Data Sheet AS1500/1/2/3
Revision 1.0, Oct 2004 Page 1 of 8
Key Features
- 256-Position
- Available in four Resistance values
- AS1500 resistance 10kOhms
- AS1501 resistance 20kOhms
- AS1502 resistance 50kOhms
- AS1503 resistance 100kOhms
- Power Shutdown —Less than 1 µA
- 3-Wire SPI-Compatible Serial Data Input
- 10 MHz Update Data Loading Rate
- 2.7 V to 5.5 V Single-Supply Operation
- Temperature Range –40°C to +125°C
- Package SO-8
- Compatible to AD8400
General Description
The AS1500 is a digital potentiometer with 256
programmable steps. The values of the resistor can be
controlled via 3 wire serial interface capable to handle
programming rates up to 10MHz. The AS1500 is available in
four different resistor values. The AS1500 incorporates a
10kΩ, the AS1501 a 20kΩ, the AS1502 a 50kΩ and the
AS1503 a 100kΩ fixed resistor. The wiper contact taps the
fixed resistor at points determined by the 8-bit digital code
word. The resistance between the wiper and the endpoint of
the resistor is linear. The switching action is performed in a
way that no glitches occur. Furthermore the AS150x product
family includes a shutdown mode, where it consumes less
than 1µA. The AS150x is available in an 8-pin SOIC
package. All parts are guaranteed to operate over the
extended industrial temperature range of –40°C to +125°C.
Applications
- Line Impedance Matching
- Volume Control, Panning
- Mechanical Potentiometer Replacement
- Power Supply Adjustment
- Programmable Filters, Delays, Time Constants
Figure 1 Pinout andfunctional Block Diagram of Digital Potentiometer AS150x family
PRELIMINARY FACT SHEET
Digital Potentiometer
AS1500/AS1501/AS1502/AS1503 DATASHEET
8-Bit
Latch
10 Bit
Serial
Latch
88
SDI
CK
CSN
A
W
B
VDD
GND
A
S1500
W
VDD
GND
CSN
7
6
2
3
A
S
1
50
x
To
p
View
CK
A
B
SDI
1
4
8
5
Data Sheet AS1500/1/2/3
Revision 1.0, Oct 2004 Page 2 of 8
ABSOLUTE MAXIMUM RATINGS
(TA = 25°C, unless otherwise noted.)
Parameter Limits
VDD to GND –0.3V, +7V
VA, VB, VW to GND 0V, VDD
AX – BX, AX – WX, BX – WX ±20mA
Digital Input and Output Voltage to GND 0V, +7V
Operating Temperature Range –40°C to +125°C
Maximum Junction Temperature (TJ max) 150°C
Storage Temperature –65°C to +150°C
Package body temperature 1260°C
Package Power Dissipation (TJ max – TA) / θJA
ESD 21kV
Table 1: Absolute Maximum Ratings
Pin Name Description
1 B Terminal B RDAC
2 GND Ground
3CSN
Chip Select Input, Active Low. When CS returns high,
data in the serial input register is loaded into the DAC
register.
4 SDI Serial Data Input
5 CK Serial Clock Input, Positive Edge Triggered.
6VDD
Positive power supply, specified for operation at both 3V
and 5V.
7 W Wiper RDAC
8 A Terminal A RDAC
Table 2: Pin Function Description
1 The reflow peak soldering temperature (body temperature) is specified according IPC/JEDEC J-STD-020C “Moisture/Reflow Sensitivity
Classification for non hermetic Solid State Surface Mount Devices”.
2 HBM MIL-Std883E 3015.7methods.
Data Sheet AS1500/1/2/3
Revision 1.0, Oct 2004 Page 3 of 8
AS1500 / AS1501 – SPECIFICATIONS
VDD = 3V±10% or 5V±10%, VA = VDD, VB = 0V, –40°C ≤ TA ≤ +125°C unless otherwise noted.
ELECTRICAL CHARACTERISTICS – 10k and 20k VERSIONS
Parameter Symbol Conditions Min Typ3Max Unit
DC CHARACTERISTICS RHEOSTAT MODE
TA = 25°C, VDD = 5V, AS1500, Version: 10kΩ81012 kΩ
Nominal Resistance4RAB TA = 25°C, VDD = 5V, AS1501, Version: 20kΩ16 20 24 kΩ
Resistance Tempco5∆RAB/∆TVAB = VDD, Wiper = No Connect 500 ppm/°C
Wiper Resistance RWVDD = 5V 20 100 200 Ω
Resistor Differential NL6R-DNL RWB, VDD = 5V, VA = No Connect –1 ±1/4 +1 LSB
Resistor Integral NL R-INL RWB, VDD = 5V, VA = No Connect –2 ±1/2 +2 LSB
DC CHARACTERISTICS POTENTIOMETER DIVIDER
Resolution N 8 Bits
VDD = 5.5V TA = 25°C –2 ±1/2 +2 LSB
Integral Nonlinearity INL VDD = 2.7V TA = 25°C –2 ±1/2 +2 LSB
VDD = 5.5V TA = 25°C –1 ±1/4 +1 LSB
Differential Nonlinearity DNL VDD = 2.7V TA = 25°C –1 ±1/4 +1 LSB
Voltage Divider Tempco ∆VW /∆TCode = 80H15 ppm/°C
Full-Scale Error VWFSE Code = FFH, VDD = 5.5V –4 –2.8 0 LSB
Zero-Scale Error VWZSE Code = 00H, VDD = 5.5V 0 1.3 2 LSB
RESISTOR TERMINALS
Voltage Range7VA, B, W 0VDDV
Capacitance8 Ax, Bx CA, B f =1MHz, Measured to GND, Code = 80H75 pF
Capacitance Wx CWf =1MHz, Measured to GND, Code = 80H120 pF
DIGITAL INPUTS AND OUTPUTS
Input Logic High VIH VDD = 5V 2.4 V
Input Logic Low VIL VDD = 5V 0.8 V
Input Logic High VIH VDD = 3V 2.1 V
Input Logic Low VIL VDD = 3V 0.6 V
Input Current IIH, IIL VIN = 5V or 0V, VDD = 5V ±1 µA
Input Capacitance CIL 5pF
POWER SUPPLIES
Power Supply Range VDD 2.7 5.5 V
Supply Current (CMOS) IDD VIH = VDD or VIL = 0V, VDD = 5.5V 0.1 1 µA
Supply Current (TTL)9IDD VIH = 2.4V or 0.8V, VDD = 5.5V 0.9 4 mA
Power Dissipation
(CMOS)10 PDISS VIH = VDD or VIL = 0V, VDD = 5.5V 27.5 µW
AS1500, Version: 10kΩ-54 -25 dB
Power Supply Suppression
Ratio PSSR VDD = 5V + 0.5VP
sine wave @ 1kHz AS1501, Version: 20kΩ-52 -25 dB
DYNAMIC CHARACTERISTICS11
BW_10k RWB = 10kΩ, VDD = 5V 1000 kHz
Bandwidth –3dB
Bandwidth –3dB BW_20k RWB = 20kΩ, VDD = 5V 500 kHz
Total Harmonic Distortion THDWVA = 1VRMS + 2VDC, VB = 2VDC, f = 1kHz 0.003 %
tS_10k RWB = 5kΩ, VA = VDD, VB = 0V, ±1% Error
Band 2µs
VW Settling Time
tS_20k RWB = 10kΩ, VA = VDD, VB = 0V, ±1% Error
Band 4µs
eNWB_10k RWB = 5kΩ, f =1kHz 9nV/ √ Hz
Resistor Noise Voltage eNWB_20k RWB = 10kΩ, f =1kHz 13 nV/ √ Hz
Table 3: Electrical Characteristics – 10k and 20k Versions
3 Typicals represent average readings at 25°C and VDD = 5V.
4 Wiper is not connected. IAB = 350µA for the 10kΩ version and 175µA for the 20kΩ version.
5 All Tempcos are guaranteed by design and not subject to production test.
6 Terminal A is not connected. IW = 350µA for the 10kΩ version and 175µA for the 20kΩ version.
7 Resistor terminals A, B, W have no limitations on polarity with respect to each other.
8 All capacitances are guaranteed by design and not subject to production test. Resistor-terminal capacitance tests are measured with 2.5V
bias on the measured terminal. The remaining resistor terminals are left open circuit.
9 Worst-case supply current consumed when input logic level at 2.4V, standard characteristic of CMOS logic.
10 PDISS is calculated from (IDD×VDD). CMOS logic level inputs result in minimum power dissipation.
11 All dynamic characteristics are guaranteed by design and not subject to production test. All dynamic characteristics use VDD=5V.
Data Sheet AS1500/1/2/3
Revision 1.0, Oct 2004 Page 4 of 8
AS1502 / AS1503 – SPECIFICATIONS
VDD = 3V±10% or 5V±10%, VA = VDD, VB = 0V, –40°C ≤ TA ≤ +125°C unless otherwise noted.
ELECTRICAL CHARACTERISTICS – 50k and 100k VERSIONS
Parameter Symbol Conditions Min Typ12 Max Unit
DC CHARACTERISTICS RHEOSTAT MODE
TA = 25°C, VDD = 5V, AS1502, Version: 50kΩ40 50 60 kΩ
Nominal Resistance13 RAB TA = 25°C, VDD = 5V, AS1503, Version: 100kΩ80 100 120 kΩ
Resistance Tempco14 ∆RAB/∆TVAB = VDD, Wiper = No Connect 500 ppm/°C
Wiper Resistance RWVDD = 5V 20 100 200 Ω
Resistor Differential NL15 R-DNL RWB, VDD = 5V, VA = No Connect –1 ±1/4 +1 LSB
Resistor Integral NL R-INL RWB, VDD = 5V, VA = No Connect –2 ±1/2 +2 LSB
DC CHARACTERISTICS POTENTIOMETER DIVIDER
Resolution N 8 Bits
VDD = 5.5V TA = 25°C –4±1+4 LSB
Integral Nonlinearity INL VDD = 2.7V TA = 25°C –4±1+4 LSB
VDD = 5.5V TA = 25°C –1 ±1/4 +1 LSB
Differential Nonlinearity DNL VDD = 2.7V TA = 25°C –1 ±1/4 +1 LSB
Voltage Divider Tempco ∆VW /∆TCode = 80H15 ppm/°C
Full-Scale Error VWFSE Code = FFH, VDD = 5.5V –1 –0.25 0 LSB
Zero-Scale Error VWZSE Code = 00H, VDD = 5.5V 0 0.1 1 LSB
RESISTOR TERMINALS
Voltage Range16 VA, B, W 0VDDV
Capacitance17 Ax, Bx CA, B f = 1MHz, Measured to GND, Code = 80H15 pF
Capacitance Wx CWf = 1MHz, Measured to GND, Code = 80H80 pF
DIGITAL INPUTS AND OUTPUTS
Input Logic High VIH VDD = 5V 2.4 V
Input Logic Low VIL VDD = 5V 0.8 V
Input Logic High VIH VDD = 3V 2.1 V
Input Logic Low VIL VDD = 3V 0.6 V
Input Current IIH, IIL VIN = 5V or 0V, VDD = 5V ±1 µA
Input Capacitance CIL 5pF
POWER SUPPLIES
Power Supply Range VDD 2.7 5.5 V
Supply Current (CMOS) IDD VIH = VDD or VIL = 0V, VDD = 5.5V 0.1 1 µA
Supply Current (TTL)18 IDD VIH = 2.4V or 0.8V, VDD = 5.5V 0.9 4 mA
Power Dissipation
(CMOS)19 PDISS VIH = VDD or VIL = 0V, VDD = 5.5V 27.5 µW
AS1502, Version: 50kΩ-43 tbd. dB
Power Supply Suppression
Ratio PSSR VDD = 5V + 0.5VP
sine wave @ 1kHz AS1503, Version:
100kΩ-48 tbd. dB
DYNAMIC CHARACTERISTICS20
BW_50k RWB = 50kΩ, VDD = 5V 220 kHz
Bandwidth –3dB
Bandwidth –3dB BW_100k RWB = 100kΩ, VDD = 5V 110 kHz
Total Harmonic Distortion THDWVA = 1VRMS + 2VDC, VB = 2VDC, f = 1kHz 0.003 %
tS_50k RWB = 50kΩ, VA = VDD, VB = 0V, ±1% Error
Band 9µs
VW Settling Time
tS_100k RWB = 100kΩ, VA = VDD, VB = 0V, ±1% Error
Band 18 µs
eNWB_50k RWB = 50kΩ, f = 1kHz 20 nV/ √ Hz
Resistor Noise Voltage eNWB_100
kRWB = 100kΩ, f = 1kHz 29 nV/ √ Hz
Table 4: Electrical Characteristics – 50k and 100k Versions
12 Typicals represent average readings at 25°C and VDD = 5V.
13 Wiper is not connected. IAB = 70µA for the 50kΩ version and 35µA for the 100kΩ version.
14 All Tempcos are guaranteed by design and not subject to production test.
15 Terminal A is not connected. IW = 70µA for the 50kΩ version and 35µA for the 100kΩ version.
16 Resistor terminals A, B, W have no limitations on polarity with respect to each other.
17 All capacitances are guaranteed by design and not subject to production test. Resistor-terminal capacitance tests are measured with 2.5V
bias on the measured terminal. The remaining resistor terminals are left open circuit.
18 Worst-case supply current consumed when input logic level at 2.4V, standard characteristic of CMOS logic.
19 PDISS is calculated from (IDD×VDD). CMOS logic level inputs result in minimum power dissipation.
20 All dynamic characteristics are guaranteed by design and not subject to production test. All dynamic characteristics use VDD=5V.
Data Sheet AS1500/1/2/3
Revision 1.0, Oct 2004 Page 5 of 8
AS150x – SPECIFICATIONS
(VDD = 3V±10% or 5V±10%, VA = VDD, VB = 0V,
–40°C≤TA≤+125°C unless otherwise noted.)
ELECTRICAL CHARACTERISTICS–ALL
VERSIONS
Parameter Sym-
bol Conditions Min Typ
21 Max Unit
SWITCHING CHARACTERISTICS 22, 23
Input Clock
Pulsewidth tCH, tCL Clock Level
High or Low 50 ns
Data Setup Time tDS 5ns
Data Hold Time tDH 5ns
CSN Setup Time tCSS 10 ns
CSN High
Pulsewidth tCSW 10 ns
CK Fall to CSN Rise
Hold Time tCSH 0ns
CSN Rise to Clock
Rise Setup tCS1 10 ns
Table 5: Switching Characteristics
Detailed Description
Serial-Programming
Programming of the AS150x is done via the 3 wire serial
interface. The three input signals are serial data input
(SDI), clock(CK) and chip select (CS). A programming
sequence consists of 10-bit, where the last eight bit
contain the code word for the resistor value. The first two
bits A1 and A0 have to be low(see Table ). The data is
shifted into the internal 10 Bit register with the rising edge
of the CK signal. With the rising edge of the CSN signal
the data becomes valid and the resistance is updated (see
figure 2). A detailed block diagram is shown in figure 3.
A1 A0 D7 D6 D5 D4 D3 D2 D1 D0
0 0 MSB Data LSB
Table 6: Serial data format (16 bits)
21 Typicals represent average readings at 25°C and VDD=5V.
22 Guaranteed by design and not subject to production test.
Resistor-terminal capacitance tests are measured with 2.5V
bias on the measured terminal. The remaining resistor
terminals are left open circuit.
23 See timing diagram for location of measured values. All input
control voltages are specified with tR = tF = 1ns (10% to 90% of
VDD) and timed from a voltage level of 1.6V. Switching
characteristics are measured using VDD=3V or 5V. To avoid
false clocking, a minimum input logic slew rate of 1V/µs should
be maintained.
Figure 2: Timing Diagram
Figure 3: Detailed Timing Diagram
Rheostat Operation
The digital potentiometer family AS150x offers nominal
resistor values of 10kΩ, 20 kΩ, 50kΩ and 100kΩ. The
resistor has 256 contact points where the wiper can access
the resistor. The 8-bit code word determines the position
of the wiper and is decoded through an internal logic. The
lowest code 00h is related to the terminal B. The
resistance is then only determined by the wiper resistance
(100Ω). The resistance for the next code 01h is the
nominal resistor RAB (10kΩ, 20 kΩ, 50kΩ or 100kΩ)
divided through 256 plus the wiper resistor. In case of
AS1501 (10kΩ) the total resistance is 39Ω+100Ω=139Ω.
Accordingly the resistor for code 02h is 78Ω+100Ω=178Ω.
The last code 255h does not connect to terminal A directly
(see Figure 5). So the maximum value is 10000Ω - 39Ω
+100Ω = 10061Ω. The general formula for the calculation
of the resistance RWB is:
RWB (Dx)= (Dx)/256⋅RAB + RW
where RAB is the nominal resistance between terminal A
and B, RW is the wiper resistance and DX is the 8-Bit Code
word. In Table 7 the resistor values between the wiper and
terminal B for AS1501 are given for specific codes DX. In
the zero-scale condition the wiper resistance of 100Ω
remains present.
1
1
1
0
0
0
0V
VOUT
CS
CK
SD
VD
DAC Register
A
1
A
0D7D6D5D4D3D2D1D0
SDI
VOUT
CK
CSN
VDD
0
0
0
0V
1
1
1
±1% Error
±1%
A
X
or
A
X
or
tDtD
tC
tCS
tCS
tCS
tCS
tS
tCL
Data Sheet AS1500/1/2/3
Revision 1.0, Oct 2004 Page 6 of 8
DX (Dec) RWB (Ω
ΩΩ
Ω)Output State
255 10061 Full Scale
128 5100 Midscale
1 139 1 LSB
0 100 Zero-Scale
(Wiper Contact Resistance)
Table 7: RDAC-Codes WB
The maximum current through the wiper and terminal B is
5mA. If the current exceeds this limit the internal switches
can degrade or even be damaged. As a mechanical
potentiometer the resistance RWA and RWB are totally
symmetrical. The relation between them is shown in Figure
4.
Figure 4: RWA and RWB versa Code
The resistance RWA is the complimentary resistor to RWB
and can be controlled digitally as well. RWA starts at the
maximum value of the nominal resistance and is reduced
with increasing 8-Bit code words. The formula to calculate
RWA is given below:
RWA (Dx)= (256 - Dx)/256⋅RAB + RW
where RAB is the nominal resistance between terminal A
and B, RW is the wiper resistance and DX is the 8-Bit Code
word. In Table 8 the resistor values between the wiper and
terminal B for AS1501 are given for specific codes DX.
DX (Dec) RWA (Ω
ΩΩ
Ω)Output State
255 89 Full Scale
128 5050 Midscale
1 10011 1 LSB
0 10050 Zero-Scale
Table 8: RDAC-Codes WA
Figure 5: Equivalent RDAC Circuit
Voltage Output Operation
The AS150x family can easily used in an voltage output
mode, where the output voltage is proportional to an
applied voltage to a given terminal. When 5V are applied to
terminal A and B is set to ground the ouput voltage at the
wiper starts at zero volts up to 1LSB less then 5V. One
LSB of voltage corresponds to the voltage applied at
terminal AB divided through 256 steps of possible wiper
settings. The formula is given by
VW (Dx)= (Dx)/256⋅VAB + VB
where VAB is the voltage applied between terminal A and B,
VW is the voltage at the wiper, DX is the 8-Bit Code word
and VB is the voltage at terminal B. The temperature drift is
significant better than in Rheostat mode, since the
temperature coefficient is determined by the internal
resistor ratio. Therefore the temperature drift is only
15ppm/°C.
Applications
The digital potentiometer can replace in many applications
the analog trimming potentiometer. The digital
potentiometer is not sensitive to vibrations and shocks. It
has an extremely small form-factor and can be adjusted
very fast (e.g. AS1500 has an update rate of 600kHz)
Furthermore the temperature drift, resolution and noise are
significant better and cannot be achieved with a
mechanical trimming potentiometer. Due to the
programmability the resistor settings can be stored in the
system memory, so that after a power down the exact
settings can be recalled easily.
All analog signals must remain within 0 to VDD range. For
standard potentiometer applications the wiper output can
be used directly. In the case of a low impedance load a
buffer shall be used.
CODE -
RWA
(
D
),
RWB
(
D
)
- % of
RWRW
0
25
50
75
10
0 64121925
RDAC
LATCH
A
ND
DECODE
RS=RNOMINAL / 256
RS
RS
RS
RS
A
W
B
D7
D6
D5
D4
D3
D2
D1
D0
Data Sheet AS1500/1/2/3
Revision 1.0, Oct 2004 Page 7 of 8
Package Information
The AS150x family is offered in a 8-pin SOIC package:
Data Sheet AS1500/1/2/3
Revision 1.0, Oct 2004 Page 8 of 8
Package Dimensions in Inch and mm (values for N = 8 Pin package are valid):
Ordering Information
Part Resistor Pin Package Delivery Form
AS1500 10kΩ8-pin SOIC Tubes
AS1501 20kΩ8-pin SOIC Tubes
AS1502 50kΩ8-pin SOIC Tubes
AS1503 100kΩ8-pin SOIC Tubes
AS1500-T 10kΩ8-pin SOIC T&R
AS1501-T 20kΩ8-pin SOIC T&R
AS1502-T 50kΩ8-pin SOIC T&R
AS1503-T 100kΩ8-pin SOIC T&R
For Pb-free package use suffix ‘-Z‘
Copyright
Copyright © 2004 austriamicrosystems. Trademarks
registered ®. All rights reserved. The material herein may
not be reproduced, adapted, merged, translated, stored, or
used without the prior written consent of the copyright
owner. To the best of its knowledge, austriamicrosystems
asserts that the information contained in this publication is
accurate and correct.
Contact
austriamicrosystems AG
A 8141 Schloss Premstätten, Austria
T. +43 (0) 3136 500 0
F. +43 (0) 3136 525 01
info@austriamicrosystems.com
