MAXIM MAX5489

19-3478; Rev 1; 1/05
Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers
The MAX5487/MAX5488/MAX5489 dual, linear-taper,
digital potentiometers function as mechanical potentiometers with a simple 3-wire SPI™-compatible digital
interface that programs the wipers to any one of 256
tap positions. These digital potentiometers feature a
nonvolatile memory (EEPROM) to return the wipers to
their previously stored positions upon power-up.
The MAX5487 has an end-to-end resistance of 10kΩ,
while the MAX5488 and MAX5489 have resistances of
50kΩ and 100kΩ, respectively. These devices have a
low 35ppm/°C end-to-end temperature coefficient, and
operate from a single +2.7V to +5.25V supply.
The MAX5487/MAX5488/MAX5489 are available in a
16-pin 3mm x 3mm x 0.8mm thin QFN package. Each
device is guaranteed over the extended -40°C to +85°C
temperature range.
Features
♦ Wiper Position Stored in Nonvolatile Memory
(EEPROM) and Recalled Upon Power-Up or
Recalled by an Interface Command
♦ 3mm x 3mm x 0.8mm Thin QFN Package
♦ ±1 LSB INL, ±0.5 LSB DNL (Voltage-Divider Mode)
♦ 256 Tap Positions
♦ 35ppm/°C End-to-End Resistance Temperature
Coefficient
♦ 5ppm/°C Ratiometric Temperature Coefficient
♦ 10kΩ, 50kΩ, and 100kΩ End-to-End Resistance
Values
♦ SPI-Compatible Serial Interface
LCD Screen Adjustment
♦ Reliability
200,000 Wiper Store Cycles
50-Year Wiper Data Retention
Audio Volume Control
♦ +2.7V to +5.25V Single-Supply Operation
Applications
Mechanical Potentiometer Replacement
Low-Drift Programmable Filters
SPI is a trademark of Motorola, Inc.
Low-Drift Programmable-Gain Amplifiers
Ordering Information/Selector Guide
PART
TEMP RANGE
PIN-PACKAGE
END-TO-END
RESISTANCE (kΩ)
TOP MARK
MAX5487ETE*
-40°C to +85°C
16 Thin QFN-EP**
10
ABR
MAX5488ETE
-40°C to +85°C
16 Thin QFN-EP**
50
ABS
MAX5489ETE
-40°C to +85°C
16 Thin QFN-EP**
100
ABT
*Future product—contact factory for availability.
**EP = Exposed pad.
Functional Diagram
WA
LA
VDD
1
SCLK
2
DIN
3
CS
4
HA
WA
LA
12 HB
HB
CS
8-BIT
LATCH
256
8
DECODER
10 LB
9
N.C.
WB
5
MAX5487
MAX5488
MAX5489
11 WB
MAX5487
MAX5488
MAX5489
POR
LB
6
7
8
N.C.
16-BIT
NV RAM
13
GND
SPI
INTERFACE
14
N.C.
DECODER
SCLK
DIN
15
N.C.
GND
16
256
8
8-BIT
LATCH
TOP VIEW
N.C.
HA
VDD
Pin Configuration
THIN QFN
3mm × 3mm
EXPOSED PAD CONNECTED TO GND.
________________________________________________________________ Maxim Integrated Products
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
MAX5487/MAX5488/MAX5489
General Description
MAX5487/MAX5488/MAX5489
Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers
ABSOLUTE MAXIMUM RATINGS
VDD to GND ...........................................................-0.3V to +6.0V
All Other Pins
to GND......................-0.3V to the lower of (VDD + 0.3V) and +6.0V
Maximum Continuous Current into H_, W_, and L_
MAX5487......................................................................±5.0mA
MAX5488......................................................................±1.3mA
MAX5489......................................................................±0.6mA
Continuous Power Dissipation (TA = +70°C)
16-Pin Thin QFN (derate 17.5mW/°C above +70°C).....1398mW
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.
DC ELECTRICAL CHARACTERISTICS
(VDD = +2.7V to +5.25V, VH = VDD, VL = GND, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +5.0V,
TA = +25°C, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DC PERFORMANCE (Voltage-Divider Mode, Figure 1)
Resolution
N
256
Taps
Integral Nonlinearity
INL
(Note 2)
±1
LSB
Differential Nonlinearity
DNL
(Note 2)
±0.5
LSB
2
LSB
Dual-Code Matching
End-To-End Resistor Tempco
Register A = register B
TCR
Ratiometric Resistor Tempco
Full-Scale Error
Zero-Scale Error
35
ppm/°C
5
ppm/°C
MAX5488
-0.6
+1.2
MAX5489
-0.3
+1.2
MAX5488
0.6
1.5
MAX5489
0.3
1
LSB
LSB
DC PERFORMANCE (Variable-Resistor Mode, Figure 1)
Resolution
256
Integral Nonlinearity (Note 3)
MAX5488/MAX5489
Differential Nonlinearity (Note 3)
MAX5488/MAX5489
Taps
VDD = 5.0V
±1.5
VDD = 3.0V
±3
VDD = 5.0V
±1
VDD = 3.0V
±1
LSB
DC PERFORMANCE (Resistor Characteristics)
Wiper Resistance (Note 4)
RW
Wiper Capacitance
CW
End-to-End Resistance
2
RHL
VDD = 5.0V
200
350
VDD = 3.0V
325
675
50
MAX5487
7.5
MAX5488
MAX5489
pF
10
12.5
37.5
50
62.5
75
100
125
_______________________________________________________________________________________
Ω
kΩ
Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers
(VDD = +2.7V to +5.25V, VH = VDD, VL = GND, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +5.0V,
TA = +25°C, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DIGITAL INPUTS
Input High Voltage (Note 5)
VIH
Input Low Voltage
VIL
Input Leakage Current
IIN
Input Capacitance
CIN
VDD = 3.6V to 5.25V
2.4
VDD = 2.7V to 3.6V
0.7 x
VDD
V
VDD = 2.7V to 5.25V (Note 5)
0.8
V
±1.0
µA
5.0
pF
-90
dB
AC PERFORMANCE
fH_ = 1kHz, L_ = GND, measurement at W_
(Note 6)
Crosstalk
MAX5488
90
MAX5489
45
-3dB Bandwidth
BW
Wiper at midscale
CW_ = 10pF
Total Harmonic Distortion
THD
VH_ = 1VRMS at 1kHz, L_ = GND,
measurement at W_
kHz
0.02
%
TIMING CHARACTERISTICS (Analog)
Wiper-Settling Time
tS
Code 0 to 127
(Note 7)
MAX5488
0.75
MAX5489
1.5
µs
TIMING CHARACTERISTICS (Digital, Figure 2, Note 8)
SCLK Frequency
5
MHz
SCLK Clock Period
tCP
200
ns
SCLK Pulse-Width High
tCH
80
ns
ns
SCLK Pulse-Width Low
tCL
80
CS Fall to SCLK Rise Setup
tCSS
80
ns
SCLK Rise to CS Rise Hold
tCSH
0
ns
DIN to SCLK Setup
tDS
50
ns
DIN Hold after SCLK
tDH
0
ns
SCLK Rise to CS Fall Delay
tCS0
20
ns
CS Rise to SCLK Rise Hold
tCS1
80
ns
CS Pulse-Width High
tCSW
200
ns
Write NV Register Busy Time
tBUSY
12
ms
Read NV Register Access Time
tACC
1
µs
Write Wiper Register to Output Delay
tWO
1
µs
NONVOLATILE MEMORY RELIABILITY
Data Retention
Mil-Std-883 test
method 1008
TA = +85°C
50
TA = +125°C
10
Endurance
Mil-Std-883 test
method 1033
TA = +85°C
200,000
TA = +125°C
50,000
Years
Stores
_______________________________________________________________________________________
3
MAX5487/MAX5488/MAX5489
DC ELECTRICAL CHARACTERISTICS (continued)
MAX5487/MAX5488/MAX5489
Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers
DC ELECTRICAL CHARACTERISTICS (continued)
(VDD = +2.7V to +5.25V, VH = VDD, VL = GND, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +5.0V,
TA = +25°C, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
5.25
V
400
µA
1
µA
POWER SUPPLIES
Power-Supply Voltage
VDD
Supply Current
IDD
Standby Current
2.70
During write cycle only, digital inputs =
VDD or GND
Digital inputs = VDD or GND, TA = +25°C
0.5
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: DNL and INL are measured with the potentiometer configured as a voltage-divider with H_ = VDD and L_ = 0. The wiper terminal
is unloaded and measured with an ideal voltmeter.
Note 3: DNL and INL are measured with the potentiometer configured as a variable resistor. H_ is unconnected and L_ = 0. For VDD =
+5V, the wiper terminal is driven with a source current of 400µA for the 10kΩ configuration, 80µA for the 50kΩ configuration,
and 40µA for the 100kΩ configuration. For VDD = +3V, the wiper terminal is driven with a source current of 200µA for the 10kΩ
configuration, 40µA for the 50kΩ configuration, and 20µA for the 100kΩ configuration.
Note 4: The wiper resistance is the worst value measured by injecting the currents given in Note 3 into W_ with L_ = GND. RW =
(VW - VH) / IW.
Note 5: The device draws higher supply current when the digital inputs are driven with voltages between (VDD - 0.5V) and (GND +
0.5V). See Supply Current vs. Digital Input Voltage in the Typical Operating Characteristics section.
Note 6: Wiper at midscale with a 10pF load.
Note 7: Wiper-settling time is the worst-case 0-to-50% rise time, measured between tap 0 and tap 127. H_ = VDD, L_ = GND, and
the wiper terminal is unloaded and measured with a 10pF oscilloscope probe (see Tap-to-Tap Switching Transient in the
Typical Operating Characteristics section).
Note 8: Digital timing is guaranteed by design and characterization, and is not production tested.
VOLTAGE-DIVIDER
CONFIGURATION
H
VARIABLE-RESISTOR
CONFIGURATION
H
W
L
L
Figure 1. Voltage-Divider/Variable-Resistor Configurations
4
_______________________________________________________________________________________
Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers
VCC = 5V
0.4
VCC = 5V
100
10
VCC = 3V
MAX5487-89toc03
400
WIPER RESISTANCE (Ω)
0.8
0.6
1000
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
1.0
10,000
MAX5487-89 toc02
MAX5487-89 toc01
1.2
WIPER RESISTANCE
vs. TAP POSITION (MAX5488)
SUPPLY CURRENT
vs. DIGITAL INPUT VOLTAGE
SUPPLY CURRENT vs. TEMPERATURE
300
200
100
1
0.2
VCC = 3V
0
0
0
-40
-15
10
35
60
85
0
1
2
3
4
TEMPERATURE (°C)
DIGITAL INPUT VOLTAGE (V)
TAP-TO-TAP SWITCHING TRANSIENT
(MAX5488)
TAP-TO-TAP SWITCHING TRANSIENT
(MAX5489)
0
5
64
96
128 160 192 224 256
TAP POSITION
WIPER TRANSIENT AT POWER-ON
MAX5487-89 toc06
MAX5487-89 toc05
MAX5487-89 toc04
VH_ = VDD
VH_ = 5.0V
VH_ = 5.0V
CS
2.0V/div
CS
2.0V/div
VDD
2.0V/div
WIPER
20mV/div
WIPER
20mV/div
WIPER
2.0V/div
1.0µs/div
32
1.0µs/div
2.0µs/div
_______________________________________________________________________________________
5
MAX5487/MAX5488/MAX5489
Typical Operating Characteristics
(VDD = +5.0V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VDD = +5.0V, TA = +25°C, unless otherwise noted.)
MIDSCALE FREQUENCY RESPONSE
(MAX5488)
MIDSCALE FREQUENCY RESPONSE
(MAX5489)
-15
CW_ = 50pF
-20
-25
-30
-30
-40
-40
-45
-45
-50
-50
1
10
100
1000
MAx5487-89 toc09
0.10
0.05
0
-0.05
-0.10
-0.15
-0.20
0.1
1
10
100
1000
0
32
64
96
128 160 192 224 256
FREQUENCY (kHz)
TAP POSITION
VARIABLE-RESISTOR INL
vs. TAP POSITION (MAX5488)
VOLTAGE-DIVIDER DNL
vs. TAP POSITION (MAX5488)
VOLTAGE-DIVIDER INL
vs. TAP POSITION (MAX5488)
0.10
0.4
DNL (LSB)
0.2
0
-0.2
0
-0.8
-0.15
-1.0
-0.20
32
64
96
128 160 192 224 256
TAP POSITION
0.6
0.2
0
-0.2
-0.4
-0.10
-0.6
0.8
0.4
0.05
-0.05
-0.4
MAx5487-89 toc12
0.15
INL (LSB)
0.6
1.0
MAx5487-89 toc11
0.20
MAx5487-89 toc10
0.8
0
0.15
FREQUENCY (kHz)
1.0
6
-25
-35
0.20
CW_ = 50pF
-20
-35
0.1
CW_ = 10pF
-10
GAIN (dB)
GAIN (dB)
-15
0
-5
DNL (LSB)
-10
VARIABLE-RESISTOR DNL
vs. TAP POSITION (MAX5488)
MAX5487-89 toc08
CW_ = 10pF
MAX5487-89 toc07
0
-5
INL (LSB)
MAX5487/MAX5488/MAX5489
Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers
-0.6
-0.8
-1.0
0
32
64
96
128 160 192 224 256
TAP POSITION
0
32
64
96
128 160 192 224 256
TAP POSITION
_______________________________________________________________________________________
Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers
VARIABLE-RESISTOR INL
vs. TAP POSITION (MAX5489)
0.10
0.20
MAx5487-89 toc14
0.15
0.8
0.6
0.15
0.10
0.4
0
-0.05
0.2
DNL (LSB)
INL (LSB)
0.05
0
-0.2
-0.15
-0.8
-1.0
-0.20
-0.20
0
128 160 192 224 256
96
32
64
96
128 160 192 224 256
0
32
64
TAP POSITION
VOLTAGE-DIVIDER INL
vs. TAP POSITION (MAX5489)
CROSSTALK vs. FREQUENCY
-30
MAx5487-89 toc16
1.0
0.8
0.6
128 160 192 224 256
96
TAP POSITION
TAP POSITION
CW_ = 10pF
-40
CROSSTALK (dB)
0.4
0.2
0
-0.2
MAX5487-89toc17
64
-0.4
-50
MAX5489
-60
-70
-80
-0.6
MAX5488
-90
-0.8
-100
-1.0
32
64
96
0.1
128 160 192 224 256
1
100
10
1000
TAP POSITION
FREQUENCY (kHz)
END-TO-END RESISTANCE CHANGE
vs. TEMPERATURE (MAX5488)
END-TO-END RESISTANCE CHANGE
vs. TEMPERATURE (MAX5489)
0.008
0.006
0.004
0.002
0
-0.002
-0.004
0.010
MAX5487-89 toc19
0.010
0.008
RESISTANCE CHANGE (%)
0
MAX5487-89 toc18
32
INL (LSB)
0
0
-0.10
-0.6
-0.15
0.05
-0.05
-0.4
-0.10
RESISTANCE CHANGE (%)
DNL (LSB)
1.0
MAx5487-89 toc13
0.20
VOLTAGE-DIVIDER DNL
vs. TAP POSITION (MAX5489)
MAx5487-89 toc15
VARIABLE-RESISTOR DNL
vs. TAP POSITION (MAX5489)
0.006
0.004
0.002
0
-0.002
-0.004
-0.006
-0.006
-0.008
-0.008
-0.010
-0.010
-40
-15
10
35
TEMPERATURE (°C)
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
_______________________________________________________________________________________
7
MAX5487/MAX5488/MAX5489
Typical Operating Characteristics (continued)
(VDD = +5.0V, TA = +25°C, unless otherwise noted.)
Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers
MAX5487/MAX5488/MAX5489
Pin Description
PIN
NAME
FUNCTION
1
VDD
2
SCLK
Serial-Interface Clock Input
3
DIN
Serial-Interface Data Input
4
CS
Active-Low Chip-Select Digital Input
5, 6, 8, 9, 16
N.C.
No Connection. Not internally connected.
7
GND
Ground
10
LB
Low Terminal of Resistor B. The voltage at L can be greater than or less than the voltage at H.
Current can flow into or out of L.
11
WB
Wiper Terminal of Resistor B
12
HB
High Terminal of Resistor B. The voltage at H can be greater than or less than the voltage at L.
Current can flow into or out of H.
13
LA
Low Terminal of Resistor A. The voltage at L can be greater than or less than the voltage at H.
Current can flow into or out of L.
14
WA
Wiper Terminal of Resistor A
15
HA
High Terminal of Resistor A. The voltage at H can be greater than or less than the voltage at L.
Current can flow into or out of H.
—
E.P.
Exposed Pad. Not internally connected. Connect to ground or leave floating.
Power Supply. Bypass to GND with a 0.1µF capacitor as close to the device as possible.
Detailed Description
The MAX5487/MAX5488/MAX5489 contain two resistor
arrays, with 255 resistive elements each. The MAX5487
has an end-to-end resistance of 10kΩ, while the
MAX5488 and MAX5489 have resistances of 50kΩ and
100kΩ, respectively. The MAX5487/MAX5488/MAX5489
allow access to the high, low, and wiper terminals on
both potentiometers for a standard voltage-divider configuration. Connect the wiper to the high terminal, and
connect the low terminal to ground, to make the device
a variable resistor (see Figure 1).
A simple 3-wire serial interface programs either wiper
directly to any of the 256 tap points. The nonvolatile
memory stores the wiper position prior to power-down
and recalls the wiper to the same point upon power-up
or by using an interface command (see Table 1). The
nonvolatile memory is guaranteed for 200,000 wiper
store cycles and 50 years for wiper data retention.
SPI Digital Interface
The MAX5487/MAX5488/MAX5489 use a 3-wire SPIcompatible serial data interface (Figures 2 and 3). This
write-only interface contains three inputs: chip-select
8
(CS), data clock (SCLK), and data in (DIN). Drive CS low
to enable the serial interface and clock data synchronously into the shift register on each SCLK rising edge.
The WRITE commands (C1, C0 = 00 or 01) require 16
clock cycles to clock in the command, address, and data
(Figure 3a). The COPY commands (C1, C0 = 10, 11) can
use either eight clock cycles to transfer only command
and address bits (Figure 3b) or 16 clock cycles, with the
device disregarding 8 data bits (Figure 3a).
After loading data into the shift register, drive CS high
to latch the data into the appropriate potentiometer
control register and disable the serial interface. Keep
CS low during the entire serial data stream to avoid corruption of the data.
Digital-Interface Format
The data format consists of three elements: command
bits, address bits, and data bits (see Table 1 and
Figure 3). The command bits (C1 and C0) indicate the
action to be taken such as changing or storing the
wiper position. The address bits (A1 and A0) specify
which potentiometer the command affects and the 8
data bits (D7 to D0) specify the wiper position.
_______________________________________________________________________________________
Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
—
—
C1
C0
—
—
A1
A0
D7
D6
D5
D4
D3
D2
D1
D0
Write Wiper Register A
0
0
0
0
0
0
0
1
D7
D6
D5
D4
D3
D2
D1
D0
Write Wiper Register B
0
0
0
0
0
0
1
0
D7
D6
D5
D4
D3
D2
D1
D0
Write NV Register A
0
0
0
1
0
0
0
1
D7
D6
D5
D4
D3
D2
D1
D0
Write NV Register B
0
0
0
1
0
0
1
0
D7
D6
D5
D4
D3
D2
D1
D0
Copy Wiper Register A to NV
Register A
0
0
1
0
0
0
0
1
—
—
—
—
—
—
—
—
Copy Wiper Register B to NV
Register B
0
0
1
0
0
0
1
0
—
—
—
—
—
—
—
—
Copy Both Wiper Registers to
NV Registers
0
0
1
0
0
0
1
1
—
—
—
—
—
—
—
—
Copy NV Register A to Wiper
Register A
0
0
1
1
0
0
0
1
—
—
—
—
—
—
—
—
Copy NV Register B to Wiper
Register B
0
0
1
1
0
0
1
0
—
—
—
—
—
—
—
—
Copy Both NV Registers to
Wiper Registers
0
0
1
1
0
0
1
1
—
—
—
—
—
—
—
—
CLOCK EDGE
CS
tCSW
tCSO
tCSS
tCL
tCH
tCP
tCSH
tCS1
SCLK
tDS
tDH
DIN
Figure 2. Timing Diagram
Write-Wiper Register (Command 00)
Data written to the write-wiper registers (C1, C0 = 00)
controls the wiper positions. The 8 data bits (D7 to D0)
indicate the position of the wiper. For example, if DIN =
0000 0000, the wiper moves to the position closest to
L_. If DIN = 1111 1111, the wiper moves closest to H_.
This command writes data to the volatile RAM, leaving the
NV registers unchanged. When the device powers up,
the data stored in the NV registers transfers to the volatile
wiper register, moving the wiper to the stored position.
Write-NV Register (Command 01)
This command (C1, C0 = 01) stores the position of the
wipers to the NV registers for use at power-up.
Alternatively, the “copy wiper register to NV register”
command can be used to store the position of the
wipers to the NV registers. Writing to the NV registers,
does not affect the position of the wipers.
Copy Wiper Register to NV Register (Command 10)
This command (C1, C0 = 10) stores the current position
of the wiper to the NV register, for use at power-up.
_______________________________________________________________________________________
9
MAX5487/MAX5488/MAX5489
Table 1. Register Map
MAX5487/MAX5488/MAX5489
Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers
A) 16-BIT COMMAND/DATA WORD
CS
SCLK
1
2
DIN
3
4
C1
C0
3
4
C1
C0
5
6
7
8
9
A1
A0
D7
10
D6
11
D5
12
D4
13
D3
14
D2
15
D1
16
D0
B) 8-BIT COMMAND WORD
CS
SCLK
1
DIN
2
5
6
7
8
A1
A0
Figure 3. Digital-Interface Format
This command may affect one potentiometer at a time,
or both simultaneously, depending on the state of A1
and A0. Alternatively, the “write NV register” command
can be used to store the current position of the wiper to
the NV register.
Copy NV Register to Wiper Register (Command 11)
This command (C1, C0 = 11) restores the wiper position
to the previously stored position in the NV register. This
command may affect one potentiometer at a time, or both
simultaneously, depending on the state of A1 and A0.
Nonvolatile Memory
The internal EEPROM consists of a nonvolatile register
that retains the last stored value prior to power-down.
The nonvolatile register is programmed to midscale at
the factory. The nonvolatile memory is guaranteed for
200,000 wiper write cycles and 50 years for wiper data
retention.
Standby
The MAX5487/MAX5488/MAX5489 feature a low-power
standby mode. When the device is not being programmed, it enters into standby mode and supply current drops to 0.5µA (typ).
Applications Information
The MAX5487/MAX5488/MAX5489 are ideal for circuits
requiring digitally controlled adjustable resistance,
such as LCD contrast control (where voltage biasing
adjusts the display contrast), or for programmable filters with adjustable gain and/or cutoff frequency.
Positive LCD Bias Control
Power-Up
Figures 4 and 5 show an application where the
MAX5487/MAX5488/MAX5489 provide an adjustable,
positive LCD-bias voltage. The op amp provides buffering and gain to the resistor-divider network made by
the potentiometer (Figure 4) or by a fixed resistor and a
variable resistor (Figure 5).
Upon power-up, the MAX5487/MAX5488/MAX5489
load the data stored in the nonvolatile wiper register
into the volatile memory register, updating the wiper
position with the data stored in the nonvolatile wiper
register. This initialization period takes 5µs.
Figure 6 shows the MAX5487/MAX5488/MAX5489 in a
1st-order programmable-filter application. Adjust the gain
of the filter with R2, and set the cutoff frequency with R3.
10
Programmable Filter
______________________________________________________________________________________
Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers
H_
30V
A =1+
W_
MAX5487
MAX5488
MAX5489
VOUT
MAX480
R1
R2
L_
fC =
1
2π × R3 × C
Adjustable Voltage Reference
Figure 4. Positive LCD-Bias Control Using a Voltage-Divider
Figure 7 shows the MAX5487/MAX5488/MAX5489 used
as the feedback resistors in multiple adjustable voltage-reference applications. Independently adjust the
output voltages of the MAX6160s from 1.23V to VIN 0.2V by changing the wiper positions of the MAX5487/
MAX5488/MAX5489.
5V
Offset Voltage and Gain Adjustment
Connect the high and low terminals of one potentiometer of a MAX5487/MAX5488/MAX5489 to the NULL
inputs of a MAX410, and connect the wiper to the op
amp’s positive supply to nullify the offset voltage over
the operating temperature range. Install the other
potentiometer in the feedback path to adjust the gain of
the MAX410 (see Figure 8).
30V
H_
VOUT
MAX480
MAX5487
MAX5488
MAX5489
W_
L_
Chip Information
TRANSISTOR COUNT: 12,177
PROCESS: BiCMOS
Figure 5. Positive LCD-Bias Control Using a Variable Resistor
WA
V+
VIN
LA
HA
R3
C
MAX410
1/2 MAX5487
1/2 MAX5488
1/2 MAX5489
VR1
HB
R2, R3 = RHL x D / 256
WHERE RHL = END-TO-END RESISTANCE
AND D = DECIMAL VALUE OF WIPER CODE
WB
R2
1/2 MAX5487
1/2 MAX5488
1/2 MAX5489
VOUT
LB
Figure 6. Programmable Filter
______________________________________________________________________________________
11
MAX5487/MAX5488/MAX5489
Use the following equations to calculate the gain (A)
and the -3dB cutoff frequency (fC):
5V
MAX5487/MAX5488/MAX5489
Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers
5V
IN
IN
V OUT1
OUT
OUT
VOUT2
HB
HA
MAX6160
MAX6160
ADJ
1/2 MAX5487
1/2 MAX5488
1/2 MAX5489
WA
R
GND
LA
ADJ
GND
1/2 MAX5487
1/2 MAX5488
1/2 MAX5489
WB
R
LB
10kΩ
FOR THE MAX5487
R
50kΩ
VOUT_ = 1.23V x
FOR THE MAX5488
R
100kΩ
VOUT_ = 1.23V x
FOR THE MAX5489
R
VOUT_ = 1.23V x
R2 = RHL x D / 256
WHERE RHL = END-TO-END RESISTANCE
AND D = DECIMAL VALUE OF WIPER CODE
Figure 7. Adjustable Voltage Reference
5V
WA 1/2 MAX5487/MAX5488/MAX5489
LA
HA
7
3
1
8
6
MAX410
2
4
R1
R2 = RHL x D / 256
WHERE RHL = END-TO-END RESISTANCE
AND = D DECIMAL VALUE OF WIPER CODE
HB
1/2 MAX5487/MAX5488/MAX5489
R2
WB
LB
Figure 8. Offset Voltage and Gain Adjustment
12
______________________________________________________________________________________
Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers
12x16L QFN THIN.EPS
D2
0.10 M C A B
b
D
D2/2
D/2
E/2
E2/2
CL
(NE - 1) X e
E
E2
L
e
CL
k
(ND - 1) X e
CL
0.10 C
CL
0.08 C
A
A2
A1
L
L
e
e
PACKAGE OUTLINE
12, 16L, THIN QFN, 3x3x0.8mm
21-0136
E
1
______________________________________________________________________________________
2
13
MAX5487/MAX5488/MAX5489
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX5487/MAX5488/MAX5489
Dual, 256-Tap, Nonvolatile, SPI-Interface,
Linear-Taper Digital Potentiometers
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
EXPOSED PAD VARIATIONS
DOWN
BONDS
ALLOWED
NOTES:
1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994.
2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES.
3. N IS THE TOTAL NUMBER OF TERMINALS.
4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO
JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED
WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR
MARKED FEATURE.
5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.20 mm AND 0.25 mm
FROM TERMINAL TIP.
6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY.
7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION.
8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.
9. DRAWING CONFORMS TO JEDEC MO220 REVISION C.
PACKAGE OUTLINE
12, 16L, THIN QFN, 3x3x0.8mm
21-0136
E
2
2
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.
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Printed USA
is a registered trademark of Maxim Integrated Products, Inc.