Dual, 256-Tap, Volatile, Low-Voltage, Linear Taper Digital Potentiometer

Transcription

1 ; Rev 1; 4/1 查询 "" 供应商 EVAUATION KIT AVAIABE General Description The dual, 256-tap, volatile, low-voltage, linear taper digital potentiometer offers three end-to-end resistance values of 1kI, 5kI, and 1kI. Operating from a single +1.7V to +5.5V power supply, the device provides a low 35ppm/NC end-to-end temperature coefficient. The device features an I 2 C interface. The small package size, low supply operating voltage, low supply current, and automotive temperature range of the makes the device uniquely suited for the portable consumer market, battery-backup industrial applications, and the automotive market. The is specified over the automotive -4NC to +125NC temperature range and is available in a 16-pin TSSOP package. Applications ow-voltage Battery Applications Portable Electronics Mechanical Potentiometer Replacement Offset and Gain Control Adjustable Voltage References/inear Regulators Automotive Electronics Features S Dual, 256-Tap inear Taper Positions S Single +1.7V to +5.5V Supply Operation S ow 12µA Quiescent Supply Current S 1kI, 5kI, 1kI End-to-End Resistance Values S I 2 C-Compatible Interface S iper Set to Midscale on Power-Up S -4NC to +125NC Operating Temperature Range Ordering Information PART PIN-PACKAGE END-TO-END RESISTANCE (ki) AUE+ 16 TSSOP 1 MAUE+ 16 TSSOP 5 NAUE+ 16 TSSOP 1 Note: All devices are specified over the -4 C to +125NC operating temperature range. +Denotes a lead(pb)-free/ros-compliant package. Functional Diagram V DD BYP A A A CARGE PUMP SDA A A1 A2 I 2 C ATC POR ATC 256 DECODER 256 DECODER B B B GND Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at , or visit Maxim s website at

2 查询 "" 供应商 ABSOUTE MAXIMUM RATINGS V DD to GND...-.3V to +6V _, _, _ to GND...-.3V to the lower of (V DD +.3V) and +6V All Other Pins to GND...-.3V to +6V Continuous Current in to _, _, and _... Q5mA M... Q2mA N... Q1mA Continuous Power Dissipation (T A = +7NC) 16-Pin TSSOP (derate 11.1m/NC above +7NC) m Operating Temperature Range... -4NC to +125NC Junction Temperature...+15NC Storage Temperature Range NC to +15NC ead Temperature (soldering, 1s)...+3NC Soldering Temperature (reflow)...+26nc Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. EECTRICA CARACTERISTICS (V DD = +1.7V to +5.5V, V _ = V DD, V _ = GND, T A = T MIN to T MAX, unless otherwise noted. Typical values are at V DD = +1.8V, T A = +25NC.) (Note 1) PARAMETER SYMBO CONDITIONS MIN TYP MAX UNITS Resolution N 256 Tap DC PERFORMANCE (Voltage Divider Mode) Integral Nonlinearity IN (Note 2) SB Differential Nonlinearity DN (Note 2) SB Dual Code Matching Register A = Register B SB Ratiometric Resistor Tempco (DV /V )/DT, no load 5 ppm/nc Full-Scale Error Code = FFh M SB N Zero-Scale Error Code = h M.6 1. SB N.3.5 DC PERFORMANCE (Variable Resistor Mode) (Note 3) Integral Nonlinearity R-IN M (Note 3) SB N (Note 3) Differential Nonlinearity R-DN (Note 3) SB DC PERFORMANCE (Resistor Characteristics) iper Resistance R (Note 4) 2 I Terminal Capacitance C _, C _ Measured to GND 1 pf iper Capacitance C _ Measured to GND 5 pf End-to-End Resistor Tempco TC R No load 35 ppm/nc End-to-End Resistor Tolerance DR iper not connected % 2

3 查询 "" 供应商 EECTRICA CARACTERISTICS (continued) (V DD = +1.7V to +5.5V, V _ = V DD, V _ = GND, T A = T MIN to T MAX, unless otherwise noted. Typical values are at V DD = +1.8V, T A = +25NC.) (Note 1) PARAMETER SYMBO CONDITIONS MIN TYP MAX UNITS AC PERFORMANCE Crosstalk (Note 5) -9 db Code = 8, 6-3dB Bandwidth B 1pF load, M 1 kz V DD = 1.8V N 5 Total armonic Distortion Plus Noise TD+N Measured at, V _ = 1VRMS at 1kz.2 % 4 iper Settling Time t S (Note 6) M 12 ns N 22 Charge-Pump Feedthrough at _ V R f CK = 6kz, C BYP = nf 6 nv P-P POER SUPPIES Supply Voltage Range V DD V Standby Current V DD = 5.5V 27 V DD = 1.7V 12 FA DIGITA INPUTS V DD = 2.6V to 5.5V 7 Minimum Input igh Voltage V I V DD = 1.7V to 2.6V 75 % x V DD V DD = 2.6V to 5.5V 3 Maximum Input ow Voltage V I V DD = 1.7V to 2.6V 25 % x V DD Input eakage Current FA Input Capacitance 5 pf TIMING CARACTERISTICS I 2 C (Notes 7 and 8) Maximum Frequency f 4 kz Setup Time for START Condition t SU:STA.6 Fs old Time for START Condition t D:STA.6 Fs igh Time t IG.6 Fs ow Time t O 1.3 Fs 3

4 查询 "" 供应商 EECTRICA CARACTERISTICS (continued) (V DD = +1.7V to +5.5V, V _ = V DD, V _ = GND, T A = T MIN to T MAX, unless otherwise noted. Typical values are at V DD = +1.8V, T A = +25NC.) (Note 1) PARAMETER SYMBO CONDITIONS MIN TYP MAX UNITS Data Setup Time t SU:DAT 1 ns Data old Time t D:DAT Fs SDA, Rise Time t R.3 Fs SDA, Fall t F.3 Fs Setup Time for STOP Condition t SU:STO.6 Fs Bus Free Time Between STOP and START Condition t BUF Minimum power-up rate =.2V/Fs 1.3 Fs Pulse Suppressed Spike idth t SP 5 ns Capacitive oad for Each Bus C B (Note 9) 4 pf Note 1: All devices are 1% production tested at T A = +25NC. Specifications over temperature limits are guaranteed by design and characterization. Note 2: DN and IN are measured with the potentiometer configured as a voltage-divider (Figure 1) with _ = V DD and _ = GND. The wiper terminal is unloaded and measured with a high-input-impedance voltmeter. Note 3: R-DN and R-IN are measured with the potentiometer configured as a variable resistor (Figure 1). DN and IN are measured with the potentiometer configured as a variable resistor. _ is unconnected and _ = GND. For V DD = +5V, the wiper terminal is driven with a source current of 4FA for the 1kI configuration, 8FA for the 5kI configuration, and 4FA for the 1kI configuration. For V DD = +1.7V, the wiper terminal is driven with a source current of 15FA for the 1kI configuration, 3FA for the 5kI configuration, and 15FA for the 1kI configuration. Note 4: The wiper resistance is the worst value measured by injecting the currents given in Note 3 to _ with _ = GND. R _ = (V _ - V _ )/I _. Note 5: Drive A with a 1kz GND to V DD amplitude tone. A = B = GND. No load. B is at midscale with a 1pF load. Measure B. Note 6: The wiper-settling time is the worst-case to 5% rise time, measured between tap and tap 127. _ = V DD, _ = GND, and the wiper terminal is loaded with 1pF capacitance to ground. Note 7: Digital timing is guaranteed by design and characterization, not production tested. Note 8: The clock period includes rise and fall times (t R = t F ). All digital input signals are specified with t R = t F = 2ns and timed from a voltage level of (V I + V I )/2. Note 9: An appropriate bus pullup resistance must be selected depending on board capacitance. For I 2 C-bus specification information from NXP Semiconductor (formerly Philips Semiconductor), refer to the UM124: I 2 C-Bus Specification and User Manual. N.C. Figure 1. Voltage-Divider and Variable Resistor Configurations 4

5 查询 "" 供应商 (V DD = 1.8V, T A = +25 C, unless otherwise noted.) SUPPY CURRENT (µa) SUPPY CURRENT vs. TEMPERATURE V DD = 2.6V V DD = 1.8V toc1 SUPPY CURRENT (µa) 1, SUPPY CURRENT vs. DIGITA INPUT VOTAGE V DD = 1.8V V DD = 2.6V Typical Operating Characteristics toc2 IDD (µa) SUPPY CURRENT vs. SUPPY VOTAGE toc TEMPERATURE ( C) DIGITA INPUT VOTAGE (V) V DD (V) _-TO-_ RESISTANCE (ki) RESISTANCE (_-TO-_) vs. (1kI) toc4 _-TO-_ RESISTANCE (ki) RESISTANCE (_-TO-_) vs. (5kI) toc5 _-TO-_ RESISTANCE (ki) RESISTANCE (_-TO-_) vs. (1kI) toc IPER RESISTANCE (I) IPER RESISTANCE vs. IPER VOTAGE (1kI) V DD = 1.8V IPER VOTAGE (V) V DD = 2.6V toc7 5. END-TO-END RESISTANCE % CANGE END-TO-END RESISTANCE PERCENTAGE CANGE vs. TEMPERATURE 5kI 1kI 1kI TEMPERATURE ( C) toc8 DN (SB) VARIABE RESISTOR DN vs. (1kI) I IPER = 15µA toc9 5

6 查询 "" 供应商 Typical Operating Characteristics (continued) (V DD = 1.8V, T A = +25 C, unless otherwise noted.) DN (SB) VARIABE RESISTOR DN vs. (5kI) -.8 I IPER = 3µA toc1 DN (SB) VARIABE RESISTOR DN vs. (1kI) -.8 I IPER = 15µA toc11 IN (SB) VARIABE RESISTOR IN vs. (1kI) -.8 I IPER = 15µA toc VARIABE RESISTOR IN vs. (5kI) toc VARIABE RESISTOR IN vs. (1kI) toc VOTAGE-DIVIDER DN vs. (1kI) toc IN (SB) IN (SB) DN (SB) I IPER = 3µA -.4 I IPER = 15µA VOTAGE-DIVIDER DN vs. (5kI) toc VOTAGE-DIVIDER DN vs. (1kI) toc VOTAGE-DIVIDER IN vs. (1kI) toc DN (SB) DN (SB) IN (SB)

7 查询 "" 供应商 Typical Operating Characteristics (continued) (V DD = 1.8V, T A = +25 C, unless otherwise noted.) IN (SB) VOTAGE-DIVIDER IN vs. (5kI) toc19 IN (SB) VOTAGE-DIVIDER IN vs. (1kI) toc2 TAP-TO-TAP SITCING TRANSIENT (CODE 127 TO 128) 1kI toc21 V _-_ 2mV/div TAP-TO-TAP SITCING TRANSIENT (CODE 127 TO 128) 5kI toc22 V _-_ 2mV/div 5V/div 5V/div 4ns/div 1µs/div TAP-TO-TAP SITCING TRANSIENT (CODE 127 TO 128) 1kI toc23 V _-_ 2mV/div PER-ON TRANSIENT (5kI) toc24 V _-_ 1V/div 5V/div V CC 5V/div 1µs/div 2µs/div 7

8 查询 "" 供应商 Typical Operating Characteristics (continued) (V DD = 1.8V, T A = +25 C, unless otherwise noted.) 1 MIDSCAE FREQUENCY RESPONSE (1kI) toc25 1 MIDSCAE FREQUENCY RESPONSE (5kI) toc26 1 MIDSCAE FREQUENCY RESPONSE (1kI) toc27 GAIN (db) -1-2 V DD = 1.8V GAIN (db) -1-2 V DD = 1.8V GAIN (db) -1-2 V DD = 1.8V V IN = 1V P-P C = 1pF , FREQUENCY (kz) V IN = 1V P-P C = 1pF , FREQUENCY (kz) V IN = 1V P-P C = 1pF , FREQUENCY (kz) CROSSTAK (db) CROSSTAK vs. FREQUENCY kI -6 5kI kI FREQUENCY (kz) toc28 TD+N (%) TOTA ARMONIC DISTORTION PUS NOISE vs. FREQUENCY kI kI kI FREQUENCY (kz) toc29 RAMP TIME (ms) BYP RAMP TIME vs. C BYP BYP CAPACITANCE (µf) toc3 VOTAGE (nvrms) CARGE-PUMP FEEDTROUG AT _ vs. C BYP toc31 AMPITUDE (µvrms) CARGE-PUMP FEEDTROUG AT _ vs. FREQUENCY toc CAPACITANCE (pf) FREQUENCY (kz) 8

9 查询 "" 供应商 TOP VIE A A A V DD N.C. Pin Configuration B B SDA A B 6 11 A1 BYP 7 1 A2 I.C. 8 9 GND TSSOP Pin Description PIN NAME FUNCTION 1 A Resistor A igh Terminal. The voltage at A can be higher or lower than the voltage at A. Current can flow into or out of A. 2 A Resistor A iper Terminal 3 A Resistor A ow Terminal. The voltage at A can be higher or lower than the voltage at A. Current can flow into or out of A. 4 B Resistor B igh Terminal. The voltage at B can be higher or lower than the voltage at B. Current can flow into or out of B. 5 B Resistor B iper Terminal 6 B Resistor B ow Terminal. The voltage at B can be higher or lower than the voltage at B. Current can flow into or out of B. 7 BYP Internal Power-Supply Bypass. For additional charge-pump filtering, bypass to GND with a capacitor close to the device. 8 I.C. Internally Connected. Connect to GND. 9 GND Ground 1 A2 Address Input 2. Connect to V DD or GND. 11 A1 Address Input 1. Connect to V DD or GND. 12 A Address Input. Connect to V DD or GND. 13 SDA I 2 C-Compatible Serial-Data Input/Output. A pullup resistor is required. 14 I 2 C-Compatible Serial-Clock Input. A pullup resistor is required. 15 N.C. No Connection. Not internally connected. 16 V DD Power-Supply Input. Bypass VDD to GND with a.1ff capacitor close to the device. 9

10 查询 "" 供应商 Detailed Description The dual, 256-tap, volatile, low-voltage linear taper digital potentiometer offers three end-to-end resistance values of 1kI, 5kI, and 1kI. The potentiometer consists of 255 fixed resistors in series between terminals _ and _. The potentiometer wiper, _, is programmable to access any one of the 256 tap points on the resistor string. The potentiometers are programmable independently of each other. The features an I 2 C interface. Charge Pump TThe contains an internal charge pump that guarantees the maximum wiper resistance, R, to be less than 2Ω for supply voltages down to 1.7V. Pins _, _, and _ are still required to be less than VDD +.3V. A bypass input, BYP, is provided to allow additional filtering of the charge-pump output, further reducing clock feedthrough that can occur on _, _, or _. The nominal clock rate of the charge pump is 6kz. BYP should remain resistively unloaded as any additional load would increase clock feedthrough. See the Charge-Pump Feedthrough at _ vs. CBYP graph in the Typical Operating Characteristics for CBYP sizing guidelines with respect to clock feedthrough to the wiper. The value of CBYP does affect the startup time of the charge pump; however, CBYP does not impact the ability to communicate with the device, nor is there a minimum CBYP requirement. The maximum wiper impedance specification is not guaranteed until the charge pump is fully settled. See the BYP Ramp Time vs. CBYP graph in the Typical Operating Characteristics for C BYP impact on charge-pump settling time. I 2 C Digital Interface The I 2 C interface contains a shift register that decodes the command and address bytes, routing the data to the appropriate control registers. Data written to a control register immediately updates the wiper position. The wipers A and B power up in midposition, D[7:] = 8h. Serial Addressing The operates as a slave device that receives data through an I 2 C/SMBusK-compatible 2-wire serial interface. The interface uses a serial-data access line (SDA) and a serial-clock line () to achieve bidirectional communication between master(s) and slave(s). A master, typically a microcontroller, initiates all data transfers to the port and generates the clock that synchronizes the data transfer. See Figure 2. Connect a pullup resistor, typically 4.7kI, between each of the SDA and lines to a voltage between VDD and 5.5V. t D:STA t SU:STD SDA t SU:DAT t SU:DTA t D:STA t O t IG t D:DAT t BUF t R t F START CONDITION (S) REPEATD START CONDITION (Sr) ACKNOEDGE (A) STOP CONDITION (P) START CONDITION (S) Figure 2. I 2 C Serial-Interface Timing Diagram SMBus is a trademark of Intel Corp. 1

11 查询 "" 供应商 Each transmission consists of a START (S) condition sent by a master, followed by a 7-bit slave address plus a NOP/ bit. See Figures 3, 4, and 7. START and STOP Conditions and SDA remain high when the interface is inactive. A master controller signals the beginning of a transmission with a START condition by transitioning SDA from high to low while is high. The master controller issues a STOP condition by transitioning the SDA from low to high while is high, after finishing communicating with the slave. The bus is then free for another transmission. See Figure 2. Bit Transfer One data bit is transferred during each clock pulse. The data on the SDA line must remain stable while is high. See Figure 5. Acknowledge The acknowledge bit is a clocked 9th bit that the recipient uses to handshake receipt of each byte of data. See Figure 6. Each byte transferred requires a total of 9 bits. The master controller generates the 9th clock pulse, and the recipient pulls down SDA during the acknowledge clock pulse, so the SDA line remains stable low during the high period of the clock pulse. SDA S P START CONDITION STOP CONDITION Figure 3. START and STOP Conditions SDA 1 1 A2 A1 A NOP/ ACK START MSB SB Figure 4. Slave Address SDA CANGE OF DATA AOED DATA STABE, DATA VAID Figure 5. Bit Transfer 11

12 查询 "" 供应商 START CONDITION SDA NOT ACKNOEDGE COCK PUSE FOR ACKNOEDGMENT 9 ACKNOEDGE Figure 6. Acknowledge ACKNOEDGE O CONTRO BYTE AND DATA BYTE MAP INTO DEVICE REGISTERS ACKNOEDGE D15 D14 D13 D12 D11 D1 D9 D8 D7 D6 D5 D4 D3 D2 D1 D S A A A P SAVE ADDRESS COMMAND BYTE 1 DATA BYTE NOP/ Figure 7. Command and Single Data Byte Received Slave Address The includes a 7-bit slave address (Figure 4). The 8th bit following the 7th bit of the slave address is the NOP/ bit. Set the NOP/ bit low for a write command and high for a no-operation command. The device does not support readback. The device provides three address inputs (A, A1, and A2), allowing up to eight devices to share a common bus (Table 1). The first 4 bits (MSBs) of the factory-set slave addresses are always 11. A2, A1, and A set the next 3 bits of the slave address. Connect each address input to VDD or GND. Each device must have a unique address to share a common bus. Message Format for riting rite to the devices by transmitting the device s slave address with NOP/ (8th bit) set to zero, followed by at least 2 bytes of information. The first byte of information is the command byte. The second byte is the data byte. The data byte goes into the internal register of the device as selected by the command byte (Figure 7 and Table 2). Table 1. Slave Addresses ADDRESS INPUTS A2 A1 A SAVE ADDRESS GND GND GND 11 GND GND V DD 111 GND V DD GND 111 GND V DD V DD 1111 V DD GND GND 111 V DD GND V DD 1111 V DD V DD GND 1111 V DD V DD V DD

13 查询 "" 供应商 Table 2. I 2 C Command Byte Summary CYCE NUMBER START (S) ADDRESS BYTE COMMAND BYTE DATA BYTE A6 A5 A4 A3 A2 A1 A ACK R7 R6 R5 R4 R3 R2 R1 R ACK D7 D6 D5 D4 D3 D2 D1 D ACK (A) (A) (A) REG A 1 1 A2 A1 A 1 1 D7 D6 D5 D4 D3 D2 D1 D REG B 1 1 A2 A1 A 1 1 D7 D6 D5 D4 D3 D2 D1 D REG A AND B 1 1 A2 A1 A D7 D6 D5 D4 D3 D2 D1 D STOP (P) Command Byte Use the command byte to select the destination of the wiper data. See Table 2. Command Descriptions REG A: The data byte writes to register A and the wiper of potentiometer A moves to the appropriate position. D[7:] indicates the position of the wiper. D[7:] = h moves the wiper to the position closest to A. D[7:] = FFh moves the wiper closest to A. D[7:] is 8h following power-on. REG B: The data byte writes to register B and the wiper of potentiometer B moves to the appropriate position. D[7:] indicates the position of the wiper. D[7:] = h moves the wiper to the position closest to B. D[7:] = FFh moves the wiper to the position closest to B. D[7:] is 8h following power-on. REG A and B: The data byte writes to registers A and B and the wipers of potentiometers A and B move to the appropriate position. D[7:] indicates the position of the wiper. D[7:] = h moves the wipers to the position closest to _. D[7:] = FFh moves the wipers to the position closest to _. D[7:] is 8h following power-on. Applications Information Variable Gain Amplifier Figure 8 shows a potentiometer adjusting the gain of a noninverting amplifier. Figure 9 shows a potentiometer adjusting the gain of an inverting amplifier. Adjustable Dual Regulator Figure 1 shows an adjustable dual linear regulator using a dual potentiometer as two variable resistors. V IN Figure 9. Variable Gain Inverting Amplifier OUT1 OUT2 V OUT V OUT1 V OUT2 V IN V OUT V+ IN MAX8866 SET1 SET2 Figure 8. Variable Gain Noninverting Amplifier Figure 1. Adjustable Dual inear Regulator 13

14 查询 "" 供应商 Adjustable Voltage Reference Figure 11 shows an adjustable voltage reference circuit using a potentiometer as a voltage-divider. Variable Gain Current to Voltage Converter Figure 12 shows a variable gain current to voltage converter using a potentiometer as a variable resistor. CD Bias Control Figure 13 shows a positive CD bias control circuit using a potentiometer as a voltage-divider. Figure 14 shows a positive CD bias control circuit using a potentiometer as a variable resistor. Programmable Filter Figure 15 shows a programmable filter using a dual potentiometer. Offset Voltage Adjustment Circuit Figure 16 shows an offset voltage adjustment circuit using a dual potentiometer. PROCESS: BiCMOS Chip Information +2.5V IN OUT MAX637 V REF 1.8V VOUT GND Figure 11. Adjustable Voltage Reference Figure 13. Positive CD Bias Control Using a Voltage Divider R3 1.8V IS R1 R2 VOUT VOUT VOUT = IS x ((R3 x (1 + R2/R1)) + R2) Figure 12. Variable Gain I-to-V Converter Figure 14. Positive CD Bias Control Using a Variable Resistor 14

15 查询 "" 供应商 VIN B R3 B B R1 VOUT 1.8V A A VOUT A A A R2 B A B B Figure 15. Programmable Filter Figure 16. Offset Voltage Adjustment Circuit Package Information For the latest package outline information and land patterns, go to Note that a +, #, or - in the package code indicates RoS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoS status. PACKAGE TYPE PACKAGE CODE Document No. 16 TSSOP U

16 查询 "" 供应商 REVISION NUMBER REVISION DATE DESCRIPTION Revision istory PAGES CANGED 1/1 Initial release 1 4/1 Added Soldering Temperature in Absolute Maximum Ratings; corrected code in Conditions of -3dB Bandwidth specification in Electrical Characteristics 2, 3 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 16 Maxim Integrated Products, 12 San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.