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X9421 Schematic ( PDF Datasheet ) - Xicor

Teilenummer X9421
Beschreibung Single Digitally Controlled (XDCP) Potentiometer
Hersteller Xicor
Logo Xicor Logo 




Gesamt 21 Seiten
X9421 Datasheet, Funktion
APPLICATION NOTES
AVAILABLE
AN99 • AN115 • AN120 • AN124 • AN133 • AN134 • AN135
Low Noise/Low Power/SPI Bus
X9421
Single Digitally Controlled (XDCP) Potentiometer
FEATURES
• Single Voltage Potentiometer
• 64 Resistor Taps
• SPI Serial Interface for write, read, and transfer
operations of the potentiometer
Wiper Resistance, 150Typical at 5V
• 4 Non-Volatile Data Registers
• Non-Volatile Storage of Multiple Wiper Positions
• Power On Recall. Loads Saved Wiper Position on
Power Up.
• Standby Current < 5µA Max
• VCC : 2.7V to 5.5V Operation
2.5K, 10KEnd to End Resistance
• 100 yr. Data Retention
• Endurance: 100, 000 Data Changes per Bit per
Register
• 14-Lead TSSOP, 16-Lead SOIC
• Low Power CMOS
DESCRIPTION
The X9421 integrates a single digitally controlled
potentiometer (XDCP) on a monolithic CMOS
integrated circuit.
The digital controlled potentiometer is implemented
using 63 resistive elements in a series array. Between
each element are tap points connected to the wiper
terminal through switches. The position of the wiper on
the array is controlled by the user through the SPI bus
interface. The potentiometer has associated with it a
volatile Wiper Counter Register (WCR) and a four non-
volatile Data Registers that can be directly written to
and read by the user. The contents of the WCR
controls the position of the wiper on the resistor array
though the switches. Powerup recalls the contents of
the default data register (DR0) to the WCR.
The XDCP can be used as a three-terminal
potentiometer or as a two terminal variable resistor in
a wide variety of applications including control,
parameter adjustments, and signal processing.
BLOCK DIAGRAM
VCC
SPI
bus
interface
address
data
status
Bus
Interface &
Control
write
read
transfer
inc / dec
control
Power On Recall
Wiper Counter
Register (WCR)
Data Registers
4 Bytes
RH/VH
wiper
10K
64-taps
POT
VSS
RW/VW RL/VL
REV 1.1.6 8/1/02
www.xicor.com
Characteristics subject to change without notice. 1 of 21






X9421 Datasheet, Funktion
X9421
Figure 1. Detailed Potentiometer Block Diagram
Serial Data Path
From Interface
Circuitry
Register 0
8
REGISTER 2
IF WCR = 00[H] THEN VW = VL
IF WCR = 3F[H] THEN VW = VH
Register 1
6
REGISTER 3
UP/DN
Modified SCK
Serial
Bus
Input
Parallel
Bus
Input
Wiper
Counter
Register
(WCR)
INC/DEC
Logic
UP/DN
CLK
C
O
U
N
T
E
R
D
E
C
O
D
E
VH
VL
VW
Write in Process
The contents of the Data Registers are saved to
nonvolatile memory when the CS pin goes from LOW
to HIGH after a complete write sequence is received by
the device. The progress of this internal write operation
can be monitored by a Write In Process bit (WIP). The
WIP bit is read with a Read Status command.
INSTRUCTIONS
Figure 2. Address/Identification Byte Format
Device Type
Identifier
0 1 0 1 1 1 0 A0
Device Address
Address/Identification (ID) Byte
The first byte sent to the X9421 from the host, following
a CS going HIGH to LOW, is called the Address or
Identification byte. The most significant four bits of the
slave address are a device type identifier, for the
X9421 this is fixed as 0101[B] (refer to Figure 2).
The least significant bit in the ID byte selects one of
two devices on the bus. The physical device address is
defined by the state of the A0 input pin. The X9421
compares the serial data stream with the address input
state; a successful compare of the address bit is
required for the X9421 to successfully continue the
command sequence. The A0 input can be actively
driven by a CMOS input signal or tied to VCC or VSS.
The remaining three bits in the ID byte must be set to
110.
Instruction Byte
The next byte sent to the X9421 contains the
instruction and register pointer information. The four
most significant bits are the instruction. The next two
bits point to one of four Data Registers. The format is
shown below in Figure 3.
Figure 3. Instruction Byte Format
Register
Select
I3 I2 I1 I0 R1 R0 0 0
Instructions
REV 1.1.6 8/1/02
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Characteristics subject to change without notice. 6 of 21

6 Page









X9421 pdf, datenblatt
X9421
ABSOLUTE MAXIMUM RATINGS
Temperature under bias . . . . . . . . . . . . –65°C to +135°C
Storage temperature . . . . . . . . . . . . . . –65°C to +150°C
Voltage on SCK any address input
with respect to VSS . . . . . . . . . . . . . . . . . –1V to +7V
V = | (VH – VL) | . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5V
Lead temperature (soldering, 10 seconds) . . . . . . 300°C
IW (10 seconds) . . . . . . . . . . . . . . . . . . . . . . . . ±6mA
Any VH/RH, VL/RL, VW/RW . . . . . . . . . . . . VSS to VCC
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
reliability.
RECOMMENDED OPERATING CONDITIONS
Temp
Commercial
Industrial
Min.
0°C
–40°C
Max.
+70°C
+85°C
Device
X9421
X9421-2.7
Supply Voltage (VCC) Limits
5V ±10%
2.7V to 5.5V
ANALOG CHARACTERISTICS (Over recommended operating conditions unless otherwise stated.)
Symbol
IW
RW
VTERM
CH/CL/CW
IAL
Parameter
End to End Resistance Tolerance
Power Rating
Wiper Current
Wiper Resistance
Voltage on any VH/RH, VL/RL, VW/RW
Noise
Resolution(4)
Absolute Linearity(1)
Relative Linearity(2)
Temperature Coefficient of RTOTAL
Ratiometric Temperature
Coefficient
Potentiometer Capacitances
Rh, RI, Rw leakage current
Min.
Limits
Typ. Max.
±20
50
±3
150 250
400 1000
VSS
-120
1.6
±300
VCC
±1
±0.2
±20
10/10/25
0.1 10
Units
%
mW
mA
V
dBV
%
MI(3)
MI(3)
ppm/°C
ppm/°C
pF
µA
Test Conditions
25°C, each pot
Wiper Current = ± 1mA,
VCC = 5V
Wiper Current = ± 1mA,
VCC = 3V
VSS = 0V
Ref: 1kHz
See Note 5
Vw(n)(actual) – Vw(n)(expected)
Vw(n + 1) – [Vw(n) + MI]
See Note 5
See Note 5
See Circuit #3
Vin = Vss to Vcc. Device is in
stand-by mode.
Notes: (1)
(2)
(3)
(4)
Absolute Linearity is utilized to determine actual wiper voltage versus expected voltage as determined by wiper position when
used as a potentiometer.
Relative Linearity is utilized to determine the actual change in voltage between two successive tap positions when used as a
potentiometer. It is a measure of the error in step size.
MI = RTOT/63 or (VH–VL)/63, single pot
Typical = Individual array resolution.
REV 1.1.6 8/1/02
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Characteristics subject to change without notice. 12 of 21

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