MCP4902/4912/4922 8/10/12-Bit Dual Voltage Output Digital-to-Analog Converter with SPI Interface Features Description • • • • • • The MCP4902/4912/4922 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.
MCP4902/4912/4922 Block Diagram LDAC CS SDI SCK Interface Logic Input Register A Input Register B String DACB String DACA Buffer Gain Logic VDD VSS DACB Register DACA Register VREF A Power-on Reset VREF B Buffer Gain Logic Output Op Amps Output Logic VOUTA DS22250A-page 2 SHDN VOUTB 2010 Microchip Technology Inc.
MCP4902/4912/4922 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...............................................
MCP4902/4912/4922 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 VOS/°C — 0.16 — ppm/°C -45°C to 25°C — -0.44 — ppm/°C +25°C to 85°C gE — -0.10 1 % of FSR G/°C — -3 — ppm/°C Input Range – Buffered Mode VREF 0.040 — VDD – 0.
MCP4902/4912/4922 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 Units Conditions Operating Voltage VDD 2.7 — 5.
MCP4902/4912/4922 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 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 THDVREF — — — dB VREF = 2.5V ±0.
MCP4902/4912/4922 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.
MCP4902/4912/4922 TEMPERATURE CHARACTERISTICS Electrical Specifications: Unless otherwise indicated, VDD = +2.7V to +5.5V, VSS = GND.
MCP4902/4912/4922 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.
MCP4902/4912/4922 Note: Unless otherwise indicated, TA = +25°C, VDD = 5V, VSS = 0V, VREF = 2.048V, Gain = 2x, 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 (ºC) 3072 4096 Code (Decimal) FIGURE 2-7: Absolute INL vs. Temperature (MCP4922). FIGURE 2-10: Note: 3 INL vs. Code (MCP4922). Single device graph (Figure 2-10) for illustration of 64 code effect. 0.2 Temp = - 40oC to +125oC 2.5 0.
MCP4902/4912/4922 Note: Unless otherwise indicated, TA = +25°C, VDD = 5V, VSS = 0V, VREF = 2.048V, Gain = 2x, RL = 5 k, CL = 100 pF. 96 128 160 192 224 256 Code FIGURE 2-13: DNL vs. Code and Temperature (MCP4902). IDD (μA) IDD Histogram (VDD = 2.7V). FIGURE 2-16: 0.5 16 o 14 o -40 C to +85 C 12 Occurrence 0.25 INL (LSB) 325 64 315 32 305 0 295 -0.06 285 215 -0.04 275 -0.02 265 0 255 0.02 245 Occurrence DNL (LSB) 0.
MCP4902/4912/4922 Note: Unless otherwise indicated, TA = +25°C, VDD = 5V, VSS = 0V, VREF = 2.048V, Gain = 2x, RL = 5 k, CL = 100 pF. 2 -0.08 VDD 5.5V 5.0V 4.0V 1 3.0V 2.7V 0.5 5.5V Gain Error (%) ISHDN (μA) 1.5 VDD -0.1 5.0V -0.12 4.0V 3.0V 2.7V -0.14 -0.16 0 -40 -20 -40 0 20 40 60 80 100 120 Ambient Temperature (ºC) FIGURE 2-18: Hardware Shutdown Current vs. Ambient Temperature and VDD. -20 0 20 40 60 80 100 120 Ambient Temperature (ºC) FIGURE 2-21: Gain Error vs.
MCP4902/4912/4922 VDD 5.5V 5.0V 4.0V 3.0V 2.7V -40 -20 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 5.5V 0.0035 0.003 5.0V 0.0025 4.0V 3.0V 2.7V 0.002 0.0015 -40 -20 0 20 40 60 80 100 120 Ambient Temperature (ºC) FIGURE 2-24: Input Hysteresis vs. Ambient Temperature and VDD. FIGURE 2-27: VOUT Low Limit vs. Ambient 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.
MCP4902/4912/4922 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 2-30: VOUT Rise Time. Time (1 µs/div) FIGURE 2-33: VOUT Rise Time. VOUT VOUT SCK SCK LDAC LDAC Time (1 µs/div) VOUT Fall Time. FIGURE 2-34: Shutdown. VOUT SCK LDAC Time (1 µs/div) FIGURE 2-32: DS22250A-page 14 VOUT Rise Time Exit Ripple Rejection (dB) FIGURE 2-31: Time (1 µs/div) VOUT Rise Time.
MCP4902/4912/4922 Note: Unless otherwise indicated, TA = +25°C, VDD = 5V, VSS = 0V, VREF = 2.50V, Gain = 2x, RL = 5 k, CL = 100 pF. 0 Attenuation (dB) -2 -4 -6 -8 -10 -12 100 FIGURE 2-36: Frequency (kHz) 160 416 672 928 1184 1440 1696 1952 2208 2464 2720 2976 3232 3488 3744 1,000 Multiplier Mode Bandwidth.
MCP4902/4912/4922 NOTES: DS22250A-page 16 2010 Microchip Technology Inc.
MCP4902/4912/4922 3.0 PIN DESCRIPTIONS The descriptions of the pins are listed in Table 3-1. TABLE 3-1: 3.1 PIN FUNCTION TABLE Pin No. Symbol Function 1 VDD Supply Voltage Input (2.7V to 5.5V) 2 NC No Connection 3 CS Chip Select Input 4 SCK Serial Clock Input 5 SDI Serial Data Input 6 NC No Connection 7 NC No Connection 8 LDAC Synchronization Input.
MCP4902/4912/4922 NOTES: DS22250A-page 18 2010 Microchip Technology Inc.
MCP4902/4912/4922 4.0 GENERAL OVERVIEW The MCP4902, MCP4912 and MCP4922 are dual voltage-output 8-bit, 10-bit and 12-bit DAC devices, respectively. These devices include input amplifiers, rail-to-rail output amplifiers, reference buffers for external 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.
MCP4902/4912/4922 4.2.2 111 110 Actual transfer function 101 100 Ideal transfer function 011 010 Wide code, > 1 LSb 001 4.2.3 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.
MCP4902/4912/4922 4.2.4 SHUTDOWN MODE The user can shut down each DAC channel selectively by using a software command or shut down all channels by using the SHDN pin. During Shutdown mode, most of the internal circuits in the channel that was shut down are turned off for power savings. The serial interface remains active, thus allowing a write command to bring the device out of the Shutdown mode.
MCP4902/4912/4922 NOTES: DS22250A-page 22 2010 Microchip Technology Inc.
MCP4902/4912/4922 5.0 SERIAL INTERFACE 5.1 Overview The MCP4902/4912/4922 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 MCP4902/4912/4922.
MCP4902/4912/4922 REGISTER 5-1: WRITE COMMAND REGISTER FOR MCP4922 (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 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 MCP4912 (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 BUF 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
MCP4902/4912/4922 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 12 data bits A/B BUF GA SHDN D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 LDAC VOUT FIGURE 5-1: Write Command for MCP4922 (12-bit DAC).
MCP4902/4912/4922 NOTES: DS22250A-page 26 2010 Microchip Technology Inc.
MCP4902/4912/4922 TYPICAL APPLICATIONS VDD Applications generally suited for the devices are: • • • • • VDD Set Point or Offset Trimming Sensor Calibration Digitally-Controlled Multiplier/Divider Portable Instrumentation (Battery Powered) Motor Control Feedback Loop 6.1 Digital Interface The MCP4902/4912/4922 utilizes a 3-wire synchronous serial protocol to transfer the DAC’s setup and output values from the digital source.
MCP4902/4912/4922 6.4 Single-Supply Operation 6.4.1.1 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 is to either reduce VREF to 0.82V or use a voltage divider on the DAC’s output. The MCP4902/4912/4922 family of devices are rail-torail voltage output DAC devices designed to operate with a VDD range of 2.7V to 5.5V.
MCP4902/4912/4922 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.
MCP4902/4912/4922 6.5 Bipolar Operation Bipolar operation is achievable using the MCP4902/ 4912/4922 family of 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: Example 6-3 illustrates a simple bipolar voltage source configuration.
MCP4902/4912/4922 6.6 Selectable Gain and Offset Bipolar Voltage Output Using a Dual DAC 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 MCP4902/4912/4922 to achieve this in a bipolar or single-supply application.
MCP4902/4912/4922 6.7 Designing a Double-Precision DAC Using a Dual DAC 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. This design is simply a voltage divider with a buffered output. As an example, if a application similar to the one developed in Section 6.5.1 “Design Example: Design a Bipolar DAC Using Example 6-3 with 12-bit MCP4922 or MCP4921” required a resolution of 1 µV instead of 1 mV and a range of 0V to 4.
MCP4902/4912/4922 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.
MCP4902/4912/4922 6.9 Using Multiplier Mode If the gain selection bit is configured for 1x mode ( = 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 ( = 0), the codes less than 2048 attenuate the signal, while the codes greater than 2048 gain the signal. The MCP4902/4912/4922 family of devices use external reference, and these devices are ideally suited for use as a multiplier/divider in a signal chain.
MCP4902/4912/4922 7.0 DEVELOPMENT SUPPORT 7.1 Evaluation and Demonstration Boards The Mixed Signal PICtailTM Demo Board supports the MCP4902/4912/4922 family of devices. Please refer to www.microchip.com for further information on this products capabilities and availability. 2010 Microchip Technology Inc.
MCP4902/4912/4922 NOTES: DS22250A-page 36 2010 Microchip Technology Inc.
MCP4902/4912/4922 8.0 PACKAGING INFORMATION 8.1 Package Marking Information 14-Lead PDIP (300 mil) Example: XXXXXXXXXXXXXX XXXXXXXXXXXXXX YYWWNNN 14-Lead SOIC (150 mil) MCP4922 E/P e3 1011256 Example: XXXXXXXXXX XXXXXXXXXX YYWWNNN Example: 14-Lead TSSOP XXXXXX YYWW 4922E/ST 1011 NNN 256 Legend: XX...
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MCP4902/4912/4922 Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging DS22250A-page 42 2010 Microchip Technology Inc.
MCP4902/4912/4922 APPENDIX A: REVISION HISTORY Revision A (April 2010) • Original Release of this Document. 2010 Microchip Technology Inc.
MCP4902/4912/4922 NOTES: DS22250A-page 44 2010 Microchip Technology Inc.
MCP4902/4912/4922 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.
MCP4902/4912/4922 NOTES: DS22250A-page 46 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.
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