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Low Noise, Low Power
X9015
Digitally-Controlled Potentiometer
FEATURES
• 32 Taps
• Three-wire Up/Down Serial Interface
• VCC = 2.7V & 5V
• Operating ICC = 50µA Max.
• Standby current = 1µA Max.
• RTOTAL = 50K
• Packages, SOIC-8
DESCRIPTION
The Xicor X9015 is a 32 tap potentiometer that is volatile.
The device consists of a string of 31 resistors that can be
programmed to connect the RW/VW wiper output with
any of the nodes between the connecting resistors. The
connection point of the wiper is determined by
information communicated to the device on the 3-wire
port. The 3-wire port changes the tap position by a falling
edge on the increment pin. 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 applications
that require a digitally controlled variable resistor to set
analog values.
FUNCTIONAL DIAGRAMS
VCC (Supply Voltage)
UP/DOWN
(U/D)
INCREMENT
(INC)
DEVICE SELECT
(CS)
CONTROL
VSS (Ground)
GENERAL
RH/VH
RW/VW
RL/VL
U/D
INC
CS
VCC
VSS
5-BIT
UP/DOWN
COUNTER
CONTROL
CIRCUITRY
31
30
29
28
ONE
OF
THIRTY TWO
DECODER
2
1
0
TRANSFER
GATES
RESISTOR
ARRAY
DETAILED
RH/VH
RL/VL
RW/VW
9900-2009.3 9/20/99 PS
1 Characteristics subject to change without notice

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X9015
PIN DESCRIPTIONS
RH/VH and RL/VL
The high (RH/VH) and low (RL/VL) terminals of the
X9015 are equivalent to the fixed terminals of a
mechanical potentiometer. The minimum voltage is VSS
and the maximum is VCC. The terminology of RL/VL and
RH/VH 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.
RW/VW
RW/Vw 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 200at VCC = 5V. At power up the wiper
position is at tap #15 (VL/RL = tap #0).
Up/Down (U/D)
The U/D input controls the direction of the wiper
movement and whether the tap postion is incremented or
decremented.
Increment (INC)
The INC input is negative-edge triggered. Toggling INC
will move the wiper and either increment or decrement
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 LOW the
X9015 will be placed in the low power standby mode until
the device is selected once again.
PIN CONFIGURATION
INC
U/D
RH/VH
VSS
SOIC
18
27
X9015
36
45
VCC
CS
RL/VL
RW/VW
PIN NAMES
Symbol
RH/VH
RW/VW
RL/VL
VSS
VCC
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
2

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X9015
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 resis-
tor array to the wiper output. The resistor array is com-
prised 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 tIW (INC to VW
change). The RTOTAL value for the device can
temporarily 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.
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 INC U/D
LH
LL
HXX
LX
Mode
Wiper Up
Wiper Down
Standby Current
Return to standby
SYMBOL TABLE
WAVEFORM
INPUTS
OUTPUTS
Must be
steady
May change
from Low to
High
May change
from High to
Low
Don’t Care:
Changes
Allowed
N/A
Will be
steady
Will change
from Low to
High
Will change
from High to
Low
Changing:
State Not
Known
Center Line
is High
Impedance
3

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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, VH, VL and VCC
with Respect to VSS.................................. –1V to +7V
V = |VH–VL| ................................................................. 5V
Lead Temperature (Soldering 10 seconds)............. 300°C
*COMMENT
Stresses above those listed under “Absolute Maximum
Ratings” may cause permanent damage to the device.
This is a stress rating only and the 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 condi-
tions for extended periods may affect device reliability.
RECOMMENDED OPERATING CONDITIONS
Temperature
Min.
Max.
Commercial
0°C
+70°C
Industrial
–40°C
+85°C
Supply Voltage (VCC)
X9015
X9015-2.7
Limits
5V ±10%
2.7V to 5.5V
POTENTIOMETER CHARACTERISTICS (Over recommended operating conditions unless otherwise stated.)
Symbol
RTOTAL
VVH
VVL
RW
RW
IW
CH/CL/CW
Parameter
End to End Resistance Variation
VH Terminal Voltage
VL Terminal Voltage
Power Rating
Wiper Resistance
Wiper Resistance
Wiper Current
Noise
Resolution
Absolute Linearity(1)
Relative Linearity(2)
RTOTAL Temperature Coefficient
Ratiometric Temperature Coefficient
Potentiometer Capacitances
Min.
–20
0
0
-1
-0.2
Limits
Typ. Max. Units
+20 %
VCC
VCC
V
V
10 mW
200 400
400 1000
±1 mA
-120
dBV
3%
+1 MI(3)
+0.2 MI(3)
±300
ppm/°C
±20 ppm/°C
10/10/25
pF
Test Conditions/Notes
RTOTAL 50K
IW = 1mA, VCC = 5V
IW = 1mA, VCC = 2.7V
Ref: 1kHz
Vw(n)(actual) – Vw(n)(expected)
Vw(n+1) – [Vw(n)+MI]
See circuit #3
Notes:
(1) Absolute Linearity is utilized to determine actual wiper voltage versus expected voltage
= (Vw(n)(actual) – Vw(n)(expected)) = ±1 Ml Maximum.
(2) Relative Linearity is a measure of the error in step size between taps = VW(n+1) – [Vw(n) + Ml] = ±0.2 Ml.
(3) 1 Ml = Minimum Increment = RTOT/31.
(4) Typical values are for TA = 25°C and nominal supply voltage.
(5) This parameter is periodically sampled and not 100% tested.
4

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X9015
D.C. OPERATING CHARACTERISTICS (Over recommended operating conditions unless otherwise specified.)
Limits
Symbol
Parameter
Min. Typ.(4) Max.
Units
Test Conditions
ICC1
ISB
ILI
VIH
VCC Active Current
(Increment)
Standby Supply Current
CS, INC, U/D Input
Leakage Current
CS, INC, U/D Input
HIGH Voltage
VCC x 0.7
50
1
±10
VCC + 0.5
µA
µA
µA
V
CS = VIL, U/D = VIL or VIH and
INC = 0.4V @ max. tCYC
CS = VCC – 0.3V, U/D and
INC = VSS or VCC – 0.3V
VIN = VSS to VCC
VIL CS, INC, U/D Input
LOW Voltage
–0.5
VCC x 0.1
V
CIN(5)
CS, INC, U/D Input
Capacitance
10 pF VCC = 5V, VIN = VSS,
TA = 25°C, f = 1MHz
Test Circuit #1
Test Circuit #2
VH/RH
VH/RH
TEST POINT
VS
TEST POINT
VWW/RW
VW/RW
FORCE
VL/RL
VLL/RL
CURRENT
Circuit #3 SPICE Macromodel
RTOTAL
RH
CH
CW CL RL
10pF
10pF
25pF
RW
5