19-1848; Rev 0; 10/00
256-Tap SOT-PoT,
Low-Drift Digital Potentiometers in SOT23
General Description
The MAX5400/MAX5401 digital potentiometers offer
256-tap SOT-PoT™ digitally controlled variable resis-
tors in tiny 8-pin SOT23 packages. Each device func-
tions as a mechanical potentiometer, consisting of a
fixed resistor string with a digitally controlled wiper con-
tact. They operate from +2.7V to +5.5V single-supply
voltages and use an ultra-low supply current of 0.1µA.
These devices also provide glitchless switching
between resistor taps, as well as a convenient power-
on reset that sets the wiper to the midscale position at
power-up. A low 5ppm/°C ratiometric temperature coef-
ficient makes it ideal for applications requiring low drift.
The MAX5400/MAX5401 serve well in applications
requiring digitally controlled resistors, including
adjustable voltage references and programmable gain
amplifiers (PGAs). A nominal end-to-end resistor tem-
perature coefficient of 50ppm/°C allows these parts to
be used as variable resistors in applications such as
low-tempco adjustable gain and other circuit configura-
tions.
Two resistance values are available: 50kΩ (MAX5400)
and 100kΩ (MAX5401). Each device is guaranteed over
the extended industrial temperature range (-40°C to
+85°C).
o
Miniature 8-Pin SOT23 (3mm x 3mm)
o
256 Tap Positions
o
Ultra-Low 0.1µA Supply Current
o
Single-Supply Operation: +2.7V to +5.5V
o
Low Ratiometric Temperature Coefficient:
5ppm/°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
50kΩ/100kΩ Resistor Values
Features
MAX5400/MAX5401
Ordering Information
PART
MAX5400EKA-T
MAX5401EKA-T
TEMP.
RANGE
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
8-SOT23
8-SOT23
R (kΩ)
50
100
________________________Applications
Mechanical Potentiometer Replacement
Low-Drift PGAs
Adjustable Voltage References
SOT-PoT is a trademark of Maxim Integrated Products.
SPI is a trademark of Motorola, Inc.
Pin Configuration appears at end of data sheet.
Functional Diagram
V
DD
H
8
8-BIT
SHIFT
REGISTER
8-BIT
LATCH
8
DECODER
W
DIN
L
MAX5400/MAX5401
SCLK
CS
CLOCK
LOGIC
POR
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 SOT-PoT,
Low-Drift Digital Potentiometers in SOT23
MAX5400/MAX5401
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
+ 0.3V)
Maximum Continuous Current into
Pins H, L, and W ...........................................................±1mA
Continuous Power Dissipation (T
A
= +70°C)
8-Pin SOT23 (derate 8.7mW/°C above +70°C)...........697mW
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 T
A
= +25°C, unless otherwise noted. Parameters are mea-
sured at T
A
= +25°C. Values over full temperature range are guaranteed by design.)
PARAMETER
Resolution
Integral Nonlinearity
(Notes 1, 2)
Differential Nonlinearity
(Notes 1, 2)
End-to-End Resistor Tempco
Ratiometric Resistor Tempco
Full-Scale Ratio Error
Zero-Scale Ratio Error
POWER SUPPLIES
Supply Voltage
Supply Current
V
DD
I
DD
CS
= SCLK = DIN = V
DD
V
DD
= 5V
V
DD
= 2.7V
8
V
CC
= 5V
INL
V
CC
= 3V
V
CC
= 5V
V
CC
= 3V
250
25
MAX5401
MAX5400
75
37.5
100
50
125
62.5
MAX5400
MAX5401
±1
±1.5
±1
±1/2
±1/2
800
LSB
LSB
2.7
0.7
0.1
5.5
5
V
µA
µA
Bits
MAX5400
MAX5401
MAX5400
MAX5401
SYMBOL
N
INL
DNL
TC
R
50
5
-0.8
-0.4
+0.8
+0.4
CONDITIONS
MIN
8
±1/2
±1/2
TYP
MAX
UNITS
Bits
LSB
LSB
ppm/°C
ppm/°C
LSB
LSB
DC PERFORMANCE (Voltage Divider Mode)
DC PERFORMANCE (Variable Resistor Mode)
Resolution
Integral Nonlinearity
(Notes 1, 3)
Differential Nonlinearity
(Notes 1, 3)
Wiper Resistance (Note 4)
Wiper Capacitance
End-to-End Resistance
N
DNL
DC PERFORMANCE (Resistor Characteristics)
R
W
C
W
R
HL
Ω
pF
kΩ
2
_______________________________________________________________________________________
256-Tap SOT-PoT,
Low-Drift Digital Potentiometers in SOT23
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V, V
H
= V
DD
, V
L
= 0, T
A
= T
MIN
to T
MAX
. Typical values are at T
A
= +25°C, unless otherwise noted. Parameters are mea-
sured at T
A
= +25°C. Values over full temperature range are guaranteed by design.)
PARAMETER
DIGITAL INPUTS
Input High Voltage
Input Low Voltage
Input High Voltage
Input Low Voltage
Input Leakage Current
Input Capacitance
TIMING CHARACTERISTICS (Voltage Divider Mode)
MAX5400 (to 50% of final value, from code 0
to code 128)
MAX5401 (to 50% of final value, from code 0
to code 128)
100
40
40
40
0
40
0
10
40
100
300
ns
600
5.0
V
IH
V
IL
V
IH
V
IL
V
CC
= 5V
V
CC
= 5V
V
CC
= 3V
V
CC
= 3V
0.7
✕
V
DD
0.3
✕
V
DD
±1.0
0.7
✕
V
DD
0.3
✕
V
DD
V
V
V
V
µA
pF
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX5400/MAX5401
Wiper Settling Time
t
IL
TIMING CHARACTERISTICS (Digital)
(Note 5)
SCLK Clock Period
SCLK Pulse Width High
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
t
CP
t
CH
t
CL
t
CSS
t
CSH
t
DS
t
DH
t
CS0
t
CS1
t
CSW
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
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 80µA for the 50kΩ configuration and 40µA for the 100kΩ configuration.
Note 4:
The wiper resistance is measured assuming the source currents given in Note 2.
Note 5:
Digital timing is guaranteed by design.
_______________________________________________________________________________________
3
256-Tap SOT-PoT,
Low-Drift Digital Potentiometers in SOT23
MAX5400/MAX5401
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
END-TO-END RESISTANCE % CHANGE
vs. TEMPERATURE
MAX5400toc02
MAX5400 toc01
WIPER RESISTANCE vs. VOLTAGE
600
500
WIPER RESISTANCE (Ω)
400
300
V
DD
= +5V
200
100
0
0
1
2
3
4
5
WIPER VOLTAGE (V)
V
DD
= +3V
0.05
END-TO-END RESISTANCE % CHANGE
0.03
0.01
-0.01
-0.03
-0.05
-0.07
-0.09
-0.11
W-to-L RESISTANCE vs. INPUT CODE
(100kΩ)
90
W-TO-L RESISTANCE (kΩ)
80
70
60
50
40
30
20
10
0
V
DD
= 2.7V
to 5.5V
MAX5400 Toc03
100
100kΩ
50kΩ
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80
TEMPERATURE (°C)
0
32
64
96
128 160 192 224 256
INPUT CODE-DECIMAL
W-to-L RESISTANCE vs. INPUT CODE
(50kΩ)
MAX5400 Toc04
VARIABLE RESISTOR DNL
vs. INPUT CODE (50kΩ)
MAX5400 Toc05
VARIABLE RESISTOR INL vs. INPUT CODE
(50kΩ)
0.15
0.10
0.05
(LSB)
0
-0.05
-0.10
-0.15
-0.20
MAX5400 Toc06
50
45
W-TO-L RESISTANCE (kΩ)
40
35
V
DD
= 2.7V
to 5.5V
0.020
0.015
0.010
0.005
(LSB)
0
-0.005
-0.010
-0.015
-0.020
0.20
30
25
20
15
10
5
0
0
32
64
96
128 160 192 224 256
INPUT CODE-DECIMAL
0
32
64
96
128 160 192 224 256
0
32
64
96
128 160 192 224 256
INPUT CODE-DECIMAL
INPUT CODE-DECIMAL
VARIABLE RESISTOR DNL
vs. INPUT CODE (100kΩ)
MAX5400 Toc07
VARIABLE RESISTOR INL
vs. INPUT CODE (100kΩ)
0.15
0.10
0.05
(LSB)
0
-0.05
-0.10
-0.15
-0.20
0
0
32
64
96
128 160 192 224 256
MAX5400 Toc08
SUPPLY CURRENT
vs. TEMPERATURE
MAX5400toc09
0.020
0.015
0.010
0.005
(LSB)
0
-0.005
-0.010
-0.015
-1.020
0
32
64
96
0.20
1.0
V
DD
= +5V
0.8
SUPPLY CURRENT (µA)
0.6
0.4
0.2
V
DD
= +3V
128 160 192 224 256
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80
TEMPERATURE (°C)
INPUT CODE-DECIMAL
INPUT CODE-DECIMAL
4
_______________________________________________________________________________________
256-Tap SOT-PoT,
Low-Drift Digital Potentiometers in SOT23
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
TAP-to-TAP SWITCHING TRANSIENT
(FROM CODE 127 toc CODE 128)
MAX5400 Toc10
MAX5400/MAX5401
SUPPLY CURRENT vs.
INPUT LOGIC VOLTAGE
10mV/div
SUPPLY CURRENT (mA)
MAX5400 Toc11
10
V
W-L
2.5V
1
V
DD
= +5V
0.1
5V/div
CS
0
0.01
V
DD
= +3V
0.001
0.0001
0
1
2
3
4
5
DIGITAL INPUT VOLTAGE (V)
VOLTAGE DIVIDER DNL
vs. INPUT CODE (50kΩ)
MAX5400 Toc12
VOLTAGE DIVIDER INL
vs. INPUT CODE (50kΩ)
V
DD
= +2.7V to +5.5V
0.15
0.10
0.05
(LSB)
0
-0.05
-0.10
-0.15
-0.20
MAX5400 Toc13
0.10
0.08
0.06
0.04
0.02
(LSB)
0
-0.02
-0.04
-0.06
-0.08
-0.10
0
32
64
96
0.20
128 160 192 224 256
0
32
64
96
128 160 192 224 256
INPUT CODE-DECIMAL
INPUT CODE-DECIMAL
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
Clock Input
Power Supply. Bypass with a 0.1µF capacitor to GND.
Wiper Terminal
High Terminal of Resistor
FUNCTION
_______________________________________________________________________________________
5
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