19-2196; Rev 0; 10/01
32-Tap Audio Logarithmic Taper
Digital Potentiometer
General Description
The MAX5407 SOT-PoT™ is a logarithmic taper digital
potentiometer with 32 tap points that has 1dB steps
between taps. This device is ideal for audio applica-
tions, 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 2-
wire serial interface. This device performs the same
function as a mechanical potentiometer. The device
has a fixed end-to-end resistance of 20kΩ 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 -40°C to +85°C.
Features
o
Miniature 3mm x 3mm 8-Pin SOT23 Package
o
Logarithmic Taper with 1dB Steps Between Taps
o
32 Tap Positions
o
Low 0.35µA 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
20kΩ End-to-End Resistance
MAX5407
Applications
Audio Volume Control
Fading/Balancing Audio Signals
Mechanical Potentiometer Replacement
PART
MAX5407EKA
Ordering Information
TEMP. RANGE
-40°C to +85°C
PIN-
PACKAGE
8 SOT23
TOP MARK
AAID
Functional Diagram
H
V
DD
GND
Pin Configuration
TOP VIEW
H
GND
W
L
1
2
3
4
8
ZCEN
V
DD
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
V
DD
to GND ..............................................................-0.3V to +6V
H, W, L, CS,
ZCEN,
and U/D to GND .........-0.3V to (V
DD
+ 0.3V)
Input and Output Latchup Immunity...............................±200mA
Maximum Continuous Current into H, L, and W ..............±500µA
Continuous Power Dissipation (T
A
= +70°C)
8-Pin SOT23-8 (derate 8.9mW/°C above +70°C) ......714mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Soldering Temperature (soldering, 10s) ..........................+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
(V
DD
= +2.7V to +5.5V, V
H
= V
DD
, V
L
= 0, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
DD
= +5V and T
A
= +25°C.)
(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
t
CU
t
CI
t
IC
t
IL
t
IH
f
TOGGLE
t
IW
Zero-crossing detection disabled (Note 4)
0.1
50
25
25
25
25
25
7
ns
ns
ns
ns
ns
MHz
µs
ms
5
V
IH
V
IL
2.4
0.8
±1
V
V
µA
pF
THD + N
PSRR
TC
R
(Notes 3, 4)
(Note 3)
(Note 3)
V
IN
= 1V
RMS
, f = 1kHz,
Tap = -6dB (Notes 3, 4)
SYMBOL
CONDITIONS
MIN
32
15
20
500
±0.25
±0.05
0.002
-80
35
5
R
W
V
DD
= 2.7V
400
1700
±1
±0.1
25
TYP
MAX
UNITS
Taps
kΩ
kHz
dB
dB
%
dB
ppm/°C
ppm/°C
Ω
2
_______________________________________________________________________________________
32-Tap Audio Logarithmic Taper
Digital Potentiometer
MAX5407
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +2.7V to +5.5V, V
H
= V
DD
, V
L
= 0, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
DD
= +5V and T
A
= +25°C.)
(Note 1)
PARAMETER
POWER SUPPLIES
Supply Voltage
Supply Current
V
DD
I
DD
All digital
inputs are
set to 0
Active (Note 7)
Standby (Note 8)
2.7
100
µA
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 T
A
= +25°C and guaranteed by design for T
A
= T
MIN
to T
MAX
.
Bandwidth is measured from H to W at the -6dB wiper tap position (see
Typical Operating Characteristics).
These specifications are only valid for I
W
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 f
TOGGLE
= 2MHz.
Supply current when wiper position is not changing.
Typical Operating Characteristics
(V
DD
= +5V, T
A
= +25°C, 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
V
DD
= +3V
300
WIPER RESISTANCE (Ω)
0.15
0
-5
-10
-15
-20
-25
-30
-35
0
4
8
12
16
20
24
28
250
200
V
DD
= +5V
150
100
0
1
2
3
4
5
WIPER VOLTAGE (V)
32
TEMPERATURE (°C)
TAP POSITION
_______________________________________________________________________________________
3
32-Tap Audio Logarithmic Taper
Digital Potentiometer
MAX5407
Typical Operating Characteristics (continued)
(V
DD
= +5V, T
A
= +25°C, 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 (µA)
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
-40
-15
10
35
60
V
DD
= +3V
V
DD
= +5V
0.40
STANDBY SUPPLY CURRENT (µA)
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
V
DD
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
_______________________________________________________________________________________
32-Tap Audio Logarithmic Taper
Digital Potentiometer
MAX5407
CS
t
CU
t
IC
t
IL
U/D
t
CI
t
IH
t
IW
W
NOTE:
W IS NOT A DIGITAL SIGNAL. IT REPRESENTS THE WIPER TRANSITIONING.
Figure 1. Serial Interface Timing Diagram, Increment Mode
CS
t
CU
t
IH
U/D
t
IC
t
CI
t
IL
W
t
IW
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 seri-
al 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 depend-
ing 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.
_______________________________________________________________________________________
5
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