A
PPLICATION
N
OTE
A V A I L A B L E
AN20 • AN42–53 • AN71 • AN73 • AN88 • AN91–92 • AN99 • AN115 • AN120 • AN124 • AN133 • AN134
Low Noise, Low Power, 100 Taps
X9317
Digitally Controlled Potentiometer (XDCP
™
)
FEATURES
•
•
•
•
•
•
•
•
•
•
•
Nonvolatile solid state potentiometer
Single device
100 resistor taps
3-wire serial up/down interface
Wiper resistance 200
Ω
typ. at 5V
R
TOTAL
values = 1k
Ω
, 10k
Ω
, 50k
Ω,
100k
Ω
Standby current < 1
µ
A
V
CC
= 5V and 2.7V to 5.5V
Endurance = 100,000 cycles
Data retention = 100 years
Packages – 8-lead DIP, SOIC, TSSOP, MSOP
DESCRIPTION
The Xicor X9317 is a nonvolatile digitally controlled
potentiometer (XDCP). The device consists of a poly-
crystalline resistor array of 99 segments and CMOS
switches that connect the wiper terminal to any one of
the 100 nodes in the array of resistors. The wiper posi-
tion is defined by the data that is transmitted to the
device on the 3 terminal serial Up/Down port. A pulse
on the increment pin causes the wiper to move one
step to the next wiper position. The direction the wiper
moves is defined by the logic state on the Up/Down
pin. A rising edge on the Chip Select pin while the
increment pin is high causes the present wiper posi-
tion to be written into an EPROM register. This value is
recalled on power up restoring the last wiper position
that was written into the register.
The device can be used in the two terminal mode, with
the wiper connected to one end of the total resistor, as
a variable resistor or can be used in the three terminal
mode as a programmable voltage reference. The
X9317 can be used to program offset voltages or set
gains on amplifiers in control circuits.
BLOCK DIAGRAM
U/D
INC
CS
7-Bit
Up/Down
Counter
99
98
97
7-Bit
Nonvolatile
Memory
96
One
of
One
Hundred
Decoder
2
V
SS
(Ground)
General
V
CC
V
SS
Store and
Recall
Control
Circuitry
1
0
R
L
/V
L
R
W
/V
W
Detailed
R
H
/V
H
V
CC
(Supply Voltage)
Up/Down
(U/D)
Increment
(INC)
Device Select
(CS)
R
H
/V
H
Control
and
Memory
R
W
/V
W
R
L
/V
L
Transfer
Gates
Resistor
Array
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Characteristics subject to change without notice.
1 of 14
X9317
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
X9317 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
when V
CC
= 5V.
Up/Down (U/D)
The U/D input controls the direction of the wiper move-
ment and whether the counter is incremented or dec-
remented.
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. The
current counter value is stored in nonvolatile memory
when CS is returned HIGH while the INC input is also
HIGH. After the store operation is complete the X9317
will be placed in the low power standby mode until the
device is selected once again.
PIN CONFIGURATION
TSSOP
CS
V
CC
INC
U/D
1
2
3
4
X9317
8
7
6
5
R
L
/V
L
R
W
/V
W
V
SS
R
H
/V
H
DIP/SOIC/MSOP
INC
U/D
R
H
/V
H
V
SS
1
2
3
4
X9317
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
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Characteristics subject to change without notice.
2 of 14
X9317
PRINCIPLES OF OPERATION
There are three sections of the X9317: the input con-
trol, counter and decode section; the nonvolatile mem-
ory; 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. Under the proper conditions the contents
of the counter can be stored in nonvolatile memory
and retained for future use. The resistor array is com-
prised of 99 individual resistors connected in series. At
either end of the array and between each resistor is an
electronic switch that transfers the potential at that
point to the wiper.
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 last wiper posi-
tion stored will be maintained in the nonvolatile mem-
ory. When power is restored, the contents of the
memory are recalled and the wiper is set to the value
last stored.
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 seven bit counter. The output of this
counter is decoded to select one of one hundred wiper
positions along the resistive array.
The value of the counter is stored in nonvolatile mem-
ory whenever CS transitions HIGH while the INC input
is also HIGH.
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
The system may select the X9317, move the wiper,
and deselect the device without having to store the lat-
est wiper position in nonvolatile memory. After the
wiper movement is performed as described above and
once the new position is reached, the system must
keep INC LOW while taking CS HIGH. The new wiper
will would be maintained until changed by the system
or until a power-up/down cycle recalled the previously
stored data.
This procedure allows the system to always power-up
to a preset value stored in nonvolatile memory; then
during system operation minor adjustments could be
made. The adjustments might be based on user pref-
erence, system parameter changes due to tempera-
ture drift, etc...
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
H
H
X
L
INC
U/D
H
L
X
X
X
Wiper Up
Mode
Wiper Down
Store Wiper Position
Standby Current
No Store, Return to Standby
SYMBOL TABLE
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Characteristics subject to change without notice.
3 of 14
X9317
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) ................................................ 8.8mA
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 specifi-
cation is not implied. Exposure to absolute maximum
rating conditions for extended periods may affect
device reliability.
RECOMMENDED OPERATING CONDITIONS
Temperature
Commercial
Industrial
Min.
0°C
–40°C
Max.
+70°C
+85°C
Supply Voltage (V
CC
)
X9317
X9317-2.7
Limits
5V ±10%
2.7V to 5.5V
POTENTIOMETER CHARACTERISTICS
(Over recommended operating conditions unless otherwise stated.)
Limits
Symbol
R
TOTAL
V
VH/RH
V
VL/RL
Parameter
End to End Resistance Variation
V
H
Terminal Voltage
V
L
Terminal Voltage
Power Rating
Power Rating
Min.
V
SS
V
SS
Typ.
Max.
±20
V
CC
V
CC
10
25
Unit
%
V
V
mW
mW
Ω
Ω
mA
dBV
%
Test Conditions/Notes
V
SS
= 0V
V
SS
= 0V
R
TOTAL
≥
10 KΩ
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
]
R
W
R
W
I
W
Wiper Resistance
Wiper Resistance
Wiper Current
Noise
Resolution
Absolute Linearity
(1)
Relative Linearity
(2)
R
TOTAL
Temperature Coefficient
Ratiometric Temperature Coefficient
200
400
-120
1
400
1000
±4.4
±1
±.2
±300
±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
/99.
(4) Typical values are for T
A
= 25°C and nominal supply voltage.
(5) This parameter is periodically sampled and not 100% tested.
REV 1.1.4 12/09/02
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Characteristics subject to change without notice.
4 of 14
X9317
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) (EEPROM Store)
Standby Supply Current
CS, INC, U/D Input
Leakage Current
CS, INC, U/D Input
HIGH Voltage
CS, INC, U/D Input
LOW Voltage
CS, INC, U/D Input
Capacitance
Min.
Typ.
(4)
Max.
50
400
1
±10
Unit
µA
µA
µA
µA
V
V
pF
Test Conditions
CS = V
IL
, U/D = V
IL
or V
IH
and
INC = 0.4V/2.4V @ 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
V
CC
x 0.7
–0.5
V
CC
+ 0.5
V
CC
x 0.1
10
V
CC
= 5V, V
IN
= V
SS
,
T
A
= 25°C, f = 1MHz
ENDURANCE AND DATA RETENTION
Parameter
Minimum endurance
Data retention
Min.
100,000
100
Unit
Data changes per bit per bit
Years
Test Circuit #1
V
H
/R
H
Test Circuit #2
V
H
Test Point
Circuit #3 SPICE Macro Model
R
TOTAL
R
H
C
H
V
W
Force
Current
10pF
R
W
C
W
25pF
C
L
10pF
R
L
V
S
Test Point
V
W
/R
W
V
L
/R
L
V
L
REV 1.1.4 12/09/02
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Characteristics subject to change without notice.
5 of 14
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