A
PPLICATION
N
OTES
A V A I L A B L E
AN42 • AN44–50 • AN52 • AN53 • AN71 • AN73
Terminal Voltage
±
5V, 32 Taps, Log Taper
X9314
X9314
E
2
POT
™
Nonvolatile Digital Potentiometer
FEATURES
DESCRIPTION
The Xicor X9314 is a solid state nonvolatile potentiom-
eter and is ideal for digitally controlled resistance trim-
ming.
The X9314 is a resistor array composed of 31 resistive
elements. Between each element and at either end are
tap points accessible to the wiper element. The position of
the wiper element is controlled by the
CS,
U/D, and
INC
inputs. The position of the wiper can be stored in nonvola-
tile memory and then be recalled upon a subsequent
power-up operation.
All Xicor nonvolatile Digitally Controlled Potentiometers
are designed and tested for applications requiring ex-
tended endurance and data retention.
•
•
•
•
•
•
Low Power CMOS
—V
CC
= 3V to 5.5V
—Active Current, 3mA Max
—Standby Current, 500
µ
A Max
31 Resistive Elements
—Temperature Compensated
—
±
20% End to End Resistance Range
— –5V to +5V Range
32 Wiper Tap Points
—Wiper Positioned via Three-Wire Interface
—Similar to TTL Up/Down Counter
—Wiper Position Stored in Nonvolatile
Memory and Recalled on Power-Up
100 Year Wiper Position Data Retention
X9314W = 10K
Ω
Packages
—8-Lead MSOP
—8-Lead PDIP
—8-Lead SOIC
FUNCTIONAL DIAGRAM
U/D
INC
CS
5-BIT
UP/DOWN
COUNTER
31
30
29
VH
5-BIT
NONVOLATILE
MEMORY
ONE
OF
THIRTY-
TWO
DECODER
28
TRANSFER
GATES
2
RESISTOR
ARRAY
VCC
GND
STORE AND
RECALL
CONTROL
CIRCUITRY
1
0
VL
VW
6427 FHD F01
E
2
POT™ is a trademark of Xicor, Inc.
©Xicor, Inc. 1994, 1995, 1996 Patents Pending
6427-1.7 6/12/96 T3/C1/D8 NS
1
Characteristics subject to change without notice
X9314
PIN DESCRIPTIONS
V
H
and V
L
The high (V
H
) and low (V
L
) terminals of the X9314
are equivalent to the fixed terminals of a mechanical
potentiometer. The minimum voltage is –5V and the
maximum is +5V. It should be noted that the terminology
of V
L
and 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.
V
W
Vw is the wiper terminal, 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 40Ω.
Up/Down (U/D)
The U/D input controls the direction of the wiper move-
ment and whether the counter 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. 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 X9314
will be placed in the low power standby mode until the
device is selected once again.
Typical Attenuation Characteristics (dB)
0
PIN CONFIGURATION
8-LEAD DIP/SOIC
INC
U/D
VH
VSS
1
2
3
4
X9314
8
7
6
5
VCC
CS
VL
VW
8-LEAD MSOP
VH
VSS
VW
VL
1
2
3
4
X9314
8
7
6
5
U/D
INC
VCC
CS
6427 ILL F02.2
PIN NAMES
Symbol
V
H
V
W
V
L
V
SS
V
CC
U/D
INC
CS
Description
High Terminal
Wiper Terminal
Low Terminal
Ground
Supply Voltage
Up/Down Input
Increment Input
Chip Select Input
6427 PGM T01
ATTENUATION (dB)
-20
-40
-43.5
-60
31
28
24
20
16
TAP POSITION
12
8
4
0
6427 ILL F07
2
X9314
DEVICE OPERATION
There are three sections of the X9314: the input control,
counter and decode section; the nonvolatile memory; 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 comprised of 31 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
INC,
U/D and
CS
inputs control the movement of the
wiper along the resistor array. With
CS
set LOW the
X9314 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 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 value of the counter is stored in nonvolatile memory
whenever
CS
transistions HIGH while the
INC
input is
also HIGH.
When the X9314 is powered-down, the last counter
position stored will be maintained in the nonvolatile
memory. When power is restored, the contents of the
memory are recalled and the counter is reset to the value
last stored.
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
Operation Notes
The system may select the X9314, move the wiper and
deselect the device without having to store the latest
wiper position in nonvolatile memory. The wiper
movement is performed as described above; once the
new position is reached, the system would keep the
INC
LOW while taking
CS
HIGH. The new wiper position
would be maintained until changed by the system or
until a power-up/down cycle recalled the previously
stored data.
This would allow 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 preference,
system parameter changes due to temperature drift,
etc...
The state of U/D may be changed while
CS
remains
LOW. This allows the host system to enable the X9314
and then move the wiper up and down until the proper
trim is attained.
T
IW
/R
TOTAL
The electronic switches on the X9314 operate in a
“make before break” mode when the wiper changes tap
positions. If the wiper is moved several positions mul-
tiple taps are connected to the wiper for t
IW
(INC to V
W
change). The R
TOTAL
value for the device can tempo-
rarily be reduced by a significant amount if the wiper is
moved several positions.
R
TOTAL
with V
CC
Removed
The end to end resistance of the array will fluctuate once
V
CC
is removed.
3
X9314
ABSOLUTE MAXIMUM RATINGS*
Temperature under Bias .................. –65°C to +135°C
Storage Temperature ....................... –65°C to +150°C
Voltage on
CS, INC,
U/D and V
CC
with Respect to V
SS ...............................
–1V to +7V
Voltage on V
H
and V
L
Referenced to V
SS .................................
–8V to +8V
∆V
= |V
H
–V
L
|
X9314W .......................................................... 10V
Lead Temperature (Soldering 10 seconds)....... 300°C
Wiper Current .....................................................
±1mA
ANALOG CHARACTERISTICS
Electrical Characteristics
End-to-End Resistance Tolerance .....................
±20%
Power Rating at 25°C
X9314W ...................................................... 10mW
Wiper Current ............................................
±1mA
Max.
Typical Wiper Resistance ......................... 40Ω at 1mA
Typical Noise .......................... < –120dB/ Hz Ref: 1V
Relative Variation
Relative variation is a measure of the error in step size
between taps = log(V
w(n)
) – log(V
w(n-1)
) = 0.07±0.003 for
tap n = 2 – 31
Temperature Coefficient
(–40°C to +85°C)
X9314W ..................................... +600 ppm/°C Typical
Ratiometric Temperature Coefficient ............
±20
ppm
Wiper Adjustability
Unlimited Wiper Adjustment (Non-Store operation)
Wiper Position Store Operations ............. 100,000
Data Changes
Physical Characteristics
Marking Includes
Manufacturer’s Trademark
Resistance Value or Code
Date Code
*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 specifica-
tion is not implied. Exposure to absolute maximum
rating conditions for extended periods may affect device
reliability.
Typical Electrical Taper
100.0%
90.0%
80.0%
70.0%
% Total Resistance
60.0%
50.0%
40.0%
30.0%
20.0%
10.0%
0.0%
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Tap
6427 ILL F06
4
31
X9314
RECOMMENDED OPERATING CONDITIONS
Temperature
Commercial
Industrial
Military
Min.
0°C
–40°C
–55°C
Max.
+70°C
+85°C
+125°C
6427 PGM T03.1
Supply Voltage
X9314
X9314-3
Limits
5V
±10%
3V to 5.5V
6427 PGM T04.1
D.C. OPERATING CHARACTERISTICS
(Over recommended operating conditions unless otherwise specified.)
Limits
Symbol
I
CC
I
SB
I
LI
V
IH
V
IL
R
W
V
VH
V
VL
C
IN(5)
Parameter
V
CC
Active Current
Standby Supply Current
CS, INC,
U/D Input
Leakage Current
CS, INC,
U/D Input
HIGH Voltage
CS, INC,
U/D Input
LOW Voltage
Wiper Resistance
VH Terminal Voltage
VL Terminal Voltage
CS, INC,
U/D Input
Capacitance
Min.
Typ.
(4)
1
Max.
3
500
±10
2
–1
40
–5
–5
V
CC
+ 1
0.8
100
+5
+5
10
Units
mA
µA
µA
V
V
Ω
V
V
pF
Max. Wiper Current
±1mA
Test Conditions
CS
= V
IL
, U/D = V
IL
or V
IH
and
INC
= 0.4V/2.4V @ max. t
CYC
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
= 5V, V
IN
= V
SS
,
T
A
= 25°C, f = 1MHz
6427 PGM T05.3
STANDARD PARTS
Part Number
X9314W
Maximum Resistance
10KΩ
Wiper Increments
Log Taper
Minimum Resistance
40Ω
6427 PGM T08.1
Notes:
(4) Typical values are for T
A
= 25°C and nominal supply voltage.
(5) This parameter is periodically sampled and not 100% tested.
Test Circuit #1
Test Circuit #2
VH
VH
TEST POINT
TEST POINT
VW
VL
6427 ILL F04
VW
VL
FORCE
CURRENT
6427 ILL F05
5
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