19-1896; Rev 0; 1/01
256-Tap, µPoT, Low-Drift,
Digital Potentiometer
General Description
The MAX5402 µPoT
™
digital potentiometer is a 256-tap
variable resistor with 10kΩ total resistance in a tiny 8-
pin µMAX package. This device functions as a mechan-
ical potentiometer, consisting of a fixed resistor string
with a digitally controlled wiper contact. It operates
from +2.7V to +5.5V single-supply voltages and uses
an ultra-low 0.1µA supply current. This device also pro-
vides glitchless switching between resistor taps, as well
as a convenient power-on reset (POR) that sets the
wiper to the midscale position at power-up. A low
5ppm/°C ratiometric temperature coefficient makes it
ideal for applications requiring low drift.
The MAX5402 serves well in applications requiring digi-
tally controlled resistors, including adjustable voltage
references and programmable gain amplifiers (PGAs).
A nominal end-to-end resistor temperature coefficient of
35ppm/°C makes this part suitable for use as a variable
resistor in applications such as low-tempco adjustable
gain and other circuit configurations. This device is
guaranteed over the extended industrial temperature
range (-40°C to +85°C).
o
Ultra-Low 100nA Supply Current
o
+2.7V to +5.5V Single-Supply Operation
o
256 Tap Positions
o
Low Ratiometric Temperature Coefficient
5ppm/°C
o
Low End-to-End Resistor Temperature Coefficient
35ppm/°C
o
Power-On Reset: Wiper Goes to Midscale
(Position 128)
o
Glitchless Switching Between the Resistor Taps
o
3-Wire SPI™-Interface Compatible
o
10kΩ Resistor Value
Features
o
Small Footprint, 8-Pin µMAX Package
MAX5402
________________________Applications
Mechanical Potentiometer Replacement
Low-Drift PGAs
Adjustable Voltage References
PART
MAX5402EUA
Ordering Information
TEMP.
RANGE
-40°C to +85°C
PIN-
PACKAGE
8 µMAX
R (kΩ)
10
µPoT is a trademark of Maxim Integrated Products.
SPI is a trademark of Motorola, Inc.
Functional Diagram
V
DD
Pin Configuration
TOP VIEW
H
R
8
8-BIT
SHIFT
REGISTER
R
8-BIT
LATCH
8
256
DECODE
W
L
L
GND
CS
1
2
8
7
H
W
V
DD
SCLK
DIN
MAX5402
3
6
5
DIN
4
MAX5402
SCLK
CS
CLOCK
LOGIC
POR
µMAX
GND
________________________________________________________________
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.
256-Tap, µPoT, Low-Drift,
Digital Potentiometer
MAX5402
ABSOLUTE MAXIMUM RATINGS
V
DD
to GND ..............................................................-0.3V to +6V
DIN, SCLK,
CS
to GND ............................................-0.3V to +6V
H, L, W to GND .............................................-0.3V to (V
DD
+ 0.3)
Maximum Continuous Current into Pins H, L, and W ...........1mA
Continuous Power Dissipation (T
A
= +70°C)
8-Pin µMAX (derate 4.1mW/°C above +70°C) ............330mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°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
= +5V, V
H
= V
DD
, V
L
= 0, T
A
= T
MIN
to T
MAX
. Typical values are at V
DD
= +5V, T
A
= +25°C, unless otherwise noted.)
PARAMETER
Resolution
Integral Nonlinearity (Notes 1, 2)
Differential Nonlinearity
(Notes 1, 2)
End-to-End Resistor Tempco
Ratiometric Resistor Tempco
Full-Scale Error
Zero-Scale Error
DC PERFORMANCE
(Variable-Resistor Mode)
Resolution
Integral Nonlinearity
(Notes 1, 3)
Differential Nonlinearity
(Notes 1, 3)
N
INL
DNL
V
DD
= +5V
V
DD
= +3V
V
DD
= +5V
V
DD
= +3V
V
DD
= +5V
V
DD
= +3V
46
7.5
0.7
✕
V
DD
0.3
✕
V
DD
±1.0
5
t
S
t
CP
t
CH
To 50% of final value from code 0 to code 128
100
40
100
10
12.5
275
550
8
±1
±3
±1/2
±1/2
Bits
LSB
LSB
LSB
LSB
SYMBOL
N
INL
DNL
TC
R
35
5
-6
+6
CONDITIONS
MIN
8
±1/2
±1
TYP
MAX
UNITS
Bits
LSB
LSB
ppm/°C
ppm/°C
LSB
LSB
DC PERFORMANCE
(Voltage-Divider Mode)
DC PERFORMANCE
(Resistor Characteristics)
Wiper Resistance (Note 4)
Wiper Capacitance
End-to-End Resistance
DIGITAL INPUTS
Input High Voltage
Input Low Voltage
Input Leakage Current
Input Capacitance
TIMING CHARACTERISTICS (ANALOG)
Wiper-Settling Time
SCLK Clock Period
SCLK Pulse Width High
ns
ns
ns
TIMING CHARACTERISTICS (DIGITAL)
(Note 5) (Figure 2)
V
IH
V
IL
V
V
µA
pF
R
W
C
W
R
HL
Ω
pF
kΩ
2
_______________________________________________________________________________________
256-Tap, µPoT, Low-Drift,
Digital Potentiometer
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V, V
H
= V
DD
, V
L
= 0, T
A
= T
MIN
to T
MAX
. Typical values are at V
DD
= +5V, T
A
= +25°C, unless otherwise noted.)
PARAMETER
SCLK Pulse Width Low
CS
Fall to SCLK Rise Setup Time
SCLK Rise to
CS
Rise Hold Time
DIN Setup Time
DIN Hold Time
SCLK Rise to
CS
Fall Delay
CS
Rise to SCLK Rise Hold
CS
Pulse Width High
POWER SUPPLIES
Supply Voltage
Supply Current
V
DD
I
DD
CS
= SCLK =
DIN = V
DD
V
DD
= +5V
V
DD
= +2.7V
2.7
0.8
0.1
5.5
5
V
µA
µA
SYMBOL
t
CL
t
CSS
t
CSH
t
DS
t
DH
t
CS0
t
CS1
t
CSW
CONDITIONS
MIN
40
40
0
40
0
10
40
100
TYP
MAX
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
MAX5402
Note 1:
Linearity is defined in terms of the H-to-L code-dependent resistance.
Note 2:
The DNL and INL are measured with the potentiometer configured as a voltage-divider with H = V
DD
and L = 0. The wiper
terminal is unloaded and measured with an ideal voltmeter.
Note 3:
The DNL and INL are measured with the potentiometer configured as a variable resistor. H is unconnected and L = 0. The
wiper terminal is driven with a source current of 200µA at V
DD
= +3V and 400µA at V
DD
= +5V.
Note 4:
The wiper resistance is the worst value measured, injecting a current, I
W
= V
DD
/R
HL
into terminal W.
Note 5:
Digital timing is guaranteed by design.
________________________________________________________________________________________
3
256-Tap, µPoT, Low-Drift,
Digital Potentiometer
MAX5402
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
WIPER RESISTANCE
vs. WIPER VOLTAGE
MAX5402 Toc01
END-TO-END RESISTANCE % CHANGE
vs. TEMPERATURE
END-TO-END RESISTANCE % CHANGE
MAX5402 Toc02
300
275
WIPER RESISTANCE (Ω)
250
225
200
175
150
125
100
0
1
2
3
4
5
WIPER VOLTAGE (V)
V
DD
= +5V
V
DD
= +3V
0.10
0.05
0.00
-0.05
-0.10
-0.15
-0.20
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90
TEMPERATURE (°C)
RESISTANCE vs. INPUT CODE
MAX5402 Toc03
VARIABLE RESISTOR DNL
vs. INPUT CODE
0.20
0.15
RDNL (LSB)
0.10
0.05
0.00
MAX5402 Toc04
10
9
W-TO-L RESISTANCE (kΩ)
8
7
6
5
4
3
2
1
0
0
32
64
96
0.25
-0.05
-0.10
-0.15
-0.20
128 160 192 224 256
0
32
64
96
128 160 192 224 256
INPUT CODE (DECIMAL)
INPUT CODE (DECIMAL)
VARIABLE RESISTOR INL
vs. INPUT CODE
MAX5402 Toc05
VOLTAGE-DIVIDER DNL vs. INPUT CODE
0.06
0.04
DNL (LSB)
0.02
0.00
-0.02
-0.04
-0.06
-0.08
0
32
64
96
128 160 192 224 256
MAX5402 Toc06
0.3
0.2
0.1
RINL (LSB)
0.0
-0.1
-0.2
-0.3
-0.4
0
32
64
96
0.08
128 160 192 224 256
INPUT CODE (DECIMAL)
INPUT CODE (DECIMAL)
4
_______________________________________________________________________________________
256-Tap, µPoT, Low-Drift,
Digital Potentiometer
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
VOLTAGE-DIVIDER INL vs. INPUT CODE
MAX5402 Toc07
MAX5402
SUPPLY CURRENT vs. TEMPERATURE
MAX5402 Toc08
0.20
0.15
0.10
INL (LSB)
0.05
0.00
-0.05
-0.10
-0.15
-0.20
0
32
64
96
1.2
1.0
SUPPLY CURRENT (µA)
V
DD
= +5V
0.8
0.6
0.4
0.2
V
DD
= +3V
0.0
128 160 192 224 256
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80
TEMPERATURE (°C)
INPUT CODE (DECIMAL)
TAP-TO-TAP SWITCHING TRANSIENT
MAX5402 toc09
INPUT LOGIC VOLTAGE
MAX5402 Toc10
10
+2.51V
1
V
W-L
+2.49V
SUPPLY CURRENT (mA)
0.1
V
DD
= +5V
+5V
CS
0
0.01
0.001
V
DD
= +3V
0.0001
200ns/div
(CODE 127 TO 128)
0
1
2
3
4
5
DIGITAL INPUT VOLTAGE (V)
Pin Description
PIN
1
2
3
4
5
6
7
8
NAME
L
GND
CS
DIN
SCLK
V
DD
W
H
Low Terminal of Resistor
Ground
Chip Select Input
Serial Data Input
Serial Clock Input
Power Supply. Bypass with a 0.1µF capacitor to GND.
Wiper Terminal
High Terminal of Resistor
FUNCTION
________________________________________________________________________________________
5
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