipated across it. EXAMPLE 6-6: DIGITALLY-CONTROLLED CURRENT SOURCE VDD or VREF VDD (a) Single Output DAC: MCP4801 MCP4811 IL VOUT DAC MCP4821 (b) Dual Output DAC: MCP4802 Load VCC+ Ib SPI MCP4812 VCC– 3-wire MCP4822 RSENSE IL I b = ---- G = Gain selection (1x or 2x) Dn = Digital value of DAC (0-255) for MCP4801/MCP4802 = Digital value of DAC (0-1023) for MCP4811/MCP4812 V OUT I L = --------------- ------------R sense + 1 where Common-Emitter Current Gain 2010-2015 Microchip Technology Inc. N = Digital value of DAC (0-4095) for MCP4821/MCP4822 = DAC bit resolution DS20002249B-page 31 MCP4802/4812/4822 NOTES: DS20002249B-page 32 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 7.0 DEVELOPMENT SUPPORT 7.1 Evaluation and Demonstration Boards The Mixed Signal PICtail™ Demo Board supports the MCP4802/4812/4822 family of devices. Refer to www.microchip.com for further information on this product’s capabilities and availability. 2010-2015 Microchip Technology Inc. DS20002249B-page 33 MCP4802/4812/4822 NOTES: DS20002249B-page 34 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 8.0 PACKAGING INFORMATION 8.1 Package Marking Information 8-Lead MSOP (3x3 mm) Example 4822E 009256 8-Lead PDIP (300 mil) Example XXXXXXXX XXXXXNNN MCP4802 E/P e3 256 YYWW 8-Lead SOIC (3.90 mm) e3 * Note: Example MCP4812E SN e3 1009 256 NNN Legend: XX...X Y YY WW NNN 1009 Customer-specific information Year code (last digit of calendar year) Year code (last 2 digits of calendar year) Week code (week of January 1 is week ‘01’) Alphanumeric traceability code Pb-free JEDEC designator for Matte Tin (Sn) This package is Pb-free. The Pb-free JEDEC designator ( e3 ) can be found on the outer packaging for this package. In the event the full Microchip part number cannot be marked on one line, it will be carried over to the next line, thus limiting the number of available characters for customer-specific information. 2010-2015 Microchip Technology Inc. DS20002249B-page 35 MCP4802/4812/4822 Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging DS20002249B-page 36 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging 2010-2015 Microchip Technology Inc. DS20002249B-page 37 MCP4802/4812/4822 Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging DS20002249B-page 38 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 8-Lead Plastic Dual In-Line (P) - 300 mil Body [PDIP] Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging D A N B E1 NOTE 1 1 2 TOP VIEW E C A2 A PLANE L c A1 e eB 8X b1 8X b .010 C SIDE VIEW END VIEW Microchip Technology Drawing No. C04-018D Sheet 1 of 2 2010-2015 Microchip Technology Inc. DS20002249B-page 39 MCP4802/4812/4822 8-Lead Plastic Dual In-Line (P) - 300 mil Body [PDIP] Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging ALTERNATE LEAD DESIGN (VENDOR DEPENDENT) DATUM A DATUM A b b e 2 e 2 e Units Dimension Limits Number of Pins N e Pitch Top to Seating Plane A Molded Package Thickness A2 Base to Seating Plane A1 Shoulder to Shoulder Width E Molded Package Width E1 Overall Length D Tip to Seating Plane L c Lead Thickness Upper Lead Width b1 b Lower Lead Width Overall Row Spacing eB § e MIN .115 .015 .290 .240 .348 .115 .008 .040 .014 - INCHES NOM 8 .100 BSC .130 .310 .250 .365 .130 .010 .060 .018 - MAX .210 .195 .325 .280 .400 .150 .015 .070 .022 .430 Notes: 1. Pin 1 visual index feature may vary, but must be located within the hatched area. 2. § Significant Characteristic 3. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .010" per side. 4. Dimensioning and tolerancing per ASME Y14.5M BSC: Basic Dimension. Theoretically exact value shown without tolerances. Microchip Technology Drawing No. C04-018D Sheet 2 of 2 DS20002249B-page 40 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging 2010-2015 Microchip Technology Inc. DS20002249B-page 41 MCP4802/4812/4822 Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging DS20002249B-page 42 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 !"#$% & ! "#$%&"'"" ($) % *++&&&! !+$ 2010-2015 Microchip Technology Inc. DS20002249B-page 43 MCP4802/4812/4822 NOTES: DS20002249B-page 44 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 APPENDIX A: REVISION HISTORY Revision B (May 2015) • Updated MSOP package marking drawing to correctly display the part’s orientation. Revision A (April 2010) • Original Release of this Document. 2010-2015 Microchip Technology Inc. DS20002249B-page 45 MCP4802/4812/4822 NOTES: DS20002249B-page 46 2010-2015 Microchip Technology Inc. MCP4802/4812/4822 PRODUCT IDENTIFICATION SYSTEM To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office. PART NO. X /XX Device Temperature Range Package Examples: a) b) Device: MCP4802: MCP4802T: MCP4812: MCP4812T: MCP4822: MCP4822T: Temperature Range: E Dual 8-Bit Voltage Output DAC Dual 8-Bit Voltage Output DAC (Tape and Reel, MSOP and SOIC only) Dual 10-Bit Voltage Output DAC Dual 10-Bit Voltage Output DAC (Tape and Reel, MSOP and SOIC only) Dual 12-Bit Voltage Output DAC Dual 12-Bit Voltage Output DAC (Tape and Reel, MSOP and SOIC only) = -40C to +125C (Extended) c) d) e) a) b) c) Package: MS P SN = = = 8-Lead Plastic Micro Small Outline (MSOP) 8-Lead Plastic Dual In-Line (PDIP) 8-Lead Plastic Small Outline - Narrow, 150 mil (SOIC) d) e) a) b) c) d) e) 2010-2015 Microchip Technology Inc. MCP4802-E/MS: Extended temperature, MSOP package. MCP4802T-E/MS: Extended temperature, MSOP package, Tape and Reel. MCP4802-E/P: Extended temperature, PDIP package. MCP4802-E/SN: Extended temperature, SOIC package. MCP4802T-E/SN: Extended temperature, SOIC package, Tape and Reel. MCP4812-E/MS: Extended temperature, MSOP package. MCP4812T-E/MS: Extended temperature, MSOP package, Tape and Reel. MCP4812-E/P: Extended temperature, PDIP package. MCP4812-E/SN: Extended temperature, SOIC package. MCP4812T-E/SN: Extended temperature, SOIC package, Tape and Reel. MCP4822-E/MS: Extended temperature, MSOP package. MCP4822T-E/MS: Extended temperature, MSOP package, Tape and Reel. MCP4822-E/P: Extended temperature, PDIP package. MCP4822-E/SN: Extended temperature, SOIC package. MCP4822T-E/SN: Extended temperature, SOIC package, Tape and Reel. DS20002249B-page 47 MCP4802/4812/4822 NOTES: DS20002249B-page 48 2010-2015 Microchip Technology Inc. Note the following details of the code protection feature on Microchip devices: • Microchip products meet the specification contained in their particular Microchip Data Sheet. • Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions. • There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property. • Microchip is willing to work with the customer who is concerned about the integrity of their code. • Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.” Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act. Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer’s risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights. Trademarks The Microchip name and logo, the Microchip logo, dsPIC, FlashFlex, flexPWR, JukeBlox, KEELOQ, KEELOQ logo, Kleer, LANCheck, MediaLB, MOST, MOST logo, MPLAB, OptoLyzer, PIC, PICSTART, PIC32 logo, RightTouch, SpyNIC, SST, SST Logo, SuperFlash and UNI/O are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. The Embedded Control Solutions Company and mTouch are registered trademarks of Microchip Technology Incorporated in the U.S.A. Analog-for-the-Digital Age, BodyCom, chipKIT, chipKIT logo, CodeGuard, dsPICDEM, dsPICDEM.net, ECAN, In-Circuit Serial Programming, ICSP, Inter-Chip Connectivity, KleerNet, KleerNet logo, MiWi, MPASM, MPF, MPLAB Certified logo, MPLIB, MPLINK, MultiTRAK, NetDetach, Omniscient Code Generation, PICDEM, PICDEM.net, PICkit, PICtail, RightTouch logo, REAL ICE, SQI, Serial Quad I/O, Total Endurance, TSHARC, USBCheck, VariSense, ViewSpan, WiperLock, Wireless DNA, and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. Silicon Storage Technology is a registered trademark of Microchip Technology Inc. in other countries. GestIC is a registered trademarks of Microchip Technology Germany II GmbH & Co. KG, a subsidiary of Microchip Technology Inc., in other countries. All other trademarks mentioned herein are property of their respective companies. © 2010-2015, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. ISBN: 978-1-63277-374-6 QUALITY MANAGEMENT SYSTEM CERTIFIED BY DNV == ISO/TS 16949 == 2010-2015 Microchip Technology Inc. Microchip received ISO/TS-16949:2009 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company’s quality system processes and procedures are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified. 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