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PDF MAX5479 Data sheet ( Hoja de datos )
| Número de pieza | MAX5479 | |
| Descripción | Dual - 256-Tap/ Nonvolatile/ I2C-Interface/ Digital Potentiometers | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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19-3379; Rev 2; 12/04
www.DataSheet4U.com
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
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 poten-
tiometer 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-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.
The MAX5477/MAX5478/MAX5479 provide three nomi-
nal 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 low-
temperature-coefficient variable resistor, such as low-
drift, programmable gain-amplifier circuit configurations.
The MAX5477/MAX5478/MAX5479 are available in 16-
pin 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.
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
Functional Diagram
VDD
8-BIT
GND
SHIFT 8
REGISTER
16-BIT
LATCH
8 256 256
POSITION
DECODER
POR
SDA
I2C
SCL INTERFACE
WP
16-BIT
NV
MEMORY
8
256 256
POSITION
DECODER
HA
WA
LA
HB
WB
Applications
Mechanical Potentiometer Replacement
Low-Drift Programmable-Gain Amplifiers
Volume Control
Liquid-Crystal Display (LCD) Contrast Control
A0 MAX5477
A1 MAX5478
A2 MAX5479
LB
†Purchase of I2C components from Maxim Integrated
Products, Inc. or one of its sublicensed Associated
Companies, conveys a license under the Philips I2C Patent
Rights to use these components in an I2C system, provided
that the system conforms to the I2C Standard Specification as
defined by Philips.
Ordering Information/Selector Guide
PART
TEMP RANGE
PIN-PACKAGE
MAX5477ETE*
-40°C to +85°C 16 Thin QFN
MAX5477EUD*
-40°C to +85°C 14 TSSOP
MAX5478ETE*
-40°C to +85°C 16 Thin QFN
MAX5478EUD
-40°C to +85°C 14 TSSOP
MAX5479ETE*
-40°C to +85°C 16 Thin QFN
MAX5479EUD
-40°C to +85°C 14 TSSOP
*Future product—contact factory for availability.
END-TO-END
RESISTANCE (kΩ)
10
10
50
50
100
100
TOP
MARK
ABO
—
ABP
—
ABQ
—
PACKAGE CODE
T1633F-3
—
T1633F-3
—
T1633F-3
—
Pin Configurations appear at end of data sheet.
________________________________________________________________ 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.
1 page  
www.DataSheet4U.com
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
Typical Operating Characteristics
(VDD = +5V, H_ = VDD, L_ = GND, TA = +25°C, unless otherwise noted.)
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-40
SUPPLY CURRENT
vs. TEMPERATURE
VDD = 5V
VDD = 3V
-15 10 35 60
TEMPERATURE (°C)
85
WIPER RESISTANCE
vs. INPUT CODE
500
450
400
350
300
250
200
150
100
50
0
0 32 64 96 128 160 192 224 256
INPUT CODE
TAP-TO-TAP SWITCHING TRANSIENT
MAX5477/78/79 toc03
SDA
2V/div
MAX5478
CL = 10pF
H_ = VDD
FROM TAP 00 TO TAP 04
W_
20mV/div
1µs/div
TAP-TO-TAP SWITCHING TRANSIENT
MAX5477/78/79 toc04
SDA
2V/div
WIPER TRANSIENT AT POWER-ON
MAX5477/78/79 toc05
VDD
2V/div
WIPER TRANSIENT AT POWER-ON
MAX5477/78/79 toc06
VDD
2V/div
MAX5479
CW_ = 10pF
H_ = VDD
FROM TAP 00 TO TAP 04
W_
20mV/div
400ns/div
4µs/div
MAX5478
TAP = 128
W_
1V/div
MAX5479
TAP = 128
W_
1V/div
2µs/div
INTEGRAL NONLINEARITY
vs. CODE (VDM MODE)
0.3
MAX5478
0.2
0.1
0
-0.1
-0.2
-0.3
0
32 64 96 128 160 192 224 256
CODE
DIFFERENTIAL NONLINEARITY
vs. CODE (VDM MODE)
0.3
MAX5478
0.2
0.1
0
-0.1
-0.2
-0.3
0
32 64 96 128 160 192 224 256
CODE
INTEGRAL NONLINEARITY
vs. CODE (VRM MODE)
0.3
MAX5478
0.2
0.1
0
-0.1
-0.2
-0.3
0
32 64 96 128 160 192 224 256
CODE
_______________________________________________________________________________________ 5
5 Page 
www.
Dual, 256-Tap, Nonvolatile, I2C-Interface,
Digital Potentiometers
D
COMMAND BYTE IS STORED ON RECEIPT OF STOP CONDITION
ACKNOWLEDGE FROM
MAX5477/MAX5478/MAX5479
S SLAVE ADDRESS
0A
NOP/W
Figure 7. Command Byte Received
D15 D14 D13 D12 D11 D10 D9 D8
COMMAND BYTE
A
ACKNOWLEDGE FROM
MAX5477/MAX5478/MAX5479
P
HOW CONTROL BYTE AND DATA BYTE MAP INTO
MAX5477/MAX5478/MAX5479 REGISTERS
ACKNOWLEDGE FROM
MAX5477/MAX5478/MAX5479
ACKNOWLEDGE FROM
MAX5477/MAX5478/MAX5479
D15 D14 D13 D12 D11 D10 D9 D8
ACKNOWLEDGE FROM
MAX5477/MAX5478/MAX5479
D7 D6 D5 D4 D3 D2 D1 D0
S SLAVE ADDRESS
0A
COMMAND BYTE
A
DATA BYTE
A
P
NOP/W
Figure 8. Command and Single Data Byte Received
slave address is the NOP/W bit. Set the NOP/W bit low for
a write command and high for a no-operation command.
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
3 bits in the slave address. Connect each address input
to VDD or GND to set these 3 bits. Each device must
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 Byte
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 2).
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.
1 BYTE
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).
VREGxNVREG: Data transfers from the volatile memory
register into the nonvolatile memory register.
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.
Connect WP to VDD or leave open to enable the write-
protect feature. The wiper position only updates with
the value in the EEPROM when WP = VDD. Connect WP
to GND to allow EEPROM write cycles and to update
the wiper position from nonvolatile memory or directly
from the I2C serial interface.
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.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet MAX5479.PDF ] | |
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