General Description
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 potentiometer or variable resistor and has 256 tap points.
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-compatible 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.
The MAX5477/MAX5478/MAX5479 provide three nominal resistance values: 10kΩ (MAX5477), 50kΩ
(MAX5478), or 100kΩ (MAX5479). The nominal resistor
temperature coefficient is 35ppm/°C end-to-end and
5ppm/°C ratiometric. The low temperature coefficient
makes the devices ideal for applications requiring a lowtemperature-coefficient variable resistor, such as lowdrift, programmable gain-amplifier circuit configurations.
The MAX5477/MAX5478/MAX5479 are available in 16pin 3mm x 3mm x 0.8mm thin QFN and 14-pin 4.4mm x
5mm TSSOP packages. These devices operate over
the extended -40°C to +85°C temperature range.
Applications
Mechanical Potentiometer Replacement
Low-Drift Programmable-Gain Amplifiers
Volume Control
Liquid-Crystal Display (LCD) Contrast Control
Features
♦ Power-On Recall of Wiper Position from
Nonvolatile Memory
♦ EEPROM Write Protection
♦ Tiny 3mm x 3mm x 0.8mm Thin QFN Package
♦ 35ppm/°C End-to-End Resistance Temperature
Coefficient
♦ 5ppm/°C Ratiometric Temperature Coefficient
♦ Fast 400kbps I2C†-Compatible Serial Interface
♦ 1µA (max) Static Supply Current
♦ Single-Supply Operation: +2.7V to +5.25V
♦ 256 Tap Positions per Potentiometer
♦ ±0.5 LSB DNL in Voltage-Divider Mode
♦ ±1 LSB INL in Voltage-Divider Mode
MAX5477/MAX5478/MAX5479
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
________________________________________________________________ Maxim Integrated Products 1
MAX5477
MAX5478
MAX5479
8-BIT
SHIFT
REGISTER
POR
16-BIT
LATCH
16-BIT
NV
MEMORY
SDA
SCL
WP
A0
A1
A2
8
256
POSITION
DECODER
8
8
256
256
POSITION
DECODER
256
HA
WA
LA
HB
WB
LB
V
DD
GND
I2C
INTERFACE
Ordering Information/Selector Guide
Functional Diagram
19-3379; Rev 2; 12/04
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.
Pin Configurations appear at end of data sheet.
†Purchase of I
2
C components from Maxim Integrated
Products, Inc. or one of its sublicensed Associated
Companies, conveys a license under the Philips I
2
C Patent
Rights to use these components in an I
2
C system, provided
that the system conforms to the I
2
C Standard Specification as
defined by Philips.
PART TEMP RANGE PIN-PACKAGE
END-TO-END
RESISTANCE (kΩ)
TOP
MARK
PACKAGE CODE
MAX5477ETE* -40°C to +85°C 16 Thin QFN 10 ABO T1633F-3
MAX5477EUD* -40°C to +85°C 14 TSSOP 10 — —
MAX5478ETE* -40°C to +85°C 16 Thin QFN 50 ABP T1633F-3
MAX5478EUD -40°C to +85°C 14 TSSOP 50 — —
MAX5479ETE* -40°C to +85°C 16 Thin QFN 100 ABQ T1633F-3
MAX5479EUD -40°C to +85°C 14 TSSOP 100 — —
*Future product—contact factory for availability.
MAX5477/MAX5478/MAX5479
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VDD= +2.7V to +5.25V, H_ = VDD, L_ = GND, TA= -40°C to +85°C, unless otherwise noted. Typical values are at VDD= +5V, TA=
+25°C.) (Note 1)
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.
SDA, SCL, VDDto GND.........................................-0.3V to +6.0V
All Other Pins to GND.................................-0.3V to (V
DD
+ 0.3V)
Maximum Continuous Current into H_, L_, and W_
MAX5477......................................................................
±5.0mA
MAX5478......................................................................±1.3mA
MAX5479......................................................................±0.6mA
Continuous Power Dissipation (T
A
= +70°C)
16-Pin Thin QFN (derate 17.5mW/°C above +70°C) 1399mW
14-Pin TSSOP (derate 9.1mW/°C above +70°C) .........727mW
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
PARAMETER
SYMBOL
CONDITIONS MIN TYP MAX
UNITS
DC PERFORMANCE (VOLTAGE-DIVIDER MODE)
Resolution 256
Taps
Integral Nonlinearity INL (Note 2) ±1 LSB
Differential Nonlinearity DNL (Note 2) ±0.5 LSB
Dual Code Matching
±1 LSB
End-to-End Resistance
Temperature Coefficient
TC
R
35
ppm/°C
Ratiometric Resistance
Temperature Coefficient
5
ppm/°C
MAX5477 -3
MAX5478 -0.6
Full-Scale Error
MAX5479 -0.3
LSB
MAX5477 3
MAX5478 0.6Zero-Scale Error
MAX5479 0.3
LSB
DC PERFORMANCE (VARIABLE-RESISTOR MODE)
V
DD
= 3V ±3
Integral Nonlinearity (Note 3) INL
V
DD
= 5V ±1.5
LSB
V
DD
= 3V, MAX5477, guaranteed
monotonic
±1
VDD = 3V, MAX5478 ±1
VDD = 3V, MAX5479 ±1
Differential Nonlinearity (Note 3) DNL
V
DD
= 5V ±1
LSB
Dual Code Matching
R0 and R1 set to same code
(all codes), V
DD
= 3V or 5V
±3 LSB
DC PERFORMANCE (RESISTOR CHARACTERISTICS)
Wiper Resistance R
W
(Note 4) 325 675 Ω
Wiper Capacitance C
W
10 pF
MAX5477 7.5 10 12.5
MAX5478 37.5 50 62.5End-to-End Resistance R
HL
MAX5479 75 100 125
kΩ
R0 and R1 set to same code (all codes)
MAX5477/MAX5478/MAX5479
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VDD= +2.7V to +5.25V, H_ = VDD, L_ = GND, TA= -40°C to +85°C, unless otherwise noted. Typical values are at VDD= +5V, TA=
+25°C.) (Note 1)
PARAMETER
CONDITIONS MIN TYP MAX
UNITS
DIGITAL INPUTS
VDD = 3.4V to 5.25V 2.4
Input High Voltage (Note 5) V
IH
VDD < 3.4V
V
Input Low Voltage V
IL
(Note 5) 0.8 V
Output Low Voltage V
OL
I
SINK
= 3mA 0.4 V
WP Pullup Resistance I
WP
255 kΩ
Input Leakage Current I
LEAK
±1 µA
Input Capacitance 5pF
DYNAMIC CHARACTERISTICS
Crosstalk
HA = 1kHz (0 to V
DD
), LA = GND,
LB = GND, measure WB
-80 dB
MAX5478 100
3dB Bandwidth (Note 6)
MAX5479 50
kHz
Total Harmonic Distortion Plus
Noise
H_ = 1V
RMS
, f = 1kHz, L_ = GND,
measure W_
%
NONVOLATILE MEMORY RELIABILITY
Data Retention TA = +85°C 50
Years
TA = +25°C
Endurance
T
A
= +85°C
Stores
POWER SUPPLY
Power-Supply Voltage V
DD
2.70 5.25 V
Writing to EEPROM, digital inputs at
GND or V
DD
(Note 7)
250 400
15 20.6
Supply Current I
DD
Normal operation, digital
inputs at GND or V
DD
WP = V
DD
0.5 1
µA
TIMING CHARACTERISTICS
(VDD= +2.7V to +5.25V, H_ = VDD, L_ = GND, TA= -40°C to +85°C, unless otherwise noted. Typical values are at VDD= +5V,
T
A
= +25°C. See Figure 1.) (Notes 8 and 9)
SYMBOL
THD+N
0.7 x V
DD
0.003
200,000
50,000
ANALOG SECTION
Wiper Settling Time (Note 10) t
DIGITAL SECTION
SCL Clock Frequency f
Setup Time for START Condition t
Hold Time for START Condition t
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
SU:STA
HD:STA
WP = GND
WS
SCL
MAX5478 500
MAX5479 1000
0.6 µs
0.6 µs
400 kHz
ns
MAX5477/MAX5478/MAX5479
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
4 _______________________________________________________________________________________
Note 1: All devices are production tested at TA= +25°C and are guaranteed by design and characterization for -40°C < TA< +85°C.
Note 2: The DNL and INL are measured with the potentiometer configured as a voltage-divider with H_ = V
DD
and L_ = GND. The
wiper terminal is unloaded and measured with a high-input-impedance voltmeter.
Note 3: The DNL and INL are measured with the potentiometer configured as a variable resistor. H_ is unconnected and L_ =
GND. For V
DD
= +5V, the wiper is driven with 400µA (MAX5477), 80µA (MAX5478), or 40µA (MAX5479). For VDD= +3V,
the wiper is driven with 200µA (MAX5477), 40µA (MAX5478), or 20µA (MAX5479).
Note 4: The wiper resistance is measured using the source currents given in Note 3.
Note 5: The devices draw 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 Supply Current vs. Digital Input Voltage in the Typical Operating Characteristics.
Note 6: 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 7: The programming current exists only during power-up and EEPROM writes.
Note 8: The SCL clock period includes rise and fall times (t
R
= tF). All digital input signals are specified with tR= tF= 2ns and
timed from a voltage level of (V
IL
+ VIH) / 2.
Note 9: Digital timing is guaranteed by design and characterization, and is not production tested.
Note 10: 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 11: An appropriate bus pullup resistance must be selected depending on board capacitance. Refer to the I
2
C-bus specifica-
tion document linked to this web address: www.semiconductors.philips.com/acrobat/literature/9398/39340011.pdf
Note 12: The idle time begins from the initiation of the STOP pulse.
PARAMETER
CONDITIONS
UNITS
SCL High Time t
HIGH
0.6 µs
SCL Low Time t
LOW
1.3 µs
Data Setup Time
100 ns
Data Hold Time
0 0.9 µs
SDA, SCL Rise Time t
R
300 ns
SDA, SCL Fall Time t
F
300 ns
Setup Time for STOP Condition
0.6 µs
Bus Free Time Between STOP
and START Condition
t
BUF
Minimum power-up rate = 0.2V/µs 1.3 µs
Pulse Width of Spike Suppressed
t
SP
50 ns
Capacitive Load for Each Bus
Line
C
B
(Note 11) 400 pF
Write NV Register Busy Time (Note 12) 12 ms
TIMING CHARACTERISTICS (continued)
(VDD= +2.7V to +5.25V, H_ = VDD, L_ = GND, TA= -40°C to +85°C, unless otherwise noted. Typical values are at VDD= +5V,
T
A
= +25°C. See Figure 1.) (Notes 8 and 9)
SYMBOL
t
SU:DAT
t
HD:DAT
t
SU:STO
MIN TYP MAX
MAX5477/MAX5478/MAX5479
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
_______________________________________________________________________________________ 5
SUPPLY CURRENT
vs. TEMPERATURE
MAX5477/78/79 toc01
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
603510-15
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0
-40 85
VDD = 5V
VDD = 3V
0
100
50
200
150
300
250
350
450
400
500
0649632 128 160 192 224 256
WIPER RESISTANCE
vs. INPUT CODE
MAX5477/78/79 toc02
INPUT CODE
WIPER RESISTANCE (Ω)
TAP-TO-TAP SWITCHING TRANSIENT
MAX5477/78/79 toc03
1µs/div
SDA
2V/div
W_
20mV/div
MAX5478
C
L
= 10pF
H_ = V
DD
FROM TAP 00 TO TAP 04
TAP-TO-TAP SWITCHING TRANSIENT
MAX5477/78/79 toc04
400ns/div
SDA
2V/div
W_
20mV/div
MAX5479
C
W_
= 10pF
H_ = V
DD
FROM TAP 00 TO TAP 04
WIPER TRANSIENT AT POWER-ON
MAX5477/78/79 toc05
4µs/div
V
DD
2V/div
W_
1V/div
MAX5478
TAP = 128
WIPER TRANSIENT AT POWER-ON
MAX5477/78/79 toc06
2µs/div
V
DD
2V/div
W_
1V/div
MAX5479
TAP = 128
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
06432 96 128 160 192 224 256
INTEGRAL NONLINEARITY
vs. CODE (VDM MODE)
MAX5477/78/79 toc07
CODE
INL (LSB)
MAX5478
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
06432 96 128 160 192 224 256
DIFFERENTIAL NONLINEARITY
vs. CODE (VDM MODE)
MAX5477/78/79 toc08
CODE
DNL (LSB)
MAX5478
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
06432 96 128 160 192 224 256
INTEGRAL NONLINEARITY
vs. CODE (VRM MODE)
MAX5477/78/79 toc09
CODE
INL (LSB)
MAX5478
Typical Operating Characteristics
(VDD= +5V, H_ = VDD, L_ = GND, TA= +25°C, unless otherwise noted.)
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