DS1666, DS1666S
Audio Digital Resistor
DS1666, DS1666S
022698 1/7
FEATURES
·
128 position, digitally controlled potentiometer
·
Operates from a +5 volts power supply with TTL sig-
nal inputs
·
Wide analog voltage range of
±
5 volts
·
Resistive elements are temperature compensated to
±
20 percent end to end
·
Lowpower CMOS
·
14pin DIP or 16pin SOIC for surface mount applica-
tions
·
Default position on power up sets wiper position at
10%
·
Operating temperature range
40
°
C to +85
°
C; industrial
Resolution/Step
Resistance values Low End High End 3dB Point
DS166610 10K
24
152
1.1 MHz
DS166650 50K
122
759
200 KHz
DS1666100100K
243
1.519K
100 KHz
PIN ASSIGNMENT
1
2
3
4
5
6
7
14
13
12
11
10
9
8
NC
U/D
INC
CS
GND
NC
NC
NC
V
CC
V
B
V
W
V
H
V
L
NC
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
U/D
NC
NC
INC
NC
CS
NC
GND
V
CC
NC
V
B
V
W
V
H
NC
NC
V
L
14PIN DIP (300 MIL)
See Mech. Drawings Section
16PIN SOIC (300 MIL)
See Mech. Drawings Section
PIN DESCRIPTION
V
H
High Terminal of Resistor
V
L
Low Terminal of Resistor
V
W
Wiper Terminal of Resistor
U/D
Up/Down Control
INC
Wiper Movement Control
CS
Chip Select for Wiper Movement
NC
No Connection
V
CC
+5 Volts
GND
Ground
V
B
0 to 5 Volts
DESCRIPTION
The DS1666 is a solidstate potentiometer which is set
to value by digitally controlled resistive elements. The
potentiometer is composed of 127 resistive sections.
Between each resistive section and both ends of the po-
tentiometer are TAP points accessible to the wiper. The
position of the wiper on the resistance array is controlled
by the CS, U/D and INC inputs. The position of the wiper
defaults to the 10% position on power up. The resolu-
tion of the DS1666 is shown in Figure 1.
The DS1666 Digital Audio Resistor is uniquely designed
to provide a potentiometer that is logarithmic rather than
linear across its entire range. The lower half of the po-
tentiometer advances 1% of total resistance for each
3% of scale advanced, providing for precise amplifica-
tion of low volume signals. The upper half of the poten-
tiometer advances 2% of resistance for every 1% of
scale advanced, providing for the lower resolution gain
required for high volume amplification.
DS1666, DS1666S
022698 2/7
GRAPH OF AUDIO TAPER Figure 1
0
10
20
30
40
50
60
70
80
90
100
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
LOW TERMINAL
HIGH TERMINAL
PERCENT
T
O
T
A
L
RESIST
ANCE
% OF ACTIVE DIGITAL TAPS
1
3
2
1
OPERATION
The CS, U/D and INC inputs control the position of the
wiper along the resistor array (Figure 1). When CS is ac-
tive (low), a high to low transition on the INC will incre-
ment or decrement an internal counter depending on the
level of the U/D pin. When the U/D pin is low, the counter
will decrement. When the U/D pin is high, the counter will
increment. The state of the U/D pin can be changed while
CS is active allowing for precise adjustment during cali-
bration. The output of the counter is decoded to set the
position of the wiper. When the CS input transitions to the
high (inactive) level, the value of the counter is stored and
the wiper position is maintained until power (V
CC
) is lost.
When power is restored, the DS1666 returns to the de-
fault setting and positions the wiper to 10 percent. The
value of the endtoend and endtowiper position is in-
determinate while V
CC
is not applied.
The DS1666 has a resistor array that resembles an au-
dio taper potentiometer as shown in Figure 1 1. Since
the taper is not linear, exact resistance values for each
of the 128 positions of the resistor is not specified. How-
ever, the end-to-end resistance is specified to be within
±
20 percent of the stated resistor value over an indus-
trial temperature range of 40
°
C to +85
°
C.
ANALOG CHARACTERISTICS
EndtoEnd Resistance Tolerance =
±
20 percent
Typical Noise = <120 dB/Hz REF:IV
Temperature Coefficient =
±
800 PPM/
°
C typical
Resistance at tap #74=18%
±
2% of total resistance.
PIN DESCRIPTIONS
V
H
The high end of the potentiometer. This
terminal is capable of handling input volt-
ages between
±
5 volts.
V
L
The Low end of the potentiometer. This
terminal is capable of handling input volt-
ages between
±
5 volts.
V
W
The wiper terminal of the potentiometer.
The value of the wiper is controlled by the
U/D and the INC pins.
Up/Down
The U/D input controls the direc-
(U/D)
tion of the wiper movement when setting
the potentiometer.
Increment
Toggling INC will move the potentiome-
(INC)
ter wiper by either incrementing or decre-
menting the counter.
Chip Select The device is selected when CS input is
(CS)
low. The current counter value is stored
when CS is returned high.
DS1666, DS1666S
022698 3/7
BLOCK DIAGRAM Figure 2
7 BIT
COUNTER
WIPER
POSITION
DECODE
TRANSFER LOGIC
ARRAY
V
H
V
L
V
W
U/D
INC
CS
1 OF 128
MODE SELECTION Figure 3
CS
INC
U/D
MODE
L
H
WIPER UP
L
L
WIPER DOWN
H
X
STORE WIPER POSITION
DS1666, DS1666S
022698 4/7
ABSOLUTE MAXIMUM RATINGS*
Voltage on CS, INC, U/D, and V
CC
Relative to Ground
0.5V to +7.0V
Voltage on V
H
, V
L
, and V
W
Relative to Ground
6.5V to +6.5V
Voltage on V
B
6.5V to Ground
Operating Temperature
40
°
C to +85
°
C
Storage Temperature
55
°
C to +125
°
C
Soldering Temperature
260
°
C for 10 seconds
* This is a stress rating only and functional operation of the device at these or any other conditions above those
indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods of time may affect reliability.
RECOMMENDED DC OPERATING CONDITIONS (40
°
C to +85
°
C)
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
NOTES
Supply Voltage
V
CC
+4.5
5.0
5.5
V
1
Input Logic 1
V
IH
2.0
V
CC
+0.5
V
1
Input Logic 0
V
IL
0.5
+0.8
V
1
V
H
, V
L
, V
W
Voltage
V
R
V
B
0.3
V
CC
+0.3
V
1
V
B
Voltage
V
B
5.5
GND
V
1
DC ELECTRICAL CHARACTERISTICS
(40
°
C to +85
°
C; V
CC
= 5.0V
±
10%)
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
NOTES
Supply Current
I
CC
0.1
5
mA
3
Input Leakage
I
LI
1
+1
µ
A
2
Wiper Resistance
R
W
350
650
Wiper Current
I
W
1
mA
3
CAPACITANCE
(t
A
= 25
°
C)
PARAMETER
SYMBOL
CONDITION
TYP
MAX
UNITS
NOTES
Capacitance
C
IN
t
A
=25
°
C
6
10
pF
2
DS1666, DS1666S
022698 5/7
AC ELECTRICAL CHARACTERISTICS
(t
A
=40
°
C to +85
°
C; V
CC
=+5V
±
10%)
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
NOTES
CS to INC Setup
t
CI
100
ns
INC High to U/D Change
t
ID
100
ns
U/D to INC Setup
t
DI
1
µ
s
INC Low Period
t
IL
500
ns
INC High Period
t
IH
1
µ
s
INC Inactive to CS Inactive
t
IC
500
ns
CS Deselect Time
t
CPH
100
ns
AC TIMING Figure 4
t
CI
t
IL
t
IH
t
IC
t
CPH
t
ID
t
DI
t
IW
CS
INC
U/D
V
W
V
VH
V
VL
NOTES:
1. All voltages are referenced to ground.
2. This parameter is periodically sampled and not 100% tested.
3. Typical values are for t
A
= 25
°
C and nominal supply voltages.
4. Wiper output open circuited.
AC TEST CONDITIONS
Input Pulse Levels
0V to 3V
Input Rise and Fall Times
10 ns
Input Level
1.5V
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