X9455YV24IZ-2.7

NOT RECOMMENDED FOR NEW DESIGNS NO RECOMMENDED REPLACEMENT contact our Technical Support Center at 1-888-INTERSIL or www.intersil.com/tsc X9455 DATASHEET FN8202 Rev 1.00 July 28, 2006 Dual Two-wiper Digitally-Controlled (XDCP™) Potentiometer The X9455 integrates 2 digitally controlled potentiometers (XDCP), each one with dual wipers, on a monolithic CMOS integrated circuit. The digitally controlled potentiometer is implemented using 255 resistive elements in a series array. Between each element are tap points connected to wiper terminals through switches. The position of each wiper on the array is controlled by the user through the U/D or 2-wire bus interface. Each potentiometer wiper has associated with it two volatile Wiper Counter Register (WCR) and each WCR has associated with it 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. The contents of the default data registers (DR0A0, DR0B0, DR1A0, DR1B0) are loaded into the WCR on power up. The DCP can be used as a four-terminal potentiometer in a wide variety of applications including the programming of bias voltages, window comparators, and three resistor programmable networks. Features • Dual two-wiper solid state potentiometer • 256 resistor tap points-0.4% resolution • 2-wire serial interface for write, read, and transfer operations of the potentiometer • Up/Down interface for individual potentiometer wipers • Wiper resistance, 40 typical • Non-volatile storage of wiper positions • Power on recall loads saved wiper position on power-up. • Standby current < 20µA Max • Maximum wiper current: 3mA • VCC: 2.7V to 5.5V operation • 2.8k,10k, 50k, 100k 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 X9455 (24 LD TSSOP) TOP VIEW DS0 A0 1 2 24 DS1 23 SCL RL1 RW0B 3 22 NC 4 21 RH1 NC 5 20 RW1A U/D 6 19 CS Vcc 7 18 Vss RL0 8 17 RH0 9 16 X9455 RW1B NC RW0A 10 15 NC A2 11 14 A1 WP 12 13 SDA FN8202 Rev 1.00 July 28, 2006 Page 1 of 19 X9455 Ordering Information PART NUMBER X9455TV24I-2.7 PART MARKING X9455TV G VCC LIMITS (V) RTOTAL (k) TEMP RANGE (°C) 2.7 to 5.5 100 -40 to 85 24 Ld TSSOP (4.4mm) MDP0044 -40 to 85 24 Ld TSSOP (4.4mm) (Pb-free) MDP0044 -40 to 85 24 Ld TSSOP (4.4mm) MDP0044 -40 to 85 24 Ld TSSOP (4.4mm) (Pb-free) MDP0044 -40 to 85 24 Ld TSSOP (4.4mm) MDP0044 -40 to 85 24 Ld TSSOP (4.4mm) (Pb-free) MDP0044 -40 to 85 24 Ld TSSOP (4.4mm) MDP0044 -40 to 85 24 Ld TSSOP (4.4mm) (Pb-free) MDP0044 X9455TV24IZ-2.7 (Note) X9455TV ZG X9455UV24I-2.7 X9455UV G 50 X9455UV24IZ-2.7 (Note) X9455UV ZG X9455WV24I-2.7 X9455WV G 10 X9455WV24IZ-2.7 (Note) X9455WV ZG X9455YV24I-2.7 X9455YV G 2.8 X9455YV24IZ-2.7 (Note) X9455YV ZG PACKAGE PKG. DWG. # NOTE: 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 RH0 VCC RH1 A2 A1 A0 2-wire Interface WCR0A DR0A0 DR0A1 DR0A2 DR0A3 SDA SCL DS0 Up/Down Interface POWERUP, INTERFACE CONTROL AND STATUS WCR0B DR0B0 DR0B1 DR0B2 DR0B3 DCP0 WCR1A DR1A0 DR1A1 DR1A2 DR1A3 WCR1B DR1B0 DR1B1 DR1B2 DR1B3 DCP1 DS1 CS U/D VSS FN8202 Rev 1.00 July 28, 2006 WP RW0A RW0B RL0 RW1A RW1B RL1 Page 2 of 19 X9455 Pin Descriptions TSSOP PIN SYMBOL BRIEF DESCRIPTION 1 DS0 2 A0 3 RW0B 4 NC No Connect 5 NC No Connect 6 U/D Increment/Decrement for Up/Down interface 7 VCC System Supply Voltage Wiper Selection input for Up/Down interface Device Address for 2-wire interface Second Wiper Terminal of DCP0 8 RL0 Low Terminal of DCP0 9 RH0 High Terminal of DCP0 10 RW0A 11 A2 First Wiper Terminal of the DCP0 Device Address for 2-wire interface 12 WP Hardware Write Protect (Active low) 13 SDA Serial Data Input/Output for 2-wire interface 14 A1 Device Address for 2-wire interface 15 NC No Connect 16 NC No Connect 17 RW1B 18 VSS 19 CS 20 RW1A 21 RH1 High Terminal of DCP1 22 RL1 Low Terminal of DCP1 23 SCL Serial Clock for 2-wire interface 24 DS1 Wiper selection input for Up/Down interface FN8202 Rev 1.00 July 28, 2006 Second Wiper Terminal of DCP1 System Ground Chip select for Up/Down interface First Wiper Terminal of DCP1 Page 3 of 19 X9455 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, 10 seconds) . . . . . . . . . . . . . . . 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 -20 DCP to DCP resistance matching Wiper current 0.75 See test circuit Wiper resistance Wiper current = -3.0 50 VCC Vss Ref: 1kHz Resolution Relative linearity (Note 2) V(RH0)=V(RH1)=VCC V(RL0)=V(RL1)=VSS % 50 mW 2.0 % +3.0 mA 150  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 SYMBOL +20 300 Ratiometric Temperature (Note 5) Coefficient DC Electrical Specifications k -1 Temperature coefficient of resistance (Note 5) IOL UNIT RTOTAL Voltage on any DCP pin Absolute linearity (Note 1) MAX 2.8, 10, 50, 100 25°C, each DCP Noise (Note 5) CH/CL/CW TYP (Note 4) ppm/C +20 10/10/25 0.1 ppm/°C pF 10 µA MAX UNITS Over the recommended operating conditions unless otherwise specified. PARAMETER TEST CONDITIONS MIN 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 Leakage current, bus interface pins Voltage at pin from VSS to VCC 10 µA ISB IL FN8202 Rev 1.00 July 28, 2006 -10 Page 4 of 19 X9455 DC Electrical Specifications SYMBOL Over the recommended operating conditions unless otherwise specified. (Continued) PARAMETER VIH Input HIGH voltage VIL Input LOW voltage VOL SDA pin output LOW voltage TEST CONDITIONS MIN MAX UNITS VCC x 0.7 VCC + 1 V -1 VCC x 0.3 V 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) Input capacitance (DS0, DS1, CS, U/D, SCL, WP, A2, A1 CIN (Note 5) and A0) TEST CONDITIONS MAX UNITS VOUT = 0V 8 pF VIN = 0V 6 pF MAX UNITS 2 ms Power-Up Timing SYMBOL PARAMETER tD (Notes 5, 9) 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 2.3k to VCC and 100 pF 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 SCL Low to SDA Data Output Valid Time 0.9 µs tAA (Note 5) tDH tIN (Note 5) tBUF (Note 5) SDA Data Output Hold Time 0 Pulse Width Suppression Time at SCL and SDA inputs Bus Free Time (Prior to Any Transmission) FN8202 Rev 1.00 July 28, 2006 ns 50 1200 ns ns Page 5 of 19 X9455 2-Wire Interface Timing (s) (Continued) SYMBOL PARAMETER MIN MAX UNITS 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 PARAMETER MIN TYP (Note 4) MAX UNITS tCI 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 tCPHS CS deselect time (STORE) 10 ms tCPHNS (Note 5) CS deselect time (NO STORE) 1 µs tIW (Note 5) SCL to RW change tCYC SCL cycle time tR, tF (Note 5) SCL input rise and fall time FN8202 Rev 1.00 July 28, 2006 100 500 5 µs µs 500 µs Page 6 of 19 X9455 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 PARAMETER tWRL (Note 5) 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. FN8202 Rev 1.00 July 28, 2006 Page 7 of 19 X9455 Hardware Write Protect Input (WP) Test Circuit 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. Test Point RW DCP Pins Force Current RH0, RL0, RH1, RL1 These pins are equivalent to the terminal connections on mechanical potentiometers. Since there are two DCPs, there is one set of RH and RL for each DCP. Equivalent Circuit RW0A, RW0B, RW1A, and RW1B RTOTAL RL RH CW CH CL The wiper pins are equivalent to the wiper terminals of mechanical potentiometers. Since there are two wipers per DCP, there are four RW pins. RW Pin Descriptions Bus Interface Pins Serial Data Input/Output (SDA) The SDA is a bidirectional serial data input/output pin for the 2wire 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. 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 X9455. 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 interface is disabled at this time. When CS is high, the 2-wire interface is enabled. 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. FN8202 Rev 1.00 July 28, 2006 Page 8 of 19 X9455 Principles of Operation The X9455 is an integrated circuit incorporating two resistor arrays with dual wipers on each array, 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 X9455 is comprised of two 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.) Each array has two independent wipers. At both ends of each array and between each resistor segment are two switches, one connected to each of the wiper pins (RWiA and RWiB). Within each individual array only one switch of each wiper may be turned on at a time. These switches are controlled by two Wiper Counter Register (WCR). The 8-bits of the WCR are decoded to select and enable one of 256 switches. 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 WCRs are 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 Level 0 (DR0A0, DR0B0, DR1A0, and DR1B0), are loaded into the corresponding wiper counter register. “i” is either 0 or 1 RHi Four Non-Volatile Data Registers DRiA0, DRiA1, DRiA2, and DRiA3 Volatile 8-bit Wiper Counter Register WCRiA WCRiA[7:0] 255 = FF hex One of 256 Decoder WCRiA[7:0] = 00 hex 254 . . . 1 0 2-wire and Up/Down Interfaces Four Non-Volatile Data Registers DRiB0, DRiB1, DRiB2, and DRiB3 WCRiB[7:0] 255 = FF hex 254 Volatile 8-bit Wiper Counter Register WCRiB . . . WCRiB[7:0] = 00 hex 1 0 RWiA RLi RWiB FIGURE 1. DETAILED BLOCK DIAGRAM OF ONE DCP FN8202 Rev 1.00 July 28, 2006 Page 9 of 19 X9455 Up/Down Interface Operation TABLE 2. 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. CS The value of the counter is stored in nonvolatile data register Level 0 of the corresponding WCR whenever CS transitions HIGH while the SCL and WP inputs are HIGH (See Table 1). During a “Store” operation bits WCRSel1 and WCRSel0 in the status register must be both “0”, which is their power up default value. Other combinations are reserved and must not be used. 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 *While in Standby, the 2-wire interface is enabled The system may select the X9455, move a 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 is 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 temperature 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 WIPER CONTROL REGISTER 0 0 Wiper A of DCP0 1 1 Wiper B of DCP0 1 0 Wiper A of DCP1 0 1 Wiper B of DCP1 FN8202 Rev 1.00 July 28, 2006 Page 10 of 19 X9455 SCL SDA START DATA STABLE DATA CHANGE DATA STABLE STOP FIGURE 2. VALID DATA CHANGES, START, AND STOP CONDITIONS 2-Wire serial interface Serial Stop Condition 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 X9455 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 X9455, 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 X9455, 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). 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). Serial Acknowledge 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). 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. SCL from Master 1 8 9 SDA Output from Transmitter SDA Output from Receiver START ACK FIGURE 3. ACKNOWLEDGE RESPONSE FROM RECEIVER FN8202 Rev 1.00 July 28, 2006 Page 11 of 19 X9455 Slave Address Byte Following a START condition, the master must output a Slave Address Byte (Refer to figure 4.). This byte includes three parts: • The four MSBs (SA7-SA4) are the Device Type Identifier, which must always be set to 0101 in order to select the X9455. • The next three bits (SA3-SA1) are the Device Address bits (AS2-AS0). To access any part of the X9455’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. Byte load completed by issuing STOP. Enter ACK Polling Issue START Issue Slave Address Byte (Read or Write) ACK returned? Issue STOP NO YES SA7 SA6 SA5 SA4 SA3 SA2 SA1 SA0 High Voltage 0 1 0 1 AS2 AS1 R/W AS0 complete. Continue command NO sequence. Device Type Identifier Device Address Read or Write YES Issue STOP Continue normal Read or Write command sequence SLAVE ADDRESS BIT(S) DESCRIPTION SA7-SA4 Device Type Identifier SA3-SA1 Device Address SA0 Read or Write Operation Select FIGURE 4. SLAVE ADDRESS (SA) FORMAT PROCEED FIGURE 5. ACKNOWLEDGE POLLING SEQUENCE 2-Wire Serial Interface Operation Nonvolatile Write Acknowledge Polling X9455 Digital Potentiometer Register Organization After a nonvolatile write command sequence is correctly issued (including the final STOP condition), the X9455 initiates an internal high voltage write cycle. This cycle typically requires 5 ms. During this time, any Read or Write command is ignored by the X9455. Write Acknowledge Polling is used to determine whether a high voltage write cycle is completed. Refer to the Functional Diagram on page 1. There are 2 Digital Potentiometers, referred to as DCP0, and DCP1. Each potentiometer has two volatile Wiper Control Registers (WCRs). Each wiper has four non-volatile registers to store wiper position or general data. See Table 2 for register numbering. During acknowledge polling, the master first issues a START condition followed by a Slave Address Byte. The Slave Address Byte contains the X9455’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.) FN8202 Rev 1.00 July 28, 2006 Page 12 of 19 X9455 TABLE 3. REGISTER NUMBERING STATUS REG (NOTE 1) (Addr: 07H) REGISTERED SELECTED (NOTE 2) DCP0 DCP2 Reserved bits 7-3 DRSel1 bit 2 DRSel0 bit 1 NVEnable bit 0 (Addr: 00h) (Addr: 11h) (Addr: 02h) (Addr: 01h) Reserved X X 0 WCR0A WCR0B WCR1A WCR1B 0 0 1 DR0A0 DR0B0 DR1A0 DR1B0 0 1 1 DR0A1 DR0B1 DR1A1 DR1B1 1 0 1 DR0A2 DR0B2 DR1A2 DR1B2 1 1 1 DR0A3 DR0B3 DR1A3 DR1B3 NOTES: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. The registers are organized in pages of four, with one page consisting of the four volatile WCRs, a second page consisting of the Level 0 Data Registers, and so forth. These pages can be written 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. Wiper Addressing for 2-wire Interface Once the Data Register Level has been selected by a 2-wire instruction, then the wiper is determined by the Address Byte of the following instruction. Note again that this enables a complete page write of all four potentiometers at once a particular Wiper Register has been chosen. The register addresses accessible in the X9455 include: The unique feature of the X9455 device is that writing or reading to a Data Register of a given wiper automatically updates the WCR of that wiper with the new value. In this manner data can be moved from a particular wiper register to that wiper’s WCR just by performing a 2-wire read operation. Simultaneously, that data byte can be utilized by the host. Status Register Organization The Status Register (SR) is used in read and write operations to select the appropriate wiper register. Before any wiper 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 6 5 4 Reserved 3 2 1 0 WCRSel1 WCRSel0 NVEnable Bits WCRSel1 and WCRSel0 determine which Data Register of a wiper is selected for a given operation. NVEnable is used to select the volatile WCR if “0”, and one of the non volatile wiper registers if “1”. Table 3 shows this register organization. FN8202 Rev 1.00 July 28, 2006 Page 13 of 19 X9455 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 0 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 Signals from the Slave 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) TABLE 4. ADDRESSING FOR 2-WIRE INTERFACE ADDRESS BYTE For example, to write 3Ahex to the Level 1 Data Register of wiper 1A (DR1A1) the following sequence is required: START Slave Address ACK Address Byte ACK Data Byte ACK ADDRESS (HEX) CONTENTS 0 Wiper 0A 1 Wiper 1B 2 Wiper 1A 3 Wiper 0B 4 Not Used (note: at this ACK, the WCRs are all updated with their 5 Not Used STOP 6 Not Used 7 Status Register 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 X9455 requires the Slave Address byte, an Address Byte, and a Data Byte (See Figure 7). After each of them, the X9455 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 X9455 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 X9455 begins the internal write cycle to the nonvolatile memory. During the internal nonvolatile write cycle, the X9455 does not respond to any requests from the master. The SDA output is at high impedance. 0101 0000 (Hardware Address = 000, and a Write command) 0000 0111 (Indicates Status Register address) 0000 0011 (Data Register Level 1 and NVEnable selected) respective DR.) START Slave Address ACK Address Byte ACK Data Byte ACK STOP 0101 0000 (Hardware address = 000, Write command) (Access Wiper 1A) 0000 0010 (Write Data Byte 3Ah) 0011 1010 During the sequence of this example, WP pin must be high, and A0, A1, and A2 pins must be low. When completed, the DR1A1 register and the WCR1A of Wiper 1A will be set to 3Ah, and the other data registers in Row 1 will transfer their contents to the respective WCRs. The SR bits and WP pin determine the register being accessed through the 2-wire interface. See Table 2 on page 9. 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. FN8202 Rev 1.00 July 28, 2006 Page 14 of 19 X9455 Write S t a r t Signals from the Master Signal at SDA 01 01 S t o p Data Byte Address Byte Slave Address 0 Signals from the Slave A C K A C K A C K FIGURE 7. BYTE WRITE SEQUENCE 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 wiper. Normally a page write operation will be used to efficiently update all four Data Registers and WCR in a single Write command. Note the special sequence for writing to a page: First wiper 0A, then 1B, then 1A, then 0B as shown in Figure 9. WCR WCR0A  WCR1B  WCR1A  WCR0B DR Level 0 DR0A0  DR1B0  DR1A0  DR0B0 DR Level 1 DR0A1  DR1B1  DR1A1  DR0B1 DR Level 2 DR0A2  DR1B2  DR1A2  DR0B2 DR Level 3 DR0A3  DR1B3  DR1A3  DR0B3 FIGURE 8. PAGE WRITE SEQUENCE* *Page writes may wrap around to the first address on a page from the last address. 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 9). After the receipt of each byte, the X9455 responds with an ACK, and the internal WCR address is incremented by one. The page address remains constant. When the address reaches the end of the page, it “rolls over” and goes back to the first byte of the same page. For example, if the master writes three bytes to a page starting at location DR1A2, the first two bytes are written to locations DR1A2 and DR0B2, while the last byte is written to location DR0A2. Afterwards, the WCR address would point to location DR1B2. If the master supplies more than four 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 WCRs, therefore in the above example, WCR1A, WCR0B, and WCR0A are also written, and WCR1B is updated with the contents of DR1B2. Write Signals from the Master S t a r t 2