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19-3478; Rev 1; 1/05
Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers
General Description
The MAX5487/MAX5488/MAX5489 dual, linear-taper, digital potentiometers function as mechanical potentiometers with a simple 3-wire SPITM-compatible digital interface that programs the wipers to any one of 256 tap positions. These digital potentiometers feature a nonvolatile memory (EEPROM) to return the wipers to their previously stored positions upon power-up. The MAX5487 has an end-to-end resistance of 10k, while the MAX5488 and MAX5489 have resistances of 50k and 100k, respectively. These devices have a low 35ppm/C end-to-end temperature coefficient, and operate from a single +2.7V to +5.25V supply. The MAX5487/MAX5488/MAX5489 are available in a 16-pin 3mm x 3mm x 0.8mm thin QFN package. Each device is guaranteed over the extended -40C to +85C temperature range.
Features
o Wiper Position Stored in Nonvolatile Memory (EEPROM) and Recalled Upon Power-Up or Recalled by an Interface Command o 3mm x 3mm x 0.8mm Thin QFN Package o 1 LSB INL, 0.5 LSB DNL (Voltage-Divider Mode) o 256 Tap Positions o 35ppm/C End-to-End Resistance Temperature Coefficient o 5ppm/C Ratiometric Temperature Coefficient o 10k, 50k, and 100k End-to-End Resistance Values o SPI-Compatible Serial Interface o Reliability 200,000 Wiper Store Cycles 50-Year Wiper Data Retention o +2.7V to +5.25V Single-Supply Operation
SPI is a trademark of Motorola, Inc.
MAX5487/MAX5488/MAX5489
Applications
LCD Screen Adjustment Audio Volume Control Mechanical Potentiometer Replacement Low-Drift Programmable Filters Low-Drift Programmable-Gain Amplifiers
Ordering Information/Selector Guide
PART MAX5487ETE* MAX5488ETE MAX5489ETE TEMP RANGE -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 16 Thin QFN-EP** 16 Thin QFN-EP** 16 Thin QFN-EP** END-TO-END RESISTANCE (k) 10 50 100 TOP MARK ABR ABS ABT
*Future product--contact factory for availability. **EP = Exposed pad.
Functional Diagram
N.C.
Pin Configuration
TOP VIEW
WA 14 HA 16 VDD SCLK DIN 1 2 3 4 5 N.C. 6 N.C. 7 GND 8 N.C. 15 13 12 HB 11 WB 10 LB 9 N.C. LA
VDD GND SCLK DIN CS 8-BIT LATCH 8 DECODER 256 SPI INTERFACE 16-BIT NV RAM 8-BIT LATCH 8 DECODER 256
HA WA
LA POR HB
MAX5487 MAX5488 MAX5489
CS
WB
MAX5487 MAX5488 MAX5489
LB
THIN QFN 3mm x 3mm EXPOSED PAD CONNECTED TO GND.
________________________________________________________________ Maxim Integrated Products
1
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Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers MAX5487/MAX5488/MAX5489
ABSOLUTE MAXIMUM RATINGS
VDD to GND ...........................................................-0.3V to +6.0V All Other Pins to GND......................-0.3V to the lower of (VDD + 0.3V) and +6.0V Maximum Continuous Current into H_, W_, and L_ MAX5487......................................................................5.0mA MAX5488......................................................................1.3mA MAX5489......................................................................0.6mA Continuous Power Dissipation (TA = +70C) 16-Pin Thin QFN (derate 17.5mW/C above +70C).....1398mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-60C to +150C Lead Temperature (soldering, 10s) .................................+300C
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.
DC ELECTRICAL CHARACTERISTICS
(VDD = +2.7V to +5.25V, VH = VDD, VL = GND, TA = -40C to +85C, unless otherwise noted. Typical values are at VDD = +5.0V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER Resolution Integral Nonlinearity Differential Nonlinearity Dual-Code Matching End-To-End Resistor Tempco Ratiometric Resistor Tempco Full-Scale Error Zero-Scale Error MAX5488 MAX5489 MAX5488 MAX5489 256 MAX5488/MAX5489 MAX5488/MAX5489 VDD = 5.0V VDD = 3.0V VDD = 5.0V VDD = 3.0V 200 325 50 MAX5487 End-to-End Resistance RHL MAX5488 MAX5489 7.5 37.5 75 10 50 100 12.5 62.5 125 k 1.5 3 1 1 350 675 LSB TCR SYMBOL N INL DNL (Note 2) (Note 2) Register A = register B 35 5 -0.6 -0.3 0.6 0.3 +1.2 +1.2 1.5 1 CONDITIONS MIN 256 1 0.5 2 TYP MAX UNITS Taps LSB LSB LSB ppm/C ppm/C LSB LSB
DC PERFORMANCE (Voltage-Divider Mode, Figure 1)
DC PERFORMANCE (Variable-Resistor Mode, Figure 1) Resolution Integral Nonlinearity (Note 3) Differential Nonlinearity (Note 3) DC PERFORMANCE (Resistor Characteristics) Wiper Resistance (Note 4) Wiper Capacitance RW CW VDD = 5.0V VDD = 3.0V pF Taps
2
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Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers
DC ELECTRICAL CHARACTERISTICS (continued)
(VDD = +2.7V to +5.25V, VH = VDD, VL = GND, TA = -40C to +85C, unless otherwise noted. Typical values are at VDD = +5.0V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER DIGITAL INPUTS VDD = 3.6V to 5.25V Input High Voltage (Note 5) Input Low Voltage Input Leakage Current Input Capacitance AC PERFORMANCE Crosstalk -3dB Bandwidth Total Harmonic Distortion TIMING CHARACTERISTICS (Analog) Wiper-Settling Time tS Code 0 to 127 (Note 7) MAX5488 MAX5489 0.75 1.5 5 tCP tCH tCL tCSS tCSH tDS tDH tCS0 tCS1 tCSW tBUSY tACC tWO Mil-Std-883 test method 1008 Mil-Std-883 test method 1033 TA = +85C TA = +125C TA = +85C TA = +125C 50 10 200,000 50,000 200 80 80 80 0 50 0 20 80 200 12 1 1 s BW THD fH_ = 1kHz, L_ = GND, measurement at W_ (Note 6) Wiper at midscale CW_ = 10pF MAX5488 MAX5489 -90 90 45 0.02 dB kHz % VIH VIL IIN CIN 5.0 VDD = 2.7V to 3.6V VDD = 2.7V to 5.25V (Note 5) 2.4 0.7 x VDD 0.8 1.0 V V A pF SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX5487/MAX5488/MAX5489
VH_ = 1VRMS at 1kHz, L_ = GND, measurement at W_
TIMING CHARACTERISTICS (Digital, Figure 2, Note 8) SCLK Frequency SCLK Clock Period SCLK Pulse-Width High SCLK Pulse-Width Low CS Fall to SCLK Rise Setup SCLK Rise to CS Rise Hold DIN to SCLK Setup DIN Hold after SCLK SCLK Rise to CS Fall Delay CS Rise to SCLK Rise Hold CS Pulse-Width High Write NV Register Busy Time Read NV Register Access Time Write Wiper Register to Output Delay NONVOLATILE MEMORY RELIABILITY Data Retention Endurance Years Stores MHz ns ns ns ns ns ns ns ns ns ns ms s s
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Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers MAX5487/MAX5488/MAX5489
DC ELECTRICAL CHARACTERISTICS (continued)
(VDD = +2.7V to +5.25V, VH = VDD, VL = GND, TA = -40C to +85C, unless otherwise noted. Typical values are at VDD = +5.0V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER POWER SUPPLIES Power-Supply Voltage Supply Current Standby Current VDD IDD During write cycle only, digital inputs = VDD or GND Digital inputs = VDD or GND, TA = +25C 0.5 2.70 5.25 400 1 V A A SYMBOL CONDITIONS MIN TYP MAX UNITS
Note 1: All devices are production tested at TA = +25C and are guaranteed by design and characterization for -40C < TA < +85C. Note 2: DNL and INL are measured with the potentiometer configured as a voltage-divider with H_ = VDD and L_ = 0. The wiper terminal is unloaded and measured with an ideal voltmeter. Note 3: DNL and INL are measured with the potentiometer configured as a variable resistor. H_ is unconnected and L_ = 0. For VDD = +5V, the wiper terminal is driven with a source current of 400A for the 10k configuration, 80A for the 50k configuration, and 40A for the 100k configuration. For VDD = +3V, the wiper terminal is driven with a source current of 200A for the 10k configuration, 40A for the 50k configuration, and 20A for the 100k configuration. Note 4: The wiper resistance is the worst value measured by injecting the currents given in Note 3 into W_ with L_ = GND. RW = (VW - VH) / IW. Note 5: The device draws higher supply current when the digital inputs are driven with voltages between (VDD - 0.5V) and (GND + 0.5V). See Supply Current vs. Digital Input Voltage in the Typical Operating Characteristics section. Note 6: Wiper at midscale with a 10pF load. Note 7: Wiper-settling time is the worst-case 0-to-50% rise time, measured between tap 0 and tap 127. H_ = VDD, L_ = GND, and the wiper terminal is unloaded and measured with a 10pF oscilloscope probe (see Tap-to-Tap Switching Transient in the Typical Operating Characteristics section). Note 8: Digital timing is guaranteed by design and characterization, and is not production tested.
VOLTAGE-DIVIDER CONFIGURATION H
VARIABLE-RESISTOR CONFIGURATION H
W
L
L
Figure 1. Voltage-Divider/Variable-Resistor Configurations
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Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers
Typical Operating Characteristics
(VDD = +5.0V, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. DIGITAL INPUT VOLTAGE
MAX5487-89 toc01 MAX5487-89 toc02
MAX5487/MAX5488/MAX5489
SUPPLY CURRENT vs. TEMPERATURE
1.2 1.0 SUPPLY CURRENT (A) 0.8 0.6 0.4 0.2 VCC = 3V 0 -40 -15 10 35 60 85 TEMPERATURE (C) 0 0 VCC = 5V 10,000
WIPER RESISTANCE vs. TAP POSITION (MAX5488)
MAX5487-89toc03
400
SUPPLY CURRENT (A)
VCC = 5V 100
WIPER RESISTANCE ()
1000
300
200
10 VCC = 3V 1
100
0 1 2 3 4 5 0 32 64 96 128 160 192 224 256 DIGITAL INPUT VOLTAGE (V) TAP POSITION
TAP-TO-TAP SWITCHING TRANSIENT (MAX5488)
MAX5487-89 toc04
TAP-TO-TAP SWITCHING TRANSIENT (MAX5489)
MAX5487-89 toc05
WIPER TRANSIENT AT POWER-ON
MAX5487-89 toc06
VH_ = 5.0V
VH_ = 5.0V
VH_ = VDD
CS 2.0V/div
CS 2.0V/div
VDD 2.0V/div
WIPER 20mV/div
WIPER 20mV/div
WIPER 2.0V/div
1.0s/div
1.0s/div
2.0s/div
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Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers MAX5487/MAX5488/MAX5489
Typical Operating Characteristics (continued)
(VDD = +5.0V, TA = +25C, unless otherwise noted.)
MIDSCALE FREQUENCY RESPONSE (MAX5488)
MAX5487-89 toc07
MIDSCALE FREQUENCY RESPONSE (MAX5489)
MAX5487-89 toc08
VARIABLE-RESISTOR DNL vs. TAP POSITION (MAX5488)
0.15 0.10 DNL (LSB) 0.05 0 -0.05 -0.10 -0.15 -0.20
MAX5487-89 toc09
0 -5 -10 -15 GAIN (dB) -20 -25 -30 -35 -40 -45 -50 0.1 1 10 FREQUENCY (kHz) 100 CW_ = 50pF CW_ = 10pF
0 -5 -10 -15 GAIN (dB) -20 -25 -30 -35 -40 -45 -50 CW_ = 50pF CW_ = 10pF
0.20
1000
0.1
1
10 FREQUENCY (kHz)
100
1000
0
32
64
96
128 160 192 224 256
TAP POSITION
VARIABLE-RESISTOR INL vs. TAP POSITION (MAX5488)
MAX5487-89 toc10
VOLTAGE-DIVIDER DNL vs. TAP POSITION (MAX5488)
MAX5487-89 toc11
VOLTAGE-DIVIDER INL vs. TAP POSITION (MAX5488)
0.8 0.6 0.4 INL (LSB) 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0
MAX5487-89 toc12
1.0 0.8 0.6 0.4
0.20 0.15 0.10 DNL (LSB) 0.05 0 -0.05 -0.10 -0.15 -0.20
1.0
INL (LSB)
0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 0 32 64 96 128 160 192 224 256 TAP POSITION
0
32
64
96
128 160 192 224 256
0
32
64
96
128 160 192 224 256
TAP POSITION
TAP POSITION
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Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers
Typical Operating Characteristics (continued)
(VDD = +5.0V, TA = +25C, unless otherwise noted.)
VARIABLE-RESISTOR DNL vs. TAP POSITION (MAX5489)
MAX5487-89 toc13
MAX5487/MAX5488/MAX5489
VARIABLE-RESISTOR INL vs. TAP POSITION (MAX5489)
MAX5487-89 toc14
VOLTAGE-DIVIDER DNL vs. TAP POSITION (MAX5489)
0.15 0.10 DNL (LSB) 0.05 0 -0.05 -0.10 -0.15 -0.20
MAX5487-89 toc15
0.20 0.15 0.10 DNL (LSB) 0.05 0 -0.05 -0.10 -0.15 -0.20 0 32 64 96
1.0 0.8 0.6 0.4 INL (LSB) 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0
0.20
128 160 192 224 256
0
32
64
96
128 160 192 224 256
0
32
64
96
128 160 192 224 256
TAP POSITION
TAP POSITION
TAP POSITION
VOLTAGE-DIVIDER INL vs. TAP POSITION (MAX5489)
MAX5487-89 toc16
CROSSTALK vs. FREQUENCY
CW_ = 10pF -40 CROSSTALK (dB) -50 MAX5489 -60 -70 -80 -90 -100 MAX5488
MAX5487-89toc17
1.0 0.8 0.6 0.4 INL (LSB) 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 0 32 64 96
-30
128 160 192 224 256
0.1
1
10 FREQUENCY (kHz)
100
1000
TAP POSITION
END-TO-END RESISTANCE CHANGE vs. TEMPERATURE (MAX5488)
MAX5487-89 toc18
END-TO-END RESISTANCE CHANGE vs. TEMPERATURE (MAX5489)
0.008 RESISTANCE CHANGE (%) 0.006 0.004 0.002 0 -0.002 -0.004 -0.006 -0.008 -0.010
MAX5487-89 toc19
0.010 0.008 RESISTANCE CHANGE (%) 0.006 0.004 0.002 0 -0.002 -0.004 -0.006 -0.008 -0.010 -40 -15 10 35 60
0.010
85
-40
-15
10
35
60
85
TEMPERATURE (C)
TEMPERATURE (C)
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Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers MAX5487/MAX5488/MAX5489
Pin Description
PIN 1 2 3 4 5, 6, 8, 9, 16 7 10 11 12 13 14 15 -- NAME VDD SCLK DIN CS N.C. GND LB WB HB LA WA HA E.P. FUNCTION Power Supply. Bypass to GND with a 0.1F capacitor as close to the device as possible. Serial-Interface Clock Input Serial-Interface Data Input Active-Low Chip-Select Digital Input No Connection. Not internally connected. Ground Low Terminal of Resistor B. The voltage at L can be greater than or less than the voltage at H. Current can flow into or out of L. Wiper Terminal of Resistor B High Terminal of Resistor B. The voltage at H can be greater than or less than the voltage at L. Current can flow into or out of H. Low Terminal of Resistor A. The voltage at L can be greater than or less than the voltage at H. Current can flow into or out of L. Wiper Terminal of Resistor A High Terminal of Resistor A. The voltage at H can be greater than or less than the voltage at L. Current can flow into or out of H. Exposed Pad. Not internally connected. Connect to ground or leave floating.
Detailed Description
The MAX5487/MAX5488/MAX5489 contain two resistor arrays, with 255 resistive elements each. The MAX5487 has an end-to-end resistance of 10k, while the MAX5488 and MAX5489 have resistances of 50k and 100k, respectively. The MAX5487/MAX5488/MAX5489 allow access to the high, low, and wiper terminals on both potentiometers for a standard voltage-divider configuration. Connect the wiper to the high terminal, and connect the low terminal to ground, to make the device a variable resistor (see Figure 1). A simple 3-wire serial interface programs either wiper directly to any of the 256 tap points. The nonvolatile memory stores the wiper position prior to power-down and recalls the wiper to the same point upon power-up or by using an interface command (see Table 1). The nonvolatile memory is guaranteed for 200,000 wiper store cycles and 50 years for wiper data retention.
(CS), data clock (SCLK), and data in (DIN). Drive CS low to enable the serial interface and clock data synchronously into the shift register on each SCLK rising edge. The WRITE commands (C1, C0 = 00 or 01) require 16 clock cycles to clock in the command, address, and data (Figure 3a). The COPY commands (C1, C0 = 10, 11) can use either eight clock cycles to transfer only command and address bits (Figure 3b) or 16 clock cycles, with the device disregarding 8 data bits (Figure 3a). After loading data into the shift register, drive CS high to latch the data into the appropriate potentiometer control register and disable the serial interface. Keep CS low during the entire serial data stream to avoid corruption of the data. Digital-Interface Format The data format consists of three elements: command bits, address bits, and data bits (see Table 1 and Figure 3). The command bits (C1 and C0) indicate the action to be taken such as changing or storing the wiper position. The address bits (A1 and A0) specify which potentiometer the command affects and the 8 data bits (D7 to D0) specify the wiper position.
SPI Digital Interface
The MAX5487/MAX5488/MAX5489 use a 3-wire SPIcompatible serial data interface (Figures 2 and 3). This write-only interface contains three inputs: chip-select
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Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers MAX5487/MAX5488/MAX5489
Table 1. Register Map
CLOCK EDGE Write Wiper Register A Write Wiper Register B Write NV Register A Write NV Register B Copy Wiper Register A to NV Register A Copy Wiper Register B to NV Register B Copy Both Wiper Registers to NV Registers Copy NV Register A to Wiper Register A Copy NV Register B to Wiper Register B Copy Both NV Registers to Wiper Registers 1 -- 0 0 0 0 0 0 0 0 0 0 2 -- 0 0 0 0 0 0 0 0 0 0 3 C1 0 0 0 0 1 1 1 1 1 1 4 C0 0 0 1 1 0 0 0 1 1 1 5 -- 0 0 0 0 0 0 0 0 0 0 6 -- 0 0 0 0 0 0 0 0 0 0 7 A1 0 1 0 1 0 1 1 0 1 1 8 A0 1 0 1 0 1 0 1 1 0 1 9 D7 D7 D7 D7 D7 -- -- -- -- -- -- 10 D6 D6 D6 D6 D6 -- -- -- -- -- -- 11 D5 D5 D5 D5 D5 -- -- -- -- -- -- 12 D4 D4 D4 D4 D4 -- -- -- -- -- -- 13 D3 D3 D3 D3 D3 -- -- -- -- -- -- 14 D2 D2 D2 D2 D2 -- -- -- -- -- -- 15 D1 D1 D1 D1 D1 -- -- -- -- -- -- 16 D0 D0 D0 D0 D0 -- -- -- -- -- --
CS tCSW tCSO tCSS SCLK tDS tDH tCL tCH tCP tCSH tCS1
DIN
Figure 2. Timing Diagram
Write-Wiper Register (Command 00) Data written to the write-wiper registers (C1, C0 = 00) controls the wiper positions. The 8 data bits (D7 to D0) indicate the position of the wiper. For example, if DIN = 0000 0000, the wiper moves to the position closest to L_. If DIN = 1111 1111, the wiper moves closest to H_. This command writes data to the volatile RAM, leaving the NV registers unchanged. When the device powers up, the data stored in the NV registers transfers to the volatile wiper register, moving the wiper to the stored position.
Write-NV Register (Command 01) This command (C1, C0 = 01) stores the position of the wipers to the NV registers for use at power-up. Alternatively, the "copy wiper register to NV register" command can be used to store the position of the wipers to the NV registers. Writing to the NV registers, does not affect the position of the wipers. Copy Wiper Register to NV Register (Command 10) This command (C1, C0 = 10) stores the current position of the wiper to the NV register, for use at power-up.
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Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers MAX5487/MAX5488/MAX5489
A) 16-BIT COMMAND/DATA WORD CS
SCLK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
DIN
C1
C0
A1
A0
D7
D6
D5
D4
D3
D2
D1
D0
B) 8-BIT COMMAND WORD CS
SCLK 1 DIN 2 3 C1 4 C0 5 6 7 A1 8 A0
Figure 3. Digital-Interface Format
This command may affect one potentiometer at a time, or both simultaneously, depending on the state of A1 and A0. Alternatively, the "write NV register" command can be used to store the current position of the wiper to the NV register. Copy NV Register to Wiper Register (Command 11) This command (C1, C0 = 11) restores the wiper position to the previously stored position in the NV register. This command may affect one potentiometer at a time, or both simultaneously, depending on the state of A1 and A0.
Standby
The MAX5487/MAX5488/MAX5489 feature a low-power standby mode. When the device is not being programmed, it enters into standby mode and supply current drops to 0.5A (typ).
Applications Information
The MAX5487/MAX5488/MAX5489 are ideal for circuits requiring digitally controlled adjustable resistance, such as LCD contrast control (where voltage biasing adjusts the display contrast), or for programmable filters with adjustable gain and/or cutoff frequency.
Nonvolatile Memory
The internal EEPROM consists of a nonvolatile register that retains the last stored value prior to power-down. The nonvolatile register is programmed to midscale at the factory. The nonvolatile memory is guaranteed for 200,000 wiper write cycles and 50 years for wiper data retention.
Positive LCD Bias Control
Figures 4 and 5 show an application where the MAX5487/MAX5488/MAX5489 provide an adjustable, positive LCD-bias voltage. The op amp provides buffering and gain to the resistor-divider network made by the potentiometer (Figure 4) or by a fixed resistor and a variable resistor (Figure 5).
Power-Up
Upon power-up, the MAX5487/MAX5488/MAX5489 load the data stored in the nonvolatile wiper register into the volatile memory register, updating the wiper position with the data stored in the nonvolatile wiper register. This initialization period takes 5s.
Programmable Filter
Figure 6 shows the MAX5487/MAX5488/MAX5489 in a 1st-order programmable-filter application. Adjust the gain of the filter with R2, and set the cutoff frequency with R3.
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Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers
5V H_ 30V MAX5487 MAX5488 MAX5489 L_ W_ MAX480 VOUT
Use the following equations to calculate the gain (A) and the -3dB cutoff frequency (fC): A =1+ R1 R2
MAX5487/MAX5488/MAX5489
fC =
1 2 x R3 x C
Adjustable Voltage Reference
Figure 7 shows the MAX5487/MAX5488/MAX5489 used as the feedback resistors in multiple adjustable voltage-reference applications. Independently adjust the output voltages of the MAX6160s from 1.23V to VIN 0.2V by changing the wiper positions of the MAX5487/ MAX5488/MAX5489.
Figure 4. Positive LCD-Bias Control Using a Voltage-Divider
5V
Offset Voltage and Gain Adjustment
30V
H_ MAX5487 MAX5488 MAX5489 L_
MAX480
VOUT
W_
Connect the high and low terminals of one potentiometer of a MAX5487/MAX5488/MAX5489 to the NULL inputs of a MAX410, and connect the wiper to the op amp's positive supply to nullify the offset voltage over the operating temperature range. Install the other potentiometer in the feedback path to adjust the gain of the MAX410 (see Figure 8).
Chip Information
TRANSISTOR COUNT: 12,177 PROCESS: BiCMOS
Figure 5. Positive LCD-Bias Control Using a Variable Resistor
WA V+ VIN LA HA R3 C MAX410 VOUT
1/2 MAX5487 1/2 MAX5488 1/2 MAX5489
R2, R3 = RHL x D / 256 WHERE RHL = END-TO-END RESISTANCE AND D = DECIMAL VALUE OF WIPER CODE R2 HB
VR1
WB
1/2 MAX5487 1/2 MAX5488 1/2 MAX5489
LB
Figure 6. Programmable Filter ______________________________________________________________________________________ 11
Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers MAX5487/MAX5488/MAX5489
5V 10k FOR THE MAX5487 R 50k VOUT_ = 1.23V x FOR THE MAX5488 R 100k VOUT_ = 1.23V x FOR THE MAX5489 R VOUT_ = 1.23V x R2 = RHL x D / 256 WHERE RHL = END-TO-END RESISTANCE AND D = DECIMAL VALUE OF WIPER CODE
IN
OUT HA
V OUT1
IN
OUT HB
VOUT2
MAX6160
ADJ GND WA R LA
MAX6160 1/2 MAX5487 1/2 MAX5488 1/2 MAX5489
ADJ GND WB R LB
1/2 MAX5487 1/2 MAX5488 1/2 MAX5489
Figure 7. Adjustable Voltage Reference
5V WA 1/2 MAX5487/MAX5488/MAX5489 HA 7 3 1 8 MAX410 2 4 R1 HB 6 R2 = RHL x D / 256 WHERE RHL = END-TO-END RESISTANCE AND = D DECIMAL VALUE OF WIPER CODE LA
1/2 MAX5487/MAX5488/MAX5489
R2 LB WB
Figure 8. Offset Voltage and Gain Adjustment
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Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers MAX5487/MAX5488/MAX5489
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
D2 b
0.10 M C A B
D D/2
D2/2
E/2
E2/2
C L
E
(NE - 1) X e
E2
L e k (ND - 1) X e
C L
C L
0.10 C 0.08 C A A2 A1 L
C L
L
e
e
PACKAGE OUTLINE 12, 16L, THIN QFN, 3x3x0.8mm
21-0136
E
1 2
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13
12x16L QFN THIN.EPS
Dual, 256-Tap, Nonvolatile, SPI-Interface, Linear-Taper Digital Potentiometers MAX5487/MAX5488/MAX5489
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
EXPOSED PAD VARIATIONS
DOWN BONDS ALLOWED
NOTES: 1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994. 2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES. 3. N IS THE TOTAL NUMBER OF TERMINALS. 4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE. 5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.20 mm AND 0.25 mm FROM TERMINAL TIP. 6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY. 7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION. 8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS. 9. DRAWING CONFORMS TO JEDEC MO220 REVISION C.
PACKAGE OUTLINE 12, 16L, THIN QFN, 3x3x0.8mm
21-0136
E
2 2
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.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.

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