19-0252; Rev 2; 5/96 Low-Cost, Triple, 8-Bit Voltage-Output DACs with Serial Interface ____________________________Features Operate from a Single +5V (MAX512) or +3V (MAX513) Supply, or from Bipolar Supplies Low Power Consumption 1mA Operating Current <1A Shutdown Current Unipolar or Bipolar Outputs 5MHz, 3-Wire Serial Interface SPI, QSPI, and Microwire Compatible Two Buffered, Bipolar-Output DACs (DACs A/B) Independently Programmable Shutdown Mode Space-Saving 14-Pin SO/DIP Packages Pin and Software Reset ______________Ordering Information PART 14 Plastic DIP MAX512CSD MAX512C/D 0C to +70C 0C to +70C 14 SO Dice* Ordering Information continued at end of data sheet. * Contact factory for dice specifications. ________________Functional Diagram DIN 1 14 LOUT CS 2 13 I.C. SCLK 3 MAX512 MAX513 12 REFAB RESET 4 11 REFC V DD 5 10 OUTC GND 6 9 OUTB V SS 7 8 OUTA DIP/SO CS 2 REFAB REFC 12 11 SCLK 3 16-BIT SHIFT REGISTER DATA (8) TOP VIEW DIN 1 DAC LATCH A DAC A DAC LATCH B DAC B DAC LATCH C DAC C CONTROL (8) __________________Pin Configuration PIN-PACKAGE 0C to +70C ________________________Applications Digital Gain and Offset Adjustment Programmable Attenuators Programmable Current Sources Programmable Voltage Sources RF Digitally Adjustable Bias Circuits VCO Tuning TEMP. RANGE MAX512CPD OUTA 8 OUTB 9 OUTC 10 MAX512 MAX513 LOUT 14 LATCH 4 RESET 5 VDD 7 VSS 6 GND Microwire is a trademark of National Semiconductor Corp. SPI and QSPI are trademarks of Motorola Inc. ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 MAX512/MAX513 _______________General Description The MAX512/MAX513 contain three 8-bit, voltage-output digital-to-analog converters (DAC A, DAC B, and DAC C). Output buffer amplifiers for DACs A and B provide voltage outputs while reducing external component count. The output buffer for DAC A can source or sink 5mA to within 0.5V of VDD or VSS. The buffer for DAC B can source or sink 0.5mA to within 0.5V of V DD or V SS . DAC C is unbuffered, providing a third voltage output with increased accuracy. The MAX512 operates with a single +5V 10% supply, and the MAX513 operates with a +2.7V to +3.6V supply. Both devices can also operate with split supplies. The 3-wire serial interface has a maximum operating frequency of 5MHz and is compatible with SPITM, QSPITM, and MicrowireTM. The serial input shift register is 16 bits long and consists of 8 bits of DAC input data and 8 bits for DAC selection and shutdown. DAC registers can be loaded ---- independently or in parallel at the positive edge of CS. A latched logic output is also available for auxiliary control. Ultra-low power consumption and small packages (14-pin DIP/SO) make the MAX512/MAX513 ideal for portable and battery-powered applications. Supply current is only 1mA, dropping to less than 1A in shutdown. Any of the three DACs can be independently shut down. In shutdown mode, the DAC's R-2R ladder network is disconnected from the reference input, minimizing system power consumption. MAX512/MAX513 Low-Cost, Triple, 8-Bit Voltage-Output DACs with Serial Interface ABSOLUTE MAXIMUM RATINGS VDD to GND ................................................................ -0.3V, +6V VSS to GND................................................................. -6V, +0.3V VDD to VSS ................................................................ -0.3V, +12V Digital Inputs and Outputs to GND............... -0.3V, (VDD + 0.3V) REFAB ................................................ (VSS - 0.3V), (VDD + 0.3V) OUTA, OUTB (Note 1) ....................................................VSS, VDD OUTC.............................................................-0.3V, (VDD + 0.3V) REFC..............................................................-0.3V, (VDD + 0.3V) Continuous Power Dissipation (TA = +70C) Plastic DIP (derate 10.00mW/C above +70C) ............800mW SO (derate 8.33mW/C above +70C) ...........................667mW CERDIP (derate 9.09mW/C above +70C) ...................727mW Operating Temperature Ranges MAX51_C_ _ .........................................................0C to +70C MAX51_E_ _.......................................................-40C to +85C MAX51_MJD ....................................................-55C to +125C Storage Temperature Range .............................-65C to +165C Lead Temperature (soldering, 10sec) .............................+300C Note 1: The outputs may be shorted to VDD, VSS, or GND if the package power dissipation is not exceeded. Typical short-circuit current to GND is 50mA. 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 (V DD = +4.5V to +5.5V for MAX512, V DD = +2.7V to +3.6V for MAX513, V SS = GND = 0V, REFAB = REFC = V DD , TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 1 LSB STATIC PERFORMANCE Resolution N Differential Nonlinearity DNL Integral Nonlinearity INL Total Unadjusted Error TUE Zero-Code Temperature Coefficient Power-Supply Rejection Ratio 8 DAC A/B (Note 2) 1.5 DAC C 1 (Note 2) 1 DAC A/B 100 DAC C PSRR Bits Guaranteed monotonic LSB V/C 5 MAX512, 4.5V VDD 5.5V, REFAB = REFC = 4.096V 0.01 MAX513, 2.7V VDD 3.6V, REFAB = REFC = 2.4V 0.015 LSB LSB %/% REFERENCE INPUTS Reference Input Voltage Range REFAB VSS VDD REFC GND VDD Reference Input Capacitance Reference Input Resistance Reference Input Resistance (shutdown mode) 2 25 RREF REFAB (Note 3) 8 REFC (Note 3) 12 REFAB, REFC V pF k 2 _______________________________________________________________________________________ M Low-Cost, Triple, 8-Bit Voltage-Output DACs with Serial Interface (V DD = +4.5V to +5.5V for MAX512, V DD = +2.7V to +3.6V for MAX513, V SS = GND = 0V, REFAB = REFC = V DD , TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS REF_ V DAC OUTPUTS Output Voltage Range 0 Capacitive Load Output Resistance DAC A 0.10 DAC B 0.01 DAC C 0 F DAC A 0.050 DAC B 0.500 DAC C 24 k DIGITAL INPUTS Input High Voltage VIH Input Low Voltage VIL (0.7)(VDD) Input Current IIN VIN = 0V or VDD Input Capacitance CIN (Notes 4, 5) Output High Voltage VOH ISOURCE 1.6mA Output Low Voltage VOL ISINK 1.6mA SR CL = 0.1F (DAC A), CL = 0.01F (DAC B) V (0.3)(VDD) 0.1 V 10 A 10 pF DIGITAL OUTPUT VDD - 0.4 V 0.4 V DYNAMIC PERFORMANCE Voltage-Output Slew Rate To 12LSB Voltage-Output Settling Time Digital Feedthrough and Crosstalk 0.1 CL = 0.1F (DAC A) 70 CL = 0.01F (DAC B) 70 CL = 0.1nF (DAC C) 35 All 0s to all 1s V/s s 10 nV-s POWER SUPPLIES MAX512 4.5 5.5 MAX513 2.7 3.6 MAX512 -5.5 -4.5 MAX513 -3.6 -2.7 Positive Supply Voltage Range VDD Negative Supply Voltage Range (Note 6) VSS Positive Supply Current IDD All inputs = 0V Negative Supply Current ISS All inputs = 0V, VSS = -5.5V Shutdown Supply Current MAX512 (VDD = 5.5V) 1.3 2.8 MAX513 (VDD = 3.6V) 0.9 2.5 V V mA -1.3 mA 0.1 A Note 2: Digital code from 24 through 232 are due to swing limitations of output amplifiers on DAC A and DAC B. See Typical Operating Characteristics. Note 3: Reference input resistance is code dependent. The lowest input resistance occurs at code 55hex. Refer to the reference input section in the Detailed Description. Note 4: Guaranteed by design. Not production tested. Note 5: Input capacitance is code dependent. The highest capacitance occurs at code 00hex. Note 6: For single-supply mode, tie VSS to GND. _______________________________________________________________________________________ 3 MAX512/MAX513 ELECTRICAL CHARACTERISTICS (continued) TIMING CHARACTERISTICS (Note 4) (VDD = +4.5V to +5.5V for MAX512, VDD = +2.7V to +3.6V for MAX513, VSS = GND = 0V, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER SYMBOL SERIAL INTERFACE TIMING ---- CS Fall to SCLK Rise Setup Time ---- SCLK Rise to CS Rise Setup Time CONDITIONS MIN TYP UNITS MAX tCSS 150 ns tCSH 150 ns DIN to SCLK Rise Setup Time tDS 50 ns DIN to SCLK Rise Hold Time tDH 50 ns SCLK Pulse Width High tCH 100 ns SCLK Pulse Width Low tCL 100 Output Delay LOUT ---- CS Pulse Width High tOD ns CL = 100pF 150 tCSPWH ns 200 ns Note 4: Guaranteed by design. Not production tested. __________________________________________Typical Operating Characteristics (TA = +25C, unless otherwise noted.) 1.5 1 VDD = 3V, VSS = GND = 0V REFAB = VDD CODE = ALL 1s 0.5 0 0.0001 0.001 0.01 0.1 10 DAC B 4.4 4.2 4.0 1 VDD = 5V, VSS = GND = 0V REFAB = VDD CODE = ALL 1s 3.8 0.0001 0.001 0.01 100 OUTPUT SOURCE CURRENT (mA) 8 1 10 0 DAC A LOADED WITH 5mA DAC B NO LOAD 0 DAC C NO LOAD -2 0 32 64 96 128 160 192 224 255 DIGITAL CODE 4 1.5 1.4 10 -20 REFAB = REFC = VDD ALL LOGIC INPUTS GROUNDED 1.3 DAC B LOADED WITH 0.5mA DAC B LOADED WITH 0.5mA DAC A NO LOAD 1 MAX512 TOC-03 100 POSITIVE SUPPLY CURRENT vs. SUPPLY VOLTAGE 1.2 IDD (mA) DAC A LOADED WITH 5mA 0.1 OUTPUT SINK CURRENT (mA) -15 2 300 200 0 0.0001 0.001 0.01 100 TUE (LSB) 6 4 DAC B 400 100 -5 -10 DAC A 600 500 TOTAL UNADJUSTED ERROR vs. DIGITAL CODE (Single Supply) MAX512 TOC-04 10 VDD = +3V, VSS = -3V REFAB = VSS, REFC = VDD CODE = ALL 1s 0.1 VDD = 3V, VSS = GND = 0V 800 REFAB = VDD CODE = ALL 1s 700 OUTPUT SOURCE CURRENT (mA) TOTAL UNADJUSTED ERROR vs. DIGITAL CODE (Dual Supplies) 12 MAX512 TOC-02 4.8 4.6 900 OUTPUT VOLTAGE (mV) DAC B 2 OUTPUT VOLTAGE vs. OUTPUT SINK CURRENT MAX512 TOC-05 OUTPUT VOLTAGE (V) 2.5 DAC A 5.0 OUTPUT VOLTAGE (V) DAC A 3 5.2 MAX512 TOC-01 3.5 OUTPUT VOLTAGE vs. OUTPUT SOURCE CURRENT (VDD = 5V) MAX512 TOC-06 OUTPUT VOLTAGE vs. OUTPUT SOURCE CURRENT (VDD = 3V) TUE (LSB) MAX512/MAX513 Low-Cost, Triple, 8-Bit Voltage Output DACs with Serial Interface 1.1 1.0 0.9 0.8 -25 0.7 -30 VDD = 3V, VSS = GND = 0V REFAB = 3V -35 0 32 64 96 128 160 192 224 255 DIGITAL CODE 0.6 0.5 2.5 3.0 3.5 4.0 VDD (V) _______________________________________________________________________________________ 4.5 5.0 5.5 Low-Cost, Triple, 8-Bit Voltage Output DACs with Serial Interface REFC GROUNDED FOR REF_ < 0 CODE = ALL 1s ISS, VDD = 3V, VSS = -3V -0.5 -1.0 1.340 -3 -2 -1 1 0 3 2 3.0 2.5 2.0 1.5 1.0 0.5 20 40 60 80 100 120 140 -60 -40 -20 0 20 40 60 80 100 120 140 REFAB = REFC (V) TEMPERATURE (C) TEMPERATURE (C) REFERENCE FEEDTHROUGH vs. FREQUENCY REFERENCE LARGE-SIGNAL FREQUENCY RESPONSE REFERENCE SMALL-SIGNAL FREQUENCY RESPONSE -40 DAC C -60 -80 DAC A, B 0 -5 -10 -15 -20 -100 -120 0.1 1 10 FREQUENCY (kHz) 100 1000 MAX512 TOC-11 5 MAX512 TOC-10 VDD = 3V, VSS = GND = 0V REF_ FROM 0V TO 2.9V NO LOAD CODE = ALL 0s 0.01 3.5 VDD = +5V, VSS = GND = 0V REFAB = REFC = VDD ALL LOGIC INPUTS = +5V 0 -60 -40 -20 0 4 0 RELATIVE OUTPUT (dB) FEEDTHROUGH (dB) VDD = +5V, VSS = GND = 0V REFAB = REFC = VDD ALL LOGIC INPUTS = +5V ALL DACs SET TO ALL 1s 1.345 ISS, VDD = 5V, VSS = -5V -5 -4 -20 MAX512 TOC-08 1.350 -1.5 0 1.355 4.0 -25 0.001 0.01 0.1 1 DAC B -40 -80 10 FREQUENCY (kHz) 100 1000 DAC A DAC C -20 -60 VDD = 3V, VSS = GND = 0V REFAB, REFC SINE WAVE 0V TO VDD MAX512 TOC-12 IDD, VDD = 3V, VSS = -3V RELATIVE OUTPUT (dB) 0 1.360 IDD (mA) ISUPPLY (mA) 0.5 1.365 4.5 SHUTDOWN SUPPLY CURRENT (A) IDD, VDD = 5V, VSS = -5V 1.0 1.370 MAX512 TOC-07 1.5 SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE MAX512 TOC-09 POSITIVE SUPPLY CURRENT vs. TEMPERATURE SUPPLY CURRENT vs. REFERENCE VOLTAGE VDD = 3V, VSS = GND = 0V REFAB, REFC SINE WAVE 40mV 0.1k 1k 10k 100k 1M 10M FREQUENCY (Hz) _______________________________________________________________________________________ 5 MAX512/MAX513 ____________________________Typical Operating Characteristics (continued) (TA = +25C, unless otherwise noted.) MAX512/MAX513 Low-Cost, Triple, 8-Bit Voltage Output DACs with Serial Interface ____________________________Typical Operating Characteristics (continued) (TA = +25C, unless otherwise noted.) LINE-TRANSIENT RESPONSE (OUTC) LINE-TRANSIENT RESPONSE (OUTA) 3.14V 3.14V A A 2.86V 2.86V B B 20s/div 20s/div REFC = 2.56V, NO LOAD, CODE = ALL 1s REFAB = 2.56V, NO LOAD, CODE = ALL 1s A : VDD, 100mV/div B : OUTA, 500V/div A : VDD, 100mV/div B : OUTC, 2mV/div CLOCK FEEDTHROUGH (OUTA) CLOCK FEEDTHROUGH (OUTC) A A B B 1s/div 1s/div 6 VSS = 0V, CS = HIGH VSS = 0V, CS = HIGH A: SCLK, 333kHz, 0V TO 2.9V, 2V/div B: OUTA, 2mV/div A: SCLK, 333kHz, 0V TO 2.9V, 2V/div B: OUTC, 2mV/div _______________________________________________________________________________________ Low-Cost, Triple, 8-Bit Voltage Output DACs with Serial Interface POSITIVE SETTLING TIME (DAC A) POSITIVE SETTLING TIME (DAC B) A A B B 20s/div 20s/div VDD = 3V, VSS = 0V, REFAB = VDD, RL = 1k , CL = 0.1F ALL BITS OFF TO ALL BITS ON VDD = 3V, VSS = 0V, REFAB = VDD, RL = 10k , CL = 0.01F ALL BITS OFF TO ALL BITS ON A: CS, 2V/div B: OUTA, 20mV/div A: CS, 2V/div B: OUTB, 20mV/div POSITIVE SETTLING TIME (DAC C) POSITIVE SETTLING TIME WITH DUAL SUPPLIES A A B B 10s/div 10s/div VDD = 3V, VSS = 0V, REFC = VDD, RL = , CL = 122pF ALL BITS OFF TO ALL BITS ON VDD = 5V, VSS = -5V, REFAB = 2.56V, RL = 1k , CL = 0.1F ALL BITS OFF TO ALL BITS ON A: CS, 2V/div B: OUTC, 20mV/div A: CS, 5V/div B: OUTA, 10mV/div _______________________________________________________________________________________ 7 MAX512/MAX513 ____________________________Typical Operating Characteristics (continued) (TA = +25C, unless otherwise noted.) MAX512/MAX513 Low-Cost, Triple, 8-Bit Voltage-Output DACs with Serial Interface _____________________________Typical Operating Characteristics (continued) (TA = +25C, unless otherwise noted.) TIME EXITING SHUTDOWN MODE OUTPUT VOLTAGE NOISE DC TO 1MHz A OUTA, 200V/div B 20s/div 2ms/div VDD = 3V, VSS = 0V, REFAB = VDD, RL = 1k , CL = 0.1F DAC LOADED WITH ALL 1s DIGITAL CODE = 80, REFAB = VDD, NO LOAD A: CS, 2V/div B: OUTA, 1V/div ______________________________________________________________Pin Description 8 PIN NAME FUNCTION 1 DIN Serial Data Input of the 16-bit shift register. Data is clocked into the register on the rising edge of SCLK. 2 ---- CS Chip Select (active low). Enables data to be shifted into the 16-bit shift register. Programming commands ---- are executed at the rising edge of C S. 3 SCLK 4 ---------- RESET Serial Clock Input. Data is clocked in on the rising edge of SCLK. Asynchronous reset input (active low). Clears all registers to their default state (FFhex for DAC A and DAC B registers); all other registers are reset to 0 (including the input shift register). 5 VDD Positive Power Supply (2.7V to 5.5V). Bypass with 0.22F to GND. 6 GND Ground 7 VSS Negative Power Supply 0V or (-1.5V to -5.5V). Tie to GND for single supply operation. If a negative supply is applied, bypass with 0.22F to GND. 8 OUTA DAC A Output Voltage (Buffered). Resets to full scale. Connect 0.1F capacitor or greater to GND. 9 OUTB DAC B Output Voltage (Buffered). Resets to full scale. Connect 0.01F capacitor or greater to GND. 10 OUTC DAC C Output Voltage (Unbuffered). Resets to zero. 11 REFC DAC C Reference Voltage 12 REFAB 13 I.C. 14 LOUT DAC A/B Reference Voltage Internally connected. Do not make connections to this pin. Logic Output (latched) _______________________________________________________________________________________ Low-Cost, Triple, 8-Bit Voltage-Output DACs with Serial Interface MAX512/MAX513 _______________Detailed Description Analog Section The MAX512/MAX513 contain three 8-bit, voltage-output, digital-to-analog converters (DACs). The DACs are "inverted" R-2R ladder networks using complementary switches that convert 8-bit digital inputs into equivalent analog output voltages in proportion to the applied reference voltages. The MAX512/MAX513 have two reference inputs: one is shared by DAC A and DAC B and the other is used by DAC C. These inputs allow different full-scale output voltages and different output voltage polarities for the DAC pair A/B and DAC C. The MAX512/MAX513 include output buffer amplifiers for DACs A and B and input logic for simple microprocessor (P) and CMOS interfaces. The MAX512/MAX513 operate in either single-supply or dual-supply mode, as determined by VSS. If VSS is within approximately -0.5V of GND, single-supply mode is assumed. If VSS is below -1.5V, the devices are in dualsupply mode. Reference Inputs and DAC Output Range The voltage at REF_ sets the full-scale output of the DACs. The input impedance of the REF_ inputs is code dependent. The lowest value, approximately 12k for REFC (8k for REFAB), occurs when the input code is 01010101 (55hex). The maximum value of infinity occurs when the input code is zero. In shutdown mode, the selected DAC output is set to zero while the value stored in the DAC register remains unchanged. This removes the load from the reference input to save power. Bringing the MAX512/MAX513 out of shutdown mode restores the DAC output voltage. Because the input resistance at REF_ is code dependent, the DAC's reference sources should have an output impedance of no more than 5. The input capacitance at the REF_ pins is also code dependent and typically does not exceed 25pF. The reference voltage on REFAB can range anywhere between the supply rails. In dual-supply mode, a positive reference input voltage on REFAB should be less than (VDD - 1.5V) to avoid saturating the buffer amplifiers. The reference voltage includes the negative supply rail. See the Output Buffer Amplifier section for more information. The REFC input accepts positive voltages up to VDD and should not be forced below ground. The absolute difference between any reference voltage and GND should not exceed 6V. R 2R 2R R 2R R 2R OUT 2R REF GND SHOWN FOR ALL 1s ON DAC; DAC C IS NOT BUFFERED Figure 1. DAC Simplified Circuit Diagram Output Buffer Amplifiers (DAC A / DAC B) DAC A and DAC B voltage outputs are internally buffered. The buffer amplifiers have a rail-to-rail (VSS to VDD) output voltage range. In single-supply mode, the DAC outputs A and B are internally divided by two and the buffer is set to a gain of two, eliminating the need for a buffer input voltage range to the positive supply rail. In dual-supply mode, the DAC outputs are not attenuated and the buffer is set to unity gain. Although only necessary for negative output voltages, the dual-supply mode may be used even if the desired DAC output voltage is positive. Possible errors associated with the divide-by-two attenuator and gain-of-two buffers in single-supply mode are eliminated in dualsupply mode. In this case, do not use reference voltages higher than (VDD - 1.5V). DAC A's output amplifier can source and sink up to 5mA of current (0.5mA for DAC B buffer). See the Total Unadjusted Error vs. Digital Code graph in the Typical Operating Characteristics for dual and single supplies. The amplifier is unity-gain stable with a capacitive load of 0.05F (0.01F for DAC B buffer) or greater. The slew rate is limited by the load capacitor and is typically 0.1V/s with a 0.1F load (0.01F for DAC B buffer). Unbuffered Output (DAC C) The output of DAC C is unbuffered and has a typical output impedance of 24k. It can be used to drive a highimpedance load, such as an op amp or comparator, and has 35s typical settling time to 1/2LSB with a single 3V supply. Use DAC C if a quick dynamic response is required. _______________________________________________________________________________________ 9 Reset ---------- --- ------- The RESET input is active low. When asserted (RESET = 0), DACs A and B are set to full scale (FFhex) and active, while DAC C is set to zero code (00hex) and active. The 16-bit serial register is cleared to 0000hex. LOUT is reset to zero. Table 1. Input Shift Register DATA BITS Shutdown Mode When programmed to shutdown mode, the outputs of DAC A and B go into a high-impedance state. Virtually no current flows into or out of the buffer amplifiers in that state. The output of DAC C goes to 0V when shut down. In shutdown mode, the REF_ inputs are high impedance (2M typ) to conserve current drain from the system reference; therefore, the system reference does not have to be powered down. The logic output LOUT remains active in shutdown. Coming out of shutdown, the DAC outputs return to the values kept in the registers. The recovery time is equivalent to the DAC settling time. CONTROL BITS MAX512/MAX513 Low-Cost, Triple, 8-Bit Voltage-Output DACs with Serial Interface Serial Interface ---- An active-low chip select (CS) enables the shift register to receive data from the serial data input. Data is clocked into the shift register on every rising edge of the serial clock signal (SCLK). The clock frequency can be as high as 5MHz. Data is sent MSB first and can be transmitted in one 16-bit word. ----The write cycle can be interrupted at any time when CS is kept active (low) to allow, for example, two 8-bit-wide transfers. After clocking all 16 bits into B0* DAC Data Bit 0 (LSB) B1 DAC Data Bit 1 B2 DAC Data Bit 2 B3 DAC Data Bit 3 B4 DAC Data Bit 4 B5 DAC Data Bit 5 B6 DAC Data Bit 6 B7 DAC Data Bit 7 (MSB) LA Load Reg DAC A, Active High LB Load Reg DAC B, Active High LC Load Reg DAC C, Active High SA Shut Down DAC A, Active High SB Shut Down DAC B, Active High SC Shut Down DAC C, Active High Q1 Logic Output Q2** Uncommitted Bit **Clocked in last. **Clocked in first. ---- the input shift register, the rising edge of CS updates the DAC outputs, the shutdown status, and the status of the logic output. Because of their single buffered structure, DACs cannot be simultaneously updated to different digital values. CS INSTRUCTION EXECUTED SCLK OPTIONAL SDIN Q2 Q1 SC SB SA LC LB LA (CONTROL BYTE) D7 D6 D5 D4 D3 D2 D1 D0 (DATA BYTE) Figure 2. MAX512/MAX513 3-Wire Serial-Interface Timing Diagram 10 ______________________________________________________________________________________ Low-Cost, Triple, 8-Bit Voltage-Output DACs with Serial Interface MAX512/MAX513 Table 2. Serial-Interface Programming Commands CONTROL DATA FUNCTION MSB LSB Q2 Q1 SC SB SA LC LB LA B7 B6 B5 B4 B3 B2 B1 B0 * * * * * 0 0 0 X X X X X X X X * * * * * 1 0 0 8-Bit DAC Data Load Register to DAC C * * * * * 0 1 0 8-Bit DAC Data Load Register to DAC B * * * * * 0 0 1 8-Bit DAC Data Load Register to DAC A * * * * * 1 1 1 8-Bit DAC Data * * 0 0 0 * * * X X X X X X X X All DACs Active * * 1 0 0 * * * X X X X X X X X Shut Down DAC C * * 0 1 0 * * * X X X X X X X X Shut Down DAC B * * 0 0 1 * * * X X X X X X X X Shut Down DAC A * * 1 1 1 * * * X X X X X X X X Shut Down All DACs X 0 * * * * * * X X X X X X X X Reset LOUT X 1 * * * * * * X X X X X X X X Set LOUT No Operation to DAC Registers Load All DAC Registers Don't care. Not shown for clarity. The functions of loading and shutting down the DACs and programming the logic can be combined in a single command. X * Serial-Input Data Format and Control Codes Table 2 lists the serial-input data format. The 16-bit input word consists of an 8-bit control byte and an 8-bit data byte. The 8-bit control byte is not decoded internally. Every control bit performs one function. Data is clocked in starting with Q2 (uncommitted bit), followed by the remaining control bits and the data byte. The LSB of the data byte (B0) is the last bit clocked into the shift register (Figure 2). Example of a 16-bit input word: Loaded in First Loaded in Last Q2 Q1 SC SB SA LC LB LA B7 B6 B5 B4 B3 B2 B1 B0 X 0 1 0 0 0 1 1 1 0 0 0 0 0 0 0 The example above performs the following functions: * 80hex (128 decimal) loaded into DAC registers A and B. * Content of the DAC C register remains unchanged. * DAC A and DAC B are active. * DAC C is shut down. * LOUT is reset to 0. Digital Inputs The digital inputs are compatible with CMOS logic. Supply current increases slightly when toggling the logic inputs through the transition zone between (0.3)(VDD) and (0.7)(VDD). Digital Output The latched digital output (LOUT) has a 1.6mA source capability while maintaining a (VDD - 0.4V) output level. With a 1.6mA sink current, the output voltage is guaranteed to be no more than 0.4V. The output can be used for digital auxiliary control. Please note that the digital output remains fully active during shutdown mode. Microprocessor Interfacing The MAX512/MAX513 serial interface is compatible with Microwire, SPI, and QSPI. For SPI and QSPI, clear the CPOL and CPHA bits (CPOL = 0 and CPHA = 0). CPOL = 0 sets the inactive state of clock to zero and CPHA = 0 changes data at the falling edge of SCLK. This setting allows both SPI and QSPI to run at full clock speeds (0.5MHz and 4MHz, respectively). If a serial port is not available on your P, three bits of a parallel port can be used to emulate a serial port by bit manipulation. Minimize digital feedthrough at the voltage outputs by operating the serial clock only when necessary. ______________________________________________________________________________________ 11 MAX512/MAX513 Low-Cost, Triple, 8-Bit Voltage-Output DACs with Serial Interface CS tCSPWH tCSS tCSH tCH SCLK tCL tDS tDH DIN tOD LOUT Figure 3. MAX512/MAX513 Detailed Serial-Interface Timing Diagram _____________ Applications Information Power-Supply and Reference Operating Ranges The MAX512 is fully specified to operate with VDD = 5V 10% and VSS = GND = 0V. The MAX513 is specified for single-supply operation with VDD ranging from 2.7V to 3.6V, covering all commonly used supply voltages in 3V systems. The MAX512/MAX513 can also be used with a negative supply ranging from -1.5V to -5.5V. Using a negative supply typically improves zero-code error and settling time (as shown in the Typical Operating Characteristics graphs). The two separate reference inputs for the DAC pair A/B and the unbuffered output C allow different full-scale output voltages and, if a negative supply is used, also allow different polarity. In dual-supply mode, REFAB can vary from VSS to (VDD - 1.5V). In single-supply mode, the specified range for REFAB is 0V to VDD. REFC can range from GND to VDD. Do not force REFC below ground. Power-supply sequencing is not critical. If a negative supply is used, make sure VSS is never more than 0.3V above ground. Do not apply signals to the digital inputs until the device is powered-up. If this is not possible, add currentlimiting resistors to the digital inputs. 12 Power-Supply Bypassing and Ground Management In single-supply operation (VSS = GND), GND and VSS should be connected to the highest quality ground available. Bypass VDD with a 0.1F to 0.22F capacitor to GND. For dual-supply operation, bypass VSS with a 0.1F to 0.22F capacitor to GND. Reference inputs can be used without bypassing. For optimum line/loadtransient response and noise performance, bypass the reference inputs with 0.1F to 4.7F to GND. Careful PC board layout minimizes crosstalk among DAC outputs, reference inputs, and digital inputs. Separate analog lines with ground traces between them. Make sure that high-frequency digital lines are not routed in parallel to analog lines. Unipolar Output With unipolar output, the output voltage and the reference voltage are the same polarity. The MAX512/ MAX513 can be used with a single supply if the reference voltages are positive. With a negative supply, the REFAB voltage can vary from V SS to approximately (VDD - 1.5V), allowing two-quadrant multiplication. ______________________________________________________________________________________ Low-Cost, Triple, 8-Bit Voltage-Output DACs with Serial Interface DAC CONTENTS ANALOG OUTPUT B7 B6 B5 B4 B3 B2 B1 B0 MAX512/MAX513 Table 3. Unipolar Code Table Table 4. Bipolar Code Table DAC CONTENTS ANALOG OUTPUT B7 B6 B5 B4 B3 B2 B1 B0 1 1 1 1 1 1 1 1 255 +REF_ x 256 1 1 1 1 1 1 1 1 127 +REF_ x 128 1 0 0 0 0 0 0 1 129 +REF_ x 256 1 0 0 0 0 0 0 1 1 +REF_ x 128 0 0 0 0 0 0 0 0V 0 0 0 0 0 0 0 128 REF_ +REF_ x = + 2 256 1 1 0 1 1 1 1 1 1 1 1 -REF_ x 128 1 127 +REF_ x 256 0 0 0 0 0 0 0 1 127 -REF_ x 128 0 0 0 0 0 0 0 0 128 -REF_ x = - REF_ 128 0 1 1 1 1 1 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 +REF_ x 256 0V Note : Note : 1LSB = REF_ x 2 -8 1 1LSB = REF_ x 2 -(8 - 1) = REF_ x 128 1 = REF_ x 256 D - 1 ANALOG OUTPUT = REF_ x 128 D ANALOG OUTPUT = REF_ x 256 Bipolar Output RF Applications Using Figure 4's circuit, the MAX512/MAX13 can be configured for bipolar outputs. Table 4 lists the bipolar codes and corresponding output voltages. There are two ways to achieve rail-to-rail outputs: 1) Operate the MAX512/MAX513 with a single supply and positive reference voltages or 2) Use dual supplies with a positive or negative voltage at REFAB and a positive voltage at REFC. In either case, the op amps need dual supplies. When using the dual-supply mode, possible errors associated with the divide-by-two attenuator and gain-of-two buffer are eliminated (see the Output Buffer Amplifier section). For maximum output swing of all outputs in dual-supply mode, connect REFAB to VSS and REFC to VDD. In single-supply mode, connect REFAB, REFC, and VDD together. With dual supplies, DACs A and B can perform fourquadrant multiplication. Please note that in dual-supply mode, the REFAB input ranges from VSS to (V DD 1.5V). Because REFC accepts only positive inputs, DAC C performs two-quadrant multiplication. Figure 4 shows Maxim's ICL7612A with rail-to-rail input common-mode range and rail-to-rail output voltage swing--ideal for a high output voltage swing from low supply voltages. Both the MAX512 and MAX513 can bias GaAs FETs, where the gate of the FETs must be negatively biased to ensure that there is no drain current. In a typical application, power to the RF amplifiers should not be turned on until the bias voltages provided by DAC A and DAC B are fully established; likewise, the supply should be turned off before the bias voltage is switched off. Figure 5 shows how DAC B supplies the negative bias VGG1 for the driver stage and DAC A provides the negative bias VGG2 for the output stage [1]. The DAC A and DAC B outputs are also ideal for controlling VCOs in mobile radios or cellular phones. Other applications include varactor and PIN diode circuits. The unbuffered DAC C provides a span within GND and VDD and is individually set at REF C. DAC C typically adjusts offset and gain in the system. 1 [John Wachsmann. "A High-Efficiency GaAs MMIC Power Amplifier for 1.9GHz PCS Applications," Proceedings of the First Annual Wireless Symposium, pp. 375, Penton Publishing, Jan. 1993.] ______________________________________________________________________________________ 13 MAX512/MAX513 Low-Cost, Triple, 8-Bit Voltage-Output DACs with Serial Interface REFAB VDD REFC DIN 1 R* CS 2 12 SCLK 3 DAC LATCH A 16-BIT SHIFT REGISTER CONTROL (8) DATA (8) R* 11 8 OUTA DAC A DAC LATCH B DAC B DAC LATCH C DAC C 0.05F 0.1F VSS R* 9 OUTB 0.1F VDD 0.1F 10 OUTC 0.1F 14 LATCH 5 VSS 7 VDD VSS 0.22F VOUT ICL7612A** MAX512 MAX513 VDD VOUT ICL7612A** R* RESET 4 0.1F LOUT VSS GND 6 0.22F * R IN 10k RANGE ** CONNECT PIN 8 TO GND Figure 4. Bipolar Output Circuit VDD1 REFAB = -4.2V VDD2 RFIN MAX512 MAX513 RFOUT VGG1 VGG2 OUTB DAC B 0.01F OUTA DAC A 0.05F Figure 5. RF Bias Circuit 14 ______________________________________________________________________________________ Low-Cost, Triple, 8-Bit Voltage-Output DACs with Serial Interface PART TEMP. RANGE ___________________Chip Topography PIN-PACKAGE MAX512EPD -40C to +85C 14 Plastic DIP MAX512ESD MAX512MJD MAX513CPD -40C to +85C -55C to +125C 0C to +70C 14 SO 14 CERDIP 14 Plastic DIP MAX513CSD MAX513C/D MAX513EPD MAX513ESD MAX513MJD 0C to +70C 0C to +70C -40C to +85C -40C to +85C -55C to +125C 14 SO Dice* 14 Plastic DIP 14 SO 14 CERDIP OUTC OUTB OUTA V SS GND V DD REFC REFAB 0.122" (3.099mm) * Contact factory for dice specifications. RESET SCLK LOUT DIN CS 0.081" (2.057mm) TRANSISTOR COUNT: 1910 SUBSTRATE CONNECTED TO VDD ______________________________________________________________________________________ 15 MAX512/MAX513 _Ordering Information (continued) MAX512/MAX513 Low-Cost, Triple, 8-Bit Voltage-Output DACs with Serial Interface ________________________________________________________Package Information DIM D1 A A1 A2 A3 B B1 C D D1 E E1 e eA eB L E E1 D A3 A A2 L A1 INCHES MAX MIN 0.200 - - 0.015 0.150 0.125 0.080 0.055 0.022 0.016 0.065 0.050 0.012 0.008 0.765 0.735 0.080 0.050 0.325 0.300 0.280 0.240 0.100 BSC 0.300 BSC 0.400 - 0.150 0.115 15 0 MILLIMETERS MIN MAX - 5.08 0.38 - 3.18 3.81 1.40 2.03 0.41 0.56 1.27 1.65 0.20 0.30 18.67 19.43 1.27 2.03 7.62 8.26 6.10 7.11 2.54 BSC 7.62 BSC - 10.16 2.92 3.81 0 15 21-330A 14-PIN PLASTIC DUAL-IN-LINE PACKAGE C e B1 eA B eB DIM E A A1 B C D E e H h L H INCHES MAX MIN 0.069 0.053 0.010 0.004 0.019 0.014 0.010 0.007 0.344 0.337 0.157 0.150 0.050 BSC 0.244 0.228 0.020 0.010 0.050 0.016 8 0 MILLIMETERS MIN MAX 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 8.55 8.75 3.80 4.00 1.27 BSC 5.80 6.20 0.25 0.50 0.40 1.27 0 8 21-331A h x 45 D A 0.127mm 0.004in. e B A1 C L 14-PIN PLASTIC SMALL-OUTLINE PACKAGE 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. 16 __________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 (c) 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.