19-0542; Rev 2; 11/08
Stereo Volume Control
with Rotary Encoder Interface
General Description
The MAX5440 dual, 40kΩ logarithmic taper volume con-
trol features a debounced up/down interface for use
with a simple rotary encoder without using a microcon-
troller (µC). Each potentiometer has 32 log-spaced tap
points with a buffered wiper output and replaces
mechanical potentiometers. An integrated bias genera-
tor provides the required ((V
DD
+ V
SS
) / 2) bias voltage,
eliminating the need for costly external op-amp circuits
in unipolar audio applications. A mode-indicator LED
output specifies volume or balance control. Five inte-
grated LED drivers indicate volume level or balance set-
tings, depending on the status of the mode indicator.
The MAX5440 includes debounced pushbutton inputs
for mute and mode. The mute input allows a single
pushbutton to change between volume control and the
-90dB (typ) mute setting. The mode input toggles
between volume and balance control. A click-and-pop
suppression feature minimizes the audible noise gener-
ated by wiper transitions. The MAX5440 provides a
nominal temperature coefficient of 35ppm/°C end-to-
end and 5ppm/°C, ratiometrically. The MAX5440 is
available in a 24-pin SSOP package and is specified for
operation over the -40°C to +85°C extended tempera-
ture range.
Features
♦
Logarithmic Taper Volume Control with (31) 2dB
Steps
♦
Low-Power Wiper Buffers Provide 0.003% THD
♦
Single +2.7V to +5.5V or Dual ±2.7V Supply
Voltage Operation
♦
Low 0.5µA Shutdown Supply Current
♦
Integrated Bias Voltage Generator
♦
Five-Segment LED Volume/Balance Indicator
♦
Clickless Switching
♦
40kΩ End-to-End Fixed Resistance Value
♦
Mute Function Toggles to -90dB (typ)
♦
Power-On Reset to -12dBFS Wiper Position
MAX5440
Ordering Information
PART
MAX5440EAG
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
24 SSOP
Applications
Stereo Volume Control
Desktop Speakers
Multimedia Docking Stations
Set-Top Boxes
Automotive Back-Seat Multimedia
V
LOGIC
Typical Operating Circuit
V
DD
V
LOGIC
Pin Configuration
TOP VIEW
V
LOGIC
RENCODEB
RENCODEA
MUTE
MODE
SHDN
GND
H0
L0
1
2
3
4
5
6
7
8
9
24 GND
23 MODEIND
22 LEDIND4
SHDN
MODEIND
V
PEAK
(V
DD +
V
SS
) / 2
MAX5440
H1
W1
RIGHT INPUT
L1
MIDBIAS
HEADPHONE
DRIVER
MAX5440
21 LEDIND3
20 LEDIND2
19 LEDIND1
18 LEDIND0
17 H1
16 L1
15 W1
14 V
SS
13 V
DD
V
SS
GND
LEDIND0
LEDIND1
LEDIND2
LEDIND3
(V
DD +
V
SS
) / 2
L0
W0
LEFT INPUT
H0
LEDIND4
BIAS
MUTE
MODE
RENCODEA
RENCODEB
W0 10
MIDBIAS 11
BIAS 12
ROTARY
ENCODER
SSOP
________________________________________________________________
Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Stereo Volume Control
with Rotary Encoder Interface
ABSOLUTE MAXIMUM RATINGS
MAX5440
SHDN, MUTE, RENCODEA, RENCODEB,
and
MODE
to GND............................-0.3V to (V
LOGIC
+ 0.3V)
H_, L_, and W_ to V
SS
...............................-0.3V to (V
DD
+ 0.3V)
LEDIND_,
MODEIND
to GND................-0.3V to (V
LOGIC
+ 0.3V)
MIDBIAS, BIAS to V
SS
......................(V
SS
- 0.3V) to (V
DD
+ 0.3V)
V
LOGIC
to GND...........................................-0.3V to (V
DD
+ 0.3V)
V
DD
to GND ..............................................................-0.3V to +6V
V
DD
to V
SS
................................................................-0.3V to +6V
V
SS
to GND...............................................................-3V to +0.3V
Input and Output Latchup Immunity...............................±200mA
Continuous Power Dissipation (T
A
= +70°C)
24-Pin SSOP (derate 12.3mW/°C above +70°C) ......987.7mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-60°C to +150°C
Lead 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
SS
= V
GND
= 0, 2.7V
≤
(V
DD
- V
SS
)
≤
5.5V, V
LOGIC
= +2.7V to V
DD
, V
H_
= V
DD
, V
L_
= V
DD
/ 2, T
A
= T
MIN
to
T
MAX
, unless otherwise specified. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
End-to-End Resistance
Absolute Tolerance
Tap-to-Tap Tolerance
V
H_
= (V
DD
/ 2) + 1V
RMS
, 1kHz tap at top, R
L
=
∞
to V
L_
= V
DD
/ 2, 20Hz to 20kHz
V
H_
= (V
DD
/ 2) + 1.5V
RMS
, 1kHz tap at top,
R
L
=
∞
to V
L_
= V
DD
/ 2, 20Hz to 20kHz
Total Harmonic Distortion Plus
Noise
THD+N
V
DD
= 5V,V
SS
= 0V, V
L_
= 1.5V, V
H_
=
(V
DD
/ 2) + 1V
RMS
, 1kHz tap at top, R
L
=
10kΩ to V
MIDBIAS
, 20Hz to 20kHz
V
DD
= 5V,V
SS
= 0V, V
L_
= 5V, V
H_
= (V
DD
/
2) + 1.5V
RMS,
1kHz tap at top, R
L
= 10kΩ
to V
MIDBIAS
, 20Hz to 20kHz
Channel Isolation
Interchannel Matching
Mute Attenuation
Power-Supply Rejection Ratio
H Terminal Capacitance
L Terminal Capacitance
End-to-End Resistance
Ratiometric Resistance
Bandwidth, -3dB
Output Noise
WIPER BUFFER
Output Voltage Swing
Output Current
Output Resistance
DC Offset
INTEGRATED BIAS GENERATOR
Output Voltage
I
LOAD
= 1mA
(V
DD
+
V
SS
) / 2
- 30mV
(V
DD
+
V
SS
)
/2
(V
DD
+
V
SS
) / 2 +
30mV
V
R
OWB
-14
1
±2
V
O
R
L
= 10kΩ to V
MIDBIAS
V
DD
- 0.2
3
10
+14
V
mA
Ω
mV
f
CUTOFF
e
n
C
W
= 33pF
20Hz to 20kHz
PSRR
C
H
C
L
SHDN
= V
DD
Input referred, 217Hz, 100mV
P-P
on V
DD
SYMBOL
R
CONDITIONS
MIN
36
TYP
40
±0.25
±0.1
0.004
0.006
%
0.004
MAX
52
UNITS
kΩ
dB
dB
0.006
100
±0.5
90
-60
5
7
35
5
100
3.2
dB
dB
dB
dB
pF
pF
ppm/°C
ppm/°C
kHz
µV
RMS
2
_______________________________________________________________________________________
Stereo Volume Control
with Rotary Encoder Interface
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +2.7V to +5.5V, V
SS
= V
GND
= 0, 2.7V
≤
(V
DD
- V
SS
)
≤
5.5V, V
LOGIC
= +2.7V to V
DD
, V
H_
= V
DD
, V
L_
= V
DD
/ 2, T
A
= T
MIN
to
T
MAX
, unless otherwise specified. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Power-Supply Rejection Ratio
Maximum Load
Output Resistance
Internal Pullup Resistor
Single Pulse Input Low Time
Repetitive Input Pulse Separation
Timeout Period
R
OBR
R
PULLUP
t
CPW
t
IPWS
t
WS
Click/pop suppression inactive
3.6V < V
LOGIC
≤
5.5V
2.7V
≤
V
LOGIC
≤
3.6V
3.6V < V
LOGIC
≤
5.5V
2.7V
≤
V
LOGIC
≤
3.6V
Inputs unconnected
-1
5
V
DD
V
SS
I
DD
I
STBY
I
SHDN
t
PU
V
LOGIC
I
L
I
LSTBY
I
LSHDN
V
LOGIC
= 2.7V, I
SINK
= 10mA
V
LOGIC
= 5.5V, I
SINK
= 10mA
0.1
3
150
V
DD
= +5V, V
SS
= 0
V
DD
= +2.7V, V
SS
= -2.7V
(Note 3)
Click/pop suppression inactive
V
SS
= 0
V
RENCODEA
=
V
RENCODEB
= 0V
(Note 4)
2.7
50
V
DD
320
1
1
0.4
0.2
10
V
SS
= 0
V
DD
= +2.7V
V
DD
- V
SS
2.7
-2.7
5.5
0
5.5
1.4
1.3
1.3
1
2.4
2.0
0.8
0.6
+1
22
66
32
SYMBOL
PSRR
BR
CONDITIONS
1kHz, 100mV on V
DD
, 1µF on BIAS
To V
DD
or GND
3
6
45
MIN
TYP
60
MAX
UNITS
dB
kΩ
Ω
kΩ
ms
ms
ms
MAX5440
CONTACT INPUTS (MUTE,
MODE, RENCODEA, RENCODEB)
DIGITAL INPUTS (MUTE,
MODE, RENCODEA, RENCODEB, SHDN)
Input High Voltage (Note 2)
Input Low Voltage (Note 2)
Input Leakage Current
Input Capacitance
POWER SUPPLIES
Supply Voltage
Negative Power Supply
Supply Voltage Difference
Active Supply Current
Standby Supply Current (Notes 3, 4)
Shutdown Supply Current
Power-Up Time
Logic Supply Voltage
Logic Active Supply Current
Logic Standby Supply Current
Logic Shutdown Current
V
V
V
mA
mA
µA
ms
V
µA
µA
µA
V
IH
V
IL
V
V
µA
pF
LED INDICATORS (LEDIND0–LEDIND4,
MODEIND)
Output Low Voltage
Output Leakage Current
Output Capacitance
Maximum Sink Current
V
OL
V
µA
pF
mA
Note 1:
Parameters are 100% production tested at +85°C and limits through temperature are guaranteed by design.
Note 2:
The device draws current in excess of the specified supply current when the digital inputs are driven with voltages between
(V
DD
- 0.5V) and (GND + 0.5V). See Digital Supply Current vs. Digital Input Voltage in the
Typical Operating Characteristics.
Note 3:
Shutdown refers to the
SHDN
input being asserted low. Standby refers to
SHDN
not being asserted and all I/O inactive.
Note 4:
Supply current measured with the wiper position fixed.
_______________________________________________________________________________________
3
Stereo Volume Control
with Rotary Encoder Interface
MAX5440
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
END-TO-END RESISTANCE % CHANGE
vs. TEMPERATURE
MAX5440 toc01
MAX5440 toc02
ATTENUATION vs. TAP POSITION
0
-10
ATTENUATION (dB)
-20
-30
-40
-50
-60
-70
0
4
8
12
16
20
24
28
32
TAP POSITION
0.10
END-TO-END RESISTANCE CHANGE (%)
0.05
0
-0.05
-0.10
-0.15
-0.20
-0.25
TOTAL SUPPLY CURRENT
vs. TEMPERATURE
1.47
TOTAL SUPPLY CURRENT (mA)
1.46
1.45
1.44
1.43
1.42
1.41
1.40
1.39
1.38
V
LOGIC
= V
DD
= 5.5V
MAX5440 toc03
1.48
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
WIPER SWITCHING TRANSIENT
MAX5440 toc04
WIPER-TO-END TERMINAL VOLTAGE
vs. TAP POSITION
MAX5440 toc05
FREQUENCY RESPONSE
0.8
0.4
0
RESPONSE (dB)
-0.4
-0.8
-1.2
-1.6
-2.0
W_ SET TO 0dB
V
H_
= 2.5
±1V
RMS
, V
L_
= 2.5V, C
L_
= 33pF
MAX5440 toc06
100
NOMINAL END-TO-END VOLTAGE (%V
HL
)
RENCODEA
RENCODEB
90
80
70
60
50
40
30
20
10
0
0
4
8
V
WL
V
HW
51ms
WIPER
TRANSITION
FROM -2dB
TO -4dB
-2.4
-2.8
20ms/div
12
16
20
24
28
32
0.01
0.1
1
10
100
1000
TAP POSITION
FREQUENCY (kHz)
FREQUENCY RESPONSE
MAX5440 toc07
THD+N vs. FREQUENCY
MAX5440 toc08
THD+N vs. FREQUENCY
V
DD
= 5.0V
V
SS
= GND
L_ = V
MIDBIAS
H_ = V
MIDBIAS
+ 1V
RMS
THD+N (%)
MAX5440 toc09
-5.2
-5.6
-6.0
RESPONSE (dB)
V
H_
= 2.5
±1V
RMS
, V
L_
= 2.5V, C
L_
= 33pF
0.1
V
DD
= 2.5V
V
SS
= -2.5V
L_ = V
MIDBIAS
H_ = V
MIDBIAS
+ 1V
RMS
THD+N (%)
0.1
-6.4
-6.8
-7.2
-7.6
-8.0
-8.4
-8.8
0.01
W_ SET TO -6dB
0.01
W_ SET AT -6dB
0.01
W_ SET AT -6dB
W_ SET AT -2dB
W_ SET AT -2dB
W_ SET AT 0dB
0.1
1
10
100
1000
0.001
0.001
0.01
0.1
1
10
100
0.001
0.001
0.01
0.1
W_ SET AT 0dB
1
10
100
FREQUENCY (kHz)
FREQUENCY (kHz)
FREQUENCY (kHz)
4
_______________________________________________________________________________________
Stereo Volume Control
with Rotary Encoder Interface
Typical Operating Characteristics (continued)
(
V
DD
= +5V, T
A
= +25°C, unless otherwise noted.)
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
-30
-35
RESPONSE (dB)
-40
-45
-50
-55
-60
-65
-70
-75
0.01
0.1
1
FREQUENCY (kHz)
10
100
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
LOGIC SUPPLY VOLTAGE (V)
0
-40
-15
10
35
60
85
TEMPERATURE (°C)
V
DD_
= 5V
±100mV
P-P
, V
H
= 5V
V
L_
= 2.5V, W_ SET TO -6dB
MAX5440 toc10
MAX5440
LOGIC SUPPLY CURRENT
vs. LOGIC SUPPLY VOLTAGE
MAX5440 toc11
ACTIVE LOGIC SUPPLY CURRENT
vs. TEMPERATURE
V
DD
= V
LOGIC
= 5.5V,
RENCODEA = RENCODEB = 0
MAX5440 toc12
-25
300
LOGIC SUPPLY CURRENT (µA)
250
ACTIVE CURRENT
200
150
100
50
SHUTDOWN
STANDBY CURRENT
350
300
250
200
150
100
50
ACTIVE SUPPLY CURRENT
vs. TEMPERATURE
MAX5440 toc13
DIGITAL SUPPLY CURRENT
vs. DIGITAL INPUT VOLTAGE
MAX5440 toc14
1.1770
1.1768
SUPPLY CURRENT (mA)
1.1766
1.1764
1.1762
1.1760
1.1758
1.1756
1.1754
1.1752
-40
-15
10
35
60
V
DD
= V
LOGIC
= 5.5V,
RENCODEA = RENCODEB = 0
1000
DIGITAL SUPPLY CURRENT (µA)
100
10
85
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
DIGITAL INPUT VOLTAGE (V)
TEMPERATURE (°C)
SPECTRAL NOISE DENSITY
MAX5440 toc15
SUPPLY CURRENT
vs. INPUT VOLTAGE SWEEP
7
SUPPLY CURRENT (mA)
6
5
4
3
2
V
DD
= V
LOGIC
= 5V, W_ AT 0dB
R
L
= 10kΩ TO V
MIDBIAS
MAX5440 toc16
1200
1000
NOISE (nV/√Hz)
800
600
400
200
0
0.01
0.1
1
FREQUENCY (kHz)
10
8
1
0
100
2.5
3.0
3.5
4.0
4.5
5.0
INPUT VOLTAGE SWEEP (V
H_
)
_______________________________________________________________________________________
LOGIC SUPPLY CURRENT (µA)
5
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