MAX5477ETE#G16 [MAXIM]
Digital Potentiometer, 1 Func, 10000ohm, 2-wire Serial Control Interface, 256 Positions, BICMOS, 3 X 3 MM, 0.80 MM HEIGHT, MO-220WEED-2, TQFN-16;型号: | MAX5477ETE#G16 |
厂家: | MAXIM INTEGRATED PRODUCTS |
描述: | Digital Potentiometer, 1 Func, 10000ohm, 2-wire Serial Control Interface, 256 Positions, BICMOS, 3 X 3 MM, 0.80 MM HEIGHT, MO-220WEED-2, TQFN-16 信息通信管理 转换器 |
文件: | 总16页 (文件大小:312K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
19-3379; Rev 5; 11/11
Dual, 256-Tap, Nonvolatile,
I2C-Interface, Digital Potentiometers
8/MAX5479
General Description
Features
The MAX5477/MAX5478/MAX5479 nonvolatile, dual,
linear-taper, digital potentiometers perform the function
of a mechanical potentiometer, but replace the
mechanics with a simple 2-wire digital interface. Each
device performs the same function as a discrete poten-
tiometer or variable resistor and has 256 tap points.
o Power-On Recall of Wiper Position from
Nonvolatile Memory
o EEPROM Write Protection
o Tiny 3mm x 3mm x 0.8mm Thin QFN Package
o 70ppm/°C End-to-End Resistance Temperature
Coefficient
The devices feature an internal, nonvolatile EEPROM
used to store the wiper position for initialization during
power-up. A write-protect feature prevents accidental
overwrites of the EEPROM. The fast-mode I2C-compati-
ble serial interface allows communication at data rates
up to 400kbps, minimizing board space and reducing
interconnection complexity in many applications. Three
address inputs allow a total of eight unique address
combinations.
o 10ppm/°C Ratiometric Temperature Coefficient
o Fast 400kbps I C-Compatible Serial Interface
2
o 1µA (max) Static Supply Current
o Single-Supply Operation: +2.7V to +5.25V
o 256 Tap Positions per Potentiometer
o
0.5 LSB DNL in Voltage-Divider Mode
1 LSB INL in Voltage-Divider Mode
o
The MAX5477/MAX5478/MAX5479 provide three nomi-
nal resistance values: 10kΩ (MAX5477), 50kΩ
(MAX5478), or 100kΩ (MAX5479). The nominal resistor
temperature coefficient is 70ppm/°C end-to-end and
10ppm/°C ratiometric. The low temperature coefficient
makes the devices ideal for applications requiring a low-
temperature-coefficient variable resistor, such as low-
drift, programmable gain-amplifier circuit configurations.
Functional Diagram
HA
V
DD
8-BIT
SHIFT
REGISTER
256
POSITION
DECODER
8
8
8
256
256
16-BIT
LATCH
GND
WA
The MAX5477/MAX5478/MAX5479 are available in 16-
pin 3mm x 3mm x 0.8mm TQFN and 14-pin 4.4mm x
5mm TSSOP packages. These devices operate over
the extended -40°C to +85°C temperature range.
POR
LA
16-BIT
NV
MEMORY
SDA
SCL
WP
HB
I2C
INTERFACE
256
POSITION
DECODER
WB
LB
Applications
Mechanical Potentiometer Replacement
Low-Drift Programmable-Gain Amplifiers
Volume Control
MAX5477
MAX5478
MAX5479
A0
A1
A2
Pin Configurations appear at end of data sheet.
Liquid-Crystal Display (LCD) Contrast Control
Ordering Information/Selector Guide
END-TO-END
RESISTANCE (kꢀ)
PART
TEMP RANGE
PIN-PACKAGE
TOP MARK
MAX5477ETE+T
MAX5477EUD+
MAX5478ETE+T
MAX5478EUD+
MAX5479ETE+T
MAX5479EUD+
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
16 TQFN-EP*
14 TSSOP
10
10
ABO
—
16 TQFN-EP*
14 TSSOP
50
ABP
—
50
16 TQFN-EP*
14 TSSOP
100
100
ABQ
—
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
*EP = Exposed pad.
________________________________________________________________ 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.
2
Dual, 256-Tap, Nonvolatile, I C-Interface,
Digital Potentiometers
ABSOLUTE MAXIMUM RATINGS
SDA, SCL, V
to GND.........................................-0.3V to +6.0V
Operating Temperature Range ...........................-40°C to +85°C
Maximum Junction Temperature .....................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
DD
All Other Pins to GND.................................-0.3V to (V
Maximum Continuous Current into H_, L_, and W_
MAX5477...................................................................... 5.0mA
MAX5478...................................................................... 1.3mA
MAX5479...................................................................... 0.6mA
+ 0.3V)
DD
Continuous Power Dissipation (T = +70°C)
A
16-Pin TQFN (derate 17.5mW/°C above +70°C) .......1398mW
14-Pin TSSOP (derate 9.1mW/°C above +70°C) .........727mW
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.
PACKAGE THERMAL CHARACTERISTICS (Note 1)
TQFN
TSSOP
Junction-to-Ambient Thermal Resistance (θ ) ......100.4°C/W
Junction-to-Ambient Thermal Resistance (θ ) ........57.2°C/W
Junction-to-Case Thermal Resistance (θ )................40°C/W
JA
JA
Junction-to-Case Thermal Resistance (θ )................30°C/W
JC
JC
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
ELECTRICAL CHARACTERISTICS
(V
= +2.7V to +5.25V, H_ = V , L_ = GND, T = -40°C to +85°C, unless otherwise noted. Typical values are at V
= +5V,
DD
DD
DD
A
T
A
= +25°C.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DC PERFORMANCE (VOLTAGE-DIVIDER MODE)
8/MAX5479
Resolution
256
Taps
LSB
LSB
LSB
Integral Nonlinearity
Differential Nonlinearity
Dual Code Matching
INL
(Note 3)
(Note 3)
1
0.5
1
DNL
R0 and R1 set to same code (all codes)
End-to-End Resistance
Temperature Coefficient
TC
70
10
ppm/°C
ppm/°C
R
Ratiometric Resistance
Temperature Coefficient
MAX5477
MAX5478
MAX5479
MAX5477
MAX5478
MAX5479
-4
-0.6
-0.3
4
Full-Scale Error
Zero-Scale Error
LSB
LSB
0.6
0.3
DC PERFORMANCE (VARIABLE-RESISTOR MODE)
V
V
= 3V
= 5V
3
DD
DD
Integral Nonlinearity (Note 4)
INL
LSB
LSB
1.5
MAX5477
MAX5478
MAX5479
1
Differential Nonlinearity (Note 4)
DNL
1
1
2
_______________________________________________________________________________________
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
8/MAX5479
ELECTRICAL CHARACTERISTICS (continued)
(V
= +2.7V to +5.25V, H_ = V , L_ = GND, T = -40°C to +85°C, unless otherwise noted. Typical values are at V
= +5V,
DD
DD
DD
A
T
A
= +25°C.) (Note 2)
PARAMETER
Dual Code Matching
SYMBOL
CONDITIONS
R0 and R1 set to same code
(all codes), V = 3V or 5V
MIN
TYP
MAX
UNITS
3
LSB
DD
DC PERFORMANCE (RESISTOR CHARACTERISTICS)
Wiper Resistance
Wiper Capacitance
R
W
C
W
(Note 5)
325
10
675
ꢀ
pF
MAX5477
MAX5478
MAX5479
7.5
37.5
75
10
12.5
62.5
125
End-to-End Resistance
R
HL
kꢀ
50
100
DIGITAL INPUTS
V
V
= 3.4V to 5.25V
< 3.4V
2.4
DD
Input High Voltage (Note 6)
V
V
IH
0.7 x V
DD
DD
Input Low Voltage
V
(Note 6)
= 3mA
0.8
0.4
V
IL
OL
WP
Output Low Voltage
V
I
V
SINK
WP Pullup Resistance
Input Leakage Current
Input Capacitance
I
255
kꢀ
µA
pF
I
1
LEAK
5
DYNAMIC CHARACTERISTICS
HA = 1kHz (0 to V ), LA = GND,
DD
LB = GND, measure WB
Crosstalk
-75
dB
kHz
%
MAX5477
400
100
50
3dB Bandwidth (Note 7)
MAX5478
MAX5479
Total Harmonic Distortion Plus
Noise
H_ = 1V
, f = 1kHz, L_ = GND,
RMS
THD+N
0.003
measure W_
NONVOLATILE MEMORY RELIABILITY
Data Retention
T
A
T
A
T
A
= +85°C
= +25°C
= +85°C
50
Years
200,000
50,000
Endurance
Stores
POWER SUPPLY
Power-Supply Voltage
V
DD
2.70
5.25
400
V
Writing to EEPROM, digital inputs at
GND or V , T = +25°C (Note 8)
250
DD
A
Supply Current
I
µA
DD
Normal operation,
digital inputs at GND or
WP = GND
WP = V
15
20.6
1
0.5
V
DD
, T = +25°C
DD
A
_______________________________________________________________________________________
3
2
Dual, 256-Tap, Nonvolatile, I C-Interface,
Digital Potentiometers
TIMING CHARACTERISTICS
(V
= +2.7V to +5.25V, H_ = V , L_ = GND, T = -40°C to +85°C, unless otherwise noted. Typical values are at V
= +5V,
DD
DD
DD
A
T
A
= +25°C. See Figure 1.) (Notes 9 and 10)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
ANALOG SECTION
MAX5477
325
500
Wiper Settling Time (Note 11)
t
ns
MAX5478
MAX5479
WS
1000
DIGITAL SECTION
SCL Clock Frequency
Setup Time for START Condition
Hold Time for START Condition
SCL High Time
f
400
kHz
µs
µs
µs
µs
ns
µs
ns
ns
µs
SCL
t
t
0.6
0.6
0.6
1.3
100
0
SU:STA
HD:STA
t
HIGH
SCL Low Time
t
LOW
Data Setup Time
t
t
SU:DAT
HD:DAT
Data Hold Time
0.9
300
300
SDA, SCL Rise Time
SDA, SCL Fall Time
Setup Time for STOP Condition
t
R
t
F
t
0.6
1.3
SU:STO
Bus Free Time Between STOP and
START Condition
t
Minimum power-up rate = 0.2V/µs
µs
BUF
Pulse Width of Spike Suppressed
Capacitive Load for Each Bus Line
Write NV Register Busy Time
t
50
400
12
ns
pF
ms
SP
C
(Note 12)
(Note 13)
B
8/MAX5479
Note 2: All devices are production tested at T = +25°C and are guaranteed by design and characterization for -40°C < T < +85°C.
A
A
Note 3: The DNL and INL are measured with the potentiometer configured as a voltage-divider with H_ = V
and L_ = GND. The
DD
wiper terminal is unloaded and measured with a high-input-impedance voltmeter.
Note 4: The DNL and INL are measured with the potentiometer configured as a variable resistor. H_ is unconnected and L_ =
GND. For V = +5V, the wiper is driven with 400µA (MAX5477), 80µA (MAX5478), or 40µA (MAX5479). For V = +3V,
DD
DD
the wiper is driven with 200µA (MAX5477), 40µA (MAX5478), or 20µA (MAX5479).
Note 5: The wiper resistance is measured using the source currents given in Note 3.
Note 6: The devices draw current in excess of the specified supply current when the digital inputs are driven with voltages between
(V - 0.5V) and (GND + 0.5V). See Supply Current vs. Digital Input Voltage in the Typical Operating Characteristics.
DD
Note 7: Wiper at midscale with a 10pF load (DC measurement). L_ = GND, an AC source is applied to H_, and the W_ output is
measured. A 3dB bandwidth occurs when the AC W_/H_ value is 3dB lower than the DC W_/H_ value.
Note 8: The programming current exists only during power-up and EEPROM writes.
Note 9: The SCL clock period includes rise and fall times (t = t ). All digital input signals are specified with t = t = 2ns and
R
F
R
F
timed from a voltage level of (V + V ) / 2.
IL
IH
Note 10: Digital timing is guaranteed by design and characterization, and is not production tested.
Note 11: This is measured from the STOP pulse to the time it takes the output to reach 50% of the output step size (divider mode). It
is measured with a maximum external capacitive load of 10pF.
Note 12: An appropriate bus pullup resistance must be selected depending on board capacitance. Refer to the I2C-bus specifica-
tion document linked to this web address: www.semiconductors.philips.com/acrobat/literature/9398/39340011.pdf
Note 13: The idle time begins from the initiation of the STOP pulse.
4
_______________________________________________________________________________________
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
8/MAX5479
Typical Operating Characteristics
(V
= +5V, H_ = V , L_ = GND, T = +25°C, unless otherwise noted.)
DD A
DD
SUPPLY CURRENT
vs. TEMPERATURE
SUPPLY CURRENT
vs. TEMPERATURE (MAX5477)
WIPER RESISTANCE
vs. INPUT CODE
500
450
400
350
300
250
200
150
100
50
15
13
11
9
1.0
WP = GND
WP = V
DD
V
= 5V
CC
0.8
0.6
0.4
0.2
0
V
= 5V
CC
V
= 3V
CC
V
= 3V
CC
7
5
0
-40
-15
10
35
60
85
-40
-15
10
35
60
85
0
32 64 96 128 160 192 224 256
INPUT CODE
TEMPERATURE (°C)
TEMPERATURE (°C)
TAP-TO-TAP SWITCHING TRANSIENT
TAP-TO-TAP SWITCHING TRANSIENT
TAP-TO-TAP SWITCHING TRANSIENT
MAX5477/78/79 toc04
MAX5477/78/79 toc03
MAX5477/78/79 toc05
SDA
2V/div
SDA
2V/div
SDA
2V/div
W_
20mV/div
W_
50mV/div
W_
20mV/div
MAX5478
C = 10pF
MAX5479
C = 10pF
W_
MAX5477
C = 10pF
L
L
H_ = V
DD
H_ = V
H_ = V
DD
DD
FROM TAP 00 TO TAP 04
FROM TAP 00 TO TAP 04
400ns/div
FROM TAP 00 TO TAP 04
1µs/div
200ns/div
WIPER TRANSIENT AT POWER-ON
WIPER TRANSIENT AT POWER-ON
WIPER TRANSIENT AT POWER-ON
MAX5477/78/79 toc07
MAX5477/78/79 toc08
MAX5477/78/79 toc06
V
DD
V
V
DD
DD
2V/div
2V/div
2V/div
W_
1V/div
W_
1V/div
W_
1V/div
MAX5479
TAP = 128
MAX5478
TAP = 128
MAX5477
TAP = 128
4µs/div
2µs/div
2µs/div
_______________________________________________________________________________________
5
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
Typical Operating Characteristics (continued)
(V
= +5V, H_ = V , L_ = GND, T = +25°C, unless otherwise noted.)
DD A
DD
INTEGRAL NONLINEARITY
vs. CODE (VDM MODE)
DIFFERENTIAL NONLINEARITY
vs. CODE (VDM MODE)
INTEGRAL NONLINEARITY
vs. CODE (VDM MODE)
0.3
0.2
0.1
0
0.3
0.2
0.1
0
0.35
MAX5477
MAX5477
MAX5478
0.30
0.25
0.20
0.15
0.10
0.05
0
-0.1
-0.2
-0.3
-0.1
-0.2
-0.3
0
32 64 96 128 160 192 224 256
CODE
0
32 64 96 128 160 192 224 256
CODE
0
32 64 96 128 160 192 224 256
CODE
DIFFERENTIAL NONLINEARITY
vs. CODE (VDM MODE)
INTEGRAL NONLINEARITY
vs. CODE (VRM MODE)
DIFFERENTIAL NONLINEARITY
vs. CODE (VRM MODE)
0.3
0.2
0.1
0
0.3
0.2
0.1
0
0.10
0.08
0.06
0.04
0.02
MAX5478
MAX5478
MAX5478
0
8/MAX5479
-0.02
-0.1
-0.2
-0.3
-0.1
-0.2
-0.3
-0.04
-0.06
-0.08
-0.10
0
32 64 96 128 160 192 224 256
CODE
0
32 64 96 128 160 192 224 256
CODE
0
32 64 96 128 160 192 224 256
CODE
INTEGRAL NONLINEARITY
vs. CODE (VDM MODE)
INTEGRAL NONLINEARITY
vs. CODE (VRM MODE)
DIFFERENTIAL NONLINEARITY
vs. CODE (VDM MODE)
0.20
0.16
0.12
0.08
0.04
0
0.20
0.16
0.12
0.08
0.04
0
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0
MAX5479
MAX5479
MAX5479
-0.02
-0.04
-0.08
-0.12
-0.16
-0.20
-0.04
-0.08
-0.12
-0.16
-0.20
-0.04
-0.06
-0.08
-0.10
-0.12
-0.14
0
32 64 96 128 160 192 224 256
CODE
0
32 64 96 128 160 192 224 256
CODE
0
32 64 96 128 160 192 224 256
CODE
6
_______________________________________________________________________________________
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
8/MAX5479
Typical Operating Characteristics (continued)
(V
= +5V, H_ = V , L_ = GND, T = +25°C, unless otherwise noted.)
DD A
DD
DIFFERENTIAL NONLINEARITY
vs. CODE (VRM MODE)
CROSSTALK vs.
FREQUENCY (MAX5477)
CROSSTALK vs.
FREQUENCY (MAX5478)
0.20
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
0
-10
-20
MAX5479
C
= 10pF
W_
CW_ = 10pF
0.16
0.12
0.08
0.04
0
-30
-40
-50
-60
-0.04
-0.08
-0.12
-0.16
-0.20
-70
-80
-90
-100
0
32 64 96 128 160 192 224 256
CODE
0.1
1
10
100
1000
10,000
0.01
0.1
1
10
100
1000
FREQUENCY (kHz)
FREQUENCY (kHz)
CROSSTALK vs.
FREQUENCY (MAX5479)
MIDSCALE WIPER RESPONSE
vs. FREQUENCY (MAX5478)
MIDSCALE WIPER RESPONSE
vs. FREQUENCY (MAX5477)
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
2
1
1
0
C
= 10pF
W_
C
= 10pF
W_
C
= 10pF
W_
0
-1
-1
-2
-3
-4
-5
-6
-7
-8
-2
-3
-4
-5
-6
-7
-8
C
= 50pF
W_
C
= 50pF
W_
0.1
1
10
100
1000 10,000
0.1
1
10
FREQUENCY (kHz)
100
1000
0.1
1
10
FREQUENCY (kHz)
100
1000
FREQUENCY (kHz)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (MAX5478)
10
MIDSCALE WIPER RESPONSE
vs. FREQUENCY (MAX5479)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (MAX5477)
1
2
1
MIDSCALE
MIDSCALE
1
0.1
0
0.1
-1
-2
-3
-4
-5
0.01
C
= 10pF
0.01
W_
0.001
0.0001
C
= 50pF
10
W_
0.001
0.01
0.1
1
10
100
0.1
1
100
1000
0.01
0.1
1
10
100
FREQUENCY (kHz)
FREQUENCY (kHz)
FREQUENCY (kHz)
_______________________________________________________________________________________
7
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
Typical Operating Characteristics (continued)
(V
= +5V, H_ = V , L_ = GND, T = +25°C, unless otherwise noted.)
DD A
DD
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (MAX5479)
END-TO-END RESISTANCE % CHANGE
vs. TEMPERATURE (MAX5478)
END-TO-END RESISTANCE % CHANGE
vs. TEMPERATURE (MAX5477)
0.5
0.4
10
0.6
0.4
0.2
0
MIDSCALE
1
0.3
0.2
0.1
0.01
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.2
-0.4
-0.6
0.001
0.0001
0.01
0.1
1
10
100
-40
-15
10
TEMPERATURE (°C)
35
60
85
-40
-15
10
35
60
85
FREQUENCY (kHz)
TEMPERATURE (°C)
END-TO-END RESISTANCE % CHANGE
vs. TEMPERATURE (MAX5479)
SUPPLY CURRENT
vs. DIGITAL INPUT VOLTAGE
0.5
0.4
600
550
500
WP = GND
0.3
450
400
350
300
0.2
8/MAX5479
0.1
V
= 5V
0
CC
250
200
-0.1
-0.2
-0.3
-0.4
-0.5
V
= 3V
CC
150
100
50
0
-40
-15
10
35
60
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)
8
_______________________________________________________________________________________
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
8/MAX5479
Pin Description
PIN
THIN QFN
NAME
FUNCTION
TSSOP
1
2
3
4
5
6
15
14
13
12
11
10
HA
WA
LA
Potentiometer A High Terminal
Potentiometer A Wiper Terminal
Potentiometer A Low Terminal
Potentiometer B High Terminal
Potentiometer B Wiper Terminal
Potentiometer B Low Terminal
HB
WB
LB
Write-Protect Input. Connect to GND to allow changes to the wiper position and the data stored
7
9
WP
in the EEPROM. Connect to V or leave unconnected to enable the write protection of the
DD
EEPROM. See the Write Protect (WP) section for operating instructions.
8
7
6
5
4
3
2
GND Ground
9
A2
A1
Address Input 2. Connect to V
or GND (see Table 1).
or GND (see Table 1).
or GND (see Table 1).
DD
DD
DD
10
11
12
13
Address Input 1. Connect to V
Address Input 0. Connect to V
A0
2
I C Serial Data
SDA
SCL
2
I C Clock Input
Power-Supply Input. Connect a +2.7V to +5.25V power supply to V
with a 0.1µF capacitor installed as close to the device as possible.
and bypass V
to GND
DD
DD
14
1
V
DD
—
—
8, 16
EP
N.C.
EP
No Connection. Do not connect.
Exposed Paddle. Do not connect.
SDA
SCL
t
BUF
t
SU:DAT
t
SU:STA
t
t
SU:STO
HD:DAT
t
LOW
t
HD:STA
t
HIGH
t
HD:STA
t
t
F
R
STOP
CONDITION
(P)
START
CONDITION
(S)
START
CONDITION
(S)
REPEATED START
CONDITION
(SR)
ACKNOWLEDGE
(A)
PARAMETERS ARE MEASURED FROM 30% TO 70%.
2
Figure 1. I C Serial-Interface Timing Diagram
_______________________________________________________________________________________
9
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
Analog Circuitry
Detailed Description
The MAX5477/MAX5478/MAX5479 consist of two resistor
arrays with 255 resistive elements; 256 tap points are
accessible to the wipers, along the resistor string
between H_ and L_. The wiper tap point is selected by
programming the potentiometer through the I2C inter-
face. An address byte, a command byte, and 8 data bits
program the wiper position for each potentiometer. The
H_ and L_ terminals of the MAX5477/MAX5478/
MAX5479 are similar to the two end terminals of a
mechanical potentiometer. The MAX5477/MAX5478/
MAX5479 feature power-on reset circuitry that loads the
wiper position from the nonvolatile memory at power-up.
The MAX5477/MAX5478/MAX5479 contain two resistor
arrays with 255 elements in each array. The MAX5477
has a total end-to-end resistance of 10kΩ, the
MAX5478 has an end-to-end resistance of 50kΩ, and
the MAX5479 has an end-to-end resistance of 100kΩ.
The MAX5477/MAX5478/MAX5479 provide access to
the high, low, and wiper terminals for a standard volt-
age-divider configuration. Connect H_, L_, and W_ in
any desired configuration as long as their voltages
remain between GND and V
.
DD
A simple 2-wire I2C-compatible serial interface moves
the wiper among the 256 tap points (Figure 2). A non-
volatile memory stores the wiper position and recalls
the stored wiper position upon power-up. The non-
volatile memory is guaranteed for 50 years for wiper
data retention and up to 200,000 wiper store cycles.
Table 1. Slave Addresses
H_
ADDRESS INPUTS
SLAVE ADDRESS
A2
A1
A0
S
256
GND
GND
GND
GND
GND
GND
GND
0101000
0101001
0101010
0101011
0101100
0101101
0101110
0101111
R
R
255
254
V
DD
S
S
255
V
V
GND
DD
DD
V
DD
8/MAX5479
V
V
V
V
GND
GND
GND
DD
DD
DD
DD
254
V
DD
R
W
256-POSITION
DECODER
V
GND
W_
DD
V
V
DD
DD
S
S
S
3
2
1
WIPER
CODE 02h
R
R
2
1
L_
Figure 2. Potentiometer Configuration
10 ______________________________________________________________________________________
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
8/MAX5479
Table 2. Write-Protect Behavior of VREG and NVREG
COMMAND
WP = 0
WP = 1
2
I C data is written to VREG.
Copy NVREG to VREG.
Wiper position updates with NVREG data.
No change to NVREG.
2
Write to VREG
Wiper position updates with I C data.
No change to NVREG.
No change to VREG or wiper position.
I C data is written to NVREG.
No change to VREG or wiper position.
No change to NVREG.
Write to NVREG
2
Copy NVREG to VREG.
Copy NVREG to VREG.
Wiper position updates with NVREG data.
No change to NVREG.
Wiper position updates with NVREG data.
No change to NVREG.
Copy NVREG to VREG
Copy VREG to NVREG
Copy VREG to NVREG.
No change to VREG or wiper position.
No change to VREG or wiper position.
No change to NVREG.
Table 3. Command Byte Summary
ADDRESS BYTE
COMMAND BYTE
DATA BYTE
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
NOTES
SCL CYCLE START
STOP
(P)
ACK
(A)
ACK
(A)
ACK
(A)
NUMBER
(S)
A6 A5 A4 A3 A2 A1 A0
TX NV V R3 R2 R1 R0
D7 D6 D5 D4 D3 D2 D1 D0
VREG
NVREG
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
A2 A1 A0
A2 A1 A0
A2 A1 A0
A2 A1 A0
A2 A1 A0
A2 A1 A0
A2 A1 A0
A2 A1 A0
A2 A1 A0
A2 A1 A0
A2 A1 A0
A2 A1 A0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
1
1
0
0
1
1
0
1
1
0
0
1
1
0
0
1
1
0
1
0
0
1
1
0
0
1
1
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
WIPER A
ONLY
NVREGxVREG
VREGxNVREG
VREG
NVREG
WIPER B
ONLY
NVREGxVREG
VREGxNVREG
VREG
NVREG
WIPERS
A AND B
NVREGxVREG
VREGxNVREG
Digital Interface
Write Protect (WP)
A write-protect feature prevents accidental overwriting of
the EEPROM. Connect WP to V or leave unconnected
The MAX5477/MAX5478/MAX5479 feature an internal,
nonvolatile EEPROM that stores the wiper state for ini-
tialization during power-up. The shift register decodes
the command and address bytes, routing the data to
the proper memory registers. Data written to a volatile
memory register immediately updates the wiper posi-
tion, or writes data to a nonvolatile register for storage
(see Table 3).
DD
to prevent any EEPROM write cycles. Writing to the
volatile register (VREG) while WP = 1 updates the wiper
position with the protected data stored in the nonvolatile
register (NVREG). Connect WP to GND to allow write
commands to the EEPROM and to update the wiper
position from either the value in the EEPROM or directly
from the I2C interface (Table 2). Connecting WP to GND
increases the supply current by 19.6µA (max).
The volatile register retains data as long as the device
is powered. Removing power clears the volatile regis-
ter. The nonvolatile register retains data even after
power is removed. Upon power-up, the power-on reset
circuitry controls the transfer of data from the non-
volatile register to the volatile register.
To ensure a fail-safe, write-protect feature, write the
data to be protected to both the nonvolatile and volatile
registers before pulling WP high. Releasing WP (WP =
0) and sending partial or invalid I2C commands (such
as single-byte address polling) can load the volatile
______________________________________________________________________________________ 11
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
register with input shift register data and change the
wiper position. Use valid 3-byte I2C commands for
proper operation. This precautionary operation is nec-
SDA
essary only when transitioning from write protected
(WP = 1) to not write protected (WP = 0).
Serial Addressing
S
P
SCL
The MAX5477/MAX5478/MAX5479 operate as slave
devices that send and receive data through an I2C-/
SMBus™-compatible 2-wire serial interface. The inter-
face uses a serial data access (SDA) line and a serial
clock line (SCL) to achieve bidirectional communication
between master(s) and slave(s). A master, typically a
microcontroller, initiates all data transfers to the
MAX5477/MAX5478/MAX5479, and generates the SCL
clock that synchronizes the data transfer (Figure 1).
START
CONDITION
STOP
CONDITION
Figure 3. START and STOP Conditions
communicating with the slave. The bus is then free for
another transmission (Figure 3).
Bit Transfer
One data bit is transferred during each clock pulse.
The data on the SDA line must remain stable while SCL
is high (Figure 5).
The MAX5477/MAX5478/MAX5479 SDA line operates
as both an input and an open-drain output. The SDA
line requires a pullup resistor, typically 4.7kΩ. The
MAX5477/MAX5478/MAX5479 SCL line operates only
as an input. The SCL line requires a pullup resistor (typ-
ically 4.7kΩ) if there are multiple masters on the 2-wire
interface, or if the master in a single-master system has
an open-drain SCL output. SCL and SDA should not
Acknowledge
The acknowledge bit is a clocked 9th bit that the recipient
uses to handshake receipt of each byte of data (Figure
6). Thus, each byte transferred effectively requires 9 bits.
The master controller generates the 9th clock pulse, and
the recipient pulls down SDA during the acknowledge
clock pulse, so the SDA line remains stable low during
the high period of the clock pulse.
exceed V
in a mixed-voltage system, despite the
DD
open-drain drivers.
Each transmission consists of a START (S) condition
(Figure 3) sent by a master, followed by the
MAX5477/MAX5478/MAX5479 7-bit slave address plus
the NOP/W bit (Figure 4), 1 command byte and 1 data
byte, and finally a STOP (P) condition (Figure 3).
8/MAX5479
Slave Address
The MAX5477/MAX5478/MAX5479 have a 7-bit-long
slave address (Figure 4). The 8th bit following the 7-bit
slave address is the NOP/W bit. Set the NOP/W bit low for
a write command and high for a no-operation command.
START and STOP Conditions
Both SCL and SDA remain high when the interface is
not busy. A master controller signals the beginning of a
transmission with a START condition by transitioning
SDA from high to low while SCL is high. The master
controller issues a STOP condition by transitioning the
SDA from low to high while SCL is high, when it finishes
The MAX5477/MAX5478/MAX5479 provide three
address inputs (A0, A1, and A2), allowing up to eight
devices to share a common bus (Table 1). The first 4
bits (MSBs) of the MAX5477/MAX5478/MAX5479 slave
addresses are always 0101. A2, A1, and A0 set the next
SDA
0
1
0
1
A2
A1
A0
NOP/W
ACK
START
MSB
LSB
SCL
Figure 4. Slave Address
SMBus is a trademark of Intel Corporation.
12 ______________________________________________________________________________________
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
8/MAX5479
CLOCK PULSE FOR
ACKNOWLEDGMENT
START
SDA
SCL
CONDITION
SCL
1
2
8
9
NOT ACKNOWLEDGE
SDA
DATA STABLE, CHANGE OF
DATA VALID DATA ALLOWED
ACKNOWLEDGE
Figure 5. Bit Transfer
Figure 6. Acknowledge
COMMAND BYTE IS STORED ON RECEIPT OF STOP CONDITION
D15
D14
D13
D12
D11
D10
D9
D8
ACKNOWLEDGE FROM
MAX5477/MAX5478/MAX5479
S
SLAVE ADDRESS
0
A
COMMAND BYTE
A
P
ACKNOWLEDGE FROM
MAX5477/MAX5478/MAX5479
NOP/W
Figure 7. Command Byte Received
ACKNOWLEDGE FROM
MAX5477/MAX5478/MAX5479
ACKNOWLEDGE FROM
MAX5477/MAX5478/MAX5479
HOW CONTROL BYTE AND DATA BYTE MAP INTO
MAX5477/MAX5478/MAX5479 REGISTERS
D15 D14 D13 D12 D11 D10 D9 D8
D7 D6 D5 D4 D3 D2 D1 D0
ACKNOWLEDGE FROM
MAX5477/MAX5478/MAX5479
A
P
S
SLAVE ADDRESS
0
A
COMMAND BYTE
A
DATA BYTE
1 BYTE
NOP/W
Figure 8. Command and Single Data Byte Received
3 bits in the slave address. Connect each address input
Command Byte
to V
or GND to set these 3 bits. Each device must
Use the command byte to select the source and desti-
nation of the wiper data (nonvolatile or volatile memory
registers) and swap data between nonvolatile and
volatile memory registers (see Table 3).
DD
have a unique address to share a common bus.
Message Format for Writing
Write to the MAX5477/MAX5478/MAX5479 by transmit-
ting the device’s slave address with NOP/W (8th bit) set
to zero, followed by at least 1 byte of information
(Figure 7). The 1st byte of information is the command
byte. The bytes received after the command byte are
the data bytes. The 1st data byte goes into the internal
register of the MAX5477/MAX5478/MAX5479 as select-
ed by the command byte (Figure 8).
Command Descriptions
VREG: The data byte writes to the volatile memory reg-
ister and the wiper position updates with the data in the
volatile memory register.
NVREG: The data byte writes to the nonvolatile memory
register. The wiper position is unchanged.
NVREGxVREG: Data transfers from the nonvolatile
memory register to the volatile memory register (wiper
position updates).
______________________________________________________________________________________ 13
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
5V
5V
H_
30V
30V
W_
MAX5477
MAX5478
MAX5479
V
OUT
H_
L_
V
MAX480
OUT
MAX480
L_
MAX5477
MAX5478
MAX5479
W_
Figure 10. Positive LCD Bias Control Using a Variable Resistor
Figure 9. Positive LCD Bias Control Using a Voltage-Divider
VREGxNVREG: Data transfers from the volatile memory
register into the nonvolatile memory register.
Positive LCD Bias Control
Figures 9 and 10 show an application where the
MAX5477/MAX5478/MAX5479 provide an adjustable,
positive LCD bias voltage. The op amp provides buffer-
ing and gain to the resistor-divider network made by
the potentiometer (Figure 9) or by a fixed resistor and a
variable resistor (see Figure 10).
Nonvolatile Memory
The internal EEPROM consists of a 16-bit nonvolatile
register that retains the value written to it prior to power
down. The nonvolatile register is programmed with the
midscale value at the factory. The nonvolatile memory
is guaranteed for 50 years for wiper position retention
and up to 200,000 wiper write cycles. A write-protect
feature prevents accidental overwriting of the EEPROM.
Programmable Filter
Figure 11 shows the MAX5477/MAX5478/MAX5479 in a
1st-order programmable application filter. Adjust the
Connect WP to V
or leave open to enable the write-
gain of the filter with R , and set the cutoff frequency
2
DD
8/MAX5479
protect feature. The wiper position only updates with
with R . Use the following equations to calculate the
3
the value in the EEPROM when WP = V . Connect WP
DD
gain (A) and the -3dB cutoff frequency (f ):
C
to GND to allow EEPROM write cycles and to update
the wiper position from nonvolatile memory or directly
from the I2C serial interface.
R
R
1
A =1+
2
Power-Up
Upon power-up, the MAX5477/MAX5478/MAX5479
load the data stored in the nonvolatile memory register
into the volatile memory register, updating the wiper
position with the data stored in the nonvolatile memory
register. This initialization period takes 10µs.
1
f
=
C
2π × R × C
3
Offset Voltage and Gain Adjustment
Connect the high and low terminals of one potentiome-
ter of a MAX5477 between the NULL inputs of a
MAX410 and the wiper to the op amp’s positive supply
to nullify the offset voltage over the operating tempera-
ture range. Install the other potentiometer in the feed-
back path to adjust the gain of the MAX410 (Figure 12).
Standby
The MAX5477/MAX5478/MAX5479 feature a low-power
standby mode. When the device is not being pro-
grammed, it enters into standby mode and supply cur-
rent drops to 500nA (typ).
Adjustable Voltage Reference
Figure 13 shows the MAX5477/MAX5478/MAX5479
used as the feedback resistors in multiple adjustable
voltage reference applications. Independently adjust
the output voltages of the MAX6160 parts from 1.23V to
- 0.2V by changing the wiper positions of the
MAX5477/MAX5478/MAX5479.
Applications Information
The MAX5477/MAX5478/MAX5479 are ideal for circuits
requiring digitally controlled adjustable resistance,
such as LCD contrast control (where voltage biasing
adjusts the display contrast), or for programmable fil-
ters with adjustable gain and/or cutoff frequency.
V
IN
14 ______________________________________________________________________________________
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
8/MAX5479
5V
WA
V+
1/2 MAX5477
WA
LA
V
IN
HA
HA
LA
R
3
C
V
OUT
MAX410
7
3
2
1
8
MAX5477
MAX5478
MAX5479
V-
6
MAX410
R
1
4
R = R x D / 256
WHERE R = END-TO-END RESISTANCE
2
HL
HB
R1
R , R = R x D / 256
HL
2
3
HL
AND = D DECIMAL VALUE OF WIPER CODE
WHERE R = END-TO-END RESISTANCE
HL
AND D = DECIMAL VALUE OF WIPER CODE
HB
WB
R
2
1/2 MAX5477
R2
WB
LB
LB
Figure 11. Programmable Filter
Figure 12. Offset Voltage Adjustment Circuit
5V
10kΩ
V
V
V
= 1.23V x
= 1.23V x
= 1.23V x
FOR THE MAX5477
FOR THE MAX5478
FOR THE MAX5479
IN
IN
OUT_
OUT_
OUT_
R
V
OUT
ADJ
OUT
V
OUT1
OUT2
50kΩ
R
HB
LB
HA
MAX6160
MAX6160
100kΩ
R
WA
WB
1/2 MAX5477
1/2 MAX5478
1/2 MAX5479
1/2 MAX5477
1/2 MAX5478
1/2 MAX5479
ADJ
WHERE R = R x D / 256
HL
AND D = DECIMAL VALUE OF WIPER CODE
R
R
GND
GND
LA
Figure 13. Adjustable Voltage Reference
Pin Configurations
Chip Information
PROCESS: BiCMOS
TOP VIEW
Package Information
N.C. HA
WA
14
LA
13
For the latest package outline information and land patterns
(footprints), go to www.maxim-ic.com/packages. Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
+
+
16
15
HA
WA
LA
1
2
3
4
5
6
7
14 V
DD
V
DD
HB
WB
LB
1
12
11
10
9
13 SCL
12 SDA
11 A0
SCL
SDA
A0
2
3
4
MAX5477
MAX5478
MAX5479
MAX5477
MAX5478
MAX5479
HB
WB
LB
PACKAGE
TYPE
16 TQFN-EP
PACKAGE
CODE
OUTLINE
NO.
21-0136
LAND
10 A1
PATTERN NO.
WP
9
8
A2
T1633F+3
90-0033
5
6
7
8
WP
GND
14 TSSOP
U14+1
21-0066
90-0113
A1
A2 GND
N.C.
THIN QFN
(3mm x 3mm)
TSSOP
(4.4mm x 5mm)
______________________________________________________________________________________ 15
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
Revision History
REVISION REVISION
PAGES
CHANGED
DESCRIPTION
NUMBER
DATE
0
4
5
8/04
1/09
Initial release
—
1
Updated Ordering Information for lead-free information.
Released TQFN packages, revised Ordering Information.
11/11
1–4, 15, 16
8/MAX5479
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. The parametric values (min and max limits) shown in
the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2011 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
相关型号:
MAX5477ETE+
Digital Potentiometer, 1 Func, 10000ohm, 2-wire Serial Control Interface, 256 Positions, BICMOS, TQFN-16
MAXIM
MAX5477EUD+T
Digital Potentiometer, 1 Func, 10000ohm, 2-wire Serial Control Interface, 256 Positions, BICMOS, PDSO14, 4.40 X 5 MM, LEAD FREE, MO-153AB-1, TSSOP-14
MAXIM
MAX5478ETE#G16
Digital Potentiometer, 1 Func, 50000ohm, 2-wire Serial Control Interface, 256 Positions, BICMOS, 3 X 3 MM, 0.80 MM HEIGHT, MO-220WEED-2, TQFN-16
MAXIM
©2020 ICPDF网 联系我们和版权申明