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ADVANCED LINEAR DEVICES, INC.
ALD1801A/ALD1801B ALD1801
8 BIT MICROPOWER MULTIPLYING D/A CONVERTER
GENERAL DESCRIPTION The ALD1801 is an 8-bit monolithic current output digital to analog converter designed to provide low power, low operating voltage and simple operation. It offers industry pin configuration of DAC-08 types, and is intended for a wide range of digital to analog conversion and control applications in +5V single power supply and 5V dual power supply systems, as well as +3V to +12V battery operated systems. Device characteristics are specified for +5V single supply and 3.3V dual supply systems. The ALD1801 is manufactured with Advanced Linear Devices' enhanced ACMOS silicon gate CMOS process and has been designed to be also used as a linear cell element in Advanced Linear Devices' "FunctionSpecific" ASIC, as it is fully compatible in design, operation, and manufacture with all other linear elements in Advanced Linear Devices' product family. The ALD1801 is designed with matching between reference and full scale currents. Digital inputs are standard CMOS logic inputs to provide ease of interface. Output currents can be directly converted to a voltage output by using a pair of resistors. When used with ALD's rail-to-rail output operational amplifiers such as the ALD1702, full scale output of 0 to +5V can be easily achieved with single +5V power supply. ORDERING INFORMATION
Operating Temperature Range -55C to +125C 0C to +70C 0C to +70C 16-Pin CERDIP Package ALD1801A DC ALD1801B DC ALD1801 DC 16-Pin Small Outline Package(SOIC) ALD1801A SC ALD1801B SC ALD1801 SC 16-Pin Plastic Dip Package ALD1801A PC ALD1801B PC ALD1801 PC
FEATURES Low voltage 3V to 12V operation Low power 1.8mW max @ 3.3V Single supply operation (5V or 3.3V) Direct CMOS logic interface Complementary current outputs Nonlinearity to 0.1% max over temperature range * High input impedance * Low full scale current * High output impedance PIN CONFIGURATION * * * * * *
N/C I OUT VIOUT MSB B1 B2 B3 B4
1
16
N/C VREFVREF+ V+ B8 LSB B7 B6 B5
2
15
3
14
4
13
5
6
12
11
7 8
10 9
TOP VIEW DC, PC, SC PACKAGE
* N/C Pin is connected internally. Do not connect externally.
* Contact factory for industrial temperature range
BLOCK DIAGRAM
4 2 VREF+ 14 V+ 13 IB1 VREF15 3 IB2 IB3 IB4 IB5 IB6 IB7 IB8 IOUT
IOUT
5 B1 MSB
6 B2
7 B3
8 B4
9 B5
10 B6
11 B7
12 B8 LSB
(c) 1998 Advanced Linear Devices, Inc. 415 Tasman Drive, Sunnyvale, California 94089 -1706 Tel: (408) 747-1155 Fax: (408) 747-1286 http://www.aldinc.com
OPERATING ELECTRICAL CHARACTERISTICS TA = 25C VS = 2.5V or VS = +5.0V unless otherwise specifie
Parameter Supply Voltage Resolution Monotonicity Nonlinearity NL tS td TC VOC V+1.5 50 2.5 Symbol VS Min 1.5 1801A Typ Max 6.0 Min 1.5 1801B Typ Max 1801 Min Typ Max 6.0 Unit V Test Conditions Dual Supply Single Supply
6.0 1.5
8 8 0.1
8 8 0.19
8 8 0.39
Bits Bits % of
Full Scale
Settling Time
5.0
2.5
5.0
2.5
5.0
s s s ppm/C
To 1/2 LSB with all bits turned on/off Each Bit All Bits
Propagation Delay Full Scale Tempco Output Compliance Output Impedance Full Scale Current Range Full Scale Symmetry Zero Scale Current
1.5 1.5 10
2.5 2.5 50 V+ +0.2 V+1.5 50
1.5 1.5 10
2.5 2.5 50 V+ V+0.2 +1.5 50
1.5 1.5 10
2.5 2.5 50 V+ +0.2
V
M A 2.5 A
Output Within Compliance limits ROUT = R OUT = 50K VREF = 2.5V; RREF =25K
IFS IFSS IZS
100 2.5
100 2.5
100
10
10
10
nA
Logic Input Level 1 Logic "0" VIL Logic "1" VIH Logic Swing Logic Threshold Range Reference Bias Current Power Supply Current Power Dissipation VLS IRB +IS - IS PD
-1.1 2.1 2.1
-1.1 2.1
-1.1
V
Supply = 2.5V
-2.8 -1.5
2.8 1.5 0.1
-2.8 -1.5
2.8 1.5 0.1
-2.8 -1.5
2.8 1.5 0.1
V V nA A
Supply = 2.5V Supply = 2.5V
500 700
800 1000 4.5
500 800 700 1000 4.5
500 700
800 1000 4.5
Full Scale Output = 100A Supply = 2.5V
mW
Compensation
Not Required
Notes:
1. Contact ALD for 1.0V/1.25V operation 2. Logic levels of VIL 0.4V and VIH 4.6V for single supply applications.
ALD1801A/ALD1801B ALD1801
Advanced Linear Devices
2
OPERATING ELECTRICAL CHARACTERISTICS TA = 25C VS = 1.65V or VS = +3.3V unless otherwise specified
Parameter Resolution Monotonicity Nonlinearity NL Symbol Min 8 8 0.1 1801A Typ Max Min 8 8 0.19 1801B Typ Max 1801 Min Typ 8 8 0.39 Max Unit Bits Bits % of
Full Scale
Test Conditions
Settling Time
tS
4.0
10.0
4.0
10.0
4.0
10.0
s
To 1/2 LSB with all bits turned on/off Each Bits All Bits
Propagation Delay Full Scale Tempco Output Compliance Output Impedance Full Scale Current Range Full Scale Symmetry Zero Scale Current Reference Bias Current Power Supply Current Power Dissipation
td
1.5 1.5 10
4.0 4.0 50
1.5 1.5 10
4.0 4.0 50
1.5 1.5 10
4.0 4.0 50
s s ppm/C
TC
VOC
V+1.5 50
V+ +0.2
V+1.5 50
V+ V+0.2 +1.5 50
V+ +0.2
V
M
Output Within Compliance limits ROUT = ROUT = 100K VREF = 2.5V; RREF =50K
IFS
50
50
50
A
IFSS
2.5
2.5
2.5
A
IZS
10
10
10
nA
IRB
0.1
0.1
0.1
nA
+IS - IS PD
350 450
500 600 1.8
350 450
500 600 1.8
350 450
500 600 1.8
A
Full Scale Output = 50A
mW
ALD1801A/ALD1801B ALD1801
Advanced Linear Devices
3
DUAL SUPPLY 2.5V RATIOMETRIC VOLTAGE OUTPUT DAC
50K 50K +VREF
V+ = 2.5V ALD 1702
+
V- = 2.5V V+ = 2.5V
VOUT
4 2
3 13
15 14
VREF-
+VREF =2.5V
25K B1 B2 B3 B4 5 6 7 8 12 11 10 9 ALD 1801 B8 B7 B6 B5 LSB
Zero Scale LSB Half Scale -LSB Half Scale Half Scale +LSB Full Scale
B1 0 0 0 1 1 1
B2 0 0 1 0 0 1
B3 0 0 1 0 0 1
B4 0 0 1 0 0 1
B5 0 0 1 0 0 1
B6 0 0 1 0 0 1
B7 0 0 1 0 0 1
B8 0 1 1 0 1 1
VOUT -2.500 -2.480 -0.019 0.000 0.019 2.480
SINGLE SUPPLY 3.3V RATIOMETRIC VOLTAGE OUTPUT DAC
50K 50K V+
V+ = 3.3V
+
VOUT 1/2 ALD2701 V+
50K
1/2 ALD2701
+
MSB B1 0.1F B2 B3 B4
4 2
3
13 15 14
25K +VREF = V+
50K
5 6 7 8
12 11 10 9 ALD 1801
B8 B7 B6 B5
LSB
Zero Scale Half Scale Full Scale
B1 0 1 1
B2 0 0 1
B3 0 0 1
B4 0 0 1
B5 0 0 1
B6 0 0 1
B7 0 0 1
B8 0 0 1
VOUT 0.000 1.650 3.287
ALD1801A/ALD1801B ALD1801
Advanced Linear Devices
4
APPLICATIONS NOTES: The ALD1801 is an 8 bit multiplying D/A converter. It has been designed to operate with standard single or split power supplies of 5V or 5V. Functionality extends down to 3V or 1.5V power supply, making it ideal for lithium battery or rechargeable battery operated systems where power efficiency and performance are important design parameters. The ALD1801 features ultra low quiescent bias current which depends on the operating current in the internal current steering circuit. A high gain internal operational amplifier is fully compensated for stable operation without any need for external capacitor compensation. The operational amplifier is placed in a negative feedback loop to generate the reference current for ratio matched transistors. It is trimmed to provide nonlinearity as specified. In some applications this feature can be used along with the multiplying nature of the ALD1801 to obtain 9 or 10 bit digital to analog conversion with external switches. The ALD1801 is a multiplying D/A converter in which the output is a current that is a function of an 8 bit digital input word multiplied by the reference current. The reference current may be a fixed reference current or a varying input current. If a fixed reference voltage or a varying low impedance voltage output source is used, a fixed value resistor (referred to as RREF) can be used to convert the voltage into a reference current for most applications. R REF is a precision fixed resistor without trimming. Trimming can be accomplished by adjusting RREF through either connecting a potentiometer in series with a fixed resistor or by substituting the fixed resistor with a multiturn potentiometer. The recommended nominal value of R REF is 25K. The ALD1801 can operate from single power supply or dual supplies up to 6.6V. Symmetrical supplies are not required in the case of dual supply operation. However, V REF- input voltage must be set at 1V or higher above the V- voltage. Due to the internal operational amplifier feedback, V REF+ input terminal would be set at the same potential as V REF- input terminal, with the input reference current determined by: Input reference current I REF = { (V REF+)- (VREF-) } / RREF The ALD1801 is fabricated in CMOS technology and provides direct logic interface to all CMOS logic families including logic levels of the CD4000 and 74C logic families operating at logic voltage levels other than 5V. It is primarily designed to operate in a power supply environment where interface takes place between digital logic circuitry and analog circuitry. Both types of circuitry operate with the same power supplies. The nonlinearity and monotonicity of the ALD1801 applies over the full rated operating temperature. The device has been developed with minimal temperature drift, typically at 10ppm/C. A single array of matched and tracked resistor networks of nominal 50K can be used for all the resistors required for the D/A converter. As an example, RREF can be set to 25K by connecting two 50K resistors in parallel where output resistors are set at 50K. Due to the very low quiescent and reference currents used, layout of the circuit board to minimize any parasitic capacitance is important in getting high frequency operation, as the settling time is due in large part to the output currents charging and discharging the node capacitances at the output. As the internal bias current levels is adaptive to the reference current, the switching speed of the device depends on the reference current selected. Characterization of the settling time has been performed at full scale current set at 100A and device operation at single 5V supply. Faster operation can be obtained by using short leads, minimizing output capacitance, load resistor values, and by adequate bypass capacitors placed on the board at the supply and reference nodes. Both Io and I o outputs can be used simultaneously. If one of the outputs is not used, then it must be connected to ground or a potential where the sum of I o and Io can maintain a constant value. Due to internal leakage currents that vary with temperature, it is recommended that IFS of 50A to 100A be used so that 1/2LSB bit current is set at as high a level as possible. The temperature coefficient of the reference resistor RREF and output resistors R OUT and ROUT should match to minimize temperature drift.
ALD1801A/ALD1801B ALD1801
Advanced Linear Devices
5
TYPICAL PERFORMANCE CHARACTERISTICS
PROPAGATION DELAY AS A FUNCTION OF FULL SCALE OUTPUT CURRENT
PROPAGATION DELAY (sec)
1.9
SUPPLY CURRENT AS A FUNCTION OF TEMPERATURE
SUPPLY CURRENT (A)
800 ISVS = 2.5V VS = 2.5V VS = 1.65V VS = 1.65V ALL BITS "HIGH " VREF = V+ RREF = 25K
1.7
600
IS+ ISIS+
1.5
400
1.3
200
1.1 0 20 40 60 80 100 120
0 -25 0 25 50 75 100 125
OUTPUT CURRENT (A)
TEMPERATURE (C)
FULL SCALE OUTPUT CURRENT (A)
SUPPLY CURRENT AS A FUNCTION OF SUPPLY VOLTAGE
SUPPLY CURRENT (A)
800 FULL SCALE TA = 25C IREF = 100A
FULL SCALE OUTPUT CURRENT AS A FUNCTION OF SUPPLY VOLTAGE
100 IREF = 100A 80 60 40 20 0 0 1 2 3 4 5 6 IREF = 50A
600
400 IREF = 0 200
0 0 1 2 3 4 5 6
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
FULL SCALE OUTPUT CURRENT AS A FUNCTION OF OUTPUT VOLTAGE (COMPLIANCE)
150
150
FULL SCALE OUTPUT CURRENT AS A FUNCTION OF REFRENCE CURRENT
OUTPUT CURRENT (A)
125 100 75 50 25 0 VS = 1.65V TO 2.5V
OUTPUT CURRENT (A)
100
VS = 2.5V VS = 1.65V
IREF = 100A
50
VS = 2.5V
VS = 1.65V
IREF = 50A
0 -2 -1 0 +1 +2
0
25
50
75
100
125
150
SUPPLY VOLTAGE (V)
REFRENCE CURRENT (A)
ALD1801A/ALD1801B ALD1801
Advanced Linear Devices
6

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