AD AD5204BR100 4-/6-channel digital potentiometer Datasheet

a
FEATURES
256 Position
Multiple Independently Programmable Channels
AD5204—4-Channel
AD5206—6-Channel
Potentiometer Replacement
10 k⍀, 50 k⍀, 100 k⍀
3-Wire SPI-Compatible Serial Data Input
+2.7 V to +5.5 V Single Supply; ⴞ2.7 V Dual Supply
Operation
Power ON Midscale Preset
APPLICATIONS
Mechanical Potentiometer Replacement
Instrumentation: Gain, Offset Adjustment
Programmable Voltage-to-Current Conversion
Programmable Filters, Delays, Time Constants
Line Impedance Matching
GENERAL DESCRIPTION
The AD5204/AD5206 provides four-/six-channel, 256 position
digitally-controlled Variable Resistor (VR) devices. These devices perform the same electronic adjustment function as a
potentiometer or variable resistor. Each channel of the AD5204/
AD5206 contains a fixed resistor with a wiper contact that taps
the fixed resistor value at a point determined by a digital code
loaded into the SPI-compatible serial-input register. The resistance between the wiper and either endpoint of the fixed resistor
varies linearly with respect to the digital code transferred into
the VR latch. The variable resistor offers a completely programmable value of resistance between the A terminal and the wiper
or the B Terminal and the wiper. The fixed A-to-B terminal
resistance of 10 kΩ, 50 kΩ, or 100 kΩ has a nominal temperature coefficient of 700 ppm/°C.
Each VR has its own VR latch which holds its programmed
resistance value. These VR latches are updated from an internal
serial-to-parallel shift register that is loaded from a standard
3-wire serial-input digital interface. Eleven data bits make up
the data word clocked into the serial input register. The first
three bits are decoded to determine which VR latch will be
loaded with the last eight bits of the data word when the CS
strobe is returned to logic high. A serial data output pin at
the opposite end of the serial register (AD5204 only) allows
simple daisy-chaining in multiple VR applications without
additional external decoding logic.
4-/6-Channel
Digital Potentiometers
AD5204/AD5206
FUNCTIONAL BLOCK DIAGRAMS
AD5204
CS
CLK
EN
SDO
A2
A1
A0
D7
DO
VDD
A1
D7
W1
RDAC
LATCH
#1
ADDR
DEC
D0
B1
R
SER
REG
A4
D7
W4
SDI
DI
RDAC
LATCH
#4
D0
8
GND
D0
POWERON
PRESET
R
VSS
PR
AD5206
CS
CLK
EN
A2
A1
A0
D7
B4
SHDN
A1
D7
W1
RDAC
LATCH
#1
ADDR
DEC
D0
VDD
B1
R
SER
REG
A6
D7
W6
SDI
DI
RDAC
LATCH
#6
D0
8
GND
POWERON
PRESET
D0
B6
R
VSS
An optional reset (PR) pin forces all the AD5204 wipers to the
midscale position by loading 80H into the VR latch.
The AD5204/AD5206 is available in both surface mount
(SOL-24), TSSOP-24 and the 24-lead plastic DIP package. All
parts are guaranteed to operate over the extended industrial
temperature range of –40°C to +85°C. For additional single,
dual, and quad channel devices, see the AD8400/AD8402/
AD8403 products.
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 1999
AD5204/AD5206–SPECIFICATIONS
(V = +5 V ⴞ 10% or +3 V ⴞ 10%, V
DD
ELECTRICAL CHARACTERISTICS unless otherwise noted.)
Parameter
Symbol
SS
= 0 V, VA = +VDD, VB = 0 V, –40ⴗC < TA < +85ⴗC
Conditions
DC CHARACTERISTICS RHEOSTAT MODE Specifications Apply to All VRs
Resistor Differential NL 2
R-DNL
RWB , VA = No Connect
R-INL
RWB , VA = No Connect
Resistor Nonlinearity Error2
∆RAB
TA = +25°C
Nominal Resistor Tolerance 3
VAB = V DD, Wiper = No Connect
Resistance Temperature Coefficient
∆RAB/∆T
CH1 to 2, 3, 4, or 5, 6; VAB = V DD
Nominal Resistance Match
∆R/RAB
Wiper Resistance
RW
IW = 1 V/R, VDD = +5 V
DC CHARACTERISTICS POTENTIOMETER DIVIDER MODE Specifications Apply to All VRs
Resolution
N
DNL
Differential Nonlinearity 4
INL
Integral Nonlinearity 4
Code = 40H
Voltage Divider Temperature Coefficient ∆VW/∆T
Code = 7FH
Full-Scale Error
VWFSE
Zero-Scale Error
VWZSE
Code = 00H
Min
Typ1
Max
Units
–1
–2
–30
± 1/4
± 1/2
+1
+2
+30
LSB
LSB
%
ppm/°C
%
Ω
700
0.25
50
8
–1
–2
–2
0
± 1/4
± 1/2
15
–1
+1
RESISTOR TERMINALS
Voltage Range5
Capacitance6 Ax, Bx
Capacitance6 Wx
Shutdown Current 7
Common-Mode Leakage
VA, VB, VW
CA, C B
CW
IA_SD
ICM
DIGITAL INPUTS AND OUTPUTS
Input Logic High
Input Logic Low
Output Logic High
Output Logic Low
Input Current
Input Capacitance6
VIH
VIL
VOH
VOL
IIL
CIL
VDD = +5 V/+3 V
VDD = +5 V/+3 V
RPULL–UP = 1 kΩ to +5 V
IOL = 1.6 mA, VLOGIC = +5 V
VIN = 0 V or +5 V
POWER SUPPLIES
Power Single Supply Range
Power Dual Supply Range
Positive Supply Current
Negative Supply Current
Power Dissipation 8
Power Supply Sensitivity
VDD Range
VDD/SS Range
IDD
ISS
PDISS
PSS
VSS = 0 V
VIH = +5 V or V IL = 0 V
VSS = –2.5 V, VDD = +2.7 V
VIH = +5 V or V IL = 0 V
∆VDD = +5 V ± 10%
0.0002
BW_10K
BW_50K
BW_100K
THDW
tS
e N_WB
RAB = 10 kΩ
RAB = 50 kΩ
RAB = 100 kΩ
VA = 1.414 V rms, V B = 0 V dc, f = 1 kHz
VA = 5 V, VB = 0 V, ± 1 LSB Error Band
RWB = 5 kΩ, f = 1 kHz, PR = 0
721
137
69
0.004
2/9/18
9
DYNAMIC CHARACTERISTICS
Bandwidth –3 dB
VSS
f = 1 MHz, Measured to GND, Code = 40H
f = 1 MHz, Measured to GND, Code = 40H
+1
+2
0
+2
VDD
45
60
0.01
1
VA = VB = VW = 0, VDD = +2.7 V, VSS = –2.5 V
1.5
100
5
2.4/2.1
0.8/0.6
4.9
0.4
±1
5
2.7
± 2.3
12
12
5.5
± 2.7
60
60
0.3
0.005
Bits
LSB
LSB
ppm/°C
LSB
LSB
V
pF
pF
µA
nA
V
V
V
V
µA
pF
V
V
µA
µA
mW
%/%
6, 9
Total Harmonic Distortion
VW Settling Time (10K/50K/100K)
Resistor Noise Voltage
INTERFACE TIMING CHARACTERISTICS Applies to All Parts 6, 10
Input Clock Pulsewidth
tCH , tCL
Clock Level High or Low
Data Setup Time
tDS
Data Hold Time
tDH
tPD
RL = 2 kΩ, CL < 20 pF
CLK to SDO Propagation Delay11
CS Setup Time
tCSS
CS High Pulsewidth
tCSW
Reset Pulsewidth
tRS
CLK Fall to CS Fall Setup
tCSH0
CLK Fall to CS Rise Hold Time
tCSH1
CS Rise to Clock Rise Setup
tCS1
20
5
5
1
15
40
90
0
0
10
kHz
kHz
kHz
%
µs
nV/√Hz
150
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
NOTES
1
Typicals represent average readings at +25°C and VDD = +5 V.
Resistor position nonlinearity error R-INL is the deviation from an ideal value measured between the maximum resistance and the minimum resistance wiper positions. R-DNL measures the relative step change from ideal between successive tap positions. Parts are guaranteed monotonic. See Figure 23 test circuit. I W = VDD/R
for both VDD = +3 V or VDD = +5 V.
3
VAB = V DD, Wiper (VW ) = No connect.
4
INL and DNL are measured at V W with the RDAC configured as a potentiometer divider similar to a voltage output D/A converter. V A = VDD and V B = 0 V.
DNL specification limits of ±1 LSB maximum are guaranteed monotonic operating conditions. See Figure 22 test circuit.
2
–2–
REV. 0
AD5204/AD5206
5
Resistor Terminals A, B, W, have no limitations on polarity with respect to each other.
Guaranteed by design and not subject to production test.
7
Measured at the Ax terminals. All Ax terminals are open-circuited in shutdown mode.
8
PDISS is calculated from (I DD × V DD). CMOS logic level inputs result in minimum power dissipation.
9
All dynamic characteristics use V DD = +5 V.
10
See timing diagrams for location of measured values. All input control voltages are specified with t R = tF = 2.5 ns (10% to 90% of 3 V) and timed from a voltage
level of 1.5 V. Switching characteristics are measured using both V DD = +3 V or +5 V.
11
Propagation delay depends on value of V DD, R L and C L. See Operation section.
6
Specifications subject to change without notice.
ABSOLUTE MAXIMUM RATINGS*
(TA = +25°C, unless otherwise noted)
VDD to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V, +7 V
VSS to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V, –7 V
VDD to VSS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7 V
VA, VB, V W to GND . . . . . . . . . . . . . . . . . . . . . . . . . . VSS , VDD
Ax–Bx, Ax–Wx, Bx–Wx . . . . . . . . . . . . . . . . . . . . . . ± 20 mA
Digital Input and Output Voltage to GND . . . . . . . 0 V, +7 V
Operating Temperature Range . . . . . . . . . . . –40°C to +85°C
Maximum Junction Temperature (TJ MAX) . . . . . . . . +150°C
Storage Temperature . . . . . . . . . . . . . . . . . . –65°C to +150°C
Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . +300°C
Package Power Dissipation . . . . . . . . . . . . . . (T J max–TA)/θJA
Thermal Resistance θ JA
P-DIP (N-24) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63°C/W
SOIC (SOL-24) . . . . . . . . . . . . . . . . . . . . . . . . . . . 70°C/W
TSSOP-24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143°C/W
*Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those indicated in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the AD5204/AD5206 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper
ESD precautions are recommended to avoid performance degradation or loss of functionality.
REV. 0
–3–
WARNING!
ESD SENSITIVE DEVICE
AD5204/AD5206
1
SDI
A2 A1 A0 D7 D6 D5 D4 D3 D2 D1 D0
1
0
tRS
PR
0
1
CLK
tS
VDD
0
61 LSB
VOUT
RDAC LATCH LOAD
1
0V
CS
61 LSB ERROR BAND
0
Figure 3. AD5204 Preset Timing Diagram
VDD
VOUT
0V
Figure 1. Timing Diagram
1
SDI
(DATA IN)
Ax OR Dx
Ax OR Dx
0
tDH
tDS
SDO
(DATA OUT)
1
Ax OR Dx
Ax OR Dx
0
tPD_MAX
tCH
tCS1
1
CLK
0
CS
tCSH0
tCSS
1
tCL
tCSH1
tCSW
0
tS
VOUT
61 LSB
VDD
61 LSB ERROR BAND
0V
Figure 2. Detail Timing Diagram
ORDERING GUIDE
Model
k⍀
Temperature Range
Package Descriptions
Package Options
AD5204BN10
AD5204BR10
AD5204BRU10
AD5204BN50
AD5204BR50
AD5204BRU50
AD5204BN100
AD5204BR100
AD5204BRU100
AD5206BN10
AD5206BR10
AD5206BRU10
AD5206BN50
AD5206BR50
AD5206BRU50
AD5206BN100
AD5206BR100
AD5206BRU100
10
10
10
50
50
50
100
100
100
10
10
10
50
50
50
100
100
100
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
24-Lead Narrow Body (PDIP)
24-Lead Wide Body (SOIC)
24-Lead Thin Shrink SO Package (TSSOP)
24-Lead Narrow Body (PDIP)
24-Lead Wide Body (SOIC)
24-Lead Thin Shrink SO Package (TSSOP)
24-Lead Narrow Body (PDIP)
24-Lead Wide Body (SOIC)
24-Lead Thin Shrink SO Package (TSSOP)
24-Lead Narrow Body (PDIP)
24-Lead Wide Body (SOIC)
24-Lead Thin Shrink SO Package (TSSOP)
24-Lead Narrow Body (PDIP)
24-Lead Wide Body (SOIC)
24-Lead Thin Shrink SO Package (TSSOP)
24-Lead Narrow Body (PDIP)
24-Lead Wide Body (SOIC)
24-Lead Thin Shrink SO Package (TSSOP)
N-24
R-24/SOL-24
RU-24
N-24
R-24/SOL-24
RU-24
N-24
R-24/SOL-24
RU-24
N-24
R-24/SOL-24
RU-24
N-24
R-24/SOL-24
RU-24
N-24
R-24/SOL-24
RU -24
The AD5204/AD5206 contains 5,925 transistors. Die size; 92 mil × 114 mil, 10,488 sq. mil.
–4–
REV. 0
AD5204/AD5206
AD5206 PIN CONFIGURATION
AD5204 PIN CONFIGURATION
NC 1
24
B4
A6 1
24
B4
NC 2
23
W4
W6 2
23
W4
GND 3
22
A4
B6 3
22
A4
CS 4
21
B2
GND 4
21
B2
PR 5
20
W2
CS 5
20
W2
AD5204
19
A2
AD5206
19
A2
(NOT TO
SCALE)
VDD 6
(NOT TO
SCALE)
VDD 6
SHDN 7
18
A1
SDI 7
18
A1
8
17
W1
CLK 8
17
W1
CLK 9
16
B1
VSS 9
16
B1
SDO 10
15
A3
B5 10
15
A3
VSS 11
14
W3
W5 11
14
W3
NC 12
13
B3
A5 12
13
B3
SDI
NC = NO CONNECT
AD5204 PIN FUNCTION DESCRIPTIONS
Pin
No.
Name
1, 2,
12
3
4
NC
GND
CS
5
PR
6
VDD
7
SHDN
8
9
10
SDI
CLK
SDO
11
VSS
13
14
15
16
17
18
19
20
21
22
23
24
B3
W3
A3
B1
W1
A1
A2
W2
B2
A4
W4
B4
REV. 0
AD5206 PIN FUNCTION DESCRIPTIONS
Description
Not Connected.
Ground.
Chip Select Input, Active Low. When CS
returns high, data in the serial input register
is decoded based on the address bits and
loaded into the target RDAC latch.
Active low preset to midscale; sets RDAC
registers to 80H.
Positive power supply, specified for
operation at both +3 V or +5 V. (Sum of
|VDD| + |VSS| <5.5 V.)
Active low input. Terminal A open-circuit.
Shutdown controls Variable Resistors #1
through #4.
Serial Data Input. MSB First.
Serial Clock Input, positive edge triggered.
Serial Data Output, Open Drain transistor
requires pull-up resistor.
Negative Power Supply, specified for
operation at both 0 V or –2.7 V. (Sum of
|VDD| + |VSS| <5.5 V.)
B Terminal RDAC #3.
Wiper RDAC #3, addr = 0102.
A Terminal RDAC #3.
B Terminal RDAC #1.
Wiper RDAC #1, addr = 0002.
A Terminal RDAC #1.
A Terminal RDAC #2.
Wiper RDAC #2, addr = 0012.
B Terminal RDAC #2.
A Terminal RDAC #4.
Wiper RDAC #4, addr = 0112.
B Terminal RDAC #4.
–5–
Pin
No.
Name
Description
1
2
3
4
5
A6
W6
B6
GND
CS
6
VDD
7
8
9
SDI
CLK
VSS
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
B5
W5
A5
B3
W3
A3
B1
W1
A1
A2
W2
B2
A4
W4
B4
A Terminal RDAC #6.
Wiper RDAC #6, addr = 1012.
B Terminal RDAC #6.
Ground.
Chip Select Input, Active Low. When CS
returns high, data in the serial input register
is decoded based on the address bits and
loaded into the target RDAC latch.
Positive power supply, specified for
operation at both +3 V or +5 V. (Sum of
|VDD| + |VSS| <5.5 V.)
Serial Data Input. MSB First.
Serial Clock Input, positive edge triggered.
Negative Power Supply, specified for
operation at both 0 V or –2.7 V. (Sum of
|VDD| + |VSS| <5.5 V.)
B Terminal RDAC #5.
Wiper RDAC #5, addr = 1002.
A Terminal RDAC #5.
B Terminal RDAC #3.
Wiper RDAC #3, addr = 0102.
A Terminal RDAC #3.
B Terminal RDAC #1.
Wiper RDAC #1, addr = 0002.
A Terminal RDAC #1.
A Terminal RDAC #2.
Wiper RDAC #2, addr = 0012.
B Terminal RDAC #2.
A Terminal RDAC #4.
Wiper RDAC #4, addr = 0112.
B Terminal RDAC #4.
AD5204/AD5206–Typical Performance Characteristics
120
110
NORMALIZED GAIN – dB
SWITCH RESISTANCE – V
VDD/VSS = 2.7V/0V
100
90
80
70
60
VDD/VSS = 5.5V/0V
VDD/VSS = 62.7V
10kV
0
VDD = 62.7V
VSS = –2.7V
VA = 100mV rms
DATA = 80H
–2
–4
50kV
VA
100kV
OP42
50
40
30
–3.0
–2.0
–1.0
0
1.0
2.0
3.0
COMMON MODE – V
4.0
5.0
6.0
Figure 4. Incremental Wiper ON Resistance vs. Voltage
0
–6.00
–6
–6.01
–12
–6.02
–18
10kV
–24
–6.05
–6.06
GAIN – dB
GAIN – dB
–6.03
–6.04
50kV
100kV
–30
–6.07
–54
1k
10k
FREQUENCY – Hz
DATA = 20H
DATA = 10H
DATA = 08H
DATA = 02H
OP42
VB = 0V
DATA = 40H
DATA = 04H
–48
–6.08
DATA = 80H
–36
–42
VA
–6.09
100
1M
Figure 7. –3 dB Bandwidth vs. Terminal Resistance,
± 2.7 V Dual Supply Operation
–5.99
VDD = 2.7V
VSS = –2.7V
VA = 100mV rms
DATA = 80H
TA = +258C
10k
100k
FREQUENCY – Hz
1k
DATA = 01H
VDD = 2.7V
VSS = –2.7V
VA = 100mV rms
TA = +258C
–60
1k
100k
Figure 5. Gain Flatness vs. Frequency
VA
OP42
10k
100k
FREQUENCY – Hz
1M
Figure 8. Bandwidth vs. Code, 10K Version
10kV
0
–2
–4
VDD = 2.7V
VSS = 0V
VA = 100mV rms
DATA = 80H
TA = +258C
DATA = 80H
–12
DATA = 40H
–18
DATA = 20H
–24
GAIN – dB
NORMALIZED GAIN – dB
0
–6
50kV
2.7V
–30
–36
100kV
–42
–48
+1.5V
–54
10k
100k
FREQUENCY – Hz
DATA = 08H
DATA = 04H
DATA = 02H
DATA = 01H
OP42
1k
DATA = 10H
–60
1k
1M
Figure 6. –3 dB Bandwidth vs. Terminal Resistance,
2.7 V Single Supply Operation
VDD = 2.7V
VSS = –2.7V
VA = 100mV rms
TA = +258C
VA
OP42
10k
100k
FREQUENCY – Hz
1M
Figure 9. Bandwidth vs. Code, 50K Version
–6–
REV. 0
AD5204/AD5206
0
8
7
DATA = 40H
–12
SUPPLY CURRENT – mA
DATA = 10H
–24
DATA = 08H
–30
DATA = 04H
–36
DATA = 02H
–42
DATA = 01H
–48
–54
–60
1k
VDD = 2.7V
VSS = –2.7V
VA = 100mV rms
TA = +258C
IDD, VDD/VSS = 5.5V/0V, DATA = 55H
6
DATA = 20H
–18
GAIN – dB
TA = +258C
DATA = 80H
–6
5
ISS, VDD/VSS = 62.7V, DATA = 55H
4
IDD, VDD/VSS = 5,5V/0V, DATA = FFH
3
ISS, VDD/VSS = 62.7V, DATA = FFH
2
IDD, VDD/VSS = 2.7V/0V, DATA = FFH
IDD, VDD/VSS = 62.7V/0V, DATA = 55H
VA
1
OP42
10k
100k
FREQUENCY – Hz
0
10k
1M
Figure 10. Bandwidth vs. Code, 100K Version
100k
1M
FREQUENCY – Hz
10M
Figure 13. Supply Current vs. Clock Frequency
2.5
60
TA = +258C
50
2.0
VSS = –3.0V 6 10%
SINGLE SUPPLY
VDD = VSS
1.0
PSRR – dB
TRIP POINT – V
40
DUAL SUPPLY
VSS = 0V
0.1
30
VDD = 3.0V 6 10%
20
0.5
10
0.0
1.0
2.0
3.0
4.0
5.0
SUPPLY VOLTAGE VDD – Volts
0
10
6.0
100
100
1k
FREQUENCY – Hz
10k
100k
Figure 14. Power Supply Rejection vs. Frequency
Figure 11. Digital Input Trip Point vs. Supply Voltage
1.0
ISS AT VDD/VSS = 62.7V
TA = +258C
10
0.1
IDD AT VDD/VSS = 5.5V/0V
THD + NOISE – %
SUPPLY CURRENT – mA
VDD = 5.0V 6 10%
1
IDD AT VDD/VSS = 62.7V
0.1
VDD = +2.7V
VSS = –2.7V
TA = +258C
RAB = 10kV
0.01
NONINVERTING TEST CIRCUIT
0.001
0.01
INVERTING TEST CIRCUIT
IDD AT VDD/VSS = 2.7V/0V
0.0001
10
0.001
0
1
2
3
4
5
INCREMENTAL INPUT LOGIC VOLTAGE – Volts
6
1k
FREQUENCY – Hz
10k
100k
Figure 15. Total Harmonic Distortion Plus Noise vs.
Frequency
Figure 12. Supply Current vs. Input Logic Voltage
REV. 0
100
–7–
AD5204/AD5206
OPERATION
data 00H . This B terminal connection has a wiper contact resistance of 45 Ω. The second connection (10 kΩ part) is the first
tap point located at 84 Ω [= RBA (nominal resistance)/256 + RW
= 84 Ω + 45 Ω] for data 01 H. The third connection is the next
tap point representing 78 + 45 = 123 Ω for data 02H. Each LSB
data value increase moves the wiper up the resistor ladder until
the last tap point is reached at 10006 Ω. The wiper does not
directly connect to the A terminal. See Figure 16 for a simplified
diagram of the equivalent RDAC circuit.
The AD5204/AD5206 provides a four-/six-channel, 256-position
digitally-controlled variable resistor (VR) device. Changing the
programmed VR settings is accomplished by clocking in a 11bit serial data word into the SDI (Serial Data Input) pin. The
format of this data word is three address bits, MSB first, followed by eight data bits, MSB first. Table I provides the serial
register data word format.
Table I. Serial-Data Word Format
ADDR
B10 B9 B8
DATA
B7 B6
A2 A1
MSB
210
D7 D6
MSB
27
A0
LSB
28
The general transfer equation determining the digitally programmed output resistance between Wx and Bx is:
B5
B4
B3
B2
B1
B0
D5
D4
D3
D2
D1
D0
LSB
20
R WB (Dx) = (Dx)/256 × R BA + R W
where Dx is the data contained in the 8-bit RDACx latch, and
RBA is the nominal end-to-end resistance.
For example, when VB = 0 V and A terminal is open-circuit, the
following output resistance values will be set for the following
RDAC latch codes (applies to the 10K potentiometer):
See Table IV for the AD5204/AD5206 address assignments to
decode the location of VR latch receiving the serial register data
in Bits B7 through B0. VR outputs can be changed one at a
time in random sequence. The AD5204 presets to a midscale by
asserting the PR pin, simplifying fault condition recovery at
power up. Both parts have an internal power ON preset that
places the wiper in a preset midscale condition at power ON. In
addition, the AD5204 contains a power shutdown SHDN pin
which places the RDAC in a zero power consumption state
where Terminals Ax are open circuited and the wiper Wx is
connected to Bx resulting in only leakage currents being consumed in the VR structure. In shutdown mode the VR latch
settings are maintained, so that, returning to operational mode
from power shutdown, the VR settings return to their previous
resistance values.
RS
SHDN
D7
D6
D5
D4
D3
D2
D1
D0
Table II.
D
(DEC)
RWB-⍀
Output State
255
128
1
0
10006
5045
84
45
Full Scale
Midscale (PR = 0 Condition)
1 LSB
Zero Scale (Wiper Contact Resistance)
Note that in the zero-scale condition a finite wiper resistance of
45 Ω is present. Care should be taken to limit the current flow
between W and B in this state to a maximum value of 20 mA to
avoid degradation or possible destruction of the internal switch
contact.
Ax
Like the mechanical potentiometer the RDAC replaces, it is
totally symmetrical. The resistance between the Wiper W and
Terminal A produces a digitally controlled resistance RWA.
When these terminals are used the B terminal should be tied to
the wiper. Setting the resistance value for RWA starts at a maximum value of resistance and decreases as the data loaded in the
latch is increased in value. The general transfer equation for this
operation is:
RS
RS
Wx
R WA (Dx) = (256–Dx)/256 × R BA + R W
RDAC
LATCH
&
DECODER
RS
(1)
(2)
where Dx is the data contained in the 8-bit RDACx latch, and
RBA is the nominal end-to-end resistance. For example, when
VA = 0 V and B terminal is tied to the Wiper W the following
output resistance values will be set for the following RDAC
latch codes:
Bx
Table III.
Figure 16. AD5204/AD5206 Equivalent RDAC Circuit
PROGRAMMING THE VARIABLE RESISTOR
Rheostat Operation
The nominal resistance of the RDAC between Terminals A and
B are available with values of 10 kΩ, 50 kΩ and 100 kΩ. The
last digits of the part number determine the nominal resistance
value, e.g., 10 kΩ = 10; 100 kΩ = 100. The nominal resistance
(RAB) of the VR has 256 contact points accessed by the wiper
terminal, plus the B terminal contact. The eight-bit data word
in the RDAC latch is decoded to select one of the 256 possible
settings. The wiper’s first connection starts at the B terminal for
–8–
D
(DEC)
RWA-⍀
Output State
255
128
1
0
84
5045
10006
10045
Full Scale
Midscale (PR = 0 Condition)
1 LSB
Zero Scale
REV. 0
AD5204/AD5206
The typical distribution of RBA from channel-to-channel matches
within ± 1%. However, device-to-device matching is process lot
dependent, having a ± 30% variation. The change in RBA with
temperature has a 700 ppm/°C temperature coefficient.
PROGRAMMING THE POTENTIOMETER DIVIDER
Voltage Output Operation
The digital potentiometer easily generates an output voltage
proportional to the input voltage applied to a given terminal.
For example, connecting A terminal to +5 V and B terminal to
ground produces an output voltage at the wiper which can be
any value starting at zero volts up to 1 LSB less than +5 V. Each
LSB of voltage is equal to the voltage applied across Terminal
AB divided by the 256-position resolution of the potentiometer
divider. The general equation defining the output voltage with
respect to ground for any given input voltage applied to terminals AB is:
VW (Dx) = Dx/256 × VAB + VB
(3)
Operation of the digital potentiometer in the divider mode results
in more accurate operation over temperature. Here the output
voltage is dependent on the ratio of the internal resistors not the
absolute value, therefore, the drift improves to 15 ppm/°C.
AD5204/AD5206
CS
CLK
EN
SDO
(AD5204
ONLY)
CLK CS PR SHDN Register Activity
VDD
W1
RDAC
LATCH
#1
D0
Table IV. Input Logic Control Truth Table
L
P
L
L
H
H
H
H
X
P
H
H
X
X
H
X
H
L
H
H
X
X
H
H
P
H
H
L
No SR effect, enables SDO pin.
Shift one bit in from the SDI pin.
The eleventh previously entered bit
is shifted out of the SDO pin.
Load SR data into RDAC latch based
on A2, A1, A0 decode (Table V).
No Operation.
Sets all RDAC latches to midscale,
wiper centered and SDO latch
cleared.
Latches all RDAC latches to 80H .
Open circuits all Resistor A terminals, connects W to B, turns off
SDO output transistor.
A1
D7
ADDR
DEC
A2
A1
DO A0
D7
transfer data to the next package’s SDI pin. The pull-up resistor
termination voltage may be larger than the VDD supply of the
AD5204 SDO output device, e.g., the AD5204 could operate at
VDD = 3.3 V and the pull-up for interface to the next device
could be set at +5 V. This allows for daisy chaining several
RDACs from a single processor serial-data line. Clock period
needs to be increased when using a pull-up resistor to the SDI
pin of the following device in the series. Capacitive loading at
the daisy chain node SDO-SDI between devices must be accounted for to successfully transfer data. When daisy chaining is
used, the CS should be kept low until all the bits of every package are clocked into their respective serial registers insuring that
the address bits and data bits are in the proper decoding location. This would require 22 bits of address and data complying
to the word format provided in Table I if two AD5204 fourchannel RDACs are daisy chained. During shutdown (SHDN)
the SDO output pin is forced to the off (logic high state) to
disable power dissipation in the pull-up resistor. See Figure 19
for equivalent SDO output circuit schematic.
B1
R
SER
REG
A4/A6
D7
W4/W6
SDI
DI
RDAC
LATCH
#4/#6
D0
D0
8
B4/B6
R
NOTE: P = positive edge, X = don’t care, SR = shift register.
SHDN
(AD5204
ONLY)
GND
Table V. Address Decode Table
PR
(AD5204 ONLY)
Figure 17. Block Diagram
DIGITAL INTERFACING
The AD5204/AD5206 contain a standard three-wire serial input
control interface. The three inputs are clock (CLK), CS and
serial data input (SDI). The positive-edge sensitive CLK input
requires clean transitions to avoid clocking incorrect data into
the serial input register. Standard logic families work well. If
mechanical switches are used for product evaluation they should
be debounced by a flip-flop or other suitable means. Figure 17
shows more detail of the internal digital circuitry. When CS is
taken active low the clock loads data into the serial register on
each positive clock edge, see Table IV. When using a positive
(VDD ) and negative (VSS) supply voltage, the logic levels are still
referenced to digital ground (GND).
The serial-data-output (SDO) pin contains an open drain nchannel FET. This output requires a pull-up resistor in order to
REV. 0
–9–
A2
A1
A0
Latch Decoded
0
0
0
0
1
1
0
0
1
1
0
0
0
1
0
1
0
1
RDAC#1
RDAC#2
RDAC#3
RDAC#4
RDAC#5 AD5206 Only
RDAC#6 AD5206 Only
The data setup and data hold times in the specification table
determine the data valid time requirements. The last 11 bits of
the data word entered into the serial register are held when CS
returns high. At the same time CS goes high it gates the address
decoder enabling one of four or six positive edge triggered RDAC
latches, see Figure 18 detail.
AD5204/AD5206
AD5204/AD5206
CS
IMS
RDAC 1
RDAC 2
ADDR
DECODE
DUT
A
W
V+
RDAC 4/6
IW = 1V/RNOMINAL
VW
B
CLK
SDI
Figure 18. Equivalent Input Control Logic
Figure 24.␣ Wiper Resistance Test Circuit
The target RDAC latch is loaded with the last eight bits of the
serial data word completing one DAC update. Four separate 8bit data words must be clocked in to change all four VR settings.
VA
V+ = VDD ± 10%
V+
SHDN
~
VDD
A
W
D
DVMS%
PSS (%/%) = –––––––
DVDD%
VMS
SDO
SERIAL
REGISTER
DV
PSRR (dB) = 20 LOG
B
CS
SDI
WHERE VW1 = VMS WHEN IW = 0
AND VW2 = VMS WHEN IW = 1/R
VMS
SERIAL
REGISTER
V+ < VDD
V W2 –[VW1 + IW (R AWII RBW)]
RW = ––––––––––––––––––––––––––
IW
MS
( –––––
)
DV
DD
Q
GND
CK RS
Figure 25. Power Supply Sensitivity Test Circuit (PSS,
PSRR)
CLK
PR
A
DUT B
Figure 19. Detail SDO Output Schematic of the AD5204
+5V
W
VIN
All digital pins are protected with a series input resistor and
parallel Zener ESD structure shown in Figure 20. Applies to
digital pins CS, SDI, SDO, PR, SHDN, CLK
OP279
OFFSET
GND
VOUT
+
OFFSET BIAS
340kV
LOGIC
Figure 26. Inverting Programmable Gain Test Circuit
VSS
+5V
Figure 20. ESD Protection of Digital Pins
OP279
VIN
A, B, W
OFFSET
GND
DUT
␣ Figure 27. Noninverting Programmable Gain Test Circuit
V+ = VDD
1LSB = V+/256
B
+15V
A
W
V+
B
OFFSET BIAS
Figure 21. ESD Protection of Resistor Terminals
A
DUT
A
VSS
VOUT
W
W
VIN
VMS
DUT
B
OFFSET
GND
+
OP42
VOUT
2.5V
–15V
Figure 22. Potentiometer Divider Nonlinearity Error Test
Circuit (INL, DNL)
␣ Figure 28. Gain vs. Frequency Test Circuit
NO CONNECT
DUT
A
W
RSW = 0.1V
ISW
DUT
IW
CODE = ØØH
W
+
B
B
VMS
0.1V
ISW
VSS TO VDD
Figure 23. Resistor Position Nonlinearity Error (Rheostat
Operation; R-INL, R-DNL)
Figure 29. Incremental ON Resistance Test Circuit
–10–
REV. 0
AD5204/AD5206
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
C3677–8–9/99
24-Lead Narrow Body PDIP
(N-24)
1.275 (32.30)
1.125 (28.60)
24
13
1
12
0.280 (7.11)
0.240 (6.10)
0.325 (8.25)
0.300 (7.62)
PIN 1
0.060 (1.52)
0.015 (0.38)
0.210
(5.33)
MAX
0.200 (5.05)
0.125 (3.18)
0.195 (4.95)
0.115 (2.93)
0.150
(3.81)
MIN
0.022 (0.558)
0.014 (0.356)
0.100
(2.54)
BSC
0.015 (0.381)
0.008 (0.204)
0.070 (1.77) SEATING
0.045 (1.15) PLANE
24-Lead SOIC
(R-24/SOL-24)
0.6141 (15.60)
0.5985 (15.20)
24
13
0.2992 (7.60)
0.2914 (7.40)
1
0.4193 (10.65)
0.3937 (10.00)
12
PIN 1
0.1043 (2.65)
0.0926 (2.35)
0.0118 (0.30) 0.0500
0.0040 (0.10) (1.27)
BSC
0.0291 (0.74)
3 458
0.0098 (0.25)
88
08
0.0192 (0.49) SEATING
0.0125 (0.32)
PLANE
0.0138 (0.35)
0.0091 (0.23)
0.0500 (1.27)
0.0157 (0.40)
24-Lead Thin Shrink SO Package (TSSOP)
(RU-24)
0.311 (7.90)
0.303 (7.70)
24
13
PRINTED IN U.S.A.
0.177 (4.50)
0.169 (4.30)
0.256 (6.50)
0.246 (6.25)
1
12
PIN 1
0.006 (0.15)
0.002 (0.05)
SEATING
PLANE
REV. 0
0.0433 (1.10)
MAX
0.0256 (0.65) 0.0118 (0.30)
BSC
0.0075 (0.19)
0.0079 (0.20)
0.0035 (0.090)
–11–
88
08
0.028 (0.70)
0.020 (0.50)
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