X9252
®
Low Power + Quad 256-tap + 2-Wire Bus + Up/Down Interface
Data Sheet
September 14, 2005
Quad Digitally-Controlled (XDCP™)
Potentiometer
FN8167.1
Features
• Quad Solid State Potentiometer
The X9252 integrates 4 digitally controlled potentiometers
(XDCP) on a monolithic CMOS integrated circuit.
The digitally controlled potentiometers are implemented
using 255 resistive elements in a series array. Between each
pair of elements are tap points connected to wiper terminals
through switches. The position of each wiper on the array is
controlled by the user through the Up/Down (U/D) or 2-wire
bus interface. The wiper of each potentiometer has an
associated volatile Wiper Counter Register (WCR) and four
non-volatile Data Registers (DRs) 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 through the
switches. At power-up, the device recalls the contents of the
default data registers DR00, DR10, DR20, DR30, to the
corresponding WCR.
Each DCP can be used as a three-terminal potentiometer or
as a two terminal variable resistor in a wide variety of
applications including the programming of bias voltages, the
implementation of ladder networks, and three resistor
programmable networks.
• 256 Wiper Tap Points-0.4% Resolution
• 2-Wire Serial Interface for Write, Read, and Transfer
Operations of the Potentiometer
• Up/Down Interface for Individual Potentiometers
• Wiper Resistance: 40Ω Typical
• Non-Volatile Storage of Wiper Positions
• Power On Recall. Loads Saved Wiper Position on PowerUp.
• Standby Current < 20µA Max
• Maximum Wiper Current: 3mA
• VCC: 2.7V to 5.5V Operation
• 2.8kΩ,10kΩ, 50kΩ, 100kΩ Version of Total Pot Resistance
• Endurance: 100, 000 Data Changes per Bit per Register
• 100 yr. Data Retention
• 24 Ld TSSOP
• Pb-Free Plus Anneal Available (RoHS Compliant)
Pinout
X9252
(24 LD TSSOP)
TOP VIEW
1
24
DS1
A0
2
23
SCL
RW3
3
22
RL2
RH3
4
21
RH2
RL3
DS0
1
5
20
RW2
U/D
6
19
CS
VCC
7
18
VSS
X9252
RL0
8
17
RW1
RH0
9
16
RH1
RW0
10
15
RL1
A2
11
14
A1
WP
12
13
SDA
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
XDCP is a trademark of Intersil Americas Inc. Copyright Intersil Americas Inc. 2005. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
X9252
Ordering Information
PART NUMBER
PART MARKING
RTOTAL (kΩ)
TEMP RANGE (°C)
PACKAGE
2.8
-40 to 85
24 Ld TSSOP (4.4mm)
-40 to 85
24 Ld TSSOP (4.4mm) (Pb-free)
-40 to 85
24 Ld SOIC (300 mil)
X9252YV24I-2.7
X9252YV G
X9252YV24IZ-2.7 (Note)
X9252YV Z G
X9252WS24I-2.7
X9252WS G
X9252WS24IZ-2.7 (Note)
X9252WS Z G
-40 to 85
24 Ld SOIC (300 mil) (Pb-Free)
X9252WV24I-2.7
X9252WV G
-40 to 85
24 Ld TSSOP (4.4mm)
X9252WV24IZ-2.7 (Note)
X9252WV Z G
-40 to 85
24 Ld TSSOP (4.4mm) (Pb-free)
-40 to 85
24 Ld SOIC (300 mil)
10
X9252US24I-2.7
50
X9252US24IZ-2.7 (Note)
X9252US Z G
-40 to 85
24 Ld SOIC (300 mil) (Pb-Free)
X9252UV24I-2.7
X9252UV G
-40 to 85
24 Ld TSSOP (4.4mm)
X9252UV24IZ-2.7 (Note)
X9252UV Z G
-40 to 85
24 Ld TSSOP (4.4mm) (Pb-free)
-40 to 85
24 Ld SOIC (300 mil)
X9252TS24I-2.7
100
X9252TS24IZ-2.7 (Note)
X9252TS Z G
-40 to 85
24 Ld SOIC (300 mil) (Pb-Free)
X9252TV24I-2.7
X9252TV G
-40 to 85
24 Ld TSSOP (4.4mm)
X9252TV24IZ-2.7 (Note)
X9252TV Z G
-40 to 85
24 Ld TSSOP (4.4mm) (Pb-free)
Intersil Pb-free plus anneal products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate
termination finish, which are RoHS compliant and compatible with both SnPb and Pb-free soldering operations. Intersil Pb-free products are MSL
classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.
Functional Diagram
RH1
RH0
VCC
RH3
RH2
A2
2-Wire
Interface
A1
SDA
SCL
Up-Down
Interface
DS0
DCP0
WCR0
DR00
DR01
DR02
DR03
A0
POWER UP,
INTERFACE
CONTROL
AND
STATUS
WCR1
DR10
DR11
DR12
DR13
DCP1
WCR2
DR20
DR21
DR22
DR23
DCP2
WCR3
DR30
DR31
DR32
DR33
DCP3
DS1
CS
U/D
VSS
WP
RW0
RL0
RW1
RL1
RW2
RL2
RW3
RL3
Pin Descriptions
TSSOP PIN
SYMBOL
1
DS0
2
A0
3
RW3
Wiper terminal of DCP3.
4
RH3
High terminal of DCP3.
5
RL3
Low terminal of DCP3.
2
BRIEF DESCRIPTION
DCP select for Up/Down interface.
Device address for 2-wire bus.
FN8167.1
September 14, 2005
X9252
Pin Descriptions (Continued)
TSSOP PIN
SYMBOL
BRIEF DESCRIPTION
6
U/D
Increment/decrement for up/down interface.
7
VCC
System supply voltage
8
RL0
Low terminal of DCP0.
9
RH0
High terminal of DCP0.
10
RW0
Wiper terminal of DCP0.
11
A2
Device address for 2-wire bus.
12
WP
Hardware write protect
13
SDA
Serial data input/output for 2-wire bus.
14
A1
15
RL1
Low terminal of DCP1.
16
RH1
High terminal of DCP1.
17
RW1
Wiper terminal DCP1.
18
VSS
System ground
19
CS
20
RW2
Wiper terminal of DCP2.
21
RH2
High terminal of DCP2.
22
RL2
Low terminal of DCP2.
23
SCL
Serial clock for 2-wire bus.
24
DS1
DCP select for up/down interface.
Device address for 2-wire bus.
Chip select for Up/Down interface.
Pin Descriptions
interface is disabled at this time. When CS is high, the 2-wire
interface is enabled.
Bus Interface Pins
Serial Data Input/Output (SDA)
The SDA is a bidirectional serial data input/output pin for the
2-wire interface. It receives device address, operation code,
wiper register address and data from a 2-wire external master
device at the rising edge of the serial clock SCL, and it shifts
out data after each falling edge of the serial clock SCL.
SDA requires an external pull-up resistor, since it’s an open
drain output.
Serial Clock (SCL)
This input is the serial clock of the 2-wire and Up/Down
interface.
Up or Down Control (U/D)
The U/D input pin is held HIGH during increment operations
and held LOW during decrement operations.
DCP Select (DS1-DS0)
The DS1-DS0 select one of the four DCPs for an Up/Down
interface operation.
Hardware Write Protect Input (WP)
When the WP pin is set low, “write” operations to non volatile
DCP Data Registers are disabled. This includes both 2-wire
interface non-volatile “Write”, and Up/Down interface “Store”
operations.
DCP Pins
Device Address (A2-A0)
The Address inputs are used to set the least significant 3 bits of
the 8-bit 2-wire interface slave address. A match in the slave
address serial data stream must be made with the Address
input pins in order to initiate communication with the X9252. A
maximum of 8 devices may occupy the 2-wire serial bus.
Chip Select (CS)
When the CS pin is low, increment or decrement operations
are possible using the SCL and U/D pins. The 2-wire
3
RH0, RL0, RH1, RL1, RH2, RL2, RH3, and RL3
These pins are equivalent to the terminal connections on
mechanical potentiometers. Since there are 4 DCPs, there is
one set of RH and RL for each DCP.
RW0, RW1, RW2, and RW3
The wiper pins are equivalent to the wiper terminal of
mechanical potentiometers. Since there are four DCPs,
there are 4 RW pins.
FN8167.1
September 14, 2005
X9252
Absolute Maximum Ratings
Recommended Operating Conditions
Junction Temperature under bias. . . . . . . . . . . . . . .-65°C to +135°C
Storage temperature . . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C
Voltage at any digital interface pin
with respect to VSS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -1V to +7V
VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -1V to +7V
Voltage at any DCP pin with
respect to VSS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -1V to VCC
Lead temperature (soldering, 10s). . . . . . . . . . . . . . . . . . . . . . 300°C
IW (10s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±6mA
Commercial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C
Industrial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-40°C to +85°C
Supply Voltage (VCC)(Note 4) Limits . . . . . . . . . . . . . . . 2.7V to 5.5V
CAUTION: 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.
Analog Specifications
SYMBOL
RTOTAL
Over recommended operating conditions unless otherwise stated.
PARAMETER
End to end resistance
TEST CONDITIONS
Y, W, U, T versions respectively
End to end resistance tolerance
Power rating
RTOTAL
Matching
IW (Note 5)
RW
VTERM
MIN
TYP
(Note 4)
2.8, 10,
50, 100
-20
25°C, each DCP
DCP to DCP resistance matching
Wiper current
0.75
See test circuit
Wiper resistance
Wiper current =
-3.0
50
VCC
RTOTAL
Voltage on any DCP pin
Vss
Noise (Note 5)
Ref: 1kHz
Resolution
Absolute linearity (Note 1)
V(RH0)=V(RH1)=V(RH2)=V(RH3)=VCC
V(RL0)=V(RL1)=V(RL2)=V(RL3)=VSS
Relative linearity (Note 2)
IOL
SYMBOL
+20
%
50
mW
2.0
%
+3.0
mA
150
Ω
Vcc
V
-120
dBV
0.4
%
+1
MI
(Note 3)
-0.3
+0.3
MI
(Note 3)
-20
Potentiometer Capacitance (Note 5)
See equivalent circuit
Leakage on DCP pins
Voltage at pin from VSS to VCC
DC Electrical Specifications
kΩ
±300
Ratiometric Temperature (Note 5)
Coefficient
UNIT
-1
Temperature coefficient of resistance
(Note 5)
CH/CL/CW
MAX
ppm/°C
+20
10/10/25
ppm/°C
pF
0.1
10
µA
MIN
MAX
UNITS
Over the recommended operating conditions unless otherwise specified.
PARAMETER
TEST CONDITIONS
ICC1
VCC supply current (Volatile write/read)
fSCL = 400kHz;SDA = Open; (for 2-Wire, Active,
Read and Volatile Write States only)
3
mA
ICC2
VCC supply current (active)
fSCL = 200kHz;
(for U/D interface, increment, decrement)
3
mA
ICC3
VCC supply current (nonvolatile write)
fSCL = 400kHz; SDA = Open;
(for 2-Wire, Active, Nonvolatile Write State only)
5
mA
VCC current (standby)
VCC = +5.5V; VIN = VSS or VCC; SDA = VCC;
(for 2-Wire, Standby State only)
20
µA
ISB
4
FN8167.1
September 14, 2005
X9252
DC Electrical Specifications
SYMBOL
IL
Over the recommended operating conditions unless otherwise specified. (Continued)
PARAMETER
TEST CONDITIONS
Leakage current, bus interface pins
Voltage at pin from VSS to VCC
MIN
MAX
UNITS
-10
10
µA
VIH
Input HIGH voltage
VCC x 0.7
VCC + 1
V
VIL
Input LOW voltage
-1
VCC x 0.3
V
VOL
SDA pin output LOW voltage
0.4
V
IOL = 3mA
Endurance and Data Retention
PARAMETER
MIN
UNITS
Minimum endurance
100,000
Data changes per bit
Data retention
100
Years
Capacitance
Symbol
Test
CIN/OUT (Note 5) Input / Output capacitance (SDA)
CIN (Note 5)
Input capacitance (SCL, WP, DS0, DS1, CS, U/D, A2, A1 and
A0)
Test Conditions
Max.
Units
VOUT = 0V
8
pF
VIN = 0V
6
pF
Power-Up Timing
SYMBOL
PARAMETER
tD (Notes 5, 9)
MAX
UNITS
2
ms
Power Up Delay from VCC power up (VCC above 2.7V) to wiper position recall
completed, and communication interfaces ready for operation.
A.C. Test Conditions
Input Pulse Levels
VCC x 0.1 to VCC x 0.9
Input rise and fall times
10ns
Input and output timing threshold level
VCC x 0.5
External load at pin SDA
2.3kΩ to VCC and 100pF to VSS
2-Wire Interface timing (s)
SYMBOL
PARAMETER
MIN
MAX
UNITS
400
kHz
fSCL
Clock Frequency
tHIGH
Clock High Time
600
ns
tLOW
Clock Low Time
1300
ns
tSU:STA
Start Condition Setup Time
600
ns
tHD:STA
Start Condition Hold Time
600
ns
tSU:STO
Stop Condition Setup Time
600
ns
tSU:DAT
SDA Data Input Setup Time
100
ns
tHD:DAT
SDA Data Input Hold Time
30
ns
tR (Note 5)
SCL and SDA Rise Time
300
ns
tF (Note 5)
SCL and SDA Fall Time
300
ns
tAA (Note 5)
SCL Low to SDA Data Output Valid Time
0.9
µs
tDH
SDA Data Output Hold Time
tIN (Note 5)
Pulse Width Suppression Time at SCL and SDA inputs
5
0
ns
50
ns
FN8167.1
September 14, 2005
X9252
2-Wire Interface timing (s) (Continued)
SYMBOL
PARAMETER
MIN
MAX
UNITS
tBUF (Note 5)
Bus Free Time (Prior to Any Transmission)
1200
ns
tSU:WPA
(Note 5)
A0, A1, A2 and WP Setup Time
600
ns
tHD:WPA
(Note 5)
A0, A1, A2 and WP Hold Time
600
ns
SDA vs SCL Timing
tHIGH
tF
SCL
tLOW
tR
tSU:DAT
tSU:STA
tHD:DAT
tHD:STA
SDA
(Input Timing)
tSU:STO
tAA
tDH
tBUF
SDA
(Output Timing)
WP, A0, A1, and A2 Pin Timing
STOP
START
SCL
Clk 1
SDA IN
tSU:WP
tHD:WP
WP, A0, A1, or A2
Increment/Decrement Timing
SYMBOL
tCI
PARAMETER
MIN
TYP (Note 4)
MAX
UNITS
CS to SCL Setup
600
ns
tID (Note 5)
SCL HIGH to U/D, DS0 or DS1 change
600
ns
tDI (Note 5)
U/D, DS0 or DS1 to SCL setup
600
ns
tIL
SCL LOW period
2.5
µs
tIH
SCL HIGH period
2.5
µs
tIC
SCL inactive to CS inactive (Nonvolatile Store Setup Time)
1
µs
CS deselect time (STORE)
10
ms
CS deselect time (NO STORE)
1
µs
tCPHS
tCPHNS
(Note 5)
tIW (Note 5)
tCYC
SCL to RW change
SCL cycle time
100
500
5
tR, tF (Note 5) SCL input rise and fall time
6
µs
µs
500
µs
FN8167.1
September 14, 2005
X9252
Increment/Decrement Timing
CS
tCYC
tCI
tIL
tIH
tCPHNS
tCPHS
tIC
90%
90%
10%
SCL
tID
tDI
tF
tR
U/D
DS0, DS1
tIW
MI
RW
(3)
High-Voltage Write Cycle Timing
SYMBOL
tWC
(Notes 5, 8)
PARAMETER
Non-volatile write cycle time
TYP
MAX
UNITS
5
10
ms
MIN
MAX
UNITS
5
20
µs
XDCP Timing
SYMBOL
tWRL (Note 5)
PARAMETER
SCL rising edge to wiper code changed, wiper response time after instruction
issued (all load instructions)
NOTES:
1. Absolute linearity is utilized to determine actual wiper voltage versus expected voltage = [V(RW(n)(actual))-V(RW(n)(expected))]/MI
V(RW(n)(expected)) = n(V(RH)-V(RL))/255 + V(RL), with n from 0 to 255.
2. Relative linearity is a measure of the error in step size between taps = [V(RW(n+1))-(V(RW(n)) + MI)]/MI, with n from 0 to 254
3. 1 Ml = Minimum Increment = [V(RH)-V(RL)]/255.
4. Typical values are for TA = 25°C and nominal supply voltage.
5. This parameter is not 100% tested.
6. Ratiometric temperature coefficient = (V(RW)T1(n)-V(RW)T2(n))/[V(RW)T1(n)(T1-T2)] x 106, with T1 & T2 being 2 temperatures, and n from 0 to
255.
7. Measured with wiper at tap position 255, RL grounded, using test circuit.
8. tWC is the minimum cycle time to be allowed for any nonvolatile write by the user, unless Acknowledge Polling is used. It is the time from a valid
STOP condition at the end of a write sequence of a 2-wire interface write operation, or from the rising edge of CS of a valid “Store” operation of
the Up/Down interface, to the end of the self-timed internal nonvolatile write cycle.
9. The recommended power up sequence is to apply VCC/VSS first, then the potentiometer voltages. During power up, the data sheet parameters
for the DCP do not fully apply until tD after VCC reaches its final value. In order to prevent unwanted tap position changes, or an inadvertant
store, bring the CS pin high before or concurrently with the VCC pin on power up.
7
FN8167.1
September 14, 2005
X9252
Test Circuit
Equivalent Circuit
RTOTAL
Test Point
RL
RH
CW
CH
RW
CL
Force
Current
RW
Principles of Operation
The X9252 is an integrated circuit incorporating four resistor
arrays, their associated registers and counters, and the
serial interface logic providing direct communication
between the host and the digitally controlled potentiometers.
This section provides detail description of the following:
- Resistor Array
- Up/Down Interface
- 2-wire Interface
Resistor Array Description
The X9252 is comprised of four resistor arrays. Each array
contains 255 discrete resistive segments that are connected
in series. The physical ends of each array are equivalent to
the fixed terminals of a mechanical potentiometer (RHi and
RLi inputs) (See Figure 1.)
At both ends of each array and between each resistor
segment is a switch connected to the wiper (RWi) pin.
Within each individual array only one switch may be turned
on at a time.
These switches are controlled by a Wiper Counter Register
(WCR). The 8-bits of the WCR (WCR[7:0]) are decoded to
select and enable one of 256 switches (see Table 1). Note
that each wiper has a dedicated WCR. When all bits of a
WCR are zeroes, the switch closest to the corresponding RL
pin is selected. When all bits of a WCR are ones, the switch
closest to the corresponding RH pin is selected.
The WCR is volatile and may be written directly. There are
four non-volatile Data Registers (DR) associated with each
WCR. Each DR can be loaded into WCR. All DRs and
WCRs can be read or written.
Power Up and Down Requirements
During power up, CS must be high, to avoid inadvertant
“store” operations. At power up, the contents of Data
Registers DR00, DR10, DR20, and DR30, are loaded into
the corresponding wiper counter register.
i = 0, 1, 2, and 3
Four
Non-Volatile
Data
Registers
DRi0, DRi1,
DRi2, and
DRi3
WCR[7:0]
= FF hex
Volatile
8-bit
Wiper
Counter
Register
WCRi
255
RHi
254
253
252
One
of
256
Decoder
WP
SCL
SDA
A2, A1, A0
CS
Interface Control and
Volatile Status Register (SR)
2
(Shared by the Four DCPs)
1
U/D
DS1, DS0
WCR[7:0]
= 00 hex
0
RLi
RWi
FIGURE 1. DETAILED BLOCK DIAGRAM OF ONE DCP
8
FN8167.1
September 14, 2005
X9252
Up/Down Interface Operation
Mode Selection for Up/Down Control
The SCL, U/D, CS, DS0 and DS1 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 SCL inputs. HIGH to LOW transitions on SCL will
increment or decrement (depending on the state of the U/D
input) a wiper counter register selected by DS0 and DS1.
The output of this counter is decoded to select one of 256
wiper positions along the resistor array.
The value of the counter is stored in nonvolatile Data
Registers DRi0 whenever CS transitions HIGH while the
SCL and WP inputs are HIGH. “i” indicates the DCP number
selected with pins DS1 and DS0. During a “Store” operation
bits DRSel1 and DRSel0 in the Status Register must be both
“0”, which is their power up default value. Other
combinations are reserved and must not be used.
The system may select the X9252, move the wiper, and
deselect the device without having to store the latest 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 SCL LOW while taking CS
HIGH. The new wiper position will be maintained until
changed by the system or until a power-down/up 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 preference, system
parameter changes due to temperate 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.
The 2-wire interface is disabled while CS remains LOW.
TABLE 1. DCP SELECTION FOR UP/DOWN CONTROL
DS1
DS0
SELECTED DCP
0
0
DCP0
0
1
DCP1
1
0
DCP2
1
1
DCP3
CS
SCL
U/D
MODE
L
H
Wiper Up
L
L
Wiper Down
H
X
Store Wiper Position to nonvolatile
memory if WP pin is high. No store,
return to standby, if WP pin is low.
X
X
Standby
L
X
No Store, Return to Standby
L
H
Wiper Up (not recommended)
L
L
Wiper Down
(not recommended)
H
2-Wire Serial Interface
Protocol Overview
The device supports a bidirectional bus oriented protocol.
The protocol defines any device that sends data onto the
bus as a transmitter, and the receiving device as the
receiver. The device controlling the transfer is called the
master and the device being controlled is called the slave.
The master always initiates data transfers, and provides the
clock for both transmit and receive operations. The X9252
operates as a slave in all applications.
All 2-wire interface operations must begin with a START,
followed by a Slave Address byte. The Slave Address
selects the X9252, and specifies if a Read or Write operation
is to be performed.
All Communication over the 2-wire interface is conducted by
sending the MSB of each byte of data first.
Serial Clock and Data
Data states on the SDA line can change only while SCL is
LOW. SDA state changes while SCL is HIGH are reserved
for indicating START and STOP conditions (See Figure 2).
On power up of the X9252, the SDA pin is in the input mode.
Serial Start Condition
All commands are preceded by the START condition, which
is a HIGH to LOW transition of SDA while SCL is HIGH. The
device continuously monitors the SDA and SCL lines for the
START condition and does not respond to any command
until this condition has been met (See Figure 2).
Serial Stop Condition
All communications must be terminated by a STOP
condition, which is a LOW to HIGH transition of SDA while
SCL is HIGH. The STOP condition is also used to place the
device into the Standby power mode after a read sequence.
A STOP condition can only be issued after the transmitting
device has released the bus (See Figure 2).
9
FN8167.1
September 14, 2005
X9252
SCL
SDA
START
DATA
STABLE
DATA
CHANGE
DATA
STABLE
STOP
FIGURE 2. VALID DATA CHANGES, START, AND STOP CONDITIONS
SCL from Master
1
8
9
SDA Output from
Transmitter
SDA Output from
Receiver
START
ACK
FIGURE 3. ACKNOWLEDGE RESPONSE FROM RECEIVER
Serial Acknowledge
Slave Address Byte
An ACK (Acknowledge), is a software convention used to
indicate a successful data transfer. The transmitting device,
either master or slave, releases the bus after transmitting
eight bits. During the ninth clock cycle, the receiver pulls the
SDA line LOW to acknowledge the reception of the eight bits
of data (See Figure 3).
Following a START condition, the master must output a Slave
Address Byte (Refer to figure 4.). This byte includes three parts:
The device responds with an ACK after recognition of a
START condition followed by a valid Slave Address byte. A
valid Slave Address byte must contain the Device Type
Identifier 0101, and the Device Address bits matching the
logic state of pins A2, A1, and A0 (See Figure 4).
If a write operation is selected, the device responds with an
ACK after the receipt of each subsequent eight-bit word.
In the read mode, the device transmits eight bits of data,
releases the SDA line, and then monitors the line for an
ACK. The device continues transmitting data if an ACK is
detected. The device terminates further data transmissions if
an ACK is not detected. The master must then issue a STOP
condition to place the device into a known state.
- The four MSBs (SA7-SA4) are the Device Type Identifier,
which must always be set to 0101 in order to select the
X9252.
- The next three bits (SA3-SA1) are the Device Address bits
(AS2-AS0). To access any part of the X9252’s memory,
the value of bits AS2, AS1, and AS0 must correspond to
the logic levels at pins A2, A1, and A0 respectively.
- The LSB (SA0) is the R/W bit. This bit defines the
operation to be performed on the device being
addressed. When the R/W bit is “1”, then a Read
operation is selected. A “0” selects a Write operation.
SA7
0
SA6
SA5
SA4
SA3
SA2
SA1
1
0
1
AS2
AS1
AS0
Device Type
Identifier
SLAVE ADDRESS
BIT(S)
Device
Address
R/W
Read or
Write
DESCRIPTION
SA7-SA4
Device Type Identifier
SA3-SA1
Device Address
SA0
SA0
Read or Write Operation Select
FIGURE 4. SLAVE ADDRESS (SA) FORMAT
10
FN8167.1
September 14, 2005
X9252
2-Wire Serial Interface Operation
Nonvolatile Write Acknowledge Polling
After a nonvolatile write command sequence is correctly
issued (including the final STOP condition), the X9252
initiates an internal high voltage write cycle. This cycle
typically requires 5ms. During this time, any Read or Write
command is ignored by the X9252. Write Acknowledge
Polling is used to determine whether a high voltage write
cycle is completed.
During acknowledge polling, the master first issues a START
condition followed by a Slave Address Byte. The Slave
Address Byte contains the X9252’s Device Type Identifier
and Device Address. The LSB of the Slave Address (R/W)
can be set to either 1 or 0 in this case. If the device is busy
within the high voltage cycle, then no ACK is returned. If the
high voltage cycle is completed, an ACK is returned and the
master can then proceed with a new Read or Write
operation. (Refer to figure 5.)
Issue START
ACK returned?
Refer to the Functional Diagram on page 2. There are four
Digitally Controlled Potentiometers, referred to as DCPi,
i=0,1,2,3. Each potentiometer has one volatile Wiper Control
Register (WCR) with the corresponding number, WCRi,
i=0,1,2,3. Each potentiometer also has four nonvolatile
registers to store wiper position or general data, these are
numbered DRi0, DRi1, DRi2 and DRi3, i=0,1,2,3.
The registers are organized in five pages of four, with one
page consisting of the WCRi (i=0-3), a second page
containing the DRi0 (i=0-3), a third page containing the
DRi1, and so forth. These pages can be written to four bytes
at time. In this manner all four potentiometer WCRs can be
updated in a single serial write (see “Page Write Operation”),
as well as all four registers of a given page in the DR array.
The unique feature of the X9252 device is that writing or
reading to a Data Register of a given DCP automatically
updates/moves the WCR of that DCP with the content of the
DR. In this manner data can be moved from a particular DCP
register to that DCP’s WCR just by performing a 2-wire read
operation. Simultaneously, that data byte can be utilized by
the host.
Byte load completed by issuing
STOP. Enter ACK Polling
Issue Slave Address
Byte (Read or Write)
X9252 Digital Potentiometer Register Organization
Issue STOP
NO
YES
Status Register Organization
The Status Register (SR) is used in read and write
operations to select the appropriate DCP register. Before
any DCP register can be accessed, the SR must be set to
the correct value. It is accessed by setting the Address Byte
to 07h (See Table 3). Do this by Writing the Slave Address
followed by a Byte Address of 07h. The SR is volatile and
defaults to 00h on power up. It is an 8-bit register containing
three control bits in the 3 LSBs as follows:
7
High Voltage
complete. Continue command
NO
6
5
Reserved
4
3
2
1
0
DRSel1
DRSel0
NVEnable
sequence.
YES
Issue STOP
Continue normal Read or Write
command sequence
Bits DRSel1 and DRSel0 determine which Data Register of a
DCP is selected for a given operation. NVEnable is used to
select the volatile WCR if “0”, and one of the nonvolatile
DCP registers if “1”. Table 2 shows this register organization.
“Store” operations using the Up/Down interface require that
bits DRSel1 and DRSel0 are set to “0”.
PROCEED
FIGURE 5. ACKNOWLEDGE POLLING SEQUENCE
11
FN8167.1
September 14, 2005
X9252
TABLE 2. REGISTER NUMBERING
STATUS REG (Note 1) (Addr: 07H)
REGISTERED SELECTED (Note 2)
RESERVED
BITS 7-3
DRSel1
bit 2
DRSel0
bit 1
NVEnable
bit 0
DCP0
DCP1
DCP2
DCP3
(Addr: 00h)
(Addr: 01h)
(Addr: 02h)
(Addr: 03h)
Reserved
X
X
0
WCR0
WCR1
WCR2
WCR3
0
0
1
DR00
DR10
DR20
DR30
0
1
1
DR01
DR11
DR21
DR31
1
0
1
DR02
DR12
DR22
DR32
1
1
1
DR03
DR13
DR23
DR33
To read or write the contents of a single Data Register or Wiper Register:
1. Load the status register (using a write command) to select the row (See Figure 6)
Writing a 1, 3, 5, or 7 to the Status Register specifies that the subsequent read or write command will access a Data Register. This Status
Register operation also initiates a transfer of the contents of the selected data register to its associated WCR for all DCPs. So, for example,
writing ‘03h’ to the status register causes the value in DR01 to move to WCR0, DR11 to move to WCR1, DR21 to move to WCR2, and DR31
to move to WCR3.
Writing a 0 to bit ‘0’ of the Status Register specifies that the subsequent read or write command will access a Wiper Counter Register. Each
WCR can be written to individually, without affecting the contents of any other.
2.
Access the desired DR or WCR using a new write or read command (see Figure 7 for write and Figure 9 for read.)
Specify the desired column (DCP number) by sending the DCP address as part of this read or write command.
If bit 0 of data byte = 1,
DR contents move to WCR
during this ACK period
Signals from
the Master
S
t
a
r
t
Slave
Address
Signal at SDA
0 1 0 1
Signals from
the Slave
0
A
C
K
Status Register
Address
DR select
Data
0 0 0 0 0 1 1 1
0 0 0 0 0 x x 1
A
C
K
S
t
o
p
A
C
K
FIGURE 6. STATUS REGISTER WRITE (USES STANDARD BYTE WRITE SEQUENCE TO SET UP ACCESS TO A DATA REGISTER)
12
FN8167.1
September 14, 2005
X9252
DCP Addressing for 2-Wire Interface
not respond to any requests from the master. The SDA
output is at high impedance.
Once the register number has been selected by a 2-wire
instruction, then the DCP number is determined by the
Address Byte of the following instruction. Note again that this
enables a complete page write of the DRs of all four
potentiometers at once. The register addresses accessible
in the X9252 include:
The SR bits and WP pin determine the register being
accessed through the 2-wire interface (See Table 2).
As noted before, any write operation to a Data Register
(DR), also transfers the contents of all the data registers in
that row to their corresponding WCR.
TABLE 3. 2-WIRE INTERFACE ADDRESS BYTE
For example, to write 3Ahex to the Data Register 1 of DCP2
the following sequence is required:
ADDRESS (HEX)
CONTENTS
0
DCP 0
1
DCP 1
2
DCP 2
3
DCP 3
4
Not Used
5
Not Used
START
Slave Address
ACK
Address Byte
ACK
Data Byte
ACK
6
Not Used
note: at this ACK, the WCRs are all updated with their respective DR.
7
Status Register
0101 0000
(Hardware Address = 000,
and a Write command)
0000 0111
(Indicates Status Register
address)
0000 0011
(Data Register 1 and
NVEnable selected)
STOP
START
Slave Address
ACK
Address Byte
ACK
Data Byte
ACK
STOP
All other address bits in the Address Byte must be set to “0”
during 2-wire write operations and their value should be
ignored when read.
Byte Write Operation
For any Byte Write operation, the X9252 requires the Slave
Address byte, an Address Byte, and a Data Byte (See Figure
7). After each of them, the X9252 responds with an ACK.
The master then terminates the transfer by generating a
STOP condition. At this time, if the write operation is to a
volatile register (WCR, or SR), the X9252 is ready for the
next read or write operation. If the write operation is to a
nonvolatile register (DR), and the WP pin is high, the X9252
begins the internal write cycle to the nonvolatile memory.
During the internal nonvolatile write cycle, the X9252 does
0101 0000
(Hardware address = 000,
Write command)
0000 0010
(Access DCP2)
0011 1010
(Write Data Byte 3Ah)
During the sequence of this example, WP pin must be high,
and A0, A1, and A2 pins must be low. When completed, the
DR21 register and the WCR2 will be set to 3Ah and the other
Data Register in Row 1 will transfer their other contents to
the respective WCR’s.
Write
Signals from the
Master
Signal at SDA
Signals from the
Slave
S
t
a
r
t
0 1 0 1
S
t
o
p
Data
Byte
Address
Byte
Slave
Address
0
A
C
K
A
C
K
A
C
K
FIGURE 7. BYTE WRITE SEQUENCE
13
FN8167.1
September 14, 2005
X9252
Page Write Operation
As stated previously, the memory is organized as a single
Status Register (SR), and four pages of four registers each.
Each page contains one Data Register for each DCP. The
order of the bytes within a page is DR0i, followed by DR1i,
followed by DR2i, and then DR3i, with i being the Data
Register number (0, 1, 2, or 3). Normally a page write
operation will be used to efficiently update all four data
registers and WCR in a single write command, starting at
DCP0 and finishing with DCP3.
In order to perform a Page Write operation to the memory
array, the NVEnable bit in the SR must first be set to “1”.
A Page Write operation is initiated in the same manner as
the byte write operation; but instead of terminating the write
cycle after the first data byte is transferred, the master can
transmit up to 4 bytes (See Figure 8). After the receipt of
each byte, the X9252 responds with an ACK, and the
internal DCP address counter is incremented by one. The
page address remains constant. When the counter reaches
the end of the page (DR3i, 03hex), it “rolls over” and goes
back to the first byte of the same page (DR0i, 00hex).
For example, if the master writes 3 bytes to a page starting
at location DR22, the first 2 bytes are written to locations
DR22 and DR32, while the last byte is written to locations
DR02. Afterwards, the DCP counter would point to location
DR12. If the master supplies more than 4 bytes of data, then
new data overwrites the previous data, one byte at a time.
The master terminates the loading of Data Bytes by issuing
a STOP condition, which initiates the nonvolatile write cycle.
As with the Byte Write operation, all inputs are disabled until
completion of the internal write cycle. If the WP pin is low,
the nonvolatile write cycle doesn’t start and the bytes are
discarded.
Notice that the Data Bytes are also written to the WCR of the
corresponding DCPs, therefore in the above example,
WCR2, WCR3, and WCR0 are also written and WCR1 is
updated with the contents of DR12.
Write
S
t
a
r
t
Signals from the
Master
2<n<4
Address
Byte
Slave
Address
Data Byte (1)
S
t
o
p
Data Byte (n)
Signal at SDA
0 1 0 1
Signals from the
Slave
0
A
C
K
A
C
K
A
C
K
A
C
K
FIGURE 8. PAGE WRITE OPERATION
14
FN8167.1
September 14, 2005
X9252
Move/Read Operation
Data Bytes as long as the master responds with an ACK
during the SCL cycle following the eight bit of each byte. The
master terminates the Move/Read operation (issuing a
STOP condition) following the last bit of the last Data Byte.
The Move/Read operation simultaneously reads the
contents of a Data Register (DR) and moves the contents
into the corresponding DCP’s WCR and the WCRs of all
DCPs are updated with the content of their corresponding
DR. Move/Read operation consists of a one byte, or three
byte instruction followed by one or more Data Bytes (See
Figure 9). To read an arbitrary byte, the master initiates the
operation issuing the following sequence: a START, the
Slave Address byte with the R/W bit set to “0”, an Address
Byte, a second START, and a second Slave Address byte
with the R/W bit set to “1”. After each of the three bytes, the
X9252 responds with an ACK. Then the X9252 transmits
The first byte being read is determined by the current DCP
address and by the Status Register bits, according to Table
2. If more than one byte is read, the DCP address is
incremented by one after each byte, in the same way as
during a Page Write operation. After reaching DCP3, the
DCP address “rolls over” to DCP0.
On power up, the Address pointer is set to the Data Register
0 of DCP0.
One or more Data Bytes
Signals
from the
Master
S
t
a
r
t
Slave
Address with
R/W=0
S
t
a
r
t
Address
Byte
Slave
Address with
R/W=1
A
C
K
S
t
o
p
A
C
K
Signal at SDA
0 1 0 1
0 1 0 1
0
A
C
K
A
C
K
Signals from the
Slave
1
A
C
K
Setting the Current Address
First Read Data
Byte
Last Read Data
Byte
Current Address Read
Random Address Read
FIGURE 9. MOVE/READ SEQUENCE
15
FN8167.1
September 14, 2005
X9252
Applications Information
Basic Configurations of Electronic Potentiometers
+VR
VR
RW
I
Three terminal
Potentiometer;
Variable voltage divider
Two terminal Variable
Resistor;
Variable current
Application Circuits
NONINVERTING AMPLIFIER
VS
VOLTAGE REGULATOR
+
VO
-
VIN
VO (REG)
317
R1
R2
Iadj
R1
R2
VO = (1+R2/R1)VS
VO (REG) = 1.25V (1+R2/R1)+Iadj R2
OFFSET VOLTAGE ADJUSTMENT
R1
COMPARATOR WITH HYSTERISIS
R2
VS
VS
+
VO
+5V
100kΩ
-
10kΩ
10kΩ
}
10kΩ
VO
TL072
}
+
R1
R2
VUL = {R1/(R1+R2)} VO(max)
RLL = {R1/(R1+R2)} VO(min)
+5V
16
FN8167.1
September 14, 2005
X9252
Application Circuits (Continued)
ATTENUATOR
FILTER
C
VS
+
R2
R1
VS
VO
-
R
VO
+
R3
R2
R4
R1 = R2 = R3 = R4 = 10kΩ
R1
GO = 1 + R2/R1
fc = 1/(2πRC)
VO = G VS
-1/2 ≤ G ≤ +1/2
R1
R2
}
}
INVERTING AMPLIFIER
EQUIVALENT L-R CIRCUIT
VS
R2
C1
-
VS
VO
+
+
R1
ZIN
VO = G VS
G = - R2/R1
R3
ZIN = R2 + s R2 (R1 + R3) C1 = R2 + s Leq
(R1 + R3) >> R2
FUNCTION GENERATOR
C
R2
-
R1
-
+
} RA
+
} RB
frequency ∝ R1, R2, C
amplitude ∝ RA, RB
17
FN8167.1
September 14, 2005
X9252
Application Circuits (Continued)
V+
}
pR
}
SHUNT LIMITER
mR nR
}
WINDOW COMPARATOR
VUL
VS
+
VO
VS
VR
V+
+
+
VO
+
-
VLL
FUNCTION GENERATOR
pR
}
}
mR nR
}
C
VO
+
+
18
FN8167.1
September 14, 2005
X9252
Packaging Information
24-Lead Plastic, TSSOP, Package Code V24
.026 (.65) BSC
.169 (4.3)
.252 (6.4) BSC
.177 (4.5)
.303 (7.70)
.311 (7.90)
.047 (1.20)
.0075 (.19)
.0118 (.30)
.002 (.06)
.005 (.15)
.010 (.25)
(4.16) (7.72)
Gage Plane
0°-8°
Seating Plane
.020 (.50)
.030 (.75)
(1.78)
Detail A (20X)
(0.42)
(0.65)
.031 (.80)
.041 (1.05)
ALL MEASUREMENTS ARE TYPICAL
See Detail “A”
NOTE: ALL DIMENSIONS IN INCHES (IN PARENTHESES IN MILLIMETERS)
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.
Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without
notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com
19
FN8167.1
September 14, 2005