19-2765; Rev 3; 8/11 EVALUATION KIT AVAILABLE MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs General Description Features The MAX174/MX574A/MX674A are complete 12-bit analog-to-digital converters (ADCs) that combine high speed, low-power consumption, and on-chip clock and voltage reference. The maximum conversion times are 8µs (MAX174), 15µs (MX674A), and 25µs (MX574A). Maxim’s BiCMOS construction reduces power dissipation 3 times (150mW) over comparable devices. The internal buried zener reference provides low-drift and low-noise performance. External component requirements are limited to only decoupling capacitors and fixed resistors. The versatile analog input structure allows for 0 to +10V or 0 to +20V unipolar or ±5V or ±10V bipolar input ranges with pin strapping. SComplete ADC with Reference and Clock S12-Bit Resolution and Linearity SNo Missing Codes Over Temperature S150mW Power Dissipation S8µs (MAX174), 15µs (MX674A), and 25µs (MX574A) Max Conversion Times SPrecision Low TC Reference: 10ppm/NC SMonolithic BiCMOS Construction S150ns Maximum Data Access Time Applications The MAX174/MX574A/MX674A use standard microprocessor interface architectures and can be interfaced to 8-, 12-, and 16-bit wide buses. Three-state data outputs are controlled by CS, CE, and R/C logic inputs. Digital Signal Processing High-Accuracy Process Control High-Speed Data Acquisition Ordering Information appears at end of data sheet. Electro-Mechanical Systems Functional Diagram VL DGND 1 VCC 15 BIPOFF VEE 7 11 10VIN 20VIN 12 13 R REFIN 10 14 5kI 2R 9.950kI 5kI 12-BIT DAC AGND REFOUT 9 8 12 SAR +10V REF MAX174 MX574A MX674A 4 4 4 LOW NIBBLE 16 D0 MIDDLE NIBBLE 19 D3 HIGH NIBBLE 20 D4 23 D7 24 D8 2 CLOCK AND CONTROL LOGIC 27 D11 28 6 3 4 12/8 CS A0 5 STS CE R/C For related parts and recommended products to use with this part, refer to www.maxim-ic.com/MAX174.related. ����������������������������������������������������������������� Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs ABSOLUTE MAXIMUM RATINGS VCC to DGND...............................................................0 to 16.5V VEE to DGND................................................................0 to 16.5V VL to DGND.......................................................................0 to 7V DGND to AGND.................................................................... Q1V Control Inputs to DGND (CE, CS, A0, 12/8, R/C)......................... -0.3V to (VCC + 0.3V) Digital Output Voltage to DGND (DB11–DB0, STS)...................................... -0.3V to (VL + 0.3V) Analog Inputs to AGND (REFIN, BIPOFF, 10VIN)............ Q16.5V 20VIN to AGND.................................................................... Q24V REFOUT.................................... Indefinite short to VCC or AGND Power Dissipation (any package) to +75NC..................1000mW Derates above +75NC ...............................................10mW/NC Operating Temperature Ranges MAX174_C, MX_74AJ/K/L....................................... 0 to +70NC MAX174_E, MX_74AJE/KE/LE......................... -40NC to +85NC MAX174_M, MX_74AS/T/U............................. -55NC to +125NC Storage Temperature Range............................. -55NC to +160NC Lead Temperature (soldering, 10s).................................+300NC Soldering Temperature (reflow) PDIP, Wide SO..............................................................+260NC PLCC.............................................................................+245NC Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS—MAX174 (VL = +5V, VEE = +15V or +12V, VEE = -15V or -12V, TA = +25NC, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS ACCURACY Resolution 12 RES TA = +25°C Integral Nonlinearity MAX174A/B MAX174C MAX174AC/BC INL TA = TMIN to TMAX MAX174AE/BE/AM/BM MAX174C Differential Nonlinearity Unipolar Offset Error (Note 1) Bipolar Offset Error (Notes 2, 3) DNL Bits ±1/2 ±1 ±1/2 ±1 12 bits, no missing codes over temperature ±1 MAX174A/B ±1 MAX174C ±2 MAX174A ±3 MAX174B/C ±4 Full-Scale Calibration Error (Note 3) LSB ±3/4 ±0.25 LSB LSB LSB % TEMPERATURE COEFFICIENTS (Using Internal Reference) (Notes 2, 3, 4) Unipolar Offset Change Bipolar Offset Change MAX174A/B ±1 MAX174C ±2 MAX174AC/BC ±1 MAX174CC ±2 MAX174AE/AM ±1 MAX174BE/BM ±2 MAX174CE/CM ±4 LSB LSB ����������������������������������������������������������������� Maxim Integrated Products 2 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs ELECTRICAL CHARACTERISTICS—MAX174 (continued) (VL = +5V, VEE = +15V or +12V, VEE = -15V or -12V, TA = +25NC, unless otherwise noted.) PARAMETER SYMBOL Full-Scale Calibration Change CONDITIONS MIN TYP MAX MAX174AC ±2 (10) MAX174BC ±5 (27) MAX174CC ±9 (50) MAX174AE ±7 (19) MAX174BE ±10 (38) MAX174CE ±20 (75) MAX174AM ±5 (12) MAX174BM ±10 (25) MAX174CM ±20 (50) UNITS LSB (ppm/°C INTERNAL REFERENCE MAX174A 9.98 10.00 10.02 MAX174B/C 9.97 10.00 10.03 Output Voltage No load Output Current (Note 5) Available for external loads, in addition to REFIN and BIPOFF load V 2 mA MAX UNITS ELECTRICAL CHARACTERISTICS—MX574A, MX674A (VL = + 5V, VEE = +15V or +12V, VEE = -15V or -12V, TA = +25NC, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP ACCURACY Resolution 12 RES TA = +25°C MX574AK/L/T/U, MX674AK/L/T/U MX574AJ/S, MX674AJ/S Integral Nonlinearity INL TA = TMIN to TMAX Differential Nonlinearity Unipolar Offset Error (Note 1) Bipolar Offset Error (Notes 2, 3) Full-Scale Calibration Error (Note 3) DNL Bits ±1/2 ±1 MX574AK/L/KE/LE ±1/2 MX674AK/L/KE/LE ±1/2 MX574AT/U, MX674AT/U ±3/4 MX574AJ/S, MX674AJ/S ±1 12 bits, no missing codes over temperature ±1 MX574AK/L/T/U, MX674AK/L/T/U ±1 MX574AJ/S, MX674AJ/S ±2 MX574AL/U, MX674AL/U ±3 MX574AJ/K/S/T, MX674AJ/K/S/T ±4 MX574AL/U ±0.125 MX574AJ/K/S/T, MX674A ±0.25 LSB LSB LSB LSB % TEMPERATURE COEFFICIENTS (Using Internal Reference) (Notes 2, 3, 4) Unipolar Offset Change MX574AK/L/T/U, MX674AK/L/T/U ±1 MX574AJ/S, MX674AJ/S ±2 LSB ����������������������������������������������������������������� Maxim Integrated Products 3 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs ELECTRICAL CHARACTERISTICS—MX574A, MX674A (continued) (VL = + 5V, VEE = +15V or +12V, VEE = -15V or -12V, TA = +25NC, unless otherwise noted.) PARAMETER SYMBOL Bipolar Offset Change Full-Scale Calibration Change CONDITIONS MIN TYP MAX MX574AK/L, MX674AK/L ±1 MX574AJ, MX674AJ ±2 MX574AU/LE, MX674AU/LE ±1 MX574AT/KE, MX674AT/KE ±2 MX574AS/JE, MX674AS/JE ±4 MX574AL, MX674AL ±2 (10) MX574AK, MX674AK ±5 (27) MX574AJ, MX674AJ ±9 (50) MX574ALE, MX674ALE ±7 (19) MX574AKE, MX674AKE ±10 (38) MX574AJE, MX674AJE ±20 (75) MX574AU, MX674AU ±5 (12) MX574AT, MX674AT ±10 (25) MX574AS, MX674AS ±20 (50) UNITS LSB LSB (ppm/°C INTERNAL REFERENCE MX574AL/U 9.99 10.00 10.01 MX574AJ/K/S/T, MX674AL/U 9.98 10.00 10.02 MX674AJ/K/S/T 9.97 10.00 10.03 Output Voltage No load Output Current (Note 5) Available for external loads, in addition to REFIN and BIPOFF load V 2 mA MAX UNITS ELECTRICAL CHARACTERISTICS—MAX174/MX574/MX674A (VL = +5V, VCC = +15V or +12V, VEE = -15V or -12V, TA = +25NC, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP ANALOG INPUT Bipolar Input Range Unipolar Input Range Input Impedance Using 10V input ±5 Using 20V input ±10 Using 10V input 0 +10 Using 20V input 0 +20 10V input 3 5 7 20V input 6 10 14 MAX174A/B, MX_74AK/L/TU ±1/8 ±1 MAX174C, MX_74AJ/S ±1/8 ±2 V V kW POWER-SUPPLY REJECTION (Max Change in Full-Scale Calibration) VCC Only 15V ±1.5V or 12V ±0.6V VEE Only 15V ±1.5V or 12V ±0.6V ±1/8 ±1/2 LSB VL Only 5V ±0.5V ±1/8 ±1/2 LSB 0.8 V LSB LOGIC INPUTS Input Low Voltage VIL Input High Voltage VIH CS, CE, R/C, A0, 12/8 CS, CE, R/C, A0, 12/8 2.0 V ����������������������������������������������������������������� Maxim Integrated Products 4 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs ELECTRICAL CHARACTERISTICS—MAX174/MX574/MX674A (continued) (VL = +5V, VCC = +15V or +12V, VEE = -15V or -12V, TA = +25NC, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS Input Current IIN CS, CE, R/C, A0, 12/8, VIN = 0 to VL Input Capacitance CIN CS, CE, R/C, A0, 12/8 Output Low Voltage VOL DB11–DB0, STS ISINK = 1.6mA Output High Voltage VOH DB11–DB0, STS ISOURCE = 500µA Floating State Leakage Current ILKG DB11–DB0, STS VOUT = 0 to VL Floating State Output Capacitance COUT DB11–DB0 MIN TYP MAX UNITS ±5 µA 7 pF LOGIC OUTPUTS 0.4 4 V V ±10 8 µA pF CONVERSION TIME 12-Bit Cycle tCONV 8-Bit Cycle tCONV MX574A 15 20 25 MX674A 9 12 15 MAX174 6 7 8 MX574A 10 14 18 MX674A 6 8 11 MAX174 4 5 6 µs µs POWER REQUIREMENTS VCC Operating Range 11.4 16.5 V VL Operating Range 4.5 5.5 V VEE Operating Range -11.4 -16.5 V VCC Supply Current (Note 5) ICC 3 5 mA VL Supply Current (Note 5) IL 3 8 mA VEE Supply Current (Note 5) IEE Power Dissipation (Note 5) PD Note Note Note Note Note VCC = +15V and VEE = -15V 6 10 mA 150 265 mW 1: Adjustable to zero. 2: With 50ω fixed resistor from REFOUT to BIPOFF. Adjustable to zero. 3: With 50ω fixed resistor from REFOUT to REFIN. Adjustable to zero. 4: Maximum change in specification from TA = +25°C to TMIN or TA = +25°C to TMAX. 5: External load current should not change during a conversion. For Q12V supply operation, REFOUT need not be buffered except when external load in addition to REFIN and BIPOFF inputs have to be driven. ����������������������������������������������������������������� Maxim Integrated Products 5 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs TIMING CHARACTERISTICS—MAX174/MX574A/MX674A (Note 6) (VL = +5V, VCC = +15V or +12V, VEE = -15V or -12V.) PARAMETER TA = -40°C TO +85°C T = -55°C TO +125°C TA = 0°C TO +70° C A UNITS TA = +25°C SYMBOL CONDITIONS MIN TYP MAX 100 200 MIN TYP MAX MIN TYP MAX CONVERT START TIMING—FULL CONTROL MODE STS Delay from CE tDSC CE Pulse Width tHEC CL = 50pF 50 CS to CE Setup tSSC CS Low During CE High tHSC R/C to CE Setup 15 250 320 ns 50 50 ns 50 50 50 ns 50 50 50 ns tSRC 50 50 50 ns R/C Low During CE High tHRC 50 50 50 ns A0 to CE Setup tSAC 0 0 0 ns A0 Valid During CE High tHAC 50 50 50 ns READ TIMING—FULL CONTROL MODE Access Time (From CE) tDD Data Valid After CE Low tHD Output Float Delay tHL CL = 100pF 60 25 120 40 150 20 75 200 15 100 ns ns 120 ns CS to CE Setup tSSR 50 50 50 ns R/C to CE Setup tSRR 0 0 0 ns A0 to CE Setup tSAR 50 50 50 ns CS Valid After CE Low tHSR 0 0 0 ns R/C High After CE Low tHRR 0 0 0 ns A0 Valid After CE Low tHAR 0 0 0 ns Low R/C Pulse Width tHRL 50 50 50 ns STS Delay from R/C tDS STAND-ALONE MODE Data Valid After R/C Low STS Delay After Data Valid 115 tHDR tHS High R/C Pulse Width tHRH Data Access Time tDDR 15 200 250 20 320 25 40 MX574A 300 600 1000 300 1000 300 1000 MX674A 30 320 600 30 600 30 600 MAX174 30 140 300 30 300 30 400 150 CL = 100pF 15 150 60 120 ns 200 150 ns ns ns 200 ns Note 6: Timing specifications guaranteed by design. All input control signals specified with tR = tF = 5ns (10% to 90% of +5V) and timed from a voltage level of +1.6V. See loading circuits in Figures 1 and 2. ����������������������������������������������������������������� Maxim Integrated Products 6 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs +5V +5V 3kI 3kI 3kI DN DN DN DN 3kI 100pF 100pF Figure 1. Load Circuit for Access Time Test LOGIC 0 TO HIGH - Z LOGIC 1 TO HIGH - Z HIGH-Z TO LOGIC 1 HIGH-Z TO LOGIC 1 100pF 100pF Figure 2. Load Circuit for Output Float Delay Test Pin Configurations TOP VIEW 28 STS 12/8 2 27 D11 A0 CS 12/8 + VL 1 CS 3 26 D10 4 3 2 A0 4 25 D9 VL STS D11 D10 27 26 R/C 5 25 D9 23 D7 CE 6 24 D8 22 D6 VCC 7 REFOUT 8 AGND 9 24 D8 REFIN 10 19 D3 VEE 11 18 D2 BIPOFF 12 17 D1 10VIN 13 16 D0 20VIN 14 15 DGND 21 D5 REFIN 10 20 D4 VEE 11 19 D3 12 13 14 15 16 17 18 D2 20 D4 D1 AGND 9 22 D6 D0 21 D5 DGND REFOUT 8 23 D7 MAX174 MX574A MX674A 20VIN VCC 7 28 10VIN CE 6 MAX174 MX574A MX674A 1 BIPOFF R/C 5 TOP VIEW PLCC DIP/SO Pin Description PIN NAME 1 3 VL 12/8 CS 4 A0 Byte Address/Short-Cycle Input. When starting a conversion, controls number of bits converted (low = 12 bits, high = 8 bits). When reading data, if 12/8 = low, enables low byte (A0 = high) or high byte (A0 = low). 5 R/C Read/Convert Input. When high, the device will be in the data-read mode. When low, the device will be in the conversion start mode. 2 FUNCTION Logic Supply, +5V Data Mode Select Input Chip-Select Input. Must be low to select device. ����������������������������������������������������������������� Maxim Integrated Products 7 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs Pin Description (continued) PIN NAME 6 CE 7 VCC 8 REFOUT 9 AGND Analog Ground 10 REFIN Reference Input 11 VEE BIPOFF 12 13 FUNCTION Chip-Enable Input. Must be high to select device. +12V or +15V Supply +10V Reference Output -12V or -15V Supply Bipolar Offset Input. Connect to REFOUT for bipolar input range. 10V Span Input 14 10VIN 20VIN 15 DGND Digital Ground 16–27 D0–D11 28 STS 20V Span Input Three-State Data Outputs Status Output Detailed Description Converter Operation The MAX174/MX574A/MX674A use a successive approximation technique to convert an unknown analog input to a 12-bit digital output code. The control logic provides easy interface to most microprocessors. Most applications require only a few external passive components to perform the analog-to-digital (A/D) function. The internal voltage output DAC is controlled by a successive approximation register (SAR) and has an output impedance of 2.5kω. The analog input is connected to the DAC output with a 5kω resistor for the 10V input and 10kω resistor for the 20V input. The comparator is essentially a zero-crossing detector, and its output is fed back to the SAR input. The SAR is set to half-scale as soon as a conversion starts. The analog input is compared to 1/2 of the full-scale voltage. The bit is kept if the analog input is greater than halfscale or dropped if smaller. The next bit, bit 10, is then set with the DAC output either at 1/4 scale, if the most significant bit (MSB) is dropped, or 3/4 scale if the MSB is kept. The conversion continues in this manner until the least significant bit (LSB) is tried. At the end of the conversion, the SAR output is latched into the output buffers. Digital Interface CE, CS, and R/C control the operation of the MAX174/ MX574A/MX674A. While both CE and CS are asserted, the state of R/C selects whether a conversion (R/C = 0) or a data read (R/C = 1) is in progress. The register control inputs, 12/8 and A0, select the data format and conversion length. A0 is usually tied to the LSB of the address bus. To perform a full 12-bit conversion, set A0 low during a convert start. For a shorter 8-bit conversion, A0 must be high during a convert start. Output Data Format During a data read, A0 also selects whether the three state buffers contain the 8 MSBs (A0 = 0) or the 4 LSBs (A0 = 1) of the digital result. The 4 LSBs are followed by 4 trailing 0s. Output data is formatted according to the 12/8 pin. If this input is low, the output will be a word broken into two 8-bit bytes. This allows direct interlace to 8-bit buses without the need for external three-state buffers. If 12/8 is high, the output will be one 12-bit word. A0 can change state while a data-read operation is in effect. To begin a conversion, the microprocessor must write to the ADC address. Then, since a conversion usually takes longer than a single clock cycle, the microprocessor must wait for the ADC to complete the conversion. Valid data will be made available only at the end of the conversion, which is indicated by STS. STS can be ether polled or used to generate an interrupt upon completion. Or, the microprocessor can be kept idle by inserting the appropriate number of No Operation (NOP) instructions between the conversion-start and data-read commands. ����������������������������������������������������������������� Maxim Integrated Products 8 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs BIPOFF 20VIN 10VIN REFIN 5kI 2R* -50I 9.950kI R* DAC 5kI 2.5kI 1.6kI REFIN 2 SAR Figure 3. Analog Equivalent Circuit CE CS X R/C X 12/8 X A0 0 X None OPERATION X 1 X X X None 1 0 0 X 0 Initiate 12-bit conversion 1 0 0 X 1 Initiate 12-bit conversion 1 0 1 1 X Enable 12-bit conversion 1 0 1 0 0 Enable 8 MSBs 1 0 1 0 1 Enable 4 LSBs + 4 trailing 0s After the conversion is completed, data can be obtained by the microprocessor. The ADCs have the required logic for 8-, 12-, and 16-bit bus interfacing, which is determined by the 12/8 input. If 12/8 is high, the ADCs are configured for a 16-bit bus. Data lines D0–D11 may be connected to the bus as either the 12 MSBs or the 12 LSBs. The other 4 bits must be masked out in software. For 8-bit bus operation, 12/8 is set low. The format is left justified, and the even address, A0 low, contains the 8 MSBs. The odd address, A0 high, contains the 4 LSBs, which is followed by 4 trailing 0s. There is no need to use a software mask when the ADCs are connected to an 8-bit bus. Table 2. MAX174/MX574A/MX674A Data Format for 8-Bit Bus D7 D6 D5 D4 D3 D2 D1 D0 High Byte (A0 = 0) MSB D10 D9 D8 D7 D6 D5 D4 Low Byte (A0 = 1) D3 D2 D1 D0 0 0 0 0 MAX174 MX574A MX674A 27 (MSB) D7 26 (D10) D6 25 (D9) D5 24 (D8) D4 23 (D7) D3 22 (D6) D2 21 (D5) D1 20 (D4) D0 19 (D3) 18 (D2) 17 (D1) 16 (LSB) DATA BUS Table 1. Truth Table HARDWIRING FOR 8-BIT DATA BUSES Note that the output cannot be forced to a right-justified format by rearranging the data lines on the 8-bit bus interface. ����������������������������������������������������������������� Maxim Integrated Products 9 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs Timing and Control Convert Start Timing—Full Control Mode R/C must be low before asserting both CE and CS. If it is high, a brief read operation occurs possibly resulting in system bus contention. To initiate a conversion, use either CE or CS. CE is recommended since it is shorter by one propagation delay than CS and is the faster input of the two. CE is used to begin the conversion in Figure 4. The STS output is high during the conversion indicating the ADC is busy. During this period, additional convert start commands will be ignored, so that the conversion cannot be prematurely terminated or restarted. However, if the state of A0 is changed after the beginning of the conversion, any additional start conversion transitions will latch the new state of A0, possibly resulting in an incorrect conversion length (8 bits vs. 12 bits) for that conversion. Read Timing—Full Control Mode Figure 5 illustrates the read-cycle timing. While reading data, access time is measured from when CE and R/C are both high. Access time is extended 10ns if CS is used to initiate a read. tHEC CE CE tHSC tHSR tSSR tSSC CS CS tHRC tSRC tSRR tHRR tSAR tHAR R/C R/C tHAC tSAC A0 A0 tDSC tC STS STS tDD D0–D11 D0–D11 tHD,tHL HIGH IMPEDANCE HIGH IMPEDANCE Figure 4. Convert Start Timing Figure 5. Read Timing ���������������������������������������������������������������� Maxim Integrated Products 10 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs Stand-Alone Operation For systems which do not use or require full bus interfacing, the MAX174/MX574A/MX674A can be operated in a stand-alone mode directly linked through dedicated input ports. When configured in the stand-alone mode, conversion is controlled by R/C. In addition, CS and A0 are wired low; CE and 12/8 are wired high. To enable the three-state buffers, set R/C low. A conversion starts when R/C is set high. This allows either a high- or a low-pulse control signal. Shown in Figure 6 is the operation with a low pulse. In this mode, the outputs, in response to the falling edge of R/C, are forced into the high-impedance state and return to valid logic-levels after the conversion is complete. The STS output goes high following the R/C falling edge and returns low when the conversion is complete. tHRL R/C tDS STS tHDR Grounding The recommended power-supply grounding practice is shown in Figure 8. The ground reference point for the onchip reference is AGND. It should be connected directly to the analog reference point of the system. The analog and digital grounds should be connected together at the package in order to gain all of the accuracy possible from the MAX174/MX574A/MX674A in high digital noise environments. In situations permitting, they can be connected to the most accessible ground-reference point. The preference is analog power return. HIGH IMPEDANCE Figure 6. Low Pulse for R//C in Stand-Alone Mode tHRH R/C tDS STS Analog Considerations Physical Layout For best system performance, PCBs should be used for the MAX174/MX574A/MX674A. Wirewrap boards are not recommended. The layout of the board should ensure that digital and analog signal lines are kept separated from each other as much as possible. Care should be taken not to run analog and digital lines parallel to each other or digital lines underneath the MAX174/MX574A/ MX674A. tHS D0–11 A high-pulse conversion initiation is illustrated in Figure 7. When R/C is high, the data lines are enabled. The next conversion starts with the falling edge of R/C. The data lines return and remain in high impedance state until another R/C high pulse. Application Hints tC tHDR tDDR HIGH IMPEDANCE D0–11 Figure 7. High Pulse for R//C in Stand-Alone Mode ANALOG SUPPLY -15V VEE GND S/H AND ANALOG CIRCUITRY GND VCC VEE DIGITAL SUPPLY +15V +5V AGND VCC VL DGND MAX174 MX574A MX674A GND +5V DGND DIGITAL CIRCUITRY Figure 8. Power-Supply Grounding Practice ���������������������������������������������������������������� Maxim Integrated Products 11 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs Power-Supply Bypassing The MAX174/MX574A/MX674A power supplies must be filtered, well regulated, and free from high-frequency noise, or unstable output codes will result. Unless great care is taken in filtering any switching spikes present in the output, switching power supplies is not suggested for applications requiring 12-bit resolution. Take note that a few millivolts of noise converts to several error counts in a 12-bit ADC. All power-supply pins should use supply decoupling capacitors connected with short lead length to the pins, as shown in Figure 9. The VCC and VEE pins should be decoupled directly to AGND. A 4.7µF tantalum type in parallel with a 0 1µF disc ceramic type is a suitable decoupling. Internal Reference When using the 20VIN as the analog input, load capacitance on the 10VIN pin must be minimized. Especially on the faster MAX174, leave the 10VIN pin open to minimize capacitance and to prevent linearity errors caused by inadequate settling time. The amplifier driving the analog input must have low enough DC output impedance for low full-scale error. Furthermore, low AC output impedance is also required since the analog input current is modulated at the clock rate during the conversion. The output impedance of an amplifier is the open-loop output impedance divided by the loop gain at the frequency of interest. MX574A and MX674A—The approximate internal clock rate is 600kHz and 1MHz, respectively, and amplifiers like the MAX400 can be used to drive the input. The MAX174/MX574A/MX674A have an internal buried zener reference that provides a 10V, low-noise and low temperature drift output. An external reference voltage can also be used for the ADC. When using ±15V supplies, the internal reference can source up to 2mA in addition to the BIPOFF and REFIN inputs over the entire operating temperature range. With ±12V supplies, the reference can drive the BIPOFF and REFIN inputs over temperature, but it CANNOT drive an additional load. MAX174—The internal clock rate is 2MHz and faster amplifiers like the OP-27, AD711, or OP-42 are required. Driving the Analog Input The input leads to AGND and 10VIN or 20VIN should be as short as possible to minimize noise pick up. If long leads are needed, use shielded cables. The STS output may be used to provide the Hold signal to the track-and-hold amplifier. However, since the A/D’s DAC is switched at approximately the same time as the conversion is initiated, the switching transients at the output of the T/H caused by the DAC switching may result in code dependent errors. It is recommended that the Hold signal to the T/H amplifier precede a conversion or be coincident with the conversion start. +5V VL C4 C1 DIGITAL GROUND DGND RECOMMENDED VCC +12V/15V C5 C2 C6 C3 ANALOG GROUND AGND VEE -12V/15V C1, C2, C4 – 0.1µF CERAMIC C4, C5, C6 – 4.7µF MAX174 MX574A MX674A Track-and-Hold Interface The analog input to the ADC must be stable to within 1/2 LSB during the entire conversion for specified 12-bit accuracy. This limits the input signal bandwidth to a couple of hertz for sinusoidal inputs even with the faster MAX174. For higher bandwidth signals, a track-and-hold amplifier should be used. The first bit decision by the A/D is made approximately 1.5 clock cycles after the start of the conversion. This is 2.5µs, 1.5µs, and 0.8µs for the MX574A, MX674A, and MAX174, respectively. The T/H hold settling time must be less than this time. For the MX574A and MX674A, the AD585 sample-and-hold is recommended (Figure 10). For the MAX174, a faster T/H amplifier, like the HA5320 or HA5330, should be used (Figure 11). Input Configurations The MAX174/MX574A/MX674A input range can be set using pin strapping. Table 3 shows the possible input ranges and ideal transition voltages. End-point errors can be adjusted in all ranges. Figure 9. Power-Supply Bypassing ���������������������������������������������������������������� Maxim Integrated Products 12 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs Table 3. Input Ranges and Ideal Digital Output Codes ANALOG INPUT VOLTAGE (V) Note Note Note Note DIGITAL OUTPUT 0 to +10V 0 to +20V ±5V ±10V +10.0000 +20.0000 +5.0000 +10.0000 1111 1111 1111 +9.9963 +19.9927 +4.9963 +9.9927 1111 1111 1110* +5.0012 +10.0024 +0.0012 +0.0024 1000 0000 0000* +4.9988 +9.9976 -0.0012 -0.0024 0111 1111 1111* +4.9963 +9.9927 -0.0037 -0.0073 0111 1111 1110* +0.0012 +0.0024 -4.9988 -9.9976 0000 0000 0000* 0.0000 0.0000 -5.0000 -10.0000 0000 0000 0000 7: For 8: For 9: For 10: For MSB LSB unipolar input ranges, output coding is straight binary. bipolar input ranges, output coding is offset binary. 0 to + 10V or ±5V ranges, 1 LSB = 2.44mV. 0 to +20V or ±10V ranges, 1 LSB = 4.88mV. *The digital outputs will be flickering between the Indicated code and the indicated code plus one. +VS +15V 4.7µF 0.1µF HOLD AD585* LREF -VS -15V 4.7µF CONTROL INPUTS STS 0.1µF D0 –11 HOLD 20VIN VOUT 10VIN -VIN MX574A* MX674A VCC 4.7µF 0.1µF 4.7µF 0.1µF 4.7µF BIPOFF VEE 50I +VIN ANALOG INPUT +15V 0.1µF REFOUT -15V 50I GND VL REFIN AGND DGND +5V *ADDITIONAL PINS OMITTED FOR CLARITY Figure 10. MX574/MX674A to AD585 Sample-and-Hold Interface ���������������������������������������������������������������� Maxim Integrated Products 13 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs +VS +15V 4.7µF S/H CONTROL INPUTS STS 0.1µF D0 –11 HA5320* MAX174* 20VIN -VS -15V 4.7µF 0.1µF VCC 10VIN VOUT -VIN +VIN 0.1µF 4.7µF VEE REFOUT GND 4.7µF BIPOFF 50I ANALOG INPUT +15V 0.1µF -15V 50I VL REFIN AGND DGND +5V 0.1µF 4.7µF *ADDITIONAL PINS OMITTED FOR CLARITY Figure 11. MAX174 to HA5320 Sample-and-Hold Interface Unipolar Input Operation The unipolar transfer function and input connections are shown in Figures 12 and 13. Because all internal resistors of the MAX174/MX574A/ MX674A are trimmed for absolute calibration, additional trimming is not necessary for most applications. The absolute accuracy for each grade is given in the specification tables. If the offset trim is not needed, BIPOFF can be tied directly to AGND. The two resistors and trimmer for BIPOFF can then be discarded. A 50ω ±1% metal film resistor should be attached between REFOUT and REFIN. For a 0 to +10V input range, the analog input is connected between AGND and 10VIN. For a 0 to +20V input range, the analog input is connected between AGND and 20VIN. These ADCs can easily handle an input signal beyond the supplies. If full-scale trim is not needed, the gain trimmer, R2, should be swapped with a 50ω resistor. Should a 10.24V input range be selected, a 200ω trimmer should be inserted in series with 10VIN. For a fullscale input range of 20.48V, use a 500ω trimmer in series with 20VIN. The nominal input impedance into 10VIN is 5kω and 10kω for 20VIN. Offset and Full-Scale Adjustment In applications where the offset and full-scale range have to be adjusted, use the circuit shown in Figure 12. The offset should be adjusted first. Apply 1/2 LSB at the analog input and adjust R1 until the digital output code flickers between 0000 0000 0000 and 0000 0000 0001. To adjust the full-scale range, apply FS - 3/2 LSB at the analog input and adjust R2 until the output code changes between 1111 1111 1110 and 1111 1111 1111. Bipolar Input Operation The bipolar transfer function is shown in Figure 14, and input connections are shown in Figure 15. One or both of the trimmers can be exchanged with a 50ω ±1% fixed resistor if the offset and gain specifications suffice. Offset and Full-Scale Adjustment To begin bipolar calibration, a signal 1/2 LSB above negative full-scale is applied. R1 is trimmed until the digital output flickers between 0000 0000 0000 and 0000 0000 0001. Next, a signal 3/2 LSB below positive full scale is applied. Then, R2 is trimmed until the output flickers between 1111 1111 1110 and 1111 1111 1111. ���������������������������������������������������������������� Maxim Integrated Products 14 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs OUTPUT CODE FS = 4069 LSBs 1111 1111 1111 OUTPUT CODE 1111 1111 1110 FS = 4069 LSBs 1111 1111 1101 1000 0000 0001 1111 1111 1111 1000 0000 0000 1111 1111 1110 FULL-SCALE TRANSITION 1111 1111 1101 0111 1111 1111 0111 1111 1110 0000 0000 0011 0000 0000 0011 0000 0000 0010 0000 0000 0010 0000 0000 0001 0000 0000 0000 0000 0000 0001 0 1 2 FS-1 FS 3 0000 0000 0000 - FS +2 2 FS 2 - - FS +1 2 -2 -1 0 FS 1 FS 2 2 2 FS 1 2 ANALOG INPUT VOLTAGE IN LSBs Figure 12. Ideal Unipolar Transfer Function GAIN REFOUT R2 100I +12V TO +15V Figure 14. Ideal Bipolar Transfer Function MAX174* MX574A MX674A GAIN REFIN R2 100I REFIN REFOUT 100kI OFFSET R1 100kI BIPOFF BIPOFF R1 100I OFFSET 100I -12V TO -15V ANALOG INPUTS MAX174* MX574A MX674A 0 TO +10V 0 TO +20V 10VIN 20VIN ANALOG INPUTS Q5V 10VIN Q10V 20VIN AGND *ADDITIONAL PINS OMITTED FOR CLARITY Figure 13. Unipolar Input Connections AGND *ADDITIONAL PINS OMITTED FOR CLARITY Figure 15. Bipolar Input Connections ���������������������������������������������������������������� Maxim Integrated Products 15 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs Ordering Information PINPACKAGE PART LINEARITY (LSB) TEMPCO (ppm/NC) 8μs Maximum Conversion Time PINPACKAGE PART LINEARITY (LSB) TEMPCO (ppm/NC) TEMP RANGE: -55NC to +125NC TEMP RANGE: 0NC to +70NC MX674ASQ 28 CERDIP* 1 50 MAX174ACPI+ 28 Plastic DIP ½ 10 MX674ATQ 28 CERDIP* ¾ 25 MAX174BCPI+ 28 Plastic DIP ½ 27 MX674AUQ 28 CERDIP* ¾ 12 MAX174CCPI+ 28 Plastic DIP 1 50 MX674ASD 28 Ceramic SB 1 50 MAX174ACWI+ 28 Wide SO ½ 10 MX674ATD 28 Ceramic SB ¾ 25 MAX174BCWI+ 28 Wide SO ½ 27 MX674AUD 28 Ceramic SB ¾ 12 MAX174CCWI+ 28 Wide SO 1 50 Dice* 1/2 — MAX174BC/D TEMP RANGE: -40NC to +85NC 25μs Maximum Conversion Time TEMP RANGE: 0NC to +70NC MX574AJN+ 28 Plastic DIP 1 50 MAX174AEPI+ 28 Plastic DIP ½ 19 MX574AKN+ 28 Plastic DIP ½ 27 MAX174BEPI+ 28 Plastic DIP ½ 38 MX574ALN+ 28 Plastic DIP ½ 10 MAX174CEPI+ 28 Plastic DIP 1 75 MX574AJCWI+ 28 Wide SO 1 50 MAX174AEWI+ 28 Wide SO ½ 19 MX574AKCWI+ 28 Wide SO ½ 27 MAX174BEWI+ 28 Wide SO ½ 38 MX574ALCWI+ 28 Wide SO ½ 10 MAX174CEWI+ 28 Wide SO 1 75 MX574AJP+ 28 PLCC 1 50 TEMP RANGE: -55NC to +125NC MX574AKP+ 28 PLCC ½ 27 MAX174AMJI 28 CERDIP ¾ 12 MX574ALP+ 28 PLCC ½ 10 MAX174BMJI 28 CERDIP ¾ 25 MX574AK/D Dice* ½ — MAX174CMJ 28 CERDIP 1/21 50 TEMP RANGE: -40NC to +85NC 15μs Maximum Conversion Time TEMP RANGE: 0NC to +70NC MX574AJEPI+ 28 Plastic DIP 1 75 MX574AKEPI+ 28 Plastic DIP ½ 38 MX674AJN+ 28 Plastic DIP 1 50 MX574ALEPI+ 28 Plastic DIP ½ 19 MX674AKN+ 28 Plastic DIP ½ 27 MX574AJEWI+ 28 Wide SO 1 75 MX674ALN+ 28 Plastic DIP ½ 10 MX574AKEWI+ 28 Wide SO ½ 38 MX674AJCWI+ 28 Wide SO 1 50 MX574ALEWI+ 28 Wide SO ½ 19 MX674AKCWI+ 28 Wide SO ½ 27 TEMP RANGE: -55NC to +125NC MX674ALCWI+ 28 Wide SO ½ 10 MX574ASQ 28 CERDIP* 1 50 Dice* ½ — MX574ATQ 28 CERDIP* ¾ 25 MX574AUQ 28 CERDIP* ¾ 12 MX674AK/D TEMP RANGE: -40NC to +85NC MX674AJEPI+ 28 Plastic DIP 1 75 MX574ASD 28 Ceramic SB 1 50 MX674AKEPI+ 28 Plastic DIP ½ 38 MX574ATD 28 Ceramic SB ¾ 25 MX674ALEPI+ 28 Plastic DIP ½ 19 MX574AUD 28 Ceramic SB ¾ 12 MX674AJEWI+ 28 Wide SO 1 75 MX674AKEWI+ 28 Wide SO ½ 38 MX674ALEWI+ 28 Wide SO ½ 19 +Denotes a lead(Pb)-free/RoHS-compliant package. *Maxim reserves the right to ship Ceramic SB in lieu of CERDIP packages. **Consult factory for dice specifications. ���������������������������������������������������������������� Maxim Integrated Products 16 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs Chip Information PROCESS: BiCMOS Package Information For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 28 PDIP P28+2 21-0044 — 28 PLCC Q28+3 21-0049 90-0235 28 Wide SO W28+2 21-0042 90-0109 ���������������������������������������������������������������� Maxim Integrated Products 17 MAX174/MX574A/MX674A Industry-Standard, Complete 12-Bit ADCs Revision History REVISION NUMBER REVISION DATE 0 3/90 Initial release 1 8/11 Updated the Electrical Characteristics and Ordering Information. Added Revision History. DESCRIPTION PAGES CHANGED — 2–4 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2011 Maxim Integrated Products 18 Maxim is a registered trademark of Maxim Integrated Products, Inc.