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19-2196; Rev 0; 10/01
32-Tap Audio Logarithmic Taper Digital Potentiometer
General Description
The MAX5407 SOT-PoTTM is a logarithmic taper digital potentiometer with 32 tap points that has 1dB steps between taps. This device is ideal for audio applications, such as volume control and fading/balancing audio signals. The MAX5407 consists of a resistor string and CMOS switches that are digitally controlled through a simple 2wire serial interface. This device performs the same function as a mechanical potentiometer. The device has a fixed end-to-end resistance of 20k and features zero-crossing detection to minimize the audible noise generated by the wiper transitions. This device has nominal resistor temperature coefficients of 35ppm/C end-to-end and 5ppm/C ratiometric. The MAX5407 is available in a space saving 8-pin SOT23 package and is guaranteed from -40C to +85C.
Features
o Miniature 3mm x 3mm 8-Pin SOT23 Package o Logarithmic Taper with 1dB Steps Between Taps o 32 Tap Positions o Low 0.35A Supply Current o +2.7V to +5.5V Single-Supply Operation o Zero-Crossing Detection to Minimize Audible Clicks During Wiper Transitions o Simple Up/Down 2-Wire Serial Data Interface o Power-On Reset Wiper Goes To Maximum Attenuation (Lowest Tap Position) o 20k End-to-End Resistance
MAX5407
Applications
Audio Volume Control Fading/Balancing Audio Signals Mechanical Potentiometer Replacement
PART MAX5407EKA
Ordering Information
TEMP. RANGE -40C to +85C PINPACKAGE 8 SOT23 TOP MARK AAID
Functional Diagram
H VDD GND
Pin Configuration
TOP VIEW
H GND W L 1 2 3 4 8 ZCEN VDD CS U/D
MAX5407
MAX5407
7 6 5
CS U/D ZCEN
UP/DOWN COUNTER
32-POSITION DECODER
W
SOT23
L
SOT-PoT is a trademark of Maxim Integrated Products, Inc.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
32-Tap Audio Logarithmic Taper Digital Potentiometer MAX5407
ABSOLUTE MAXIMUM RATINGS
VDD to GND ..............................................................-0.3V to +6V H, W, L, CS, ZCEN, and U/D to GND .........-0.3V to (VDD + 0.3V) Input and Output Latchup Immunity...............................200mA Maximum Continuous Current into H, L, and W ..............500A Continuous Power Dissipation (TA = +70C) 8-Pin SOT23-8 (derate 8.9mW/C above +70C) ......714mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Soldering 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.
ELECTRICAL CHARACTERISTICS
(VDD = +2.7V to +5.5V, VH = VDD, VL = 0, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VDD = +5V and TA = +25C.) (Note 1)
PARAMETER Number of Resistor Taps End-to-End Resistance Bandwidth (Note 2) Absolute Tolerance (Note 5) Tap-to-Tap Tolerance (Note 6) Total Harmonic Distortion + Noise Power-Supply Rejection Ratio End-to-End Resistance Temperature Coefficient Ratiometric Resistance Temperature Coefficient Wiper Resistance DIGITAL INPUTS Input High Voltage Input Low Voltage Input Leakage Current Input Capacitance TIMING CHARACTERISTICS (Figures 1, 2) U/D Mode to CS Setup CS to U/D Step Setup CS to U/D Step Hold U/D Step Low Period U/D Step High Period Up/Down Toggle Rate Wiper Switching Time Zero-Crossing Timeout tCU tCI tIC tIL tIH fTOGGLE tIW Zero-crossing detection disabled (Note 4) 0.1 50 25 25 25 25 25 7 ns ns ns ns ns MHz s ms 5 VIH VIL 2.4 0.8 1 V V A pF THD + N PSRR TCR (Notes 3, 4) (Note 3) (Note 3) VIN = 1VRMS, f = 1kHz, Tap = -6dB (Notes 3, 4) SYMBOL CONDITIONS MIN 32 15 20 500 0.25 0.05 0.002 -80 35 5 RW VDD = 2.7V 400 1700 1 0.1 25 TYP MAX UNITS Taps k kHz dB dB % dB ppm/C ppm/C
2
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32-Tap Audio Logarithmic Taper Digital Potentiometer MAX5407
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +2.7V to +5.5V, VH = VDD, VL = 0, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VDD = +5V and TA = +25C.) (Note 1)
PARAMETER POWER SUPPLIES Supply Voltage Supply Current VDD IDD All digital inputs are set to 0 Active (Note 7) Standby (Note 8) 2.7 100 A 0.35 1 5.5 V SYMBOL CONDITIONS MIN TYP MAX UNITS
Note 1: Note 2: Note 3: Note 4: Note 5: Note 6: Note 7: Note 8:
All devices are 100% production tested at TA = +25C and guaranteed by design for TA = TMIN to TMAX. Bandwidth is measured from H to W at the -6dB wiper tap position (see Typical Operating Characteristics). These specifications are only valid for IW less than 100nA of continuous wiper current. Measured with 20pF load capacitor. Absolute tolerance is defined as the variation of the attenuation for any given tap from its expected value. Tap-to-tap tolerance is defined as the variation between any two adjacent taps from the typical value of 1dB. Supply current when fTOGGLE = 2MHz. Supply current when wiper position is not changing.
Typical Operating Characteristics
(VDD = +5V, TA = +25C, unless otherwise noted.)
WIPER RESISTANCE vs. WIPER VOLTAGE
MAX5407 toc01
END-TO-END RESISTANCE % CHANGE vs. TEMPERATURE
ENE-TO-END RESISTANCE CHANGE (%) 0.10 0.05 0 -0.05 -0.10 -0.15 -0.20 -0.25 -40 -15 10 35 60 85 ATTENUATION (dB)
MAX5407 toc02
ATTENUATION vs. TAP POSITION
MAX5407 toc03
350 VDD = +3V 300 WIPER RESISTANCE ()
0.15
0 -5 -10 -15 -20 -25 -30 -35 0 4 8 12 16 20 24 28
250
200 VDD = +5V
150
100 0 1 2 3 4 5 WIPER VOLTAGE (V)
32
TEMPERATURE (C)
TAP POSITION
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3
32-Tap Audio Logarithmic Taper Digital Potentiometer MAX5407
Typical Operating Characteristics (continued)
(VDD = +5V, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
MAX5407 toc04
TAP-TO-TAP SWITCHING TRANSIENT
MAX5407 toc05
STANDBY SUPPLY CURRENT vs. SUPPLY VOLTAGE
0.35 0.30 0.25 0.20 0.15 0.10 0.05 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
MAX5407 toc06
0.50 0.45 0.40 SUPPLY CURRENT (A) 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0 -40 -15 10 35 60 VDD = +3V VDD = +5V
0.40 STANDBY SUPPLY CURRENT (A)
U/D 2V/div
OUTPUT W 200mV/div
85
40ns/div
TEMPERATURE (C)
SUPPLY VOLTAGE (V)
FREQUENCY RESPONSE
MAX5407 toc07
TOTAL HARMONIC DISTORTION + NOISE vs. FREQUENCY
TAP POSITION 6
MAX5407 toc08
0 TAP POSITION 6 -5
0.01
0.001 -10 THD+N (%) 0.0001 -15 0.00001 0.01 0.1 1 10 100 1000 0.01 0.1 1 FREQUENCY (kHz) 10 100 FREQUENCY (kHz) GAIN (dB)
-20 0.001
Pin Description
PIN 1 2 3 4 5 6 7 8 NAME H GND W L U/D CS VDD ZCEN High Terminal of Resistor Ground Wiper Terminal of Resistor Low Terminal of Resistor Up/Down Control Input. With CS high, a low-to-high transition increments or decrements the wiper position, depending on the mode. Chip-Select Input. A low-to-high CS transition determines the mode: increment if U/D is high, decrement if U/D is low. Power Supply Zero-Crossing Detection Enable Input. Set to low to enable zero-crossing detection. FUNCTION
4
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32-Tap Audio Logarithmic Taper Digital Potentiometer MAX5407
CS tCU tIC
tIL
U/D tCI tIH
tIW
W
NOTE: W IS NOT A DIGITAL SIGNAL. IT REPRESENTS THE WIPER TRANSITIONING.
Figure 1. Serial Interface Timing Diagram, Increment Mode
CS tCU tIH U/D tIC
tCI
tIL
W
tIW NOTE: W IS NOT A DIGITAL SIGNAL. IT REPRESENTS THE WIPER TRANSITIONING.
Figure 2. Serial Interface Timing Diagram, Decrement Mode
Detailed Description
Digital Interface Operation
The MAX5407 has two modes of operation when the serial interface is active: increment and decrement mode. The serial interface is only active when CS is high. The CS and U/D inputs control the position of the wiper along the resistor array. When CS transitions from low to high, the part will go into increment mode if U/D is
high and into decrement mode if U/D is low. Once the mode is set, the device will remain in that mode until CS goes low again. A low-to-high transition at the U/D pin will increment or decrement the wiper position depending on the mode (Figures 1 and 2). When the CS input transitions to low (serial interface inactive), the value of the counter is stored and the wiper position is maintained.
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32-Tap Audio Logarithmic Taper Digital Potentiometer MAX5407
Power-On Reset
The power-on reset feature sets the wiper to the maximum attenuation (tap position 31, -31dB) at power-up. If CS is initially high, the MAX5407 is in the increment mode by default.
Applications Information
The MAX5407 is intended for circuits requiring digitally controlled adjustable voltage or adjustable gain, such as applications involving volume control.
Zero-Crossing Detection
When the ZCEN input is low, the zero-crossing detect feature is enabled. This feature reduces the audible noise ("clicks and pops") that result from wiper transitions. When zero-crossing detection is enabled, the wiper changes position only when the voltage at L is the same as the voltage at H. If no zero crossing is detected after 50ms, the device will timeout and change the wiper position.
Volume Control
The zero-crossing feature of the MAX5407 makes it ideal for applications involving volume control. Figure 3 shows a typical application circuit, where the MAX5407 is followed by an op amp for output buffering and gain. VCM represents the common voltage around which the audio signal swings.
Signal Attenuator
Figure 4 shows a typical signal attenuator. Use an op amp to provide buffering and gain to the output of the MAX5407. Connect the MAX5407 to the positive input of a noninverting op amp to select the level of attenuation of the input signal, by digitally controlling the wiper terminal.
Digital Logic Inputs
The MAX5407 can interface to +3V logic as well as +5V logic, while using a +3V to +5V power supply. In order to minimize the supply current, set all digital inputs low while the part is inactive.
Adjustable Gain
AUDIO INPUT +5V H CS U/D ZCEN L VCM W VDD VDD
MAX5407
Figure 5 shows how to use the MAX5407 to digitally adjust the gain of a noninverting op amp configuration. The MAX5407 has a low 5ppm/C ratiometric tempco that allows for a very stable adjustable gain configuration over temperature.
MAX4336
VOUT
Chip Information
TRANSISTOR COUNT: 1942
Figure 3. Volume Control Circuit
MAX5407
SIGNAL INPUT +5V H VDD
MAX5407
VDD VIN VOUT
CS U/D +5V ZCEN L W
VDD
MAX4336 MAX4336
VOUT W L H
MAX5407
Figure 4. Signal Attenuator Circuit 6
Figure 5. Adjustable Gain Circuit
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32-Tap Audio Logarithmic Taper Digital Potentiometer
Package Information
SOT23, 8L.EPS
MAX5407
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 7 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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