General Description
The MAX5427/MAX5428/MAX5429 linear-taper digital
potentiometers function as mechanical potentiometers,
but replace the mechanics with a simple 2-wire digital
interface. These digital potentiometers are unique in that
they have an optional one-time programmable feature
that either sets the wiper’s power-on reset (POR) posi-
tion to a user-defined value, or the wiper can be set and
the interface disabled to prevent further adjustment.
The MAX5427 has an end-to-end resistance of 100kΩ,
the MAX5428 a resistance of 50kΩ, and the MAX5429 a
resistance of 10kΩ. All these devices have 32 wiper
positions, operate from a single 2.7V to 5.5V supply, and
use less than 1.5µA (max) static supply current.
The MAX5427/MAX5428/MAX5429 are available in
8-pin thin QFN and µMAX packages. Each device is
guaranteed over the extended temperature range of
-40°C to +85°C.
Applications
Mechanical Potentiometer Replacement
Products Using One-Time Factory Calibration
Features
♦Wiper Position Stored After One-Time Fuse
Programming
♦User-Defined Power-On Reset Position
♦35ppm/°C End-to-End Temperature Coefficient
and 5ppm/°C Ratiometric Temperature Coefficient
♦32 Tap Positions
♦Tiny 8-Pin Thin QFN and µMAX Packages
♦Ultra-Low 1.5µA (max) Static Supply Current
♦2.7V to 5.5V Single-Supply Operation
♦Wiper Position Programmed Through Simple
2-Wire Serial Interface
♦10kΩ, 50kΩ, and 100kΩEnd-to-End Resistances
MAX5427/MAX5428/MAX5429
One-Time Programmable, Linear-Taper
Digital Potentiometers
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
MAX5427
MAX5428
MAX5429
32-
POSITION
DECODER
UP/DOWN
COUNTER
ONE-TIME
PROGRAM
BLOCK
8
H
S31
S32
S30
S2
S3
S1
R31
R30
RW
R2
R1
1W
7
L
3
4
2
6
5
VDD
VPP
GND
CS
U/D
Functional Block Diagram
19-2462; Rev 1; 7/02
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.
EVALUATION KIT
AVAILABLE
PART TEMP RANGE PIN-PACKAGE R (kΩ)
MAX5427EUA -40°C to +85°C 8 µMAX 100
MAX5427ETA -40°C to +85°C 8 Thin QFN-EP* 100
MAX5428EUA -40°C to +85°C 8 µMAX 50
MAX5428ETA -40°C to +85°C 8 Thin QFN-EP* 50
MAX5429EUA -40°C to +85°C 8 µMAX 10
MAX5429ETA -40°C to +85°C 8 Thin QFN-EP* 10
VPP
GND
1
2
8
7
H
L
VDD
W
µMAX
TOP VIEW
3
4
6
5
MAX5427
MAX5428
MAX5429
CS
U/D
VPP
GND
*EXPOSED PADDLE. CONNECTED TO GND.
8
7
H
L
VDD
W
QFN
6
5
MAX5427
MAX5428
MAX5429
CS
U/D
1
2
3
4
*
*
Pin Configurations
*EP = Exposed paddle.
MAX5427/MAX5428/MAX5429
One-Time Programmable, Linear-Taper
Digital Potentiometers
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VDD = 2.7V to 5.5V, VPP = GND, 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)
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.
VDD to GND...........................................................-0.3V to +6.0V
VPP to GND..........................................................-0.3V to +12.0V
All Other Pins to GND.................................-0.3V to (VDD + 0.3V)
Input and Output Latchup Immunity...............................±200mA
Maximum Continuous Current into H, L, and W
MAX5427 .................................................................±1.5mA
MAX5428 .................................................................±1.5mA
MAX5429 .................................................................±2.0mA
Continuous Power Dissipation (TA= +70°C)
8-Pin µMAX (derate 4.5mW/°C above +70°C) .............362mW
8-Pin QFN-EP (derate 24.4mW/°C above +70°C)......1951mW
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
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
DC PERFORMANCE
Resolution 32 Taps
MAX5427 75 100 125
MAX5428 37.5 50 62.5
End-to-End Resistance
MAX5429 7.5 10 12.5
kΩ
End-to-End Resistance Tempco TCR35 ppm/°C
MAX5427/MAX5428 5
Ratiometric Resistance Tempco MAX5429 10 ppm/°C
Integral Nonlinearity INL Potentiometer configuration, no load,
Figure 1 ±1 LSB
Differential Nonlinearity DNL Potentiometer configuration, no load,
Figure 1 ±1 LSB
Full-Scale Error Potentiometer configuration, no load,
Figure 1 -0.5 LSB
Zero-Scale Error Potentiometer configuration, no load,
Figure 1 +0.5 LSB
Wiper Resistance RWMAX5427 IW = 20µA; MAX5428 IW = 40µA;
MAX5429 IW = 200µA 100 240 Ω
DIGITAL INPUTS (CS, U/D)
Input High Voltage VIH 0.7 x
VDD V
Input Low Voltage VIL 0.3 x
VDD V
Input Current IIN ±0.1 ±1 µA
Input Capacitance CIN 5pF
TIMING CHARACTERISTICS (Note 2)
U/D Mode to CS Setup tCU Figures 2, 3 50 ns
CS Hold to U/D Mode tCI Figures 2, 3 50 ns
U/D Step Hold to CS tIC Figures 2, 3 0 ns
U/D Step Low Time tIL Figures 2, 3 100 ns
MAX5427/MAX5428/MAX5429
One-Time Programmable, Linear-Taper
Digital Potentiometers
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 2.7V to 5.5V, VPP = GND, 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
U/D Step High Time tIH Figures 2, 3 100 ns
Wiper Switching Time tIW CL = 0pF, Figures 2, 3 100 ns
VPP Rising Edge to CS Falling
Edge tPC Figure 4 1 ms
CS Falling Edge to VPP Falling
Edge tCP Figure 4 5 ms
CS Step Low Time tCL Figure 4 5 ms
CS Step High Time tCH Figure 4 5 ms
VPP Falling Edge to CS Rising
Edge tPH Figure 4 1 ms
U/D Frequency fU/DMAX 5 MHz
Power-Up Time tUP (Note 3) 1 ms
100kΩ variable resistor configuration,
CL = 10pF, Figure 1 1
Output Settling Time tSETTLE 100kΩ potentiometer configuration,
CL = 10pF, Figure 1 0.25
µs
POWER SUPPLY
Supply Voltage VDD 2.7 5.5 V
Static Supply Current IDD (Note 4) 1.5 µA
TA < +50°C 10.45 11.55
Programming Voltage VPP TA ≥ +50°C 11 11.55 V
Programming Current IPP VPP = 11V 5 mA
Note 1: All devices are production tested at TA= +25°C and are guaranteed by design for TA= -40°C to +85°C.
Note 2: Digital timing is guaranteed by design, not production tested.
Note 3: Power-up time is the period of time from when the power supply is applied until the serial interface is ready for writing.
Note 4: Digital inputs CS and U/Dare connected to GND or VDD.
H
L
W
POTENTIOMETER
CONFIGURATION
VARIABLE-RESISTOR
CONFIGURATION
H
L
Figure 1. Potentiometer/Variable-Resistor Configuration
MAX5427/MAX5428/MAX5429
One-Time Programmable, Linear-Taper
Digital Potentiometers
4 _______________________________________________________________________________________
Typical Operating Characteristics
(VDD = 5.0V, TA = +25°C, unless otherwise noted.)
WIPER RESISTANCE vs. WIPER VOLTAGE
MAX5427 toc01
WIPER VOLTAGE (V)
WIPER RESISTANCE (Ω)
4321
100
120
140
160
80
05
VDD = 3.3V
VDD = 5.0V
END-TO-END RESISTANCE PERCENT
CHANGE vs. TEMPERATURE
MAX5427-29 toc02
TEMPERATURE (°C)
END-TO-END RESISTANCE CHANGE (%)
603510-15
-0.2
-0.1
0
0.1
0.2
0.3
-0.3
-40 85
MAX5429
MAX5428
MAX5427
W-TO-L RESISTANCE
vs. TAP POSITION
MAX5427-29 toc03
TAP POSITION
W-TO-L RESISTANCE (kΩ)
252015105
10
20
30
40
50
60
70
80
90
100
0
030
MAX5427
MAX5428
MAX5429
SUPPLY CURRENT vs. TEMPERATURE
MAX5427-29 toc04
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
603510-15
0.05
0.10
0.15
0.20
0.25
0.30
0
-40 85
VDD = 5.0V
VDD = 3.3V
R-DNL ERROR vs. INPUT CODE
(MAX5427)
MAX5427-29 toc07
INPUT CODE (DECIMAL)
R-DNL (LSB)
252051015
-0.015
-0.010
-0.005
0
0.005
0.010
0.015
0.020
-0.020
030
R-INL ERROR vs. INPUT CODE
(MAX5427)
MAX5427-29 toc08
INPUT CODE (DECIMAL)
R-INL (LSB)
252015105
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
0.08
0.10
-0.10
030
R-DNL ERROR vs. INPUT CODE
(MAX5428)
MAX5427-29 toc09
INPUT CODE (DECIMAL)
R-DNL (LSB)
252051015
-0.015
-0.010
-0.005
0
0.005
0.010
0.015
0.020
-0.020
030
TAP-TO-TAP SWITCHING TRANSIENT
MAX5427-29 toc05
100ns/div
OUTPUT
W
100mV/div
U/D
2V/div
CL = 10pF
WIPER TRANSIENT AT POWER-ON
MAX5427-29 toc06
2µs/div
OUTPUT
W
1V/div
VDD
2V/div
Detailed Description
The MAX5427/MAX5428/MAX5429 are 100kΩ/50kΩ/
10kΩ(end-to-end resistance) digitally controlled poten-
tiometers. They have 32 tap positions that are accessible
to the wiper along the resistor array between H and L.
The wiper (W) position is adjusted sequentially through
the tap positions using a simple 2-wire interface. These
digital potentiometers have an optional one-time pro-
grammable feature that sets the POR position of the
wiper. The 2-wire interface can then be disabled, perma-
nently preventing unwanted adjustment.
Digital Interface Operation
The MAX5427/MAX5428/MAX5429 have two modes of
operation when the serial interface is active: increment
mode and decrement mode. The serial interface is only
active when CS is low.
The CS and U/Dinputs control the position of the wiper
along the resistor array. When CS transitions from high
to low, the part goes into increment mode if U/Dis high
(Figure 2), and into decrement mode if U/Dis low
(Figure 3). Once the mode is set, the device remains in
that mode until CS goes high. A low-to-high transition at
the U/Dincrements or decrements the wiper position
depending on the current mode.
When the CS input transitions to high (when serial inter-
face is inactive) and U/Dis low, the wiper increments or
decrements one position. If U/Dis high when CS transi-
tions to high, the wiper remains in the same position.
MAX5427/MAX5428/MAX5429
One-Time Programmable, Linear-Taper
Digital Potentiometers
_______________________________________________________________________________________ 5
Pin Description
Typical Operating Characteristics (continued)
(VDD = 5.0V, TA = +25°C, unless otherwise noted.)
R-INL ERROR vs. INPUT CODE
(MAX5428)
MAX5427-29 toc10
INPUT CODE (DECIMAL)
R-INL (LSB)
252015105
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
0.08
0.10
-0.10
030
R-DNL ERROR vs. INPUT CODE
(MAX5429)
MAX5427-29 toc11
INPUT CODE (DECIMAL)
R-DNL (LSB)
252015105
-0.020
-0.015
-0.010
-0.005
0
0.005
0.010
0.015
0.020
0.025
-0.025
030
R-INL ERROR vs. INPUT CODE
(MAX5429)
MAX5427-29 toc12
INPUT CODE (DECIMAL)
R-INL (LSB)
252015105
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
0.08
0.10
-0.10
030
PIN NAME FUNCTION
1 W Wiper Connection
2CS
Chip-Select Input. A high-to-low CS transition determines the mode: increment if U/D is high, or
decrement if U/D is low. CS is also used for one-time programming (see the One-Time Programming
section).
3V
DD Power-Supply Voltage
4 GND Ground
5V
PP Programming Voltage for One-Time Programming. Connect VPP to 10V supply when one-time
programming the device. For normal operation, connect to ground or let float.
6U/DUp/Down Control Input. With CS low, a low-to-high transition increments or decrements the wiper
position.
7 L Low Terminal of Resistor
8 H High Terminal of Resistor
MAX5427/MAX5428/MAX5429
The value of the counter is then stored and the wiper
position is maintained.
The wiper performs a make-before-break transition,
ensuring that there is never an open circuit during a tran-
sition from one resistor tap to another. When the wiper is
at either end (max/min) of the resistor array, additional
transitions in the direction of the endpoint do not change
the counter value (the counter does not wrap around).
One-Time Programming
The factory-set default position of the wiper on power-
up is tap 16. However, the power-up position can be
changed once using the one-time programming fea-
ture. After the wiper is moved to the desired position,
the programming sequence is initiated by setting U/D
high, applying 11V to VPP, and then taking CS low. Five
pulses on CS (consisting of CS starting from low and
going high for tCH and then low for tCL) program the
device (Figure 4). The programming voltage should
then be taken to zero. After the device is programmed,
VPP can be set to zero or be allowed to float. The wiper
position is still adjustable, but always returns to this
programmed position on power-up.
If the intent is to program the device to a specific wiper
position and not to allow further adjustments, then six
programming pulses are required (as opposed to five),
as shown in Figure 4. The sixth pulse locks the wiper
position and disables the serial interface. This also
allows U/Dand CS to float without any increase in sup-
ply current. Once the lockout bit is set, no further
adjustment to the potentiometer is possible, effectively
changing the potentiometer into a fixed resistor-divider
(Table 1).
One-Time Programmable, Linear-Taper
Digital Potentiometers
6 _______________________________________________________________________________________
VDD
U/D
CS
VW
tUP
tCU tCI tIL
tIW
tIH tIC
Figure 2. Increment Mode Serial Interface Timing Diagram
VDD
U/D
CS
VW
tUP
tCU tCI tIH
tIW
tIL tIC
Figure 3. Decrement Mode Serial Interface Timing Diagram
MODE
POWER-ON
RESET WIPER
POSITION
ADJUSTABLE
WIPER
Factory Default
(Unprogrammed) Tap 16 Yes
Programmed
(5 Programming Pulses)
Programmed
position Yes
Lock-Bit Set
(6 Programming Pulses)
Programmed
position No
Table 1. One-Time Programming Options
It is recommended that the user either use six CS puls-
es (convert to a fixed voltage-divider) or five pulses
(program the initial power-up value of the device, but
still be able to adjust the wiper). If the device is pro-
grammed with five pulses and later it is desired to dis-
able the interface (convert to a fixed voltage-divider),
then care must be taken to ensure that the wiper is in
the same position as it was originally set to (when pro-
grammed with five pulses). The full six programming
pulses must be applied. If the wiper is not in its original
programmed position prior to disabling the interface,
the final locked-out position is correct. Note that once
the six-pulse program occurs, no further programming
is possible.
The VPP power supply must be able to source at least
5mA and have a good transient response. The VPP power
supply should be decoupled with 22µF and have no more
than 250µH of inductance and/or 40Ωof parasitic resis-
tance between the capacitors and the device (Figure 5).
The device does not require decoupling capacitors near
VPP, provided the above guidelines are met.
MAX5427/MAX5428/MAX5429
One-Time Programmable, Linear-Taper
Digital Potentiometers
_______________________________________________________________________________________ 7
VPP
CS
11V
0V
5 BITS RECORD WIPER POSITION OPTIONAL LOCKOUT BIT
U/D
tCH tCL tCP tPH
tPC
Figure 4. One-Time Program Mode Serial Interface Timing Diagram
LPARASITIC RPARASITIC
TRACE PARASITICS
MAX5427
MAX5428
MAX5429
VPP = 11V
22µF< 250µH < 40Ω
VPP
Figure 5. VPP Power-Supply Connection
Chip Information
TRANSISTOR COUNT: 2270
PROCESS: BiCMOS
MAX5427/MAX5428/MAX5429
One-Time Programmable, Linear-Taper
Digital Potentiometers
8 _______________________________________________________________________________________
6, 8, &10L, QFN THIN.EPS
PACKAGE OUTLINE, 6, 8 & 10L,
QFN THIN (DUAL), EXPOSED PAD, 3x3x0.80 mm
21-0137 C
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.)
MAX5427/MAX5428/MAX5429
One-Time Programmable, Linear-Taper
Digital Potentiometers
_______________________________________________________________________________________ 9
COMMON DIMENSIONS
SYMBOL MIN. MAX.
A0.70 0.80
D2.90 3.10
E2.90 3.10
A1 0.00 0.05
L0.20 0.40
PKG. CODE
6
N
T633-1 1.50±0.10
D2
2.30±0.10
E2
0.95 BSC
e
MO229 / WEEA
JEDEC SPEC
0.40±0.05
b
1.90 REF
[(N/2)-1] x e
1.50±0.10 MO229 / WEEC 1.95 REF0.30±0.05
0.65 BSC
2.30±0.10T833-1 8
PACKAGE VARIATIONS
21-0137
PACKAGE OUTLINE, 6, 8 & 10L,
QFN THIN (DUAL), EXPOSED PAD, 3x3x0.80 mm
C
0.25±0.05 2.00 REFMO229 / WEED-30.50 BSC1.50±0.10 2.30±0.1010T1033-1
0.25 MIN
k
A2 0.20 REF.
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.)
MAX5427/MAX5428/MAX5429
One-Time Programmable, Linear-Taper
Digital Potentiometers
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.
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
8LUMAXD.EPS
PACKAGE OUTLINE, 8L uMAX/uSOP
1
1
21-0036 J
REV.DOCUMENT CONTROL NO.APPROVAL
PROPRIETARY INFORMATION
TITLE:
MAX
0.043
0.006
0.014
0.120
0.120
0.198
0.026
0.007
0.037
0.0207 BSC
0.0256 BSC
A2 A1
c
eb
A
L
FRONT VIEW SIDE VIEW
E H
0.6±0.1
0.6±0.1
ÿ 0.50±0.1
1
TOP VIEW
D
8
A2 0.030
BOTTOM VIEW
16∞
S
b
L
H
E
D
e
c
0∞
0.010
0.116
0.116
0.188
0.016
0.005
8
4X S
INCHES
-
A1
A
MIN
0.002
0.950.75
0.5250 BSC
0.25 0.36
2.95 3.05
2.95 3.05
4.78
0.41
0.65 BSC
5.03
0.66
6∞0∞
0.13 0.18
MAX
MIN
MILLIMETERS
- 1.10
0.05 0.15
α
α
DIM
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.)
