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
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’ "Function-
Specific" 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.
8 BIT MICROPOWER MULTIPLYING D/A CONVERTER
ALD1801A/ALD1801B
ALD1801
ADVANCED
LINEAR
DEVICES, INC.
Operating Temperature Range
-55°C to +125°C0°C to +70°C0°C to +70°C
16-Pin 16-Pin 16-Pin
CERDIP Small Outline Plastic Dip
Package Package(SOIC) Package
ALD1801A DC ALD1801A SC ALD1801A PC
ALD1801B DC ALD1801B SC ALD1801B PC
ALD1801 DC ALD1801 SC ALD1801 PC
ORDERING INFORMATION
* Contact factory for industrial temperature range
BLOCK DIAGRAM
V
REF+
V
REF-
14
3
13
15
V+
I
B1
5
B
1
MSB
I
B2
6
B
2
I
B3
7
B
3
I
B4
8
B
4
I
B5
9
B
5
I
B7
11
B
7
I
B6
10
B
6
I
B8
12
B
8
LSB
4
2
IOUT
IOUT
PIN CONFIGURATION
* N/C Pin is connected internally. Do not connect externally.
V
REF-
V-
V+
MSB B
1
B
2
B
4
1
2
3
4
5
6
7
14
13
12
11
10
9
8
15
16
TOP VIEW
DC, PC, SC PACKAGE
B
3
B
5
B
6
B
8
LSB
B
7
V
REF+
I OUT
I
OUT
N/C N/C
© 1998 Advanced Linear Devices, Inc. 415 T asman Drive, Sunnyvale, California 94089 -1706 Tel: (408) 747-1 155 Fax: (408) 747-1286 http://www .aldinc.com
ALD1801A/ALD1801B Advanced Linear Devices 2
ALD1801
Supply VS±1.5 ±6.0 ±1.5 ±6.0 ±1.5 ±6.0 V Dual Supply
Voltage Single Supply
Resolution 8 8 8 Bits
Monotonicity 8 8 8 Bits
Nonlinearity NL±0.1 ±0.19 ±0.39 % of
Full Scale
Settling Time tS2.5 5.0 2.5 5.0 2.5 5.0 µs To 1/2 LSB with all bits
turned on/off
Propagation td1.5 2.5 1.5 2.5 1.5 2.5 µs Each Bit
Delay 1.5 2.5 1.5 2.5 1.5 2.5 µs All Bits
Full Scale TC±10 ±50 ±10 ±50 ±10 ±50 ppm/°C
Tempco
Output VOC V-V+V-V+V-V+V
Compliance +1.5 +0.2 +1.5 +0.2 +1.5 +0.2
Output 50 50 50 MΩOutput Within
Impedance Compliance limits
Full Scale IFS 100 100 100 µAR
OUT = ROUT = 50KΩ
Current Range VREF = 2.5V; RREF =25KΩ
Full Scale IFSS ±2.5 ±2.5 ±2.5 µA
Symmetry
Zero Scale IZS 10 10 10 nA
Current
Logic Input Level 1
Logic "0" VIL -1.1 -1.1 -1.1 V Supply = ±2.5V
Logic "1" VIH 2.1 2.1 2.1
Logic Swing
Logic Threshold VLS -2.8 2.8 -2.8 2.8 -2.8 2.8 V Supply = ±2.5V
Range -1.5 1.5 -1.5 1.5 -1.5 1.5 V Supply = ±2.5V
Reference Bias IRB 0.1 0.1 0.1 nA
Current
Power Supply +IS500 800 500 800 500 800 µA Full Scale
Current - IS700 1000 700 1000 700 1000 Output = 100µA
Power Dissipation PD4.5 4.5 4.5 mW Supply = ±2.5V
Compensation Not Required
OPERATING ELECTRICAL CHARACTERISTICS
TA = 25°C VS = ±2.5V or VS = +5.0V unless otherwise specifie
1801A 1801B 1801
Parameter Symbol Min Typ Max Min Typ Max Min Typ Max Unit Test Conditions
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 Advanced Linear Devices 3
ALD1801
Resolution 8 8 8 Bits
Monotonicity 8 8 8 Bits
Nonlinearity NL±0.1 ±0.19 ±0.39 % of
Full Scale
Settling Time tS4.0 10.0 4.0 10.0 4.0 10.0 µs To 1/2 LSB with all bits
turned on/off
Propagation td1.5 4.0 1.5 4.0 1.5 4.0 µs Each Bits
Delay 1.5 4.0 1.5 4.0 1.5 4.0 µs All Bits
Full Scale TC±10 ±50 ±10 ±50 ±10 ±50 ppm/°C
Tempco
Output VOC V-V+V-V+V-V+V
Compliance +1.5 +0.2 +1.5 +0.2 +1.5 +0.2
Output 50 50 50 MΩOutput Within
Impedance Compliance limits
Full Scale IFS 50 50 50 µAR
OUT = ROUT = 100KΩ
Current Range VREF = 2.5V; RREF =50KΩ
Full Scale IFSS ±2.5 ±2.5 ±2.5 µA
Symmetry
Zero Scale IZS 10 10 10 nA
Current
Reference Bias IRB 0.1 0.1 0.1 nA
Current
Power Supply +IS350 500 350 500 350 500 µA Full Scale
Current - IS450 600 450 600 450 600 Output = 50µA
Power Dissipation PD1.8 1.8 1.8 mW
OPERATING ELECTRICAL CHARACTERISTICS
TA = 25°C VS = ±1.65V or VS = +3.3V unless otherwise specified
1801A 1801B 1801
Parameter Symbol Min Typ Max Min Typ Max Min Typ Max Unit Test Conditions
ALD1801A/ALD1801B Advanced Linear Devices 4
ALD1801
DUAL SUPPLY ±2.5V
RATIOMETRIC VOLTAGE OUTPUT DAC
SINGLE SUPPLY 3.3V
RATIOMETRIC VOLTAGE OUTPUT DAC
-
+
215
14
12
11
10
9
13
34
5
6
7
8
50K
50K
V+ = 2.5V
V
OUT
ALD
1702
+V
REF
=2.5V
LSB
B8
B5
B6
B7
B1
B4
B3
B2
+V
REF
V- = 2.5V
V+ = 2.5V
V
REF-
25K
ALD 1801
B1 B2 B3 B4 B5 B6 B7 B8 VOUT
Zero Scale 0 0 0 00000-2.500
LSB 00000001-2.480
Half Scale -LSB 0 1 1 11111 -0.019
Half Scale 1 0 0 000000.000
Half Scale +LSB 1 0 0 000010.019
Full Scale 1 1 1 111112.480
-
+
215
14
12
11
10
9
13
34
5
6
7
8
-
+
50K
50K
V+
V+ = 3.3V
V
OUT
1/2 ALD2701
V+
25K
1/2 ALD2701
+V
REF
= V+
LSB
B8
0.1µF
50K
50K
B5
B6
B7
MSBB1
B4
B3
B2
ALD 1801
B1 B2 B3 B4 B5 B6 B7 B8 VOUT
Zero Scale 0 0 0 000000.000
Half Scale 1 0 0 000001.650
Full Scale 1 1 1 111113.287
ALD1801A/ALD1801B Advanced Linear Devices 5
ALD1801
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.
RREF 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 multi-
turn potentiometer. The recommended nominal value of
RREF is 25KΩ.
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,
VREF- input voltage must be set at 1V or higher above the
V- voltage. Due to the internal operational amplifier
feedback, VREF+ input terminal would be set at the same
potential as VREF- input terminal, with the input reference
current determined by: Input reference current
IREF = { (VREF+)- (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 50KΩ can be used for all the
resistors required for the D/A converter. As an example,
RREF can be set to 25KΩ by connecting two 50KΩ resistors
in parallel where output resistors are set at 50KΩ.
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 100µA 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 Io 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 Io and Io can
maintain a constant value. Due to internal leakage currents
that vary with temperature, it is recommended that I FS of
50µA to 100µA 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 ROUT
and ROUT should match to minimize temperature drift.
ALD1801A/ALD1801B Advanced Linear Devices 6
ALD1801
TYPICAL PERFORMANCE CHARACTERISTICS
SUPPLY CURRENT AS A FUNCTION
OF TEMPERATURE
TEMPERATURE (°C)
400
0
SUPPLY CURRENT (µA)
0 255075100
800 ALL BITS "HIGH "
V
REF
= V+
R
REF
= 25K
200
600
125-25
I
S+
I
S-
I
S-
I
S+
V
S
= ±2.5V
V
S
= ±1.65V
V
S
= ±1.65V
V
S
= ±2.5V
FULL SCALE OUTPUT CURRENT
AS A FUNCTION OF OUTPUT
VOLTAGE (COMPLIANCE)
SUPPLY VOLTAGE (V)
50
0
OUTPUT CURRENT (µA)
-2 -1 0+1 +2
100 I
REF
= 100µA
I
REF
= 50µA
150
V
S
= ±2.5V
V
S
= ±1.65V
V
S
= ±2.5V V
S
= ±1.65V
FULL SCALE OUTPUT CURRENT
AS A FUNCTION
OF REFRENCE CURRENT
REFRENCE CURRENT (µA)
50
0
OUTPUT CURRENT (µA)
25 50 75 100 125
100
150
V
S
= ±1.65V TO ±2.5V
25
75
125
1500
PROPAGATION DELAY AS A FUNCTION
OF FULL SCALE OUTPUT CURRENT
OUTPUT CURRENT (µA)
1.3
PROPAGATION DELAY (µsec)
20 40 60 80 100
1.7
1.1
1.5
1200
1.9
FULL SCALE OUTPUT CURRENT
AS A FUNCTION OF SUPPLY VOLTAGE
SUPPLY VOLTAGE (V)
80
60
40
20
0
FULL SCALE OUTPUT CURRENT (µA)
0±1±2±3±4±5±6
100 I
REF
= 100µA
I
REF
= 50µA
SUPPLY CURRENT AS A FUNCTION
OF SUPPLY VOLTAGE
SUPPLY VOLTAGE (V)
400
0
SUPPLY CURRENT (µA)
±1±2±3±4±5
800 FULL SCALE
T
A
= 25°C
200
600
±60
I
REF
= 100µA
I
REF
= 0