MCP4901/4911/4921 8/10/12-Bit Voltage Output Digital-to-Analog Converter with SPI Interface Features Description * * * * * * The MCP4901/4911/4921 devices are single channel 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 an SPI compatible Serial Peripheral Interface. The user can configure the full-scale range of the device to be VREF or 2*VREF by setting the gain selection option bit (gain of 1 of 2). Applications * * * * * Set Point or Offset Trimming Precision Selectable Voltage Reference Motor Control Feedback Loop Digitally-Controlled Multiplier/Divider Calibration of Optical Communication Devices Related Products P/N DAC Resolution No. of Channels MCP4801 8 1 MCP4811 10 1 MCP4821 12 1 Voltage Reference (VREF) Internal (2.048V) The user can shut down the device by setting the Configuration Register bit. In Shutdown mode, most of the internal circuits are turned off for power savings, and the output amplifier is configured to present a known high resistance output load (500 ktypical. The devices include double-buffered registers, allowing synchronous updates of the DAC output 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 Differential Non-Linearity (DNL) error and fast settling time. These devices are specified over the extended temperature range (+125C). 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 MCP4901/4911/4921 devices are available in the PDIP, SOIC, MSOP and DFN packages. Package Types MCP4802 8 2 MCP4812 10 2 MCP4822 12 2 VDD 1 MCP4901 8 1 CS 2 MCP4911 10 1 MCP4921 12 1 MCP4902 8 2 MCP4912 10 2 MCP4922 12 2 8-Pin PDIP, SOIC, MSOP External Note: The products listed here have similar AC/DC performances. 2010 Microchip Technology Inc. SCK 3 SDI 4 MCP49x1 * * * * * * MCP4901: 8-Bit Voltage Output DAC MCP4911: 10-Bit Voltage Output DAC MCP4921: 12-Bit Voltage Output DAC Rail-to-Rail Output SPI Interface with 20 MHz Clock Support Simultaneous Latching of the DAC Output with LDAC Pin Fast Settling Time of 4.5 s Selectable Unity or 2x Gain Output External Voltage Reference Input External Multiplier Mode 2.7V to 5.5V Single-Supply Operation Extended Temperature Range: -40C to +125C DFN-8 (2x3)* 8 VOUT VDD 1 8 VOUT 7 VSS 6 VREF CS 2 SCK 3 EP 7 VSS 9 6 VREF 5 LDAC SDI 4 5 LDAC MCP4901: 8-bit single DAC MCP4911: 10-bit single DAC MCP4921: 12-bit single DAC * Includes Exposed Thermal Pad (EP); see Table 3-1. DS22248A-page 1 MCP4901/4911/4921 Block Diagram LDAC CS SDI SCK Interface Logic Power-on Reset Input Register VDD VSS DAC Register VREF String DAC Buffer Gain Logic Output Op Amp Output Logic VOUT DS22248A-page 2 2010 Microchip Technology Inc. MCP4901/4911/4921 1.0 ELECTRICAL CHARACTERISTICS Absolute Maximum Ratings VDD ............................................................................................................. 6.5V 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. All inputs and outputs w.r.t ................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 .....................................-65C to +150C Ambient temp. with power applied ................-55C to +125C ESD protection on all pins 4 kV (HBM), 400V (MM) Maximum Junction Temperature (TJ) . .........................+150C 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 +85C. Typical values are at +25C. Parameters Sym Min Typ Max Units Conditions Operating Voltage VDD 2.7 -- 5.5 Supply Current IDD -- 175 350 A 125 250 A VDD = 5V VDD = 3V VREF input is unbuffered, all digital inputs are grounded, all analog outputs (VOUT) are unloaded. Code = 0x000h -- -- 3.3 6 A -- 2.0 -- V 8 -- -- Bits Power Requirements Software Shutdown Current ISHDN_SW Power-On-Reset Threshold VPOR Power-on Reset circuit remains on DC Accuracy MCP4901 Resolution n INL Error INL -1 0.125 1 LSb DNL DNL -0.5 0.1 +0.5 LSb n 10 -- -- Bits Note 1 MCP4911 Resolution INL Error INL -3.5 0.5 3.5 LSb DNL DNL -0.5 0.1 +0.5 LSb n 12 -- -- Bits Note 1 MCP4921 Resolution Note 1: 2: INL Error INL -12 2 12 LSb DNL DNL -0.75 0.2 +0.75 LSb Note 1 Guaranteed monotonic by design over all codes. This parameter is ensured by design, and not 100% tested. 2010 Microchip Technology Inc. DS22248A-page 3 MCP4901/4911/4921 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 +85C. Typical values are at +25C. Parameters Offset Error Offset Error Temperature Coefficient Sym Min Typ Max Units Conditions VOS -- 0.02 1 % of FSR VOS/C -- 0.16 -- ppm/C -45C to 25C +25C to 85C Code = 0x000h -- -0.44 -- ppm/C gE -- -0.10 1 % of FSR G/C -- -3 -- ppm/C Input Range - Buffered Mode VREF 0.040 -- VDD - 0.040 V Input Range - Unbuffered Mode VREF 0 -- VDD V Input Impedance RVREF -- 165 -- k Input Capacitance - Unbuffered Mode CVREF -- 7 -- pF Multiplier Mode -3 dB Bandwidth fVREF -- 450 -- kHz VREF = 2.5V 0.2Vp-p, Unbuffered, G = 1 fVREF -- 400 -- kHz VREF = 2.5V 0.2 Vp-p, Unbuffered, G = 2 THDVREF -- -73 -- dB VREF = 2.5V 0.2Vp-p, Frequency = 1 kHz VOUT -- 0.01 to VDD - 0.04 -- V Accuracy is better than 1 LSb for VOUT = 10 mV to (VDD - 40 mV) Gain Error Gain Error Temperature Coefficient Code = 0xFFFh, not including offset error Input Amplifier (VREF Input) Multiplier Mode - Total Harmonic Distortion Note 2 Code = 2048 VREF = 0.2 Vp-p, f = 100 Hz and 1 kHz Unbuffered Mode Output Amplifier Output Swing Phase Margin m -- 66 -- Degrees Slew Rate SR -- 0.55 -- V/s ISC -- 15 24 mA tsettling -- 4.5 -- s DAC-to-DAC Crosstalk -- 10 -- nV-s Major Code Transition Glitch -- 45 -- nV-s Digital Feedthrough -- 10 -- nV-s Analog Crosstalk -- 10 -- nV-s Short Circuit Current Settling Time 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. DS22248A-page 4 2010 Microchip Technology Inc. MCP4901/4911/4921 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 +125C by characterization or simulation. Parameters Sym Min Typ Max Units Conditions Input Voltage VDD 2.7 -- 5.5 Input Current IDD -- 200 -- A VREF input is unbuffered, all digital inputs are grounded, all analog outputs (VOUT) are unloaded. Code = 0x000h -- 5 -- A -- 1.85 -- V 8 -- -- Bits Power Requirements Software Shutdown Current ISHDN_SW Power-on Reset Threshold VPOR DC Accuracy MCP4901 Resolution n INL Error INL 0.25 LSb DNL DNL 0.2 LSb Note 1 MCP4911 Resolution n 10 -- -- Bits INL Error INL 1 LSb DNL DNL 0.2 LSb Note 1 MCP4921 Resolution n 12 -- -- Bits INL Error INL 4 LSb DNL DNL 0.25 LSb Note 1 VOS -- 0.02 -- % of FSR VOS/C -- -5 -- ppm/C gE -- -0.10 -- % of FSR G/C -- -3 -- ppm/C Input Range - Buffered Mode VREF -- 0.040 to VDD0.040 -- V Input Range - Unbuffered Mode VREF 0 -- VDD V Input Impedance RVREF -- 174 -- k Input Capacitance - Unbuffered Mode CVREF -- 7 -- pF Multiplying Mode -3 dB Bandwidth fVREF -- 450 -- kHz VREF = 2.5V 0.1 Vp-p, Unbuffered, G = 1x fVREF -- 400 -- kHz VREF = 2.5V 0.1 Vp-p, Unbuffered, G = 2x Offset Error Offset Error Temperature Coefficient Gain Error Gain Error Temperature Coefficient Code = 0x000h +25C to +125C Code = 0xFFFh, not including offset error Input Amplifier (VREF Input) Note 1: 2: Note 1 Code = 2048, VREF = 0.2 Vp-p, f = 100 Hz and 1 kHz Unbuffered Mode Guaranteed monotonic by design over all codes. This parameter is ensured by design, and not 100% tested. 2010 Microchip Technology Inc. DS22248A-page 5 MCP4901/4911/4921 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 +125C by characterization or simulation. Parameters Sym Min Typ Max Units THDVREF -- -- -- dB VREF = 2.5V 0.1Vp-p, Frequency = 1 kHz 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 m -- 66 -- Degrees Slew Rate SR -- 0.55 -- V/s ISC -- 17 -- mA tsettling -- 4.5 -- s Within 1/2 LSB of final value from 1/4 to 3/4 full-scale range Major Code Transition Glitch -- 45 -- nV-s 1 LSB change around major carry (0111...1111 to 1000...0000) Digital Feedthrough -- 10 -- nV-s Multiplying Mode - Total Harmonic Distortion Conditions Output Amplifier Short Circuit Current Settling Time Dynamic Performance (Note 2) Note 1: 2: Guaranteed monotonic by design over all codes. This parameter is ensured by design, and not 100% tested. DS22248A-page 6 2010 Microchip Technology Inc. MCP4901/4911/4921 AC CHARACTERISTICS (SPI TIMING SPECIFICATIONS) Electrical Specifications: Unless otherwise indicated, VDD= 2.7V - 5.5V, TA= -40 to +125C. Typical values are at +25C. 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 -- Input Leakage Current ILEAKAGE -1 -- 1 A LDAC = CS = SDI = SCK = VREF = VDD or VSS Digital Pin Capacitance (All inputs/outputs) CIN, COUT -- 10 -- pF VDD = 5.0V, TA = +25C, fCLK = 1 MHz (Note 1) Clock Frequency FCLK -- -- 20 MHz Clock High Time tHI 15 -- -- ns Note 1 Clock Low Time tLO 15 -- -- ns Note 1 tCSSR 40 -- -- ns Applies only when CS falls with CLK high (Note 1) 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 High Time tCSH 15 -- -- ns Note 1 tLD 100 -- -- ns Note 1 tLS 40 -- -- ns Note 1 tIDLE 40 -- -- ns Note 1 Hysteresis of Schmitt Trigger Inputs CS Fall to First Rising CLK Edge Data Input Setup Time LDAC Pulse Width LDAC Setup Time SCK Idle Time before CS Fall Note 1: Conditions TA = +25C (Note 1) 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 SI MSB in LSB in LDAC tLS FIGURE 1-1: tLD SPI Input Timing Data. 2010 Microchip Technology Inc. DS22248A-page 7 MCP4901/4911/4921 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-DFN (2 x 3) JA -- 68 -- C/W Thermal Resistance, 8L-PDIP JA -- 90 -- C/W Thermal Resistance, 8L-SOIC JA -- 150 -- C/W Thermal Resistance, 8L-MSOP JA -- 211 -- C/W Conditions Temperature Ranges Note 1 Thermal Package Resistances Note 1: The MCP4901/4911/4921 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 150C. DS22248A-page 8 2010 Microchip Technology Inc. MCP4901/4911/4921 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 = +25C, VDD = 5V, VSS = 0V, VREF = 2.048V, Gain = 2x, RL = 5 k, CL = 100 pF. 0.0766 0.3 Absolute DNL (LSB) DNL (LSB) 0.2 0.1 0 -0.1 -0.2 0.0764 0.0762 0.076 0.0758 0.0756 0.0754 0.0752 0.075 -0.3 0 1024 2048 3072 -40 4096 FIGURE 2-1: DNL vs. Code (MCP4921). 20 40 60 80 100 120 0.35 Absolute DNL (LSB) 0.1 DNL (LSB) 0 FIGURE 2-4: Absolute DNL vs. Temperature (MCP4921). 0.2 0 -0.1 0.3 0.25 0.2 0.15 0.1 0.05 0 -0.2 0 1024 2048 3072 Code (Decimal) 1 4096 125C 85C INL (LSB) 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 2048 Code (Decimal) 3072 1 2 4096 3 4 5.5 FIGURE 2-3: DNL vs. Code and VREF, Gain=1 (MCP4921). 2010 Microchip Technology Inc. 4 5 FIGURE 2-5: Absolute DNL vs. Voltage Reference (MCP4921). 0.3 1024 3 Voltage Reference (V) 0.4 0 2 25C FIGURE 2-2: DNL vs. Code and Temperature (MCP4921). DNL (LSB) -20 Ambient Temperature (C) Code (Decimal) 5 4 3 2 1 0 -1 -2 -3 -4 -5 Ambient Temperature 125C 0 1024 85 2048 3072 Code (Decimal) 25 4096 FIGURE 2-6: INL vs. Code and Temperature (MCP4921). DS22248A-page 9 MCP4901/4911/4921 Note: Unless otherwise indicated, TA = +25C, VDD = 5V, VSS = 0V, VREF = 2.048V, Gain = 2, RL = 5 k, CL = 100 pF. 2 2 0 INL (LSB) Absolute INL (LSB) 2.5 1.5 1 -2 -4 0.5 0 -6 -40 -20 0 20 40 60 80 100 120 0 1024 Ambient Temperature (C) 3072 4096 Code (Decimal) FIGURE 2-7: Absolute INL vs. Temperature (MCP4921). FIGURE 2-10: Note: 3 INL vs. Code (MCP4921). Single device graph (Figure 2-10) for illustration of 64 code effect. 0.2 Temp = - 40oC to +125oC 2.5 0.1 2 DNL (LSB) Absolute INL (LSB) 2048 1.5 1 0 -0.1 0.5 0 1 2 3 4 -0.2 5 0 Voltage Reference (V) FIGURE 2-8: (MCP4921). Absolute INL vs. VREF 3 1 2 3 384 512 640 Code 768 896 1024 1.5 4 5.5 0.5 1 0 INL (LSB) INL (LSB) 256 FIGURE 2-11: DNL vs. Code and Temperature (MCP4911). VREF 2 128 -1 -2 o 85 C -0.5 -1.5 o -3 1024 FIGURE 2-9: (MCP4921). DS22248A-page 10 2048 3072 Code (Decimal) 4096 INL vs. Code and VREF - 40 C o 125 C -4 0 25 C o -2.5 -3.5 0 128 256 384 512 640 Code 768 896 1024 FIGURE 2-12: INL vs. Code and Temperature (MCP4911). 2010 Microchip Technology Inc. MCP4901/4911/4921 Note: Unless otherwise indicated, TA = +25C, VDD = 5V, VSS = 0V, VREF = 2.048V, Gain = 2, RL = 5 k, CL = 100 pF. 0.06 18 Temp = -40oC to +125oC 16 14 Occurrence 0.02 0 -0.02 12 10 8 6 4 2 -0.04 0 32 64 96 128 160 192 224 256 Code 167 165 163 161 159 157 155 153 151 IDD (A) FIGURE 2-16: 2.7V). FIGURE 2-13: DNL vs. Code and Temperature (MCP4901). 149 147 143 0 -0.06 145 DNL (LSB) 0.04 IDD Histogram (VDD = 9 0.5 8 o o -40 C to +85 C 7 Occurrence INL (LSB) 0.25 0 6 5 4 3 2 -0.25 o 1 125 C 0 151 156 161 166 171 176 181 186 191 196 201 -0.5 0 32 64 96 128 160 Code 192 224 IDD (A) 256 FIGURE 2-17: 5.0V). FIGURE 2-14: INL vs. Code and Temperature (MCP4901). 210 IDD Histogram (VDD = 5.5V 5.0V IDD (A) 190 4.0V 3.0V 2.7V 170 VDD 150 130 110 -40 -20 FIGURE 2-15: VDD. 0 20 40 60 80 100 120 Ambient Temperature (C) IDD vs. Temperature and 2010 Microchip Technology Inc. DS22248A-page 11 MCP4901/4911/4921 Note: Unless otherwise indicated, TA = +25C, VDD = 5V, VSS = 0V, VREF = 2.048V, Gain = 2, RL = 5 k, CL = 100 pF. 6 VDD 4 ISHDN_SW (A) 5 5.0V 4 4.0V 3 3.0V 2.7V 2 VDD 1 VIN Hi Threshold (V) 5.5V 5.0V 3 2.5 4.0V 2 3.0V 2.7V 1.5 1 0 -40 -20 -40 0 20 40 60 80 100 120 Ambient Temperature (C) -20 0 20 40 60 80 100 120 Ambient Temperature (C) FIGURE 2-21: VIN High Threshold vs. Temperature and VDD. FIGURE 2-18: Shutdown Current vs. Temperature and VDD. 0.12 0.08 VDD 0.06 0.04 5.5V 0.02 0 5.0V 4.0V 3.0V 2.7V -0.02 -40 -20 0 20 40 60 80 Offset Error vs.Temperature -0.08 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 -40 100 120 Ambient Temperature (C) FIGURE 2-19: and VDD. VIN Low Threshold (V) 1.6 0.1 Offset Error (%) 5.5V 3.5 -20 0 20 40 60 80 100 120 Ambient Temperature (C) FIGURE 2-22: VIN Low Threshold vs. Temperature and VDD. VDD Gain Error (%) 5.5V -0.1 5.0V -0.12 4.0V 3.0V 2.7V -0.14 -0.16 -40 -20 0 20 40 60 80 100 120 Ambient Temperature (C) FIGURE 2-20: and VDD. DS22248A-page 12 Gain Error vs. Temperature 2010 Microchip Technology Inc. MCP4901/4911/4921 VDD 5.5V 5.0V 4.0V 3.0V 2.7V 0.0045 VOUT_LOW Limit (Y-AVSS)(V) 2.5 2.25 2 1.75 1.5 1.25 1 0.75 0.5 0.25 0 0.004 5.5V 0.0035 0.003 5.0V 0.0025 4.0V 3.0V 2.7V 0.002 -40 -20 0 20 40 60 80 100 120 Ambient Temperature (C) 0 20 40 60 80 100 120 Ambient Temperature (C) FIGURE 2-26: VOUT Low Limit vs. Temperature and VDD. FIGURE 2-23: Input Hysteresis vs. Temperature and VDD. 18 175 VREF_UNBUFFERED Impedance (kOhm) 5.5V 2.7V VDD 170 165 160 VDD 17 5.5V 5.0V 4.0V 3.0V 2.7V 16 15 14 13 12 11 10 155 -40 -20 -40 0 20 40 60 80 100 120 Ambient Temperature (C) FIGURE 2-24: VREF Input Impedance vs. Temperature and VDD. 0.045 5.0 0.035 VREF=4.0 4.0V 0.03 0.025 3.0V 2.7V 0.02 VDD 0.015 0.01 0 20 40 60 80 100 120 Ambient Temperature (C) 6.0 5.5V 5.0V 0.04 -20 FIGURE 2-27: IOUT High Short vs. Temperature and VDD. VOUT (V) VOUT_HI Limit (VDD-Y)(V) VDD 0.0015 -40 -20 IOUT_HI_SHORTED (mA) VIN_SPI Hysteresis (V) Note: Unless otherwise indicated, TA = +25C, VDD = 5V, VSS = 0V, VREF = 2.048V, Gain = 2, RL = 5 k, CL = 100 pF. 4.0 Output Shorted to VDD 3.0 2.0 1.0 Output Shorted to VSS 0.005 0.0 0 -40 -20 0 20 40 60 80 100 120 Ambient Temperature (C) FIGURE 2-25: VOUT High Limit vs. Temperature and VDD. 2010 Microchip Technology Inc. 0 2 FIGURE 2-28: 4 6 8 10 IOUT (mA) 12 14 16 IOUT vs. VOUT. Gain = 1. DS22248A-page 13 MCP4901/4911/4921 Note: Unless otherwise indicated, TA = +25C, VDD = 5V, VSS = 0V, VREF = 2.048V, Gain = 2, RL = 5 k, CL = 100 pF. VOUT VOUT SCK LDAC LDAC Time (1 s/div) FIGURE 2-29: VOUT Rise Time Time (1 s/div) FIGURE 2-32: VOUT Rise Time VOUT VOUT SCK SCK LDAC LDAC Time (1 s/div) VOUT Fall Time. FIGURE 2-33: Shutdown. VOUT SCK LDAC Time (1 s/div) FIGURE 2-31: DS22248A-page 14 VOUT Rise Time Exit Ripple Rejection (dB) FIGURE 2-30: Time (1 s/div) VOUT Rise Time Frequency (Hz) FIGURE 2-34: PSRR vs. Frequency. 2010 Microchip Technology Inc. MCP4901/4911/4921 Note: Unless otherwise indicated, TA = +25C, VDD = 5V, VSS = 0V, VREF = 2.50V, Gain = 2, RL = 5 k, CL = 100 pF. 0 Attenuation (dB) -2 -4 -6 -8 -10 -12 100 FIGURE 2-35: Frequency (kHz) 160 416 672 928 1184 1440 1696 1952 2208 2464 2720 2976 3232 3488 3744 1,000 Multiplier Mode Bandwidth. D= D= D= D= D= D= D= D= D= D= D= D= D= D= D= -45 qVREF - qVOUT D= D= D= D= D= D= D= D= D= D= D= D= D= D= D= 0 -90 -135 -180 100 FIGURE 2-37: Frequency (kHz) 160 416 672 928 1184 1440 1696 1952 2208 2464 2720 2976 3232 3488 3744 1,000 Phase Shift. Bandwidth (kHz) Figure 2-35 calculation: Attenuation (dB) = 20 log (VOUT/VREF) - 20 log (G(D/4096)) 600 580 560 540 520 500 480 460 440 420 400 G=1 G=2 44 37 88 34 32 32 76 29 20 27 64 24 08 22 52 19 96 16 40 14 84 11 8 92 2 67 6 41 0 16 Worst Case Codes (decimal) FIGURE 2-36: Codes. -3 db Bandwidth vs. Worst 2010 Microchip Technology Inc. DS22248A-page 15 MCP4901/4911/4921 NOTES: DS22248A-page 16 2010 Microchip Technology Inc. MCP4901/4911/4921 3.0 PIN DESCRIPTIONS The descriptions of the pins are listed in Table 3-1. TABLE 3-1: PIN FUNCTION TABLE PDIP, MSOP, SOIC DFN Symbol 1 1 VDD 2 2 CS Chip Select Input 3 3 SCK Serial Clock Input 4 4 SDI Serial Data Input 5 5 LDAC DAC Output Synchronization Input. This pin is used to transfer the input register (DAC settings) to the output register (VOUT) 6 6 VREF Voltage Reference Input 7 7 VSS Ground reference point for all circuitry on the device 8 8 VOUT -- 9 EP 3.1 Description Supply Voltage Input (2.7V to 5.5V) DAC Analog Output Exposed Thermal Pad. This pad must be connected to VSS in application 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 good DAC performance. It is recommended to use an appropriate bypass capacitor of about 0.1 F (ceramic) to ground. An additional 10 F 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, which requires an active-low signal to enable serial clock and data functions. 3.3 Serial Clock Input (SCK) SCK is the SPI compatible serial clock input. 3.4 Serial Data Input (SDI) 3.5 Latch DAC Input (LDAC) The LDAC (latch DAC synchronization input) pin is used to transfer the input latch register to the DAC register (output latches, VOUT). When this pin is low, VOUT is updated with input register content. 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 Output (VOUT) VOUT is the DAC analog output pin. The DAC output has an 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). 3.7 Voltage Reference Input (VREF) VREF is the voltage reference input for the device. The reference on this pin is utilized to set the reference voltage on the string DAC. The input voltage can range from VSS to VDD. This pin can be tied to VDD. 3.8 Exposed Thermal Pad (EP) There is an internal electrical connection between the Exposed Thermal Pad (EP) and the VSS pin. They must be connected to the same potential on the PCB. SDI is the SPI compatible serial data input. 2010 Microchip Technology Inc. DS22248A-page 17 MCP4901/4911/4921 NOTES: DS22248A-page 18 2010 Microchip Technology Inc. MCP4901/4911/4921 4.0 GENERAL OVERVIEW The MCP4901, MCP4911 and MCP4921 are single channel voltage output 8-bit, 10-bit and 12-bit DAC devices, respectively. These devices include a VREF input buffer, a rail-to-rail output amplifier, 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: VOUT = ------------------------------ G n 2 Where: VREF Dn G n ANALOG OUTPUT VOLTAGE (VOUT) VREF Dn = = = = = = = = = EXternal voltage reference DAC input code Gain Selection 2 for <GA> bit = 0 1 for <GA> bit = 1 DAC Resolution 8 for MCP4901 10 for MCP4911 12 for MCP4912 TABLE 4-1: LSb OF EACH DEVICE Gain Selection Device LSb Size 1x VREF/256 2x (2*VREF)/256 MCP4911 1x VREF/1024 (n = 10) 2x (2*VREF)/1024 MCP4921 1x VREF/4096 (n = 12) 2x (2*VREF)/4096 where VREF is the external voltage reference. MCP4901 (n = 8) 4.1 4.1.1 DC Accuracy INL ACCURACY Integral Non-Linearity (INL) error is the maximum deviation between an actual code transition point and its corresponding ideal transition point, after offset and gain errors have been removed. The two endpoints (from 0x000 and 0xFFF) method 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 The ideal output range of each device is: 110 * MCP4901 (n = 8) 101 (a) 0V to 255/256*VREF when gain setting = 1x. (b) 0V to 255/256*2*VREF when gain setting = 2x. * MCP4911 (n = 10) Actual Transfer Function Digital Input Code 100 011 Ideal Transfer Function (a) 0V to 1023/1024*VREF when gain setting = 1x. 010 (b) 0V to 1023/1024*2*VREF when gain setting = 2x. * MCP4921 (n = 12) 001 (a) 0V to 4095/4096*VREF when gain setting = 1x. 000 (b) 0V to 4095/4096*2*VREF when gain setting = 2x. Note: See the output swing voltage specification in Section 1.0 "Electrical Characteristics". 1 LSb is the ideal voltage difference between two successive codes. Table 4-1 illustrates the LSb calculation of each device. 2010 Microchip Technology Inc. INL < 0 DAC Output FIGURE 4-1: 4.1.2 Example for INL Error. DNL ACCURACY 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. DS22248A-page 19 MCP4901/4911/4921 4.2.2 111 110 Actual Transfer Function 101 100 Ideal Transfer Function 011 010 Wide Code, > 1 LSb 4.2.3 000 Narrow Code, < 1 LSb DAC Output FIGURE 4-2: Example for DNL Accuracy. OFFSET ERROR An offset error is the deviation from zero voltage output when the digital input code is zero. 4.1.4 GAIN ERROR A gain error is the deviation from the ideal output, VREF- 1 LSB, excluding the effects of offset error. 4.2 4.2.1 Circuit Descriptions OUTPUT AMPLIFIER The DAC's output is 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 output allows VOUT to be used as a programmable voltage reference in a system. Selecting a gain of 2 reduces the bandwidth of the amplifier in Multiplying mode. Refer to Section 1.0 "Electrical Characteristics" for the Multiplying mode bandwidth for given load conditions. POWER-ON RESET CIRCUIT The internal Power-on Reset (POR) circuit monitors the power supply voltage (VDD) during device operation. The circuit also ensures that the device powers up with high output impedance (<SHDN> = 0, typically 500 k. The devices will continue to have a highimpedance 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 device will be held in its Reset state. It 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 F decoupling capacitor, mounted as close as possible to the VDD pin, can provide additional transient immunity. 5V Supply Voltages 001 4.1.3 The input buffer amplifier for the MCP4901/4911/4921 devices provides low offset voltage and low noise. A Configuration bit for each DAC allows the VREF input to bypass the VREF input buffer amplifier, achieving Buffered or Unbuffered mode. Buffered mode provides a very high input impedance, with only minor limitations on the input range and frequency response. Unbuffered mode provides a wide input range (0V to VDD), with a typical input impedance of 165 k with 7 pF. Unbuffered mode (<BUF> = 0) is the default configuration. VPOR VDD - VPOR Transient Duration Time 10 Transient Duration (s) Digital Input Code VOLTAGE REFERENCE AMPLIFIER 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 is a gain of 2x (<GA> = 0). DS22248A-page 20 FIGURE 4-3: = 6 4 Transients above the 2 Transients 0 4.2.1.1 TA 8 1 below the 2 3 4 VDD - VPOR (V) 5 Typical Transient Response. 2010 Microchip Technology Inc. MCP4901/4911/4921 4.2.4 SHUTDOWN MODE The user can shut down the device by using a software command. During Shutdown mode, most of the internal circuits, including the output amplifier, are turned off for power savings. The serial interface remains active, thus allowing a write command to bring the device out of Shutdown mode. There will be no analog output at the VOUT pin, and the VOUT pin is internally switched to a known resistive load (500 k typical. Figure 4-4 shows the analog output stage during Shutdown mode. The device will remain in Shutdown mode until it receives a write command with <SHDN> bit = 1 and the bit is latched into the device. When the device is changed from Shutdown to Active mode, the output settling time takes less than 10 s, but more than the standard active mode settling time (4.5 s). 2010 Microchip Technology Inc. VOUT OP Amp Power-Down Control Circuit Resistive Load 500 k Resistive String DAC FIGURE 4-4: Mode. Output Stage for Shutdown DS22248A-page 21 MCP4901/4911/4921 NOTES: DS22248A-page 22 2010 Microchip Technology Inc. MCP4901/4911/4921 5.0 SERIAL INTERFACE 5.1 Overview The MCP4901/4911/4921 devices are designed to interface directly with the Serial Peripheral Interface (SPI) port, which is 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, thus the data cannot be read out of the MCP4901/4911/4921. 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 through Register 5-3 detail the input register that is used to configure and load the DAC register for each device. Figure 5-1 through Figure 5-3 show the write command for each device. Refer to Figure 1-1 and the SPI Timing Specifications Table for detailed input and output timing specifications for both Mode 0,0 and Mode 1,1 operation. 2010 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 DAC's input register. The MCP4901/4911/4921 utilizes a double-buffered latch structure to allow the analog output to be synchronized with the LDAC pin, if desired. By bringing the LDAC pin down to a low state, the content stored in the DAC's input register is transferred into the DAC's output register (VOUT), and VOUT is updated. All writes to the MCP4901/4911/4921 devices are 16-bit words. Any clocks past the 16th clock will be ignored. The Most Significant 4 bits are Configuration bits. The remaining 12 bits are data bits. No data can be transferred into the device with CS high. This transfer will only occur if 16 clocks have been transferred into the device. If the rising edge of CS occurs prior to that, shifting of data into the input register will be aborted. DS22248A-page 23 MCP4901/4911/4921 REGISTER 5-1: WRITE COMMAND REGISTER FOR MCP4921 (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 0 BUF 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 MCP4911 (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 0 BUF GA SHDN D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 x W-x x bit 15 bit 0 REGISTER 5-3: WRITE COMMAND REGISTER FOR MCP4901 (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 0 BUF GA SHDN D7 D6 D5 D4 D3 D2 D1 D0 x x x W-x bit 15 x bit 0 Where: bit 15 0 = Write to DAC register 1 = Ignore this command bit 14 BUF: VREF Input Buffer Control bit 1 = Buffered 0 = Unbuffered bit 13 GA: Output Gain Selection bit 1 = 1x (VOUT = VREF * D/4096) 0 = 2x (VOUT = 2 * VREF * D/4096) bit 12 SHDN: Output Shutdown Control bit 1 = Active mode operation. VOUT is available. 0 = Shutdown the device. Analog output is not available. VOUT pin is connected to 500 ktypical) 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 DS22248A-page 24 x = bit is unknown 2010 Microchip Technology Inc. MCP4901/4911/4921 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 SDI 0 12 data bits BUF GA SHDN D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 LDAC VOUT FIGURE 5-1: Write Command for MCP4921 (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 SDI 0 12 data bits BUF GA SHDN D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 X X LDAC VOUT FIGURE 5-2: Write Command for MCP4911 (10-bit DAC). Note: X are don't care bits. 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 SDI 0 BUF GA SHDN D7 12 data bits D6 D5 D4 D3 D2 D1 D0 X X X X LDAC VOUT FIGURE 5-3: Write Command for MCP4901(8-bit DAC). Note: X are don't care bits. 2010 Microchip Technology Inc. DS22248A-page 25 MCP4901/4911/4921 NOTES: DS22248A-page 26 2010 Microchip Technology Inc. MCP4901/4911/4921 TYPICAL APPLICATIONS VDD C1 VDD VREF Applications generally suited for the devices are: * * * * * Set Point or Offset Trimming Sensor Calibration Digitally-Controlled Multiplier/Divider Portable Instrumentation (Battery Powered) Motor Control Feedback Loop 6.1 Digital Interface The MCP4901/4911/4921 devices utilize a 3-wire synchronous serial protocol to transfer the DAC's setup and output values from the digital source. The serial protocol can be interfaced to SPI or Microwire peripherals that are common on many microcontrollers, including Microchip's PIC(R) MCUs and dsPIC(R) DSCs. In addition to the three serial connections (CS, SCK and SDI), the LDAC pin synchronizes the analog output (VOUT) with the pin event. By bringing the LDAC pin down "low", the DAC input code and settings in the input register are latched into the output register, and the analog output is updated. 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 4 to 3 I/O pins. In this case, the DAC output can be immediately updated when a valid 16-clock transmission has been received and CS pin has been raised. 6.2 Power Supply Considerations The typical application will require a bypass capacitor in order to filter high-frequency noise. 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 F (ceramic) and (b) 10 F (tantalum). These capacitors should be placed as close to the device power pin (VDD) as possible (within 4 mm). VOUT C1 VDD C2 CS1 SDI VREF VOUT SDI C2 C1 AVSS SDO SCK LDAC PIC(R) Microcontroller C1 = 10 F C2 = 0.1 F MCP49X1 The MCP4901/4911/4921 family devices are general purpose DACs intended to be used in applications where precision with low-power and moderate bandwidth is required. MCP49X1 6.0 CS0 VSS AVSS FIGURE 6-1: Diagram. 6.3 Typical Connection Layout Considerations Inductively-coupled AC transients and digital switching noises can degrade the input and output signal integrity, potentially reducing the device's 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 best performance. Particularly harsh environments may require shielding of critical signals. Breadboards and wire-wrapped boards are not recommended if low noise is desired. 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 should reside on the analog plane. 2010 Microchip Technology Inc. DS22248A-page 27 MCP4901/4911/4921 6.4 6.4.1.1 Single-Supply Operation The MCP4901/4911/4921 devices are rail-to-rail 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 an external output buffer for most applications. 6.4.1 DC SET POINT OR CALIBRATION A common application for DAC devices is digitally-controlled set points and/or calibration of variable parameters, such as sensor offset or slope. For example, the MCP4921 and MCP4922 provide 4096 output steps. If the external voltage reference (VREF) is 4.096V, the LSb size is 1 mV. If a smaller output step size is desired, a lower external voltage reference is needed. Decreasing Output Step Size 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 V resolution per step. Two common methods to achieve a 0.8V range is to either reduce VREF to 0.82V or use a voltage divider on the DAC's output. 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 an 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. 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. (a) Single Output DAC: MCP4901 MCP4911 MCP4921 VDD (b) Dual Output DAC: MCP4902 MCP4912 MCP4922 VCC+ RSENSE VDD VREF VO DAC VOUT Comparator R1 VTRIP R2 0.1 uF VCC- SPI 3-wire Dn V OUT = V REF G -----N 2 R2 Vtrip = V OUT -------------------- R1 + R2 EXAMPLE 6-1: DS22248A-page 28 G = Gain selection (1x or 2x) Dn = Digital value of DAC (0-255) for MCP4901/MCP4902 = Digital value of DAC (0-1023) for MCP4911/MCP4912 = Digital value of DAC (0-4095) for MCP4921/MCP4922 N = DAC Bit Resolution EXAMPLE CIRCUIT OF SET POINT OR THRESHOLD CALIBRATION. 2010 Microchip Technology Inc. MCP4901/4911/4921 6.4.1.2 Building a "Window" DAC If the threshold is not near VREF 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 pull-up and pull-down resistor. Example 6-2 and Example 6-4 illustrate 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. (a) Single Output DAC: MCP4901 MCP4911 MCP4921 (b) Dual Output DAC: MCP4902 MCP4912 MCP4922 VREF VCC+ VCC+ Rsense VDD DAC VOUT R3 R1 Comparator Vtrip 0.1 F R2 VCC- SPI 3 VCC- Dn V OUT = VREF G -----N 2 G = Gain selection (1x or 2x) Dn = Digital value of DAC (0-255) for MCP4901/MCP4902 = Digital value of DAC (0-1023) for MCP4911/MCP4912 = Digital value of DAC (0-4095) for MCP4921/MCP4922 N = DAC Bit Resolution Thevenin Equivalent R 2 R3 R 23 = -----------------R2 + R 3 R1 VOUT V CC+ R2 + VCC- R3 V 23 = ---------------------------------------------------R 2 + R3 V OUT R23 + V 23 R1 V trip = ------------------------------------------R 2 + R23 EXAMPLE 6-2: VO R23 V23 SINGLE-SUPPLY "WINDOW" DAC. 2010 Microchip Technology Inc. DS22248A-page 29 MCP4901/4911/4921 6.5 Bipolar Operation Bipolar operation is achievable using the MCP4901/ 4911/4921 family devices by using 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 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 VREF instead of VSS if a higher offset is desired. Note that a pull-up to VREF could be used, instead of R4, if a higher offset is desired. VREF (a) Single Output DAC: MCP4901 MCP4911 MCP4921 VREF VDD VOUT (b) Dual Output DAC: R3 DAC MCP4902 MCP4912 MCP4922 VCC+ R1 VO VIN+ VCC- R4 0.1 F SPI 3 Dn VOUT = V REF G -----N 2 VIN+ V OUT R4 = ------------------R3 + R 4 R2 R VO = V IN+ 1 + -----2- - VDD ------ R1 R1 EXAMPLE 6-3: 6.5.1 G = Gain selection (1x or 2x) Dn = Digital value of DAC (0 - 255) for MCP4901/MCP4902 = Digital value of DAC (0 - 1023) for MCP4911/MCP4912 = Digital value of DAC (0 - 4095) for MCP4921/MCP4922 N = DAC Bit Resolution DIGITALLY-CONTROLLED BIPOLAR VOLTAGE SOURCE. DESIGN EXAMPLE: DESIGN A BIPOLAR DAC USING EXAMPLE 6-3 WITH 12-BIT MCP4912 OR MCP4922 An output step magnitude of 1 mV with an output range of 2.05V is desired for a particular application. The following steps show the details: 1. Calculate the range: +2.05V - (-2.05V) = 4.1V. 2. Calculate the resolution needed: 4.1V/1 mV = 4100 Since 212 = 4096, 12-bit resolution is desired. 3. The amplifier gain (R2/R1), multiplied by VREF, 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 source needs to be determined first. If a VREF of 4.1V is used, solve for the gain by setting the DAC to 0, knowing that the output needs to be -2.05V. The equation can be simplified to: - R2 - 2.05 - 2.05 --------- = ------------- = ------------R1 V REF 4.1 4. Next, solve for R3 and R4 by setting the DAC to 4096, knowing that the output needs to be +2.05V. R4 2.05V + 0.5V REF 2 ----------------------- = ----------------------------------------- = --1.5VREF R3 + R 4 3 If R4 = 20 k, then R3 = 10 k R2 1 ------ = --R1 2 If R1 = 20 k and R2 = 10 k, the gain will be 0.5 DS22248A-page 30 2010 Microchip Technology Inc. MCP4901/4911/4921 6.6 Selectable Gain and Offset Bipolar Voltage Output Using DAC Devices This circuit is typically used in Multiplier mode and is ideal for linearizing a sensor whose slope and offset varies. Refer to Section 6.9 "Using Multiplier Mode" for more information on Multiplier mode. In some applications, precision digital control of the output range is desirable. Example 6-4 illustrates how to use the DAC devices to achieve this in a bipolar or single-supply application. The equation to design a bipolar "window" DAC would be utilized if R3, R4 and R5 are populated. R2 VREFA VDD VOUTA VCC+ R1 DACA DACA (Gain Adjust) VDD VREFB VOUTB VCC+ VO R5 R3 DACB DACB (Offset Adjust) SPI R4 3 0.1uF VCC- VCC- DA VOUTA = V REFA G A -----N 2 DB V OUTB = VREFB G B -----N 2 GX = Gain selection (1x or 2x) N = DAC Bit Resolution DA, DB = Digital value of DAC (0-255) for MCP4901/MCP4902 VOUTB R 4 + VCC- R3 V IN+ = ----------------------------------------------R3 + R4 = Digital value of DAC (0-1023) for MCP4911/MCP4912 = Digital value of DAC (0-4095) for MCP4912/MCP4922 R2 R V O = V IN+ 1 + -----2- - V OUTA ------ R 1 R 1 Offset Adjust Gain Adjust Bipolar "Window" DAC using R4 and R5 Thevenin Equivalent V CC+ R4 + V CC- R 5 V45 = ------------------------------------------R4 + R5 VOUTB R 45 + V45 R 3 V IN+ = ---------------------------------------------R3 + R 45 R4 R5 R 45 = -----------------R4 + R5 R2 R V O = VIN+ 1 + -----2- - V OUTA ------ R1 R1 Offset Adjust Gain Adjust EXAMPLE 6-4: BIPOLAR VOLTAGE SOURCE WITH SELECTABLE GAIN AND OFFSET. 2010 Microchip Technology Inc. DS22248A-page 31 MCP4901/4911/4921 6.7 Designing a Double-Precision DAC 1. Example 6-5 illustrates how to design a single-supply voltage output capable of up to 24-bit resolution by using 12-bit DACs. This design is simply a voltage divider with a buffered output. As an example, if a similar application to the one developed in Section 6.5.1 "Design Example: Design a bipolar dac using example 6-3 with 12-bit MCP4912 or MCP4922" required a resolution of 1 V instead of 1 mV and a range of 0V to 4.1V, then 12-bit resolution would not be adequate. 2. 3. 4. VDD VREF DACA VDD DACB Calculate the resolution needed: 4.1V/1 V = 4.1x 106. Since 222 = 4.2 x 106, 22-bit resolution is desired. Since DNL = 0.75 LSB, this design can be done with the MCP4921 or MCP4922. Since the DACB`s VOUTB has a resolution of 1 mV, its output only needs to be "pulled" 1/1000 to meet the 1 V target. Dividing VOUTA by 1000 would allow the application to compensate for DACB's DNL error. If R2 is 100, then R1 needs to be 100 k. The resulting transfer function is not perfectly linear, as shown in the equation of Example 6-5. VCC+ VOUTA VO DACA (Fine Adjust) R1 R1 >> R2 VOUTB R2 0.1 F VCC- DACB (Course Adjust) SPI 3 DA V OUTA = VREFA GA ------12 2 G = Gain selection (1x or 2x) D = Digital value of DAC (0-4096) VOUTA R 2 + VOUTB R 1 V O = ----------------------------------------------------R 1 + R2 DB V OUTB = VREFB GB ------12 2 EXAMPLE 6-5: DS22248A-page 32 SIMPLE, DOUBLE PRECISION DAC WITH MCP4921 OR MCP4922. 2010 Microchip Technology Inc. MCP4901/4911/4921 6.8 Building Programmable Current Source 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 for 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 is dissipated across it. 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 the resolution around the range of interest. VDD or VREF (a) Single Output DAC: VREF VDD IL VOUT DAC (b) Dual Output DAC: MCP4902 MCP4912 MCP4922 Load VCC+ MCP4901 MCP4911 MCP4921 Ib SPI 3-wire VCC- RSENSE I Ib = ----L VOUT IL = --------------- -----------R sense + 1 where Common-Emitter Current Gain Dn VOUT = V REF G -----N 2 EXAMPLE 6-6: G = Gain select (1x or 2x) Dn = Digital value of DAC (0-255) for MCP4901/MCP4902 = Digital value of DAC (0-1023) for MCP4911/MCP4912 = Digital value of DAC (0-4095) for MCP4921/MCP4922 N = DAC Bit Resolution DIGITALLY-CONTROLLED CURRENT SOURCE. 2010 Microchip Technology Inc. DS22248A-page 33 MCP4901/4911/4921 6.9 Using Multiplier Mode If the gain selection bit is configured for 1x mode (<GA> = 1), the resulting input signal will be attenuated by D/2n. With the 12-bit DAC (MCP4921 or MCP4922), if the gain is configured for 2x mode (<GA> = 0), codes less than 2048 attenuate the signal, while codes greater than 2048 gain the signal. The MCP4901/4911/4921 and MCP4902/MCP4912/ MCP4922 family devices use external reference, and these devices are ideally suited for use as a multiplier/ divider in a signal chain. Common applications are: (a) precision programmable gain/attenuator amplifiers and (b) motor control feedback loops. The wide input range (0V - VDD) is in Unbuffered mode, and near rail-to-rail range in Buffered mode. Its bandwidth (> 400 kHz), selectable 1x/2x gain and low power consumption give maximum flexibility to meet the application's needs. A DAC provides significantly more gain/attenuation resolution when compared to typical programmable gain amplifiers. Adding an op amp to buffer the output, as illustrated in Examples 6-2 through 6-6, extends the output range and power to meet the precise needs of the application. To configure the device for multiplier applications, connect the input signal to VREF and serially configure the DAC's input buffer, gain and output value. The DAC's output can utilize any of the examples from 6-1 to 6-6, depending on the application requirements. Example 6-7 is an illustration of how the DAC can operate in a motor control feedback loop. VRPM_SET VRPM (a) Single Output DAC: MCP4901 MCP4911 MCP4921 (b) Dual Output DAC: MCP4902 MCP4912 MCP4922 VDD DAC VREF ZFB VOUT VCC+ + - VCC- SPI 3 Rsense Dn V OUT = V REF G -----N 2 EXAMPLE 6-7: DS22248A-page 34 MULTIPLIER MODE USING VREF INPUT. 2010 Microchip Technology Inc. MCP4901/4911/4921 7.0 DEVELOPMENT SUPPORT 7.1 Evaluation & Demonstration Boards The Mixed Signal PICtailTM Board supports the MCP4901/4911/4921 family of devices. Please refer to www.microchip.com for further information on this product's capabilities and availability. 2010 Microchip Technology Inc. DS22248A-page 35 MCP4901/4911/4921 NOTES: DS22248A-page 36 2010 Microchip Technology Inc. MCP4901/4911/4921 8.0 PACKAGING INFORMATION 8.1 Package Marking Information 8-Lead DFN (2x3) Example: AHS 010 25 XXX YWW NN Example: 8-Lead MSOP XXXXXX 4901E YWWNNN 010256 8-Lead PDIP (300 mil) XXXXXXXX XXXXXNNN YYWW MCP4901 E/P e3 256 1010 8-Lead SOIC (150 mil) XXXXXXXX XXXXYYWW NNN Legend: XX...X Y YY WW NNN e3 * Note: Example: Example: MCP4901E SN e3 1010 256 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 Microchip Technology Inc. DS22248A-page 37 MCP4901/4911/4921 !"##$&'* + 2% & %! % * ") ' % * $%% "% %% 133)))& &3 * e D b N N L K E2 E EXPOSED PAD NOTE 1 NOTE 1 2 1 1 2 D2 BOTTOM VIEW TOP VIEW A A3 A1 NOTE 2 4% & 5&% 6!&( $ 55,, 6 6 67 8 9 % 7 : % 9 %"$$ . 0%%* + ,2 7 5 % /0 7 ;"% , ,# ""5 % + < ,# "";"% , . < . ( . + 0%%5 % 5 + . 0%%%,# "" = < < 0%%;"% ./0 +/0 .. + !" #$ %! &'(!%&! %( % ")%% % " * & & # "% ( % " + * ) !% " & "% ,-. /01 / & % #%! ))%!%% ,21 $ & '! !)%!%% '$$&% ! ) 0+0 DS22248A-page 38 2010 Microchip Technology Inc. MCP4901/4911/4921 !"##$&'* + 2% & %! % * ") ' % * $%% "% %% 133)))& &3 * 2010 Microchip Technology Inc. DS22248A-page 39 MCP4901/4911/4921 /:# ; <:':;* + 2% & %! % * ") ' % * $%% "% %% 133)))& &3 * D N E E1 NOTE 1 1 2 e b A2 A c L L1 A1 4% & 5&% 6!&( $ 55,, 6 6 67 8 9 % 7 : % < >./0 < " "* * . 9. . %"$$ < . 7 ;"% , " "* ;"% , +/0 7 5 % +/0 2%5 % 5 2% % 5 /0 > 9 .,2 2% I ? < 9? 5 "* 9 < + 5 ";"% ( < + !" #$ %! &'(!%&! %( % ")%% % " & ","%!" &"$ %! "$ %! % # ".&& " + & "% ,-. /01 / & % #%! ))%!%% ,21 $ & '! !)%!%% '$$&% ! ) 0/ DS22248A-page 40 2010 Microchip Technology Inc. MCP4901/4911/4921 Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging 2010 Microchip Technology Inc. DS22248A-page 41 MCP4901/4911/4921 :# ; <://>!"##$&':;?* + 2% & %! % * ") ' % * $%% "% %% 133)))& &3 * D e N E E1 NOTE 1 1 2 3 h b h A2 A c L A1 L1 4% & 5&% 6!&( $ 55,, 6 6 67 8 9 % 7 : % < /0 < " "* * . < < %"$$@ < . 7 ;"% , " "* ;"% , +/0 7 5 % /0 . >/0 0&$ A %B . < . 2%5 % 5 < 2% % 5 ,2 2% ? < 9? 5 "* < . 5 ";"% ( + < . "$% .? < .? "$% /%%& .? < .? + !" #$ %! &'(!%&! %( % ")%% % " @ $%0% % + & ","%!" &"$ %! "$ %! % # ".&& " & "% ,-. /01 / & % #%! ))%!%% ,21 $ & '! !)%!%% '$$&% ! ) 0./ DS22248A-page 42 2010 Microchip Technology Inc. MCP4901/4911/4921 :# ; <://>!"##$&':;?* + 2% & %! % * ") ' % * $%% "% %% 133)))& &3 * 2010 Microchip Technology Inc. DS22248A-page 43 MCP4901/4911/4921 ?< <# $&'?* + 2% & %! % * ") ' % * $%% "% %% 133)))& &3 * N NOTE 1 E1 1 3 2 D E A2 A L A1 c e eB b1 b 4% & 5&% 6!&( $ 60:, 6 6 67 8 9 % % % < < " "* * . + . / % % . < < !" %!" ;"% , + +. " "* ;"% , . 9 7 5 % +9 +>. % % 5 . + . 5 "* 9 . ( > ( 9 / < < 4 5 ";"% 5) 5 ";"% 7 ) @ /0 + + !" #$ %! &'(!%&! %( % ")%% % " @ $%0% % + & ","%!" &"$ %! "$ %! % # "C " & "% ,-. /01/ & % #%! ))%!%% ) 09/ DS22248A-page 44 2010 Microchip Technology Inc. MCP4901/4911/4921 APPENDIX A: REVISION HISTORY Revision A (April 2010) * Original Release of this Document. 2010 Microchip Technology Inc. DS22248A-page 45 MCP4901/4911/4921 NOTES: DS22248A-page 46 2010 Microchip Technology Inc. MCP4901/4911/4921 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 MCP4901: 8-Bit Voltage Output DAC MCP4901T: 8-Bit Voltage Output DAC (Tape and Reel) MCP4911: 10-Bit Voltage Output DAC MCP4911T: 10-Bit Voltage Output DAC (Tape and Reel) MCP4921: 12-Bit Voltage Output DAC MCP4921T: 12-Bit Voltage Output DAC (Tape and Reel) c) d) e) f) Temperature Range E = -40C to +125C Package MC = MS SN = = P = (Extended) 8-Lead Plastic Dual Flat, No Lead Package 2x3x0.9 mm Body (DFN) 8-Lead Plastic Micro Small Outline (MSOP) 8-Lead Plastic Small Outline - Narrow, 150 mil (SOIC) 8-Lead Plastic Dual In-Line (PDIP) g) h) i) j) k) l) m) n) o) p) q) r) s) t) u) 2010 Microchip Technology Inc. MCP4901-E/P: Extended temperature, PDIP package. MCP4901-E/SN: Extended temperature, SOIC package. MCP4901T-E/SN: Extended temperature, SOIC package Tape and Reel. MCP4901-E/MS: Extended temperature, MSOP package. MCP4901T-E/MS: Extended temperature, MSOP package Tape and Reel. MCP4901-E/MC: Extended temperature, DFN package. MCP4901T-E/MC:Extended temperature, DFN package Tape and Reel. Extended temperature, PDIP package. MCP4911-E/SN: Extended temperature, SOIC package. MCP4911T-E/SN: Extended temperature, SOIC package Tape and Reel. MCP4911-E/MS: Extended temperature, MSOP package. MCP4911T-E/MS: Extended temperature, MSOP package Tape and Reel. MCP4911-E/MC: Extended temperature, DFN package. MCP4911T-E/MC: Extended temperature, DFN package Tape and Reel. MCP4911-E/P: Extended temperature, PDIP package. MCP4921-E/SL: Extended temperature, SOIC package. MCP4921T-E/SL: Extended temperature, SOIC package Tape and Reel. MCP4921-E/MS: Extended temperature, MSOP package. MCP4921T-E/MS: Extended temperature, MSOP package Tape and Reel. MCP4921-E/MC: Extended temperature, DFN package. MCP4921T-E/MC:Extended temperature, DFN package Tape and Reel. MCP4921-E/P: DS22248A-page 47 MCP4901/4911/4921 NOTES: DS22248A-page 48 2010 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, KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART, PIC32 logo, rfPIC and UNI/O are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. FilterLab, Hampshire, HI-TECH C, Linear Active Thermistor, MXDEV, MXLAB, SEEVAL and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A. Analog-for-the-Digital Age, Application Maestro, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, HI-TIDE, In-Circuit Serial Programming, ICSP, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, mTouch, Octopus, Omniscient Code Generation, PICC, PICC-18, PICDEM, PICDEM.net, PICkit, PICtail, REAL ICE, rfLAB, Select Mode, Total Endurance, TSHARC, UniWinDriver, WiperLock 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. All other trademarks mentioned herein are property of their respective companies. (c) 2010, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. ISBN: Microchip received ISO/TS-16949:2002 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(R) MCUs and dsPIC(R) DSCs, KEELOQ(R) 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. 2010 Microchip Technology Inc. DS22248A-page 49 WORLDWIDE SALES AND SERVICE AMERICAS ASIA/PACIFIC ASIA/PACIFIC EUROPE Corporate Office 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7200 Fax: 480-792-7277 Technical Support: http://support.microchip.com Web Address: www.microchip.com Asia Pacific Office Suites 3707-14, 37th Floor Tower 6, The Gateway Harbour City, Kowloon Hong Kong Tel: 852-2401-1200 Fax: 852-2401-3431 India - Bangalore Tel: 91-80-3090-4444 Fax: 91-80-3090-4123 India - New Delhi Tel: 91-11-4160-8631 Fax: 91-11-4160-8632 Austria - Wels Tel: 43-7242-2244-39 Fax: 43-7242-2244-393 Denmark - Copenhagen Tel: 45-4450-2828 Fax: 45-4485-2829 India - Pune Tel: 91-20-2566-1512 Fax: 91-20-2566-1513 France - Paris Tel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79 Japan - Yokohama Tel: 81-45-471- 6166 Fax: 81-45-471-6122 Germany - Munich Tel: 49-89-627-144-0 Fax: 49-89-627-144-44 Atlanta Duluth, GA Tel: 678-957-9614 Fax: 678-957-1455 Boston Westborough, MA Tel: 774-760-0087 Fax: 774-760-0088 Chicago Itasca, IL Tel: 630-285-0071 Fax: 630-285-0075 Cleveland Independence, OH Tel: 216-447-0464 Fax: 216-447-0643 Dallas Addison, TX Tel: 972-818-7423 Fax: 972-818-2924 Detroit Farmington Hills, MI Tel: 248-538-2250 Fax: 248-538-2260 Kokomo Kokomo, IN Tel: 765-864-8360 Fax: 765-864-8387 Los Angeles Mission Viejo, CA Tel: 949-462-9523 Fax: 949-462-9608 Santa Clara Santa Clara, CA Tel: 408-961-6444 Fax: 408-961-6445 Toronto Mississauga, Ontario, Canada Tel: 905-673-0699 Fax: 905-673-6509 Australia - Sydney Tel: 61-2-9868-6733 Fax: 61-2-9868-6755 China - Beijing Tel: 86-10-8528-2100 Fax: 86-10-8528-2104 China - Chengdu Tel: 86-28-8665-5511 Fax: 86-28-8665-7889 Korea - Daegu Tel: 82-53-744-4301 Fax: 82-53-744-4302 China - Chongqing Tel: 86-23-8980-9588 Fax: 86-23-8980-9500 Korea - Seoul Tel: 82-2-554-7200 Fax: 82-2-558-5932 or 82-2-558-5934 China - Hong Kong SAR Tel: 852-2401-1200 Fax: 852-2401-3431 Malaysia - Kuala Lumpur Tel: 60-3-6201-9857 Fax: 60-3-6201-9859 China - Nanjing Tel: 86-25-8473-2460 Fax: 86-25-8473-2470 Malaysia - Penang Tel: 60-4-227-8870 Fax: 60-4-227-4068 China - Qingdao Tel: 86-532-8502-7355 Fax: 86-532-8502-7205 Philippines - Manila Tel: 63-2-634-9065 Fax: 63-2-634-9069 China - Shanghai Tel: 86-21-5407-5533 Fax: 86-21-5407-5066 Singapore Tel: 65-6334-8870 Fax: 65-6334-8850 China - Shenyang Tel: 86-24-2334-2829 Fax: 86-24-2334-2393 Taiwan - Hsin Chu Tel: 886-3-6578-300 Fax: 886-3-6578-370 China - Shenzhen Tel: 86-755-8203-2660 Fax: 86-755-8203-1760 Taiwan - Kaohsiung Tel: 886-7-536-4818 Fax: 886-7-536-4803 China - Wuhan Tel: 86-27-5980-5300 Fax: 86-27-5980-5118 Taiwan - Taipei Tel: 886-2-2500-6610 Fax: 886-2-2508-0102 China - Xian Tel: 86-29-8833-7252 Fax: 86-29-8833-7256 Thailand - Bangkok Tel: 66-2-694-1351 Fax: 66-2-694-1350 Italy - Milan Tel: 39-0331-742611 Fax: 39-0331-466781 Netherlands - Drunen Tel: 31-416-690399 Fax: 31-416-690340 Spain - Madrid Tel: 34-91-708-08-90 Fax: 34-91-708-08-91 UK - Wokingham Tel: 44-118-921-5869 Fax: 44-118-921-5820 China - Xiamen Tel: 86-592-2388138 Fax: 86-592-2388130 China - Zhuhai Tel: 86-756-3210040 Fax: 86-756-3210049 01/05/10 DS22248A-page 50 2010 Microchip Technology Inc.