A
PPLICATION
N
OTE
A V A I L A B L E
AN99 • AN115 • AN120 • AN124 • AN133 • AN134
Low Noise, Low Power, Volatile
X9015
Digitally Controlled Potentiometer (XDCP
™
)
FEATURES
•
•
•
•
•
•
•
32 taps
Three-wire up/down serial interface
V
CC
= 2.7V–5V
Operating I
CC
= 50µA max.
Standby current = 1µA max.
R
TOTAL
= 10K
Ω
, 50K
Ω
, 100K
Ω
Packages SOIC-8, MSOP-8
DESCRIPTION
The Xicor X9015 is a 32 tap potentiometer that is vola-
tile. The device consists of a string of 31 resistors that
can be programmed to connect the R
W
/V
W
wiper out-
put with any of the nodes between the connecting
resistors. The connection point of the wiper is deter-
mined by information communicated to the device on
the 3-wire port. The 3-wire port changes the tap posi-
tion by a falling edge on the increment pin. The direction
the wiper moves is determined by the state of the up/
down pin. The wiper position at power up is Tap #15.
The X9015 can be used in a wide variety of applica-
tions that require a digitally controlled variable resistor
to set analog values.
BLOCK DIAGRAM
V
CC
(Supply Voltage)
U/D
INC
CS
5-Bit
Up/Down
Counter
31
30
29
One 28
of
Thirty
Two
Decoder
2
R
H
/V
H
Up/Down
(U/D)
Increment
(INC)
Device Select
(CS)
Control
R
H
/V
H
R
W
/V
W
R
L
/V
L
V
SS
(Ground)
General
V
CC
V
SS
Control
Circuitry
Transfer
Gates
Resistor
Array
1
0
R
L
/V
L
R
W
/V
W
Detailed
XDCP is a trademark of Xicor, Inc.
REV 1.0 6/26/00
www.xicor.com
Characteristics subject to change without notice.
1 of 12
X9015
PIN DESCRIPTIONS
R
H
/V
H
and R
L
/V
L
The high (R
H
/V
H
) and low (R
L
/V
L
) terminals of the
X9015 are equivalent to the fixed terminals of a
mechanical potentiometer. The minimum voltage is
V
SS
and the maximum is V
CC
. The terminology of R
L
/
V
L
and R
H
/V
H
references the relative position of the
terminal in relation to wiper movement direction
selected by the U/D input, and not the voltage potential
on the terminal.
R
W
/V
W
R
W
/V
w
is the wiper terminal and is equivalent to the
movable terminal of a mechanical potentiometer. The
position of the wiper within the array is determined by
the control inputs. The wiper terminal series resistance
is typically 200
Ω
at V
CC
= 5V. At power up the wiper
position is at Tap #15. (V
L
/R
L
= Tap #0).
Up/Down (U/D)
The U/D input controls the direction of the wiper move-
ment and whether the tap position is incremented or
decremented.
Increment (INC)
The INC input is negative-edge triggered. Toggling
INC will move the wiper and either increment or decre-
ment the counter in the direction indicated by the logic
level on the U/D input.
Chip Select (CS)
The device is selected when the CS input is LOW.
When CS is returned HIGH while the INC input is also
HIGH the X9015 will be placed in the low power
standby mode until the device is selected once again.
PIN CONFIGURATION
SOIC/MSOP
INC
U/D
R
H
/V
H
V
SS
1
2
3
4
X9015
8
7
6
5
V
CC
CS
R
L
/V
L
R
W
/V
W
PIN NAMES
Symbol
R
H
/V
H
R
W
/V
W
R
L
/V
L
V
SS
V
CC
U/D
INC
CS
Description
High terminal
Wiper terminal
Low terminal
Ground
Supply voltage
Up/Down control input
Increment control input
Chip select control input
PRINCIPLES OF OPERATION
There are two sections of the X9015: the input control,
counter and decode section; and the resistor array.
The input control section operates just like an up/down
counter. The output of this counter is decoded to turn
on a single electronic switch connecting a point on the
resistor array to the wiper output. The resistor array is
comprised of 31 individual resistors connected in
series.
The wiper, when at either fixed terminal, acts like its
mechanical equivalent and does not move beyond the
last position. That is, the counter does not wrap
around when clocked to either extreme.
The electronic switches on the device operate in a
“make before break” mode when the wiper changes
tap positions. If the wiper is moved several positions,
multiple taps are connected to the wiper for t
IW
(INC to
V
W
change). The R
TOTAL
value for the device can tem-
porarily be reduced by a significant amount if the wiper
is moved several positions.
When the device is powered-down, the wiper position
is lost. When power is restored, the wiper is set to Tap
#15.
INSTRUCTIONS AND PROGRAMMING
The INC, U/D and CS inputs control the movement of
the wiper along the resistor array. With CS set LOW
the device is selected and enabled to respond to the
U/D and INC inputs. HIGH to LOW transitions on INC
will increment or decrement (depending on the state of
the U/D input) a five bit counter. The output of this
counter is decoded to select one of thirty two wiper
positions along the resistive array.
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Characteristics subject to change without notice.
2 of 12
X9015
The system may select the X9015, move the wiper
and deselect the device. The new wiper position will be
maintained until changed by the system or until a
power-up/down cycle.
The state of U/D may be changed while CS remains
LOW. This allows the host system to enable the device
and then move the wiper up and down until the proper
trim is attained.
MODE SELECTION
CS
L
L
*
L
H
L
SYMBOL TABLE
WAVEFORM
INPUTS
Must be
steady
May change
from Low to
High
May change
from High to
Low
Don’t Care:
Changes
Allowed
N/A
OUTPUTS
Will be
steady
Will change
from Low to
High
Will change
from High to
Low
Changing:
State Not
Known
Center Line
is High
Impedance
INC
U/D
H
L
X
X
Wiper up
Mode
Wiper down
Standby mode
Normal mode
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Characteristics subject to change without notice.
3 of 12
X9015
ABSOLUTE MAXIMUM RATINGS
Temperature under bias ....................–65
°
C to +135
°
C
Storage temperature .........................–65°C to +150°C
Voltage on CS, INC, U/D, V
H
, V
L
and
V
CC
with respect to V
SS
......................... –1V to +7V
∆
V = |V
H
–V
L
|........................................................... 5V
Lead temperature (soldering 10 seconds)..........300°C
I
W
(10 seconds) .............................................. ±7.5mA
COMMENT
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
listed in the operational sections of this specification)
is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reli-
ability.
RECOMMENDED OPERATING CONDITIONS
Temperature
Commercial
Industrial
Min.
0°C
–40°C
Max.
+70°C
+85°C
Supply Voltage (V
CC
)
X9015
X9015-2.7
Limits
5V ±10%
2.7V to 5.5V
POTENTIOMETER CHARACTERISTICS
(Over recommended operating conditions unless otherwise stated.)
Limits
Symbol
R
TOTAL
V
VH
V
VL
R
W
R
W
I
W
Parameter
End to End Resistance Variation
V
H
/R
H
Terminal Voltage
V
L
/R
L
Terminal Voltage
Power Rating
Wiper Resistance
Wiper Resistance
Wiper Current
Noise
Resolution
Absolute Linearity
(1)
Relative Linearity
(2)
R
TOTAL
Temperature Coefficient
Ratiometric Temperature Coefficient
Min.
–20
0
0
Typ.
Max.
+20
V
CC
V
CC
10
Units
%
V
V
mW
Ω
Ω
mA
dBV
%
Test Conditions/Notes
R
TOTAL
≤
1 KΩ
I
W
= 1mA, V
CC
= 5V
I
W
= 1mA, V
CC
= 2.7V
Ref: 1kHz
V
w(n)(actual)
– V
w(n)(expected)
V
w(n+1)
– [V
w(n)+MI
]
200
400
-3.75
-120
3
-1
-0.2
±300
400
1000
3.75
+1
+0.2
±20
10/10/25
MI
(3)
MI
(3)
ppm/°C
ppm/°C
pF
C
H
/C
L
/C
W
Potentiometer Capacitances
See circuit #3
Notes:
(1) Absolute Linearity is utilized to determine actual wiper voltage versus expected voltage = (V
w(n)
(actual) – V
w(n)
(expected)) = ±1 Ml
Maximum.
(2) Relative Linearity is a measure of the error in step size between taps = V
W(n+1)
– [V
w(n)
+ Ml] = ±0.2 Ml.
(3) 1 Ml = Minimum Increment = R
TOT
/31.
(4) Typical values are for T
A
= 25°C and nominal supply voltage.
(5) This parameter is periodically sampled and not 100% tested.
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Characteristics subject to change without notice.
4 of 12
X9015
D.C. OPERATING CHARACTERISTICS
(Over recommended operating conditions unless otherwise specified)
Limits
Symbol
I
CC1
I
CC2
I
SB
I
LI
V
IH
V
IL
C
IN(5)
Parameter
V
CC
active current (increment)
V
CC
active current (Store) (EE-
PROM Store)
Standby supply current
CS, INC, U/D input leakage
current
Min.
Typ.
(4)
Max.
50
400
1
±10
V
CC
+ 0.5
V
CC
x 0.1
10
Units
µA
µA
µA
µA
V
V
pF
Test Conditions
CS = V
IL
, U/D = V
IL
or V
IH
and
INC = 0.4V @ max. t
CYC
CS = V
IH
, U/D = V
IL
or V
IH
and
INC = V
IH
@ max. t
WR
CS = V
CC
– 0.3V, U/D and INC
= V
SS
or V
CC
– 0.3V
V
IN
= V
SS
to V
CC
CS, INC, U/D input HIGH voltage V
CC
x 0.7
CS, INC, U/D input LOW voltage
CS, INC, U/D input capacitance
–0.5
V
CC
= 5V, V
IN
= V
SS
, T
A
= 25°C,
f = 1MHz
Test Circuit #1
Test Circuit #2
V
H
/R
H
Test Point
Circuit #3 SPICE Macro Model
R
TOTAL
R
H
C
H
C
W
25pF
10pF
R
W
C
L
10pF
R
L
V
H
/R
H
V
S
Test Point
V
W
/R
W
V
L
/R
L
V
L
/R
L
L
V
W
VW/R
W
Force
Current
REV 1.0 6/26/00
www.xicor.com
Characteristics subject to change without notice.
5 of 12
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