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19-1435; Rev 1; 4/99
Low-Power Digital Potentiometers
General Description
The MAX5160/MAX5161 linear-taper digital potentiometers perform the same function as a mechanical potentiometer or a variable resistor. They consist of a fixed resistor and a wiper contact with 32 tap points that are digitally controlled by three lines for the 8-pin MAX5160 or by two lines for the 6-pin MAX5161. These parts are ideal for applications requiring digitally controlled resistors. Three resistance values are available for each part type: 50k, 100k, and 200k. A nominal resistor temperature coefficient of 50ppm/C end-to-end and only 5ppm/C ratiometric makes the MAX5160 ideal for applications requiring a low-temperature-coefficient variable resistor, such as low-tempco, adjustable-gain circuit configurations. The MAX5160 is available in an 8-pin MAX package, and the MAX5161 is available in a 6-pin SOT23 package. Both devices are guaranteed over the extendedindustrial temperature range (-40C to +85C). o 32 Tap Positions o 50k, 100k, and 200k Resistance Values o 400 Wiper Resistance o 25% Resistance Tolerance o 3-Wire Serial Data Input o 1LSB DNL o 0.5LSB INL o 100nA Supply Current o Single-Supply Operation: +2.7V to +5.5V o Power-On Reset: Wiper Goes to Midscale (position 16) o 2kV ESD Protection o Small-Footprint Packages 6-Pin SOT23 (MAX5161) 8-Pin MAX (MAX5160) o Glitchless Switching Between the Resistor Taps
Features
MAX5160/MAX5161
Applications
LCD Screen Adjustment Volume Control Mechanical Potentiometer Replacement
PART MAX5160NEUA MAX5160MEUA MAX5160LEUA MAX5161NEUT MAX5161MEUT MAX5161LEUT
Ordering Information
TEMP. RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PINPACKAGE 8 MAX 8 MAX 8 MAX 6 SOT23-6 6 SOT23-6 6 SOT23-6 R (k) 200 100 50 200 100 50
Functional Diagram Pin Configurations
H
TOP VIEW
VDD GND
MAX5160 MAX5161
INC U/D 1 2 3 4 8 VDD CS L W
L1 7 6 5
6
VDD
CS INC U/D
UP/DN COUNTER
POSITION DECODER
H W GND
MAX5160
H2
MAX5161
5
INC
MAX
GND 3
4
U/D
SOT23-6
L
________________________________________________________________ Maxim Integrated Products
1
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Low-Power Digital Potentiometers MAX5160/MAX5161
ABSOLUTE MAXIMUM RATINGS
VDD to GND ..............................................................-0.3V to +6V CS, INC, U/D to GND ...............................................-0.3V to +6V H, L, W to GND.......................................... -0.3V to (VDD + 0.3V) Input and Output Latchup Immunity ..............................200mA Maximum Continuous Current into H, L, and W MAX516_ _ E _ _..............................................................1mA Continuous Power Dissipation (TA = +70C) 6-Pin SOT23 (derate 8.7mW/C above +70C).............696mW 8-Pin MAX (derate 4.1mW/C above +70C) ..............330mW Operating Temperature Range .......................... -40C to +85C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10sec) ............................+300 C
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.
ELECTRICAL CHARACTERISTICS
(VDD = +2.7V to +5.5V, VH = VDD, VL = 0, TA = TMIN to TMAX. Typical values are at VDD = 5V, TA = +25C, unless otherwise noted.) PARAMETER DC PERFORMANCE Resolution Integral Nonlinearity (Note 1) Differential Nonlinearity (Note 1) End-to-End Resistor Tempco Ratiometric Resistor Tempco Full-Scale Error Zero-Scale Error Wiper Resistance Wiper Capacitance End-to-End Resistance DIGITAL INPUTS Input High Voltage Input Low Voltage Input Leakage Current Input Capacitance TIMING CHARACTERISTICS (Figure 6) CS to INC Setup Time CS to INC Hold Time INC Low Period INC High Period U/D to INC Hold U/D to INC Setup Wiper-Settling Time INC Frequency POWER SUPPLIES Supply Voltage Supply Current VDD IDD CS = INC = U/D = VDD or GND VDD = 5V VDD = 2.7V 2.7 0.6 135 5.5 10 V A nA tCI tIC tIL tIH tID tDI tIW fIMAX 25 0 25 25 0 50 1 7 ns ns ns ns ns ns s MHz 5 VIH VIL 0.7 * VDD 0.3 * VDD 1 V V A pF RW CW MAX516_NE_ _ HL MAX516_ME_ _ MAX516_LE_ _ 150 75 37.5 400 10 200 100 50 250 125 62.5 k INL DNL TCR 50 5 -0.1 +0.1 1700 3 1/2 1 % LSB LSB ppm/C ppm/C LSB LSB pF SYMBOL CONDITIONS MIN TYP MAX UNITS
Note 1: For the MAX5160, linearity is defined in terms of H to L code-dependent resistance. 2 _______________________________________________________________________________________
Low-Power Digital Potentiometers
Typical Operating Characteristics
(VDD = +5V, TA = +25C, unless otherwise noted.)
WIPER RESISTANCE vs. WIPER VOLTAGE
MAX5160/61 toc01
MAX5160/MAX5161
END-TO-END RESISTANCE % CHANGE vs. TEMPERATURE
END-TO-END RESISTANCE % CHANGE 0.04 0.02 0 -0.02 -0.04 -0.06 -0.08 -0.1 -0.12 -0.14 -0.16 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 TEMPERATURE (C) 50k 200k 100k 100k 200k 50k
MAX5160/61 toc02
1,000 RWMAX = 574.0804 800 WIPER RESISTANCE () VDD = +2.7V
0.06
600
400
VDD = +5V
200
0 0 1 2 3 4 5 WIPER VOLTAGE (V)
END-TO-END RESISTANCE vs. TAP POSITION
MAX5160/61 toc03
END-TO-END RESISTANCE vs. TAP POSITION
100 90 80 RESISTANCE (k) 70 60 50 40 30 20 10 0 1 5 9 13 17 21 25 29 33 TAP POSITION 100k
MAX5160/61 toc04
225 200 175 RESISTANCE (k) 150 125 100 75 50 25 0 1 5 9 13 17 21 25 29 200k
110
33
TAP POSITION
END-TO-END RESISTANCE vs. TAP POSITION
45 40 RESISTANCE (k) 35 30 25 20 15 10 5 0 1 5 9 13 17 21 25 29 33 TAP POSITION 50k
MAX5160/61 toc05
50
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Low-Power Digital Potentiometers MAX5160/MAX5161
Typical Operating Characteristics (continued)
(VDD = +5V, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
0.8 SUPPLY CURRENT (A) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 -40 -20 0 20 40 60 80 100 VDD = +2.7V INC 2V/div 0V 0V VDD = +5V
MAX5160/61 toc06
TAP-TO-TAP SWITCHING TRANSIENT
OUTPUT W 50mV/div
MAX5160/61 toc07
0.9
5s/div
TEMPERATURE (C)
Pin Description
PIN MAX5160 1 PIN NAME MAX5161 5 INC Wiper Increment Control Input. With CS low, a high-to-low transition increments (U/D high) or decrements (U/D low) the wiper position. Up/Down Control Input. With CS low, a high-to-low INC transition increments (U/D high) or decrements (U/D low) the wiper position. High Terminal of Resistor Ground Wiper Terminal of Resistor Low Terminal of Resistor Chip-Select Input. Drive low to change the wiper position via INC and U/D. Power Supply FUNCTION
2 3 4 5 6 7 8
4 2 3 -- 1 -- 6
U/D H GND W L CS VDD
4
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Low-Power Digital Potentiometers
Detailed Description
The MAX5160/MAX5161 consist of resistor arrays with 31 resistive elements. Thirty-two tap points are accessible to the wiper along the resistor string between H and L. Logic inputs CS, U/D, and INC determine the position of the wiper. With CS low and U/D high, a high-tolow transition on INC increments the internal counter, increasing the resistance between W and L. When both CS and U/D are low, a high-to-low INC transition decrements the internal counter, decreasing the resistance between W and L. At either end (maximum or minimum positions), additional transitions in the direction of the end points will not change the counter value (the counter will not wrap around). The H and L terminals of the MAX5160 are similar to the two end terminals of a mechanical potentiometer. The tap W is equivalent to the variable tap (wiper) of the potentiometer. The MAX5161 is similar to the MAX5160 except that CS internally connects to ground and the wiper terminal (W) is shorted to the high terminal (H). The MAX5161 acts as a variable resistor (a potentiometer with the wiper and one end terminal shorted together). The MAX5160/MAX5161 feature power-on reset circuitry that sets the wiper position to midscale at power-up.
MAX5160/MAX5161
Applications Information
The MAX5160/MAX5161 are intended for circuits requiring digitally controlled adjustable voltage or adjustable gain, such as LCD contrast control, where voltage biasing adjusts the display contrast.
Controlling a Switch-Mode LCD Bias Generator
Figure 1 shows an application where the MAX5161 is used with a MAX1771 to make an adjustable positive LCD-bias circuit. The output of the MAX1771 is a positive voltage that is digitally controlled through the MAX5160/MAX5161. Similarly, Figure 2 shows the application of the MAX5161 in a digitally controlled negative LCD-bias circuit along with the MAX774/ MAX775/MAX776.
VIN = 5V C1 68F C2 0.1F 2 V+ 5 REF C3 0.1F 4 SHDN 6 AGND L1 22H D1 1N5817-22 N MTD20N03HDL RSENSE 40m C4 300F VOUT = 12V AT 0.5A VIN C1 150F C2 0.1F R2 1 OUT 3 2 FB RVAR 1N5822/ MBR340 REF GND 8 L1 22H C4* SHDN MAX774 V+ 5 R3 0.07 Q1 Si9435 P
MAX1771
EXT
1
MAX5161
MAX775 CS 6 MAX776 7
EXT
VOUT
CS
8 R2 R1 4 C3 0.1F
FB GND 7
3
C5
MAX5161
R1 VREF = 1.5V
RVAR
* MAX774 = 330F, 10V
MAX775, MAX776 = 120F, 20V
VOUT(MAX) R2 = +1 R1 VREF VOUT(MIN) R2 = R1 + RVAR(MAX) VREF
VOUT(MAX) R2 VOUT(MIN) R2 = , = R1 VREF R1 + RVAR VREF
(
)
+1
VREF - VFB 5A (FOR 2% GAIN-SETTING ACCURACY) R1 + RVAR
Figure 1. Adjustable Positive LCD Bias
Figure 2. Adjustable Negative LCD Bias
5
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Low-Power Digital Potentiometers MAX5160/MAX5161
Alternative Positive LCD Bias Control
Alternatively, use an op amp to provide buffering and gain to the output of the MAX5160/MAX5161. Connect the MAX5160 to the positive input of a noninverting op amp (Figure 3) to select a portion of the input signal by digitally controlling the wiper terminal. Figure 4 shows a similar circuit for the MAX5161.
Adjustable Gain
Figure 5 shows how to use the MAX5161 to digitally adjust the gain of a noninverting op amp configuration. Connect the MAX5161 in series with a resistor to ground to form the adjustable gain control of a noninverting amplifier. The MAX5160/MAX5161 have a low 5ppm/C ratiometric tempco that allows for a very stable adjustable gain configuration over temperature.
Serial Interface
Figure 6 is the serial-interface timing diagram.
+5V +5V H INC U/D CS GND L
+5V
+5V H MAX5161
MAX5160
VDD W 30V
INC U/D VOUT VDD GND L
30V
VOUT
GAIN 6
GAIN 6
Figure 3. MAX5160 Positive LCD Bias Control
VCC VIN VOUT
Figure 4. MAX5161 Positive LCD Bias Control
VCC VIN VOUT
+5V H INC U/D VDD GND L W L H
MAX5161
MAX5160
a)
b)
Figure 5. Adjustable Gain Circuit: a) MAX5161; b) MAX5160
6 _______________________________________________________________________________________
Low-Power Digital Potentiometers MAX5160/MAX5161
CS
tCI tIL INC
tIC
tIH tDI
U/D tID
tIW
W
Figure 6. Serial-Interface Timing Diagram
Truth Table
CS H L L L L U/D xx-X L H L H INC X RW O O O -- +
Chip Information
TRANSISTOR COUNT: 969
X = Don't care O = Previous state + = Increment -- = Decrement = High-to-Low Transition = Low-to-High Transition
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Low-Power Digital Potentiometers MAX5160/MAX5161
Package Information
8LUMAXD.EPS
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.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
6LSOT.EPS

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