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19-1562; Rev 0; 10/99
10-Bit Voltage-Output DAC in 8-Pin MAX
General Description
The MAX5304 combines a low-power, voltage-output, 10-bit digital-to-analog converter (DAC) and a precision output amplifier in an 8-pin MAX package. It operates from a single +5V supply, drawing less than 280A of supply current. The output amplifier's inverting input is available to the user, allowing specific gain configurations, remote sensing, and high output-current capability. This makes the MAX5304 ideal for a wide range of applications, including industrial process control. Other features include a software shutdown and power-on reset. The serial interface is SPITM/QSPITM/MICROWIRETM compatible. The DAC has a double-buffered input, organized as an input register followed by a DAC register. A 16-bit serial word loads data into the input register. The DAC register can be updated independently or simultaneously with the input register. All logic inputs are TTL/CMOS-logic compatible and buffered with Schmitt triggers to allow direct interfacing to optocouplers. o +5V Single-Supply Operation o Low Supply Current 0.28mA Normal Operation 2A Shutdown Mode o Available in 8-Pin MAX o Power-On Reset Clears DAC Output to Zero o SPI/QSPI/MICROWIRE Compatible o Schmitt-Trigger Digital Inputs for Direct Optocoupler Interface
Features
o 10-Bit DAC with Configurable Output Amplifier
MAX5304
Applications
Digital Offset and Gain Adjustment Industrial Process Control Microprocessor-Controlled Systems Portable Test Instruments Remote Industrial Control
_________________Ordering Information
PART MAX5304CUA MAX5304EUA TEMP. RANGE 0C to +70C -40C to +85C PIN-PACKAGE 8 MAX 8 MAX
Functional Diagram
GND VDD REF FB OUT DAC OUT 1 CS 2 INPUT REGISTER CS DIN SCLK DIN 3 SCLK 4 16-BIT SHIFT REGISTER
Pin Configuration
TOP VIEW
DAC REGISTER CONTROL
8
VDD GND REF FB
MAX5304
7 6 5
MAX5304 MAX
SPI and QSPI are trademarks of Motorola, Inc. MICROWIRE is a trademark of National Semiconductor Corp. ________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769.
10-Bit Voltage-Output DAC in 8-Pin MAX MAX5304
ABSOLUTE MAXIMUM RATINGS
VDD to GND...............................................................-0.3V to +6V REF, OUT, FB to GND.................................-0.3V to (VDD + 0.3V) Digital Inputs to GND................................................-0.3V to +6V Continuous Current into Any Pin.......................................20mA Continuous Power Dissipation (TA = +70C) 8-Pin MAX (derate 4.10mW/C above+70C) ..........330mW Operating Temperature Ranges MAX5304CUA ...................................................0C to +70C MAX5304EUA ................................................-40C to +85C Junction Temperature......................................................+150C Storage Temperature Range.............................-65C to +150C Lead Temperature (soldering, 10s)........................... ......+300C
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
(Circuit of Figure 8, VDD = +5V 10%, VREF = +2.5V, RL = 5k, CL = 100pF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C. Output buffer connected in unity-gain configuration.) PARAMETER Resolution Differential Nonlinearity Integral Nonlinearity (Note 1) Offset Error Offset-Error Tempco Gain Error (Note 1) Gain-Error Tempco Power-Supply Rejection Ratio REFERENCE INPUT Reference Input Range Reference Input Resistance Reference -3dB Bandwidth Reference Feedthrough Signal-to-Noise Plus Distortion Ratio DIGITAL INPUTS Input High Voltage Input Low Voltage Input Leakage Current Input Capacitance VIH VIL IIN CIN VIN = 0 or VDD 0.001 8 2.4 0.8 0.5 V V A pF SINAD VREF RREF Code dependent, minimum at code 1550 hex VREF = 0.67Vp-p Input code = all 0s, VREF = 3.6Vp-p at 1kHz VREF = 1Vp-p at 25kHz, code = full scale 0 18 30 650 -84 77 VDD - 1.4 V k kHz dB dB PSRR 4.5V VDD 5.5V SYMBOL N DNL INL VOS TCVOS GE 0.3 6 -0.3 1 800 2 Guaranteed monotonic CONDITIONS MIN 10 1.0 4 8 TYP MAX UNITS Bits LSB LSB mV ppm/C LSB ppm/C V/V STATIC PERFORMANCE--ANALOG SECTION
MULTIPLYING-MODE PERFORMANCE
2
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10-Bit Voltage-Output DAC in 8-Pin MAX MAX5304
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 8, VDD = +5V 10%, VREF = +2.5V, RL = 5k, CL = 100pF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C. Output buffer connected in unity-gain configuration.) PARAMETER DYNAMIC PERFORMANCE DIGITAL INPUTS Voltage Output Slew Rate Output Settling Time Output Voltage Swing Current into FB Start-Up Time Digital Feedthrough POWER SUPPLIES Supply Voltage Supply Current Supply Current in Shutdown Reference Current in Shutdown TIMING CHARACTERISTICS (Figure 6) SCLK Clock Period SCLK Pulse Width High SCLK Pulse Width Low CS Fall to SCLK Rise Setup Time SCLK Rise to CS Rise Hold Time DIN Setup Time DIN Hold Time SCLK Rise to CS Fall Delay CS Rise to SCLK Rise Hold Time CS Pulse Width High tCP tCH tCL tCSS tCSH tDS tDH tCS0 tCS1 tCSW 100 40 40 40 0 40 0 40 40 100 ns ns ns ns ns ns ns ns ns ns VDD IDD (Note 3) (Note 3) 4.5 0.28 4 0.001 5.5 0.4 20 0.5 V mA A A CS = VDD, DIN = 100kHz SR To 1/2LSB, VSTEP = 2.5V Rail-to-rail (Note 2) 0.6 10 0 to VDD 0.001 20 5 0.1 V/s s V A s nVs SYMBOL CONDITIONS MIN TYP MAX UNITS
Note 1: Guaranteed from code 3 to code 1023 in unity-gain configuration. Note 2: Accuracy is better than 1LSB for VOUT = 8mV to (VDD - 100mV), guaranteed by a power-supply rejection test at the end points. Note 3: RL = , digital inputs at GND or VDD.
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3
10-Bit Voltage-Output DAC in 8-Pin MAX MAX5304
__________________________________________Typical Operating Characteristics
(VDD = +5V, RL = 5k, CL = 100pF, TA = +25C, unless otherwise noted.)
INTEGRAL NONLINEARITY vs. REFERENCE VOLTAGE
MAX5304-01
REFERENCE VOLTAGE INPUT FREQUENCY RESPONSE
MAX5304-02
SUPPLY CURRENT vs. TEMPERATURE
380 360 SUPPLY CURRENT (A) 340 320 300 280 260 240 220 RL =
MAX5304-03
0.050
0
400
0.025 RELATIVE OUTPUT (dB) INL (LSB)
-4
-8
0
-12
-0.025
-16
-0.050 0.4 1.2 2.0 2.8 3.6 4.4 REFERENCE VOLTAGE (V)
-20 0 500k 1M 1.5M 2M 2.5M 3M FREQUENCY (Hz)
200 -60
-20
20
60
100
140
TEMPERATURE (C)
POWER-DOWN SUPPLY CURRENT vs. TEMPERATURE
MAX5304-04
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX5304-05
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
-55 -60 THD + NOISE (dB) -65 -70 -75 -80 -85 -90 1 10 FREQUENCY (kHz) 100 VREF = +2.5VDC + 1Vp-p SINE CODE = FULL SCALE
MAX5304-06
10 POWER-DOWN SUPPLY CURRENT (A) 9 8
500 450 400 SUPPLY CURRENT (A) 350 300 250 200 150 100 50 0
-50
7 6 5 4 3 2 1 0 -60 -20 20 60 100 140
4.0
4.4
4.8
5.2
5.6
6.0
TEMPERATURE (C)
SUPPLY VOLTAGE (V)
OUTPUT FFT PLOT
MAX5304-07
OUTPUT VOLTAGE vs. LOAD
MAX5304-08
REFERENCE FEEDTHROUGH AT 1kHz
REFERENCE INPUT SIGNAL -20 SIGNAL AMPLITUDE (dB)
MAX5304-09a/09b
0
-20 SIGNAL AMPLITUDE (dB)
VREF = +3.6Vp-p CODE = FULL SCALE fIN = 1kHz
2.49980 2.49976 OUTPUT VOLTAGE (V) 2.49972 2.49968 2.49964 2.49960 2.49956 0.1k
0
-40
-40
-60
-60 OUTPUT FEEDTHROUGH -80
-80
-100 0.5 1.6 2.7 3.8 4.9 6.0 FREQUENCY (kHz)
-100 1k 10k LOAD () 100k 1M 0.5 1.6 2.7 3.8 4.9 6.0 FREQUENCY (kHz)
4
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10-Bit Voltage-Output DAC in 8-Pin MAX
____________________________Typical Operating Characteristics (continued)
(VDD = +5V, RL = 5k, CL = 100pF, TA = +25C, unless otherwise noted.)
MAX5304
MAJOR-CARRY TRANSITION
MAX5304-10a
DIGITAL FEEDTHROUGH (fSCLK = 100kHz)
MAX5304-11a
CS 5V/div
SCLK 2V/div
OUT AC-COUPLED 100mV/div
OUT AC-COUPLED 10mV/div CODE = 512 10s/div CS = 5V 2s/div
DYNAMIC RESPONSE
MAX5304-12a
OUT 1V/div
GND
10s/div GAIN = +2V/V, SWITCHING FROM CODE 0 TO 1005
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5
10-Bit Voltage-Output DAC in 8-Pin MAX MAX5304
_____________________Pin Description
FB
PIN 1 2 3 4 5 6 7 8
NAME OUT CS DIN SCLK FB REF GND VDD
FUNCTION DAC Output Voltage Chip-Select Input. Active low. Serial-Data Input Serial-Clock Input DAC Output Amplifier Feedback Reference Voltage Input Ground Positive Power Supply
REF AGND SHOWN FOR ALL 1s ON DAC 2R 2R 2R 2R 2R MSB R R R OUT
Figure 1. Simplified DAC Circuit Diagram
_______________Detailed Description
The MAX5304 contains a voltage-output digital-to-analog converter (DAC) that is easily addressed using a simple 3-wire serial interface. Each IC includes a 16-bit shift register, and has a double-buffered input composed of an input register and a DAC register (see the Functional Diagram). In addition to the voltage output, the amplifier's negative input is available to the user. The DAC is an inverted R-2R ladder network that converts a digital input (10 data bits plus 3 sub-bits) into an equivalent analog output voltage in proportion to the applied reference voltage. Figure 1 shows a simplified circuit diagram of the DAC.
In shutdown mode, the MAX5304's REF input enters a high-impedance state with a typical input leakage current of 0.001A. The reference input capacitance is also code dependent and typically ranges from 15pF (with an input code of all 0s) to 50pF (at full scale). The MAX873 +2.5V reference is recommended for use with the MAX5304.
Output Amplifier
The MAX5304's DAC output is internally buffered by a precision amplifier with a typical slew rate of 0.6V/s. Access to the output amplifier's inverting input provides the user greater flexibility in output gain setting/signal conditioning (see the Applications Information section). With a full-scale transition at the MAX5304 output, the typical settling time to 1/2LSB is 10s when loaded with 5k in parallel with 100pF (loads less than 2k degrade performance). The amplifier's output dynamic responses and settling performances are shown in the Typical Operating Characteristics.
Reference Inputs
The reference input accepts positive DC and AC signals. The voltage at the reference input sets the fullscale output voltage for the DAC. The reference input voltage range is 0V to (VDD - 1.4V). The output voltage (VOUT) is represented by a digitally programmable voltage source, as expressed in the following equation: VOUT = (VREF * NB / 1024) Gain where NB is the numeric value of the DAC's binary input code (0 to 1023), VREF is the reference voltage, and Gain is the externally set voltage gain. The impedance at the reference input is code dependent, ranging from a low value of 18k when the DAC has an input code of 1550 hex, to a high value exceeding several gigohms (leakage currents) with an input code of 0000 hex. Because the input impedance at the reference pin is code dependent, load regulation of the reference source is important.
6
Shutdown Mode
The MAX5304 features a software-programmable shutdown that reduces supply current to a typical value of 4A. Writing 111X XXXX XXXX XXXX as the input-control word puts the device in shutdown mode (Table 1).
_______________________________________________________________________________________
10-Bit Voltage-Output DAC in 8-Pin MAX
In shutdown mode, the amplifier's output and the reference input enter a high-impedance state. The serial interface remains active. Data in the input register is retained in shutdown, allowing the MAX5304 to recall the output state prior to entering shutdown. Exit shutdown mode by either recalling the previous configuration or updating the DAC with new data. When powering up the device or bringing it out of shutdown, allow 20s for the outputs to stabilize.
MAX5304
SCLK
SK
MAX5304
DIN
SO
MICROWIRE PORT
Serial-Interface Configurations
The MAX5304's 3-wire serial interface is compatible with MICROWIRE (Figure 2) and SPI/QSPI (Figure 3). The serial-input word consists of three control bits followed by 10+3 data bits (MSB first), as shown in Figure 4. The 3-bit control code determines the MAX5304's response outlined in Table 1. The MAX5304's digital inputs are double buffered. Depending on the command issued through the serial interface, the input register can be loaded without affecting the DAC register, the DAC register can be loaded directly, or the DAC register can be updated from the input register (Table 1).
CS I/O
Figure 2. Connections for MICROWIRE
+5V
Serial-Interface Description
The MAX5304 requires 16 bits of serial data. Table 1 lists the serial-interface programming commands. For certain commands, the 10+3 data bits are "don't cares." Data is sent MSB first and can be sent in two 8bit packets or one 16-bit word (CS must remain low until 16 bits are transferred). The serial data is composed of three control bits (C2, C1, C0), followed by the 10+3 data bits D9...D0, S2, S1, S0 (Figure 4). Set the sub-bits (S2, S1, S0) to zero. The 3-bit control code determines the register to be updated and the configuration when exiting shutdown. Figure 5 shows the serial-interface timing requirements. The chip-select pin (CS) must be low to enable the DAC's serial interface. When CS is high, the interface control circuitry is disabled. CS must go low at least tCSS before the rising serial-clock (SCLK) edge to properly clock in the first bit. When CS is low, data is clocked into the internal shift register through the serialdata input pin (DIN) on SCLK's rising edge. The maximum guaranteed clock frequency is 10MHz. Data is latched into the MAX5304 input/DAC register on CS's rising edge.
SS
DIN
MOSI SPI/QSPI PORT
MAX5304
SCLK
SCK
CS
I/O
CPOL = 0, CPHA = 0
Figure 3. Connections for SPI/QSPI
MSB ..................................................................................LSB 16 Bits of Serial Data Control Bits C2 C1 3 Control Bits Figure 4. Serial-Data Format C0 Data Bits MSB............................LSB Sub-Bits D9 ...............................D0, S2, S1, S0 10+3 Data Bits
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7
10-Bit Voltage-Output DAC in 8-Pin MAX MAX5304
Table 1. Serial-Interface Programming Commands
16-BIT16-BIT SERIAL WORD SERIAL WORD C2 C1 X X X 1 0 0 0 1 1 1 C0 0 1 0 1 1 D9.......................D0 MSB LSB 10 bits of data 10 bits of data XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX FUNCTION S2...S0 000 000 XXX XXX XXX Load input register; DAC register immediately updated (also exit shutdown). Load input register; DAC register unchanged. Update DAC register from input register (also exit shutdown; recall previous state). Shutdown No operation (NOP)
X = Don't care
CS COMMAND EXECUTED 1 DIN C2 C1 C0 D9 D8 D7 D6 8 D5 D4 9 D3 D2 D1 D0 S2 S1 16 S0
SCLK
Figure 5. Serial-Interface Timing Diagram
CS tCSO SCLK tDS DIN tDH tCSS tCL tCH tCP tCSH tCS1
tCSW
Figure 6. Detailed Serial-Interface Timing Diagram
8
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10-Bit Voltage-Output DAC in 8-Pin MAX MAX5304
DIN SCLK CS1 CS2 CS3
TO OTHER SERIAL DEVICES
CS
CS
CS
MAX5304
SCLK DIN SCLK DIN
MAX5304
SCLK DIN
MAX5304
Figure 7. Multiple MAX5304s Sharing Common DIN and SCLK Lines
Figure 7 shows a method of connecting several MAX5304s. In this configuration, the clock and the data bus are common to all devices, and separate chipselect lines are used for each IC.
Table 2. Unipolar Output Codes
MSB DAC CONTENTS LSB (000) ANALOG OUTPUT
1023 +VREF 1024 513 +VREF 1024 512 + VREF +VREF = 2 1024 511 +VREF 1024 1 +VREF 1024
Applications Information
Unipolar Output
For a unipolar output, the output voltage and the reference input have the same polarity. Figure 8 shows the MAX5304 unipolar output circuit, which is also the typical operating circuit. Table 2 lists the unipolar output codes. Figure 9 illustrates a Rail-to-Rail(R) output configuration. This circuit shows the MAX5304 with the output amplifier configured for a closed-loop gain of +2V/V to provide a 0 to 5V full-scale range when a 2.5V reference is used.
11 1111 1111
10 0000 0001
(000)
10 0000 0000
(000)
01 1111 1111
(000)
00 0000 0001 00 0000 0000
(000) (000)
Bipolar Output
The MAX5304 output can be configured for bipolar operation using Figure 10's circuit according to the following equation: VOUT = VREF [(2NB / 1024) - 1] where NB is the numeric value of the DAC's binary input code. Table 3 shows digital codes (offset binary) and corresponding output voltages for Figure 10's circuit.
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd. Note: ( ) are for sub-bits.
0V
Using an AC Reference
In applications where the reference has AC signal components, the MAX5304 has multiplying capability within the reference input range specifications. Figure 11 shows a technique for applying a sine-wave signal to the reference input where the AC signal is offset before being applied to REF. The reference voltage must never be more negative than GND.
9
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10-Bit Voltage-Output DAC in 8-Pin MAX MAX5304
Table 3. Bipolar Output Codes
MSB DAC CONTENTS LSB (000) ANALOG OUTPUT
511 +VREF 512 1 +VREF 512
The MAX5304's total harmonic distortion plus noise (THD+N) is typically less than -77dB (full-scale code), given a 1Vp-p signal swing and input frequencies up to 25kHz. The typical -3dB frequency is 650kHz, as shown in the Typical Operating Characteristics graphs.
11 1111 1111
Digitally Programmable Current Source
Figure 12's circuit places an NPN transistor (2N3904 or similar) within the op amp feedback loop to implement a digitally programmable, unidirectional current source. The output current is calculated with the following equation: IOUT = (VREF / R)(NB / 1024) where NB is the numeric value of the DAC's binary input code, and R is the sense resistor shown in Figure 12.
10 0000 0001 10 0000 0000 01 1111 1111
(000) (000) (000)
0V
1 -VREF 512 511 -VREF 512 512 -VREF = - VREF 512
00 0000 0001
(000)
00 0000 0000
(000)
Note: ( ) are for sub-bits.
+5V REF VDD FB REF
+5V
VDD
FB
10k 10k
MAX5304
DAC OUT GND
MAX5304
DAC OUT GND
Figure 8. Unipolar Output Circuit
Figure 9. Unipolar Rail-to-Rail Output Circuit
10
______________________________________________________________________________________
10-Bit Voltage-Output DAC in 8-Pin MAX MAX5304
+5V R1 REF R2 26k AC REFERENCE INPUT +5V
MAX495
+5V
VDD FB
V+
500mVp-p 10k REF VDD
VOUT
DAC OUT DAC
V-
OUT
MAX5304
GND
MAX5304
GND
R1 = R2 = 10k 0.1%
Figure 10. Bipolar Output Circuit
Figure 11. AC Reference Input Circuit
Power-Supply Considerations
+5V
REF VDD VL
MAX5304
DAC OUT IOUT 2N3904
On power-up, the input and DAC registers are cleared (set to zero code). For rated MAX5304 performance, REF must be at least 1.4V below VDD. Bypass VDD with a 4.7F capacitor in parallel with a 0.1F capacitor to GND. Use short lead lengths, and place the bypass capacitors as close to the supply pins as possible.
Grounding and Layout Considerations
Digital or AC transient signals on GND can create noise at the analog output. Connect GND to the highest-quality ground available. Good PC board ground layout minimizes crosstalk between the DAC output, reference input, and digital input. Reduce crosstalk by keeping analog lines away from digital lines. Wire-wrapped boards are not recommended.
FB GND
R
Figure 12. Digitally Programmable Current Source
___________________Chip Information
TRANSISTOR COUNT: 3053 SUBSTRATE CONNECTED TO AGND
______________________________________________________________________________________
11
10-Bit Voltage-Output DAC in 8-Pin MAX MAX5304
Package Information
8LUMAXD.EPS
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.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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