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19-2462; Rev 1; 7/02
KIT ATION EVALU ILABLE AVA
One-Time Programmable, Linear-Taper Digital Potentiometers
General Description Features
o Wiper Position Stored After One-Time Fuse Programming o User-Defined Power-On Reset Position o 35ppm/C End-to-End Temperature Coefficient and 5ppm/C Ratiometric Temperature Coefficient o 32 Tap Positions o Tiny 8-Pin Thin QFN and MAX Packages o Ultra-Low 1.5A (max) Static Supply Current o 2.7V to 5.5V Single-Supply Operation o Wiper Position Programmed Through Simple 2-Wire Serial Interface o 10k, 50k, and 100k End-to-End Resistances
MAX5427/MAX5428/MAX5429
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) position 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 100k, the MAX5428 a resistance of 50k, and the MAX5429 a resistance of 10k. All these devices have 32 wiper positions, operate from a single 2.7V to 5.5V supply, and use less than 1.5A (max) static supply current. The MAX5427/MAX5428/MAX5429 are available in 8-pin thin QFN and MAX packages. Each device is guaranteed over the extended temperature range of -40C to +85C.
Ordering Information
PART MAX5427EUA MAX5427ETA MAX5428EUA MAX5428ETA MAX5429EUA MAX5429ETA TEMP RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 8 MAX 8 Thin QFN-EP* 8 MAX 8 Thin QFN-EP* 8 MAX 8 Thin QFN-EP* R (k) 100 100 50 50 10 10
Applications
Mechanical Potentiometer Replacement Products Using One-Time Factory Calibration
Pin Configurations
TOP VIEW
*EP = Exposed paddle.
W CS VDD GND
1 2 3 4
MAX5427 MAX5428 MAX5429
8H 7L 6 U/D 5 VPP
VDD GND 3 4
Functional Block Diagram
H 8 S32 MAX5427 MAX5428 MAX5429
R31
MAX
S31
R30
* W CS VDD GND
1 2 3 4
MAX5427 MAX5428 MAX5429
*
8H 7L 6 U/D 5 VPP
CS U/D
2 6 UP/DOWN COUNTER
32POSITION DECODER R2
S30 S3
RW
1
W
VPP
5
ONE-TIME PROGRAM BLOCK R1
S2
S1
QFN
7
*EXPOSED PADDLE. CONNECTED TO GND.
L
________________________________________________________________ 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.
One-Time Programmable, Linear-Taper Digital Potentiometers MAX5427/MAX5428/MAX5429
ABSOLUTE MAXIMUM RATINGS
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 = +70C) 8-Pin MAX (derate 4.5mW/C above +70C) .............362mW 8-Pin QFN-EP (derate 24.4mW/C above +70C)......1951mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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
(VDD = 2.7V to 5.5V, VPP = GND, VH = VDD, VL = GND, TA = -40C to +85C, unless otherwise noted. Typical values are at VDD = 5.0V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER DC PERFORMANCE Resolution MAX5427 End-to-End Resistance End-to-End Resistance Tempco Ratiometric Resistance Tempco Integral Nonlinearity Differential Nonlinearity Full-Scale Error Zero-Scale Error Wiper Resistance DIGITAL INPUTS (CS, U/D) Input High Voltage Input Low Voltage Input Current Input Capacitance TIMING CHARACTERISTICS (Note 2) U/D Mode to CS Setup CS Hold to U/D Mode U/D Step Hold to CS U/D Step Low Time tCU tCI tIC tIL Figures 2, 3 Figures 2, 3 Figures 2, 3 Figures 2, 3 50 50 0 100 ns ns ns ns VIH VIL IIN CIN 0.1 5 0.7 x VDD 0.3 x VDD 1 V V A pF RW INL DNL TCR MAX5427/MAX5428 MAX5429 Potentiometer configuration, no load, Figure 1 Potentiometer configuration, no load, Figure 1 Potentiometer configuration, no load, Figure 1 Potentiometer configuration, no load, Figure 1 MAX5427 IW = 20A; MAX5428 IW = 40A; MAX5429 IW = 200A 100 MAX5428 MAX5429 32 75 37.5 7.5 100 50 10 35 5 10 1 1 -0.5 +0.5 240 125 62.5 12.5 ppm/C ppm/C LSB LSB LSB LSB k Taps SYMBOL CONDITIONS MIN TYP MAX UNITS
2
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One-Time Programmable, Linear-Taper Digital Potentiometers
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 2.7V to 5.5V, VPP = GND, VH = VDD, VL = GND, TA = -40C to +85C, unless otherwise noted. Typical values are at VDD = 5.0V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER U/D Step High Time Wiper Switching Time VPP Rising Edge to CS Falling Edge CS Falling Edge to VPP Falling Edge CS Step Low Time CS Step High Time VPP Falling Edge to CS Rising Edge U/D Frequency Power-Up Time SYMBOL tIH tIW tPC tCP tCL tCH tPH fU/DMAX tUP (Note 3) 100k variable resistor configuration, CL = 10pF, Figure 1 100k potentiometer configuration, CL = 10pF, Figure 1 2.7 (Note 4) TA < +50C TA +50C VPP = 11V 10.45 11 5 1 s 0.25 Figures 2, 3 CL = 0pF, Figures 2, 3 Figure 4 Figure 4 Figure 4 Figure 4 Figure 4 1 5 5 5 1 5 1 CONDITIONS MIN 100 100 TYP MAX UNITS ns ns ms ms ms ms ms MHz ms
MAX5427/MAX5428/MAX5429
Output Settling Time
tSETTLE
POWER SUPPLY Supply Voltage Static Supply Current Programming Voltage Programming Current VDD IDD VPP IPP 5.5 1.5 11.55 11.55 V A V mA
Note 1: Note 2: Note 3: Note 4:
All devices are production tested at TA = +25C and are guaranteed by design for TA = -40C to +85C. Digital timing is guaranteed by design, not production tested. Power-up time is the period of time from when the power supply is applied until the serial interface is ready for writing. Digital inputs CS and U/D are connected to GND or VDD.
POTENTIOMETER CONFIGURATION H
VARIABLE-RESISTOR CONFIGURATION H
W
L
L
Figure 1. Potentiometer/Variable-Resistor Configuration _______________________________________________________________________________________ 3
One-Time Programmable, Linear-Taper Digital Potentiometers MAX5427/MAX5428/MAX5429
Typical Operating Characteristics
(VDD = 5.0V, TA = +25C, unless otherwise noted.)
END-TO-END RESISTANCE PERCENT CHANGE vs. TEMPERATURE
MAX5427-29 toc02
WIPER RESISTANCE vs. WIPER VOLTAGE
MAX5427 toc01
W-TO-L RESISTANCE vs. TAP POSITION
90 W-TO-L RESISTANCE (k) 80 70 60 50 40 30 20 10 MAX5429 MAX5427 MAX5428
MAX5427-29 toc03
160
0.3 END-TO-END RESISTANCE CHANGE (%) 0.2 0.1 MAX5429 0 -0.1 MAX5427 -0.2 -0.3 MAX5428
100
WIPER RESISTANCE ()
140 VDD = 3.3V 120
100 VDD = 5.0V 80 0 1 2 3 4 5 WIPER VOLTAGE (V)
0 -40 -15 10 35 60 85 0 5 10 15 20 25 30 TEMPERATURE (C) TAP POSITION
SUPPLY CURRENT vs. TEMPERATURE
MAX5427-29 toc04
TAP-TO-TAP SWITCHING TRANSIENT
MAX5427-29 toc05
WIPER TRANSIENT AT POWER-ON
MAX5427-29 toc06
0.30 0.25 SUPPLY CURRENT (A) 0.20 0.15 0.10 0.05 0 -40 -15 10 35 60 VDD = 3.3V VDD = 5.0V
U/D 2V/div
VDD 2V/div
OUTPUT W 100mV/div CL = 10pF 85 100ns/div
OUTPUT W 1V/div
2s/div
TEMPERATURE (C)
R-DNL ERROR vs. INPUT CODE (MAX5427)
MAX5427-29 toc07
R-INL ERROR vs. INPUT CODE (MAX5427)
MAX5427-29 toc08
R-DNL ERROR vs. INPUT CODE (MAX5428)
0.015 0.010 R-DNL (LSB) 0.005 0 -0.005 -0.010 -0.015 -0.020
MAX5427-29 toc09
0.020 0.015 0.010 R-DNL (LSB) 0.005 0 -0.005 -0.010 -0.015 -0.020 0 5 10 15 20 25 30 INPUT CODE (DECIMAL)
0.10 0.08 0.06 0.04 R-INL (LSB) 0.02 0 -0.02 -0.04 -0.06 -0.08 -0.10 0 5 10 15 20 25 30 INPUT CODE (DECIMAL)
0.020
0
5
10
15
20
25
30
INPUT CODE (DECIMAL)
4
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One-Time Programmable, Linear-Taper Digital Potentiometers
Typical Operating Characteristics (continued)
(VDD = 5.0V, TA = +25C, unless otherwise noted.)
R-INL ERROR vs. INPUT CODE (MAX5428)
MAX5427-29 toc10
MAX5427/MAX5428/MAX5429
R-DNL ERROR vs. INPUT CODE (MAX5429)
MAX5427-29 toc11
R-INL ERROR vs. INPUT CODE (MAX5429)
0.08 0.06 0.04 R-INL (LSB) 0.02 0 -0.02 -0.04 -0.06 -0.08 -0.10
MAX5427-29 toc12
0.10 0.08 0.06 0.04 0.02 0 -0.02 -0.04 -0.06 -0.08 -0.10 0 5 10 15 20 25 30 INPUT CODE (DECIMAL) R-INL (LSB)
0.025 0.020 0.015 0.010 R-DNL (LSB) 0.005 0 -0.005 -0.010 -0.015 -0.020 -0.025 0 5 10 15 20 25 30 INPUT CODE (DECIMAL)
0.10
0
5
10
15
20
25
30
INPUT CODE (DECIMAL)
Pin Description
PIN 1 2 3 4 5 6 7 8 NAME W CS VDD GND VPP U/D L H FUNCTION Wiper Connection 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). Power-Supply Voltage Ground 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. Up/Down Control Input. With CS low, a low-to-high transition increments or decrements the wiper position. Low Terminal of Resistor High Terminal of Resistor
Detailed Description
The MAX5427/MAX5428/MAX5429 are 100k/50k/ 10k (end-to-end resistance) digitally controlled potentiometers. 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 programmable feature that sets the POR position of the wiper. The 2-wire interface can then be disabled, permanently preventing unwanted adjustment.
mode and decrement mode. The serial interface is only active when CS is low. The CS and U/D inputs 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/D is high (Figure 2), and into decrement mode if U/D is 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/D increments or decrements the wiper position depending on the current mode. When the CS input transitions to high (when serial interface is inactive) and U/D is low, the wiper increments or decrements one position. If U/D is high when CS transitions to high, the wiper remains in the same position.
Digital Interface Operation
The MAX5427/MAX5428/MAX5429 have two modes of operation when the serial interface is active: increment
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5
One-Time Programmable, Linear-Taper Digital Potentiometers MAX5427/MAX5428/MAX5429
VDD tUP CS tCU U/D tIW VW tCI tIL tIH tIC
Figure 2. Increment Mode Serial Interface Timing Diagram
VDD tUP CS
tCU U/D
tCI
tIH
tIL
tIC
tIW VW
Figure 3. Decrement Mode Serial Interface Timing Diagram
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 transition 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 powerup is tap 16. However, the power-up position can be changed once using the one-time programming feature. 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/D and CS to float without any increase in supply 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).
Table 1. One-Time Programming Options
MODE Factory Default (Unprogrammed) Programmed (5 Programming Pulses) Lock-Bit Set (6 Programming Pulses) POWER-ON RESET WIPER POSITION Tap 16 Programmed position Programmed position ADJUSTABLE WIPER Yes Yes No
6
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One-Time Programmable, Linear-Taper Digital Potentiometers MAX5427/MAX5428/MAX5429
U/D 11V VPP 0V CS tPC 5 BITS RECORD WIPER POSITION OPTIONAL LOCKOUT BIT
tCH
tCL
tCP
tPH
Figure 4. One-Time Program Mode Serial Interface Timing Diagram
It is recommended that the user either use six CS pulses (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 programmed with five pulses and later it is desired to disable 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 programmed 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 22F and have no more than 250H of inductance and/or 40 of parasitic resistance between the capacitors and the device (Figure 5). The device does not require decoupling capacitors near VPP, provided the above guidelines are met.
TRACE PARASITICS VPP = 11V 22F VPP
LPARASITIC < 250H
RPARASITIC < 40
MAX5427 MAX5428 MAX5429
Figure 5. VPP Power-Supply Connection
Chip Information
TRANSISTOR COUNT: 2270 PROCESS: BiCMOS
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7
One-Time Programmable, Linear-Taper Digital Potentiometers MAX5427/MAX5428/MAX5429
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.)
PACKAGE OUTLINE, 6, 8 & 10L, QFN THIN (DUAL), EXPOSED PAD, 3x3x0.80 mm
21-0137
C
8
_______________________________________________________________________________________
6, 8, &10L, QFN THIN.EPS
One-Time Programmable, 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.)
MAX5427/MAX5428/MAX5429
COMMON DIMENSIONS SYMBOL A D E A1 L k A2 MIN. 0.70 2.90 2.90 0.00 0.20 MAX. 0.80 3.10 3.10 0.05 0.40
0.25 MIN 0.20 REF.
PACKAGE VARIATIONS PKG. CODE T633-1 T833-1 T1033-1 N 6 8 10 D2 1.500.10 1.500.10 1.500.10 E2 2.300.10 2.300.10 2.300.10 e 0.95 BSC 0.65 BSC 0.50 BSC JEDEC SPEC MO229 / WEEA MO229 / WEEC MO229 / WEED-3 b 0.400.05 0.300.05 0.250.05 [(N/2)-1] x e 1.90 REF 1.95 REF 2.00 REF
PACKAGE OUTLINE, 6, 8 & 10L, QFN THIN (DUAL), EXPOSED PAD, 3x3x0.80 mm
21-0137
C
_______________________________________________________________________________________
9
One-Time Programmable, Linear-Taper Digital Potentiometers MAX5427/MAX5428/MAX5429
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.)
8LUMAXD.EPS
8
4X S
8
INCHES DIM A A1 A2 b c D e E H MIN 0.002 0.030 MAX 0.043 0.006 0.037
MILLIMETERS MAX MIN 0.05 0.75 1.10 0.15 0.95
y 0.500.1 0.60.1
E
H
1
0.60.1
1
D
L
S
BOTTOM VIEW
0.014 0.010 0.007 0.005 0.120 0.116 0.0256 BSC 0.120 0.116 0.198 0.188 0.026 0.016 6 0 0.0207 BSC
0.25 0.36 0.13 0.18 2.95 3.05 0.65 BSC 2.95 3.05 4.78 5.03 0.41 0.66 0 6 0.5250 BSC
TOP VIEW
A2
A1
A
e
c b L
SIDE VIEW
FRONT VIEW
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
APPROVAL DOCUMENT CONTROL NO. REV.
21-0036
J
1 1
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 (c) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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