ADVANCED
LINEAR
DEVICES, INC.
ALD1801A/ALD1801B
ALD1801
8 BIT MICROPOWER MULTIPLYING D/A CONVERTER
GENERAL DESCRIPTION
FEATURES
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.
•
•
•
•
•
•
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
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.
PIN CONFIGURATION
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
N/C
1
16
N/C
I OUT
2
15
VREF-
V-
3
14
VREF+
IOUT
4
13
V+
MSB B1
5
12
B8 LSB
B2
6
11
B7
B3
7
10
B6
B4
8
9
B5
Operating Temperature Range
-55°C to +125°C
0°C to +70°C
0°C to +70°C
16-Pin
CERDIP
Package
16-Pin
Small Outline
Package(SOIC)
16-Pin
Plastic Dip
Package
ALD1801A DC
ALD1801B DC
ALD1801 DC
ALD1801A SC
ALD1801B SC
ALD1801 SC
ALD1801A PC
ALD1801B PC
ALD1801 PC
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
IOUT
V+
13
IB1
VREF15
IOUT
IB2
IB5
IB4
IB3
IB7
IB6
IB8
3
5
B1
MSB
6
7
8
9
B2
B3
B4
B5
10
B6
11
B7
12
B8
LSB
© 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 = 25 °C VS = ±2.5V or VS = +5.0V unless otherwise specifie
Parameter
Symbol
Supply
Voltage
VS
Min
1801A
Typ
±1.5
1801B
Typ Max
1801
Min Typ
Max
Min
±6.0
±1.5
±6.0 ±1.5
Max
Unit
Test Conditions
±6.0
V
Dual Supply
Single Supply
Resolution
8
8
8
Bits
Monotonicity
8
8
8
Bits
Nonlinearity
±0.1
NL
±0.19
±0.39
% of
Full Scale
Settling Time
tS
2.5
5.0
2.5
5.0
2.5
5.0
µs
To 1/2 LSB with all bits
turned on/off
Propagation
Delay
td
1.5
1.5
2.5
2.5
1.5
1.5
2.5
2.5
1.5
1.5
2.5
2.5
µs
µs
Each Bit
All Bits
Full Scale
Tempco
TC
±10
±50
±10
±50
±10
±50
ppm/°C
Output
Compliance
VOC
Output
Impedance
V+1.5
V+
+0.2
50
Full Scale
Current Range
IFS
Full Scale
Symmetry
IFSS
Zero Scale
Current
IZS
Logic Input Level 1
Logic "0"
VIL
Logic "1"
VIH
Logic Swing
Logic Threshold
Range
VLS
Reference Bias
Current
IRB
Power Supply
Current
+IS
- IS
Power Dissipation
PD
V+1.5
V+
V+0.2 +1.5
50
50
100
100
100
Output Within
Compliance limits
µA
ROUT = R OUT = 50KΩ
VREF = 2.5V; RREF =25KΩ
±2.5
µA
10
10
10
nA
-1.1
2.1
2.8
1.5
-2.8
-1.5
-1.1
V
Supply = ±2.5V
2.8
1.5
V
V
Supply = ±2.5V
Supply = ±2.5V
0.1
nA
800
1000
µA
Full Scale
Output = 100µA
mW
Supply = ±2.5V
2.1
2.8
1.5
0.1
0.1
800
1000
500 800
700 1000
4.5
4.5
-2.8
-1.5
Compensation
Notes:
MΩ
±2.5
-1.1
500
700
V
±2.5
2.1
-2.8
-1.5
V+
+0.2
500
700
4.5
Not Required
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 = 25°C VS = ±1.65V or VS = +3.3V unless otherwise specified
Parameter
Symbol
Min
1801A
Typ
Max
Min
1801B
Typ Max
1801
Min Typ
Max
Unit
Resolution
8
8
8
Bits
Monotonicity
8
8
8
Bits
Nonlinearity
±0.1
NL
±0.19
±0.39
Test Conditions
% of
Full Scale
Settling Time
tS
4.0
10.0
4.0
10.0
4.0
10.0
µs
To 1/2 LSB with all bits
turned on/off
Propagation
Delay
td
1.5
1.5
4.0
4.0
1.5
1.5
4.0
4.0
1.5
1.5
4.0
4.0
µs
µs
Each Bits
All Bits
Full Scale
Tempco
TC
±10
±50
±10
±50
±10
±50
ppm/°C
Output
Compliance
VOC
Output
Impedance
V+1.5
V+
+0.2
50
Full Scale
Current Range
IFS
Full Scale
IFSS
50
V+1.5
V+
V+0.2 +1.5
50
50
50
V+
+0.2
50
V
MΩ
Output Within
Compliance limits
µA
ROUT = ROUT = 100KΩ
VREF = 2.5V; RREF =50KΩ
±2.5
±2.5
±2.5
µA
IZS
10
10
10
nA
Reference Bias
Current
IRB
0.1
0.1
0.1
nA
Power Supply
Current
+IS
- IS
500
600
µA
Power Dissipation
PD
1.8
mW
Symmetry
Zero Scale
Current
ALD1801A/ALD1801B
ALD1801
350
450
500
600
1.8
350
450
500
600
1.8
Advanced Linear Devices
350
450
Full Scale
Output = 50µA
3
DUAL SUPPLY ±2.5V
RATIOMETRIC VOLTAGE OUTPUT DAC
50K
V+ = 2.5V
50K
+VREF
ALD
1702
+
VOUT
V- = 2.5V
V+ = 2.5V
4
2
3 13
15
+VREF =2.5V
VREF-
14
25K
12
11
10
9
5
6
7
8
B1
B2
B3
B4
B8
B7
B6
B5
LSB
ALD 1801
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
V+ = 3.3V
50K
+
V+
1/2 ALD2701
V+
1/2 ALD2701
50K
VOUT
+
4
2
3
13 15
25K
14
+VREF = V+
MSB
B1
0.1µF B2
50K
B3
B4
12
11
10
9
5
6
7
8
B8
B7
B6
B5
LSB
ALD 1801
Zero Scale
Half Scale
Full Scale
ALD1801A/ALD1801B
ALD1801
B1
0
1
1
B2
0
0
1
B3
0
0
1
B4
0
0
1
B5
0
0
1
Advanced Linear Devices
B6
0
0
1
B7
0
0
1
B8
0
0
1
VOUT
0.000
1.650
3.287
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 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,
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
ALD1801A/ALD1801B
ALD1801
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 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
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 R OUT
and ROUT should match to minimize temperature drift.
Advanced Linear Devices
5
TYPICAL PERFORMANCE CHARACTERISTICS
SUPPLY CURRENT AS A FUNCTION
OF TEMPERATURE
1.9
SUPPLY CURRENT (µA)
PROPAGATION DELAY (µsec)
PROPAGATION DELAY AS A FUNCTION
OF FULL SCALE OUTPUT CURRENT
1.7
1.5
1.3
1.1
800
IS-
VS = ±2.5V
600
IS+
VS = ±2.5V
IS-
VS = ±1.65V
400
IS+
200
20
40
60
80
120
100
-25
0
OUTPUT CURRENT (µA)
FULL SCALE OUTPUT CURRENT (µA)
SUPPLY CURRENT (µA)
FULL SCALE
TA = 25°C
800
600
IREF = 100µA
400
IREF = 0
200
0
0
±1
±2
±3
±4
50
75
100
125
FULL SCALE OUTPUT CURRENT
AS A FUNCTION OF SUPPLY VOLTAGE
100
IREF = 100µA
80
60
20
0
±6
±5
IREF = 50µA
40
0
±1
±2
±3
±4
±5
±6
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
FULL SCALE OUTPUT CURRENT
AS A FUNCTION OF OUTPUT
VOLTAGE (COMPLIANCE)
FULL SCALE OUTPUT CURRENT
AS A FUNCTION
OF REFRENCE CURRENT
150
150
VS = ±2.5V
IREF = 100µA
VS = ±1.65V
VS = ±2.5V
VS = ±1.65V
IREF = 50µA
0
OUTPUT CURRENT (µA)
OUTPUT CURRENT (µA)
25
TEMPERATURE (°C)
SUPPLY CURRENT AS A FUNCTION
OF SUPPLY VOLTAGE
50
VS = ±1.65V
0
0
100
ALL BITS "HIGH "
VREF = V+
RREF = 25K
VS = ±1.65V TO ±2.5V
125
100
75
50
25
0
-2
-1
0
+1
+2
0
SUPPLY VOLTAGE (V)
ALD1801A/ALD1801B
ALD1801
25
50
75
100
125
150
REFRENCE CURRENT (µA)
Advanced Linear Devices
6