MAX5394
Single, 256-Tap Volatile, SPI, Low-Voltage Linear
Taper Digital Potentiometer
General Description
The MAX5394 single, 256-tap volatile, low-voltage
linear taper digital potentiometer offers three end-to-
end resistance values of 10kΩ, 50kΩ, and 100kΩ.
Potentiometer terminals are independent of supply for
voltages up to 5.25V with single-supply operation from
1.7V to 5.5V (charge pump enabled). User-controlled
shutdown modes allow the H, W, or L terminal to be
opened with the wiper position set to zero-code, mid-
code, full-code, or the value contained in the wiper
register. Ultra-low-quiescent supply current (< 1µA) can
be achieved for supply voltages between 2.6V and 5.5V
by disabling the internal charge pump and not allowing
potentiometer terminals to exceed the supply voltage by
more than 0.3V. The MAX5394 provides a low 50ppm/°C
end-to-end temperature coefficient and features a SPI
serial interface.
The small package size, low operating supply voltage,
low supply current, and automotive temperature range
of the MAX5394 make the device uniquely suited for the
portable consumer market, battery-backup industrial
applications, and automotive market.
The MAX5394 is available in a lead-free, 8-pin TDFN
(2mm x 2mm) package. The device operates over the
-40°C to +125°C automotive temperature range.
Features
S Single Linear Taper 256-Tap Positions
S 10kI, 50kI, and 100kI End-to-End Resistance
S 1.7V to 5.5V Extended Single Supply
S 0 to 5.25V H, W, L Operating Voltage Independent
of VDD
S 1µA (typ) Supply Current in Low-Power Mode
S ±1.0 LSB INL, ±0.5 LSB DNL (max) Wiper Accuracy
S Power-On Sets Wiper to Midscale
S 50ppm/NC End-to-End Temperature Coefficient
S 5ppm/NC Ratiometric Temperature Coefficient
S -40NC to +125NC Operating Temperature Range
S 2mm x 2mm, 8-Pin TDFN Package
S SPI-Compatible Serial Interface
Applications
Portable Electronics
System Calibration
Battery-Powered Systems
Automotive Electronics
Mechanical Potentiometer Replacement
Typical Operating Circuit
19-6392; Rev 0; 7/12
Ordering Information appears at end of data sheet.
For related parts and recommended products to use with this part, refer to: www.maxim-ic.com/MAX5394.related
SPI
INTERFACE
1.7V TO 5.5V
(CHARGE PUMP ENABLED) H
W
LR1
VS
VO
+5V
VDD
MAX5394
MAX4250
GND
VO/VS = 1 + RMAX5394/R1
DIN
SCLK
CS
1
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
MAX5394
Single, 256-Tap Volatile, SPI, Low-Voltage Linear
Taper Digital Potentiometer
2
(All voltages referenced to GND.)
VDD .........................................................................-0.3V to +6V
H, W, L (charge pump enabled) ......................... -0.3V to +5.5V
H, W, L (charge pump disabled) ................ -0.3V to the lower of
(VDD + 0.3V) or +6V
All Other Pins .........................................................-0.3V to +6V
Continuous Power Dissipation (TA = +70NC)
TDFN (derate 11.9mW/NC above +70NC) ................. 953.5mW
Operating Temperature Range ....................... -40NC to +125NC
Storage Temperature Range ........................... -65NC to + 150NC
Junction Temperature .....................................................+150NC
Lead Temperature (soldering, 10s) .............................. + 300NC
Soldering Temperature (reflow) .....................................+260NC
TDFN
Junction-to-Ambient Thermal Resistance (qJA) .......83.9°C/W
Junction-to-Case Thermal Resistance (qJC) ............37.0°C/W
ABSOLUTE MAXIMUM RATINGS
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion 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.
PACKAGE THERMAL CHARACTERISTICS (Note 1)
ELECTRICAL CHARACTERISTICS
(VDD = 1.7V to 5.5V, VH = VDD, VL = GND, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VDD = 1.8V,
TA = +25°C.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
RESOLUTION
256-Tap Family N 256 Tap
DC PERFORMANCE (VOLTAGE-DIVIDER MODE)
Integral Nonlinearity (Note 3) INL -1.0 +1.0 LSB
Differential Nonlinearity DNL (Note 3) -0.5 +0.5 LSB
Ratiometric Resistor Tempco (DVW/VW)/DT, VH = VDD, VL = GND, no load 5 ppm/°C
Full-Scale Error (Code FFh)
Charge pump enabled, 1.7V < VDD < 5.5V -0.5
LSB
Charge pump disabled,
2.6V < VDD < 5.5VS
MAX5394M
MAX5394N -0.5
MAX5394L -1.0
Zero-Scale Error (Code 00h)
Charge pump enabled, 1.7V < VDD < 5.5V +0.5
LSB
Charge pump disabled,
2.6V < VDD < 5.5V
MAX5394M
MAX5394N +0.5
MAX5394L +1.0
DC PERFORMANCE (VARIABLE RESISTOR MODE)
Integral Nonlinearity (Note 4) R-INL
Charge pump enabled, 1.7V < VDD < 5.5V -1.0 +1.0
LSB
Charge pump disabled,
2.6V < VDD < 5.5V
MAX5394M
MAX5394N -1.0 +1.0
MAX5394L -1.5 +1.5
MAX5394
Single, 256-Tap Volatile, SPI, Low-Voltage Linear
Taper Digital Potentiometer
3
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 1.7V to 5.5V, VH = VDD, VL = GND, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VDD = 1.8V,
TA = +25°C.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Differential Nonlinearity R-DNL (Note 4) -0.5 +0.5 LSB
Wiper Resistance (Note 5) RWL
Charge pump enabled, 1.7V < VDD < 5.5V 25 50 Ω
Charge pump disabled, 2.6V < VDD < 5.5V 200
DC PERFORMANCE (RESISTOR CHARACTERISTICS)
Terminal Capacitance CH, CLMeasured to GND 10 pF
Wiper Capacitance CWMeasured to GND 20 pF
End-to-End Resistor Tempco TCR No load 50 ppm/°C
End-to-End Resistor
Tolerance Wiper not connected -25 +25 %
AC PERFORMANCE
-3dB Bandwidth BW Code = 80h, 10pF load,
VDD = 1.8V
10kΩ 1600
kHz50kΩ 340
100kΩ 165
Total Harmonic Distortion
Plus Noise THD+N (Note 6) 0.035 %
Wiper Settling Time tS(Note 7)
10kΩ 190
ns50kΩ 400
100kΩ 664
Charge-Pump Feedthrough
at W VRW 600 nVRMS
POWER SUPPLIES
Supply Voltage Range VDD 1.7 5.5 V
Terminal Voltage Range (H,
W, L to GND)
Charge pump enabled, 1.7V < VDD < 5.5V 0 5.25 V
Charge pump disabled, 2.6V < VDD < 5.5V 0 VDD
Supply Current (Note 8) IVDD
Charge pump disabled, 2.6V < VDD < 5.5V 1
µA
Charge pump enabled,
1.7V < VDD < 5.5V
VDD = 5.5V 25
VDD = 1.7V 20
DIGITAL INPUTS
Minimum Input High Voltage VIH
2.6V < VDD < 5.5V 70 % x VDD
1.7V < VDD < 2.6V 80
Maximum Input Low Voltage VIL
2.6V < VDD < 5.5V 30 % x VDD
1.7V < VDD < 2.6V 20
Input Leakage Current -1 +1 µA
Input Capacitance 5 pF
MAX5394
Single, 256-Tap Volatile, SPI, Low-Voltage Linear
Taper Digital Potentiometer
4
Note 2: All devices are production tested at TA = +25°C and are guaranteed by design and characterization for TA = -40°C to
+125°C.
Note 3: DNL and INL are measured with the potentiometer configured as a voltage-divider with VH = 5.25 (QP enabled) or VDD
(QP disabled) and VL = GND. The wiper terminal is unloaded and measured with an ideal voltmeter.
Note 4: R-DNL and R-INL are measured with the potentiometer configured as a variable resistor (Figure 1). H is unconnected and
L = GND.
For charge pump enabled, VDD = 1.7V to 5.5V, 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 charge pump disabled and VDD = 5.5V, 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 charge pump disabled and VDD = +2.6V, 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 5: The wiper resistance is the maximum value measured by injecting the currents given in Note 4 into W with L = GND.
RW = (VW - VH)/IW.
Note 6: Measured at W with H driven with a 1kHz, 0V to VDD amplitude tone and VL = GND. 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 loaded with 10pF capacitance to ground.
Note 8: Digital inputs at VDD or GND.
Note 9: Digital timing is guaranteed by design and characterization, and is not production tested.
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 1.7V to 5.5V, VH = VDD, VL = GND, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VDD = 1.8V,
TA = +25°C.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
TIMING CHARACTERISTICS (Note 9)
SCLK Frequency fSCLK
2.6V < VDD < 5.5V 50 MHz
1.7V < VDD < 2.6V 25
SCLK Period tSCLK
2.6V < VDD < 5.5V 20 ns
1.7V < VDD < 2.6V 40
SCLK Pulse-Width High tCH 8 ns
SCLK Pulse-Width Low tCL 8 ns
CS Fall to SCLK Fall Setup
Time tCSS0 To 1st SCLK falling
edge (FE)
2.6V < VDD < 5.5V 8ns
1.7V < VDD < 2.6V 16
CS Fall to SCLK Fall Hold
Time tCSH0 Applies to inactive FE preceding 1st FE 0 ns
CS Rise to SCLK Fall Hold
Time tCSH1 Applies to 16th FE 0 ns
CS Rise to SCLK Fall tCSA Applies to 16th FE,
aborted sequence
2.6V < VDD < 5.5V 12 ns
1.7V < VDD < 2.6V 16
SCLK Fall to CS Fall tCSF Applies to 16th FE 100 ns
CS Pulse-Width High tCSPW 20 ns
DIN to SCLK Fall Setup Time tDS 5 ns
DIN to SCLK Fall Hold Time tDH 4.5 ns
CS Pulse-Width High tCSPW 20 ns
MAX5394
Single, 256-Tap Volatile, SPI, Low-Voltage Linear
Taper Digital Potentiometer
5
Figure 1. Voltage-Divider and Variable Resistor Configurations
Figure 2. SPI Timing Diagram
W
H
L
W
N.C.
L
DIN15
DIN
SCLK
tCSPW
DIN14 DIN13 DIN12 DIN11 DIN10 DIN9 DIN8 DIN2 DIN1 DIN
0D
IN15
CS
tCSH0 tCSS0
12345678 14 15 16 1
tDS tDH tCP
tCH tCL tCSA tCSH1
tCSF
MAX5394
Single, 256-Tap Volatile, SPI, Low-Voltage Linear
Taper Digital Potentiometer
6
Typical Operating Characteristics
(VDD = 1.8V, TA = +25NC, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
MAX5394 toc01
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
1109580655035205-10-25
40
0
-40 125
5
10
15
20
25
30
35
VDD = 1.8V
SUPPLY CURRENT
vs. DIGITAL INPUT VOLTAGE
MAX5394 toc02
DIGITAL INPUT VOLTAGE (V)
SUPPLY CURRENT (µA)
4321
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
0
05
VDD = 5V
(LOW-HIGH)
VDD = 3.3V
(LOW-HIGH)
VDD = 1.8V
(LOW-HIGH)
VDD = 1.8V
(HIGH-LOW)
VDD = 3.3V
(HIGH-LOW)
VDD = 5V
(HIGH-LOW)
SUPPLY CURRENT vs. INPUT VOLTAGE
MAX5394 toc03
INPUT VOLTAGE (V)
4.553.602.651.70 5.50
SUPPLY CURRENT (µA)
40
0
5
10
15
20
25
30
35
TA = -40°C
TA = +25°C
TA = +125°C
RESISTANCE (W-TO-L)
vs. TAP POSITION (10kI)
MAX5394 toc04
TAP POSITION
W-TO-L RESISTANCE (kI)
1
2
3
4
5
6
7
8
9
10
0
0 256224192128 16064 9632
RESISTANCE (W-TO-L)
vs. TAP POSITION (50kI)
MAX5394 toc05
TAP POSITION
W-TO-L RESISTANCE (kI)
5
10
15
20
25
30
35
40
45
50
0
0 256224192128 16064 9632
RESISTANCE (W-TO-L)
vs. TAP POSITION (100kI)
MAX5394 toc06
TAP POSITION
W-TO-L RESISTANCE (kI)
10
20
30
40
50
60
70
80
90
100
0
0 256224192128 16064 9632
WIPER RESISTANCE
vs. WIPER VOLTAGE
WIPER VOLTAGE (V)
WIPER RESISTANCE (I)
0.5
0
5
0 1.0
MAX5394 toc07a
VDD = 2.6V, QP OFF
VDD = 5V, QP OFF
5.04.54.03.53.02.52.01.5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
5
10
15
20
25
30
35
WIPER RESISTANCE
vs. WIPER VOLTAGE
WIPER VOLTAGE (V)
WIPER RESISTANCE (I)
0.5
0
0 1.0
MAX5394 toc07b
VDD = 1.8V, QP ON
5.04.54.03.53.02.52.01.5
40
END-TO-END RESISTANCE PERCENTAGE
CHANGE vs. TEMPERATURE
MAX5394 toc08
TEMPERATURE (°C)
END-TO-END RESISTANCE PERCENTAGE CHANGE (%)
1109580655035205-10-25
-0.2
-40 125
0
0.2
0.4
0.6
0.8
50kI
10kI
100kI
MAX5394
Single, 256-Tap Volatile, SPI, Low-Voltage Linear
Taper Digital Potentiometer
7
Typical Operating Characteristics (continued)
(VDD = 1.8V, TA = +25NC, unless otherwise noted.)
TAP-TO-TAP SWITCHING TRANSIENT
(CODE 127 TO 128 10kI)
MAX5394 toc09
VW-L
10mV/div
VSCLK
2V/div
200ns/div
TAP-TO-TAP SWITCHING TRANSIENT
(CODE 127 TO 128 50kI)
MAX5394 toc10
VW-L
10mV/div
VSCLK
2V/div
200ns/div
TAP-TO-TAP SWITCHING TRANSIENT
(CODE 127 TO 128 100kI)
MAX5394 toc11
VW-L
10mV/div
VSCLK
2V/div
200ns/div
POWER-ON TRANSIENT (10kI)
MAX5394 toc12a
VW-L
1V/div
VDD
1V/div
10µs/div
POWER-ON TRANSIENT (50kI)
MAX5394 toc12b
VW-L
1V/div
VDD
1V/div
10µs/div
POWER-ON TRANSIENT (100kI)
MAX5394 toc12c
VW-L
1V/div
VDD
1V/div
10µs/div
MAX5394
Single, 256-Tap Volatile, SPI, Low-Voltage Linear
Taper Digital Potentiometer
8
Typical Operating Characteristics (continued)
(VDD = 1.8V, TA = +25NC, unless otherwise noted.)
MIDSCALE FREQUENCY
RESPONSE (10kI)
FREQUENCY (Hz)
GAIN (dB)
1M100k10k1k0.1k
-20
-10
0
10
-30
0.01k 10M
MAX5394 toc13
VDD = 1.8V
VDD = 5V
VIN = 1VP-P
CW = 10pF
MIDSCALE FREQUENCY
RESPONSE (50kI)
FREQUENCY (Hz)
GAIN (dB)
1M100k10k1k0.1k
-20
-10
0
10
-30
0.01k 10M
MAX5394 toc14
VDD = 1.8V
VDD = 5V
VIN = 1VP-P
CW = 10pF
MIDSCALE FREQUENCY
RESPONSE (100kI)
FREQUENCY (Hz)
GAIN (dB)
1M100k10k1k0.1k
-20
-10
0
10
-30
0.01k 10M
MAX5394 toc15
VDD = 1.8V
VDD = 5V
VIN = 1VP-P
CW = 10pF
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
MAX5394 toc16
FREQUENCY (kHz)
THD+N (%)
1010.1
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
0
0.01 100
10kI50kI
100kI
VARIABLE-RESISTOR DNL
vs. TAP POSITION (10kI)
MAX5394 toc18a
TAP POSITION
DNL (LSB)
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-0.5
0256224192128 16064 9632
VDD = 1.8V, VH = 5.0V, CHARGE PUMP ON
VDD = 2.6V, VH = 2.6V, CHARGE PUMP OFF
VDD = 5.0V, VH = 5.0V, CHARGE PUMP OFF
CHARGE-PUMP FEEDTHROUGH AT W
MAX5394 toc17
FREQUENCY (MHz)
0.50 2.00
VOLTAGE (nVRMS)
100
200
300
400
500
600
700
800
900
1000
0
1.75
1.501.251.000.75
100kI
50kI
10kI
VARIABLE-RESISTOR DNL
vs. TAP POSITION (50kI)
MAX5394 toc18b
TAP POSITION
DNL (LSB)
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-0.5
0 256224192128 16064 9632
VDD = 1.8V, VH = 5.0V, CHARGE PUMP ON
VDD = 2.6V, VH = 2.6V, CHARGE PUMP OFF
VDD = 5.0V, VH = 5.0V, CHARGE PUMP OFF
VARIABLE-RESISTOR DNL
vs. TAP POSITION (100kI)
MAX5394 toc18c
TAP POSITION
DNL (LSB)
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-0.5
0 256224192128 16064 9632
VDD = 1.8V, VH = 5.0V, CHARGE PUMP ON
VDD = 2.6V, VH = 2.6V, CHARGE PUMP OFF
VDD = 5.0V, VH = 5.0V, CHARGE PUMP OFF
VARIABLE-RESISTOR INL
vs. TAP POSITION (10kI)
MAX5394 toc19a
TAP POSITION
INL (LSB)
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-0.5
0 256224192128 16064 9632
VDD = 1.8V, VH = 5.0V, CHARGE PUMP ON
VDD = 5.0V, VH = 5.0V, CHARGE PUMP OFF
VDD = 2.6V,
VH = 2.6V,
CHARGE
PUMP OFF
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
MAX5394
Single, 256-Tap Volatile, SPI, Low-Voltage Linear
Taper Digital Potentiometer
9
VOLTAGE-DIVIDER INL
vs. TAP POSITION (10kI)
MAX5394 toc21a
TAP POSITION
INL (LSB)
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-0.5
0256224192128 16064 9632
VDD = 1.8V, VH = 5.0V, CHARGE PUMP ON
VDD = 2.6V, VH = 2.6V, CHARGE PUMP OFF
VDD = 5.0V, VH = 5.0V, CHARGE PUMP OFF
VOLTAGE-DIVIDER DNL
vs. TAP POSITION (100kI)
MAX5394 toc20c
TAP POSITION
DNL (LSB)
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-0.5
0256224192128 16064 9632
VDD = 1.8V, VH = 5.0V, CHARGE PUMP ON
VDD = 2.6V, VH = 2.6V, CHARGE PUMP OFF
VDD = 5.0V, VH = 5.0V, CHARGE PUMP OFF
VARIABLE-RESISTOR INL
vs. TAP POSITION (50kI)
MAX5394 toc19b
TAP POSITION
INL (LSB)
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-0.5
0 256224192128 16064 9632
VDD = 1.8V, VH = 5.0V, CHARGE PUMP ON
VDD = 5.0V, VH = 5.0V, CHARGE PUMP OFF
VDD = 2.6V, VH = 2.6V, CHARGE PUMP OFF
VARIABLE-RESISTOR INL
vs. TAP POSITION (100kI)
MAX5394 toc19c
TAP POSITION
INL (LSB)
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-0.5
0 256224192128 16064 9632
VDD = 1.8V, VH = 5.0V, CHARGE PUMP ON
VDD = 2.6V, VH = 2.6V, CHARGE PUMP OFF
VDD = 5.0V, VH = 5.0V, CHARGE PUMP OFF
VOLTAGE-DIVIDER DNL
vs. TAP POSITION (10kI)
MAX5394 toc20a
TAP POSITION
DNL (LSB)
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-0.5
0 256224192128 16064 9632
VDD = 1.8V, VH = 5.0V, CHARGE PUMP ON
VDD = 2.6V, VH = 2.6V, CHARGE PUMP OFF
VDD = 5.0V, VH = 5.0V, CHARGE PUMP OFF
VOLTAGE-DIVIDER DNL
vs. TAP POSITION (50kI)
MAX5394 toc20b
TAP POSITION
DNL (LSB)
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-0.5
0 256224192128 16064 9632
VDD = 1.8V, VH = 5.0V, CHARGE PUMP ON
VDD = 2.6V, VH = 2.6V, CHARGE PUMP OFF
VDD = 5.0V, VH = 5.0V, CHARGE PUMP OFF
VOLTAGE-DIVIDER INL
vs. TAP POSITION (50kI)
MAX5394 toc21b
TAP POSITION
INL (LSB)
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-0.5
0 256224192128 16064 9632
VDD = 1.8V, VH = 5.0V, CHARGE PUMP ON
VDD = 2.6V, VH = 2.6V, CHARGE PUMP OFF
VDD = 5.0V, VH = 5.0V, CHARGE PUMP OFF
VOLTAGE-DIVIDER INL
vs. TAP POSITION (100kI)
MAX5394 toc21c
TAP POSITION
INL (LSB)
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-0.5
0 256224192128 16064 9632
VDD = 1.8V, VH = 5.0V, CHARGE PUMP ON
VDD = 2.6V, VH = 2.6V, CHARGE PUMP OFF
VDD = 5.0V, VH = 5.0V, CHARGE PUMP OFF
MAX5394
Single, 256-Tap Volatile, SPI, Low-Voltage Linear
Taper Digital Potentiometer
10
Pin Configuration
Pin Description
PIN NAME FUNCTION
1 L Low Terminal. The voltage at L can be greater than or less than the voltage at H. Current can flow into or
out of L.
2 GND Ground
3CS Active-Low Chip-Select Digital Input
4 DIN Serial-Interface Data Input
5 SCLK Serial-Interface Clock Input
6 VDD Power Supply
7 W Wiper Terminal
8 H High Terminal. The voltage at H can be greater than or less than the voltage at L. Current can flow into or
out of H.
— EP Exposed Pad. Internally connected to GND. Connected to ground.
1
+
3
4
8
6
5
H
VDD
SCLK
MAX5394
27W
L
EP
DIN
GND
TDFN
TOP VIEW
CS
MAX5394
Single, 256-Tap Volatile, SPI, Low-Voltage Linear
Taper Digital Potentiometer
11
Functional Diagram
Detailed Description
The MAX5394 single, 256-tap volatile, low-voltage
linear taper digital potentiometer offers three end-to-
end resistance values of 10kΩ, 50kΩ, and 100kΩ.
Potentiometer terminals are independent of supply for
voltages up to +5.25V with single-supply operation from
1.7V to 5.5V (charge pump enabled). User-controlled
shutdown modes allow the H, W, or L terminals to
be opened with the wiper position set to zero-code,
midcode, full-code, or the value contained in the wiper
register. Ultra-low-quiescent supply current (< 1µA) can
be achieved for supply voltages between 2.6V and 5.5V
by disabling the internal charge pump and not allowing
potentiometer terminals to exceed the supply voltage by
more than 0.3V. The MAX5394 provides a low 50ppm/°C
end-to-end temperature coefficient and features a SPI
serial interface.
The small package size, low supply operating voltage,
low supply current, and automotive temperature range
of the MAX5394 make the device uniquely suited for the
portable consumer market, battery-backup industrial
applications, and automotive market.
Charge Pump
The MAX5394 contains an internal charge pump that
guarantees the maximum wiper resistance, RWL, to be
less than 50Ω (25Ω typ) for supply voltages down to
1.7V and allows pins H, W, and L to be driven between
GND and 5.25V independent of VDD. Minimal charge-
pump feedthrough is present at the terminal outputs
and is illustrated by the Charge-Pump Feedthrough
at W vs. Frequency graph in the Typical Operating
Characteristics. The charge pump is on by default but
can be disabled with QP_OFF and enabled with the
QP_ON commands (Table 1). The MAX5394 minimum
supply voltage with charge pump disabled is limited
to 2.6V and terminal voltage cannot exceed -0.3V to
(VDD + 0.3V).
SPI Interface
The digital interface is powered from VDD, not the internal
charge-pump voltage. Therefore the VIH and VIL logic
thresholds will follow VDD as specified in the Electrical
Characteristics table.
The SPI digital interface uses a 3-wire serial data interface
to control the wiper tap position. This write-only interface
contains three inputs: Chip Select (CS), Data In (DIN),
and Data Clock (SCLK). When CS is taken low, data
from the DIN pin is synchronously loaded into the serial
shift register on each falling edge of each SCLK pulse
(Figure 3). After all the data bits have been shifted in,
they are latched into the potentiometer control register.
Data written to a memory register immediately updates
the wiper position.
Keep CS low during the entire data stream to prevent
the data from being terminated. The power-on default
position of the wiper is midscale (D[7:0] = 80H).
Figure 3. SPI Digital Interface Format
H
L
CS
GND
DIN
W
VDD
SCLK
MAX5394
SPI
INTERFACE
C7DIN
SCLK
C6 C5 C4 C3 C2 C1 C0 D7 D6 D5 D4 D3
WIPER REGISTER
LOADED
D2 D1 D0
CS
MAX5394
Single, 256-Tap Volatile, SPI, Low-Voltage Linear
Taper Digital Potentiometer
12
WIPER Command
The data byte writes to the wiper register and the
potentiometer moves to the appropriate position. D[7:0]
indicates the position of the wiper. D[7:0] = 0x00 moves
the wiper to the position closest to L. D[7:0] = 0xFF
moves the wiper closest to H. D[7:0] = 0x80 following
power-on.
SD_CLR Command
Removes any existing shutdown condition. Connects
all potentiometer terminals and returns the wiper to the
value stored in the wiper register. The command does
not affect the current status of the charge pump.
SD_H_WREG Command
Opens the H terminal and maintains the wiper at the
wiper register location. Writes cannot be made to the
wiper register while shutdown mode is engaged. Clearing
shutdown mode will close the H terminal and allow the
wiper register to be written. A RST will also deassert
shutdown mode and return the wiper to midscale (0x80).
This command does not affect the charge-pump status.
SD_H_ZERO Command
Moves wiper to zero-scale position (0x00) and opens the
H terminal. The wiper register remains unaltered. Writes
cannot be made to the wiper register while shutdown
mode is engaged. Clearing shutdown mode will return
the wiper to the position contained in the wiper register
and close the H terminal. A RST will also deassert
shutdown mode and return the wiper to midscale (0x80).
This command does not affect the charge-pump status.
SD_H_MID Command
Moves wiper to midscale position (0x80) and opens the
H terminal. The wiper register remains unaltered. Writes
cannot be made to the wiper register while shutdown
mode is engaged. Clearing shutdown mode will return
the wiper to the position contained in the wiper register
and close the H terminal. A RST will also deassert
shutdown mode and return the wiper to midscale (0x80).
This command does not affect the charge-pump status.
SD_H_FULL Command
Moves wiper to full-scale position (0xFF) and opens H
terminal. The wiper register remains unaltered. Writes
cannot be made to the wiper register while shutdown
mode is engaged. Clearing shutdown mode will return
the wiper to the position contained in the wiper register
and close the H terminal. A RST will also deassert
shutdown mode and return the wiper to midscale (0x80).
This command does not affect the charge-pump status.
SD_L_WREG Command
Opens the L terminal and maintains the wiper at the wiper
register location. Writes cannot be made to the wiper
register while shutdown mode is engaged. Clearing
shutdown mode will close the L terminal and allow wiper
Table 1. SPI Write Command Byte Summary
COMMAND COMMAND BYTE DATA BYTE
C7 C6 C5 C4 C3 C2 C1 C0 D7 D6 D5 D4 D3 D2 D1 D0
WIPER 0 0 0 0 0 0 0 0 D7 D6 D5 D4 D3 D2 D1 D0
SD_CLR 1 0 0 0 0 0 0 0 X X X X X X X X
SD_H_WREG 1 0 0 1 0 0 0 0 X X X X X X X X
SD_H_ZERO 1 0 0 1 0 0 0 1 X X X X X X X X
SD_H_MID 1 0 0 1 0 0 1 0 X X X X X X X X
SD_H_FULL 1 0 0 1 0 0 1 1 X X X X X X X X
SD_L_WREG 1 0 0 0 1 0 0 0 X X X X X X X X
SD_L_ZERO 1 0 0 0 1 0 0 1 X X X X X X X X
SD_L_MID 1 0 0 0 1 0 1 0 X X X X X X X X
SD_L_FULL 1 0 0 0 1 0 1 1 X X X X X X X X
SD_W 1 0 0 0 0 1 X X X X X X X X X X
QP_OFF 1 0 1 0 0 0 0 0 X X X X X X X X
QP_ON 1 0 1 0 0 0 0 1 X X X X X X X X
RST 1 1 0 0 0 0 0 0 X X X X X X X X
MAX5394
Single, 256-Tap Volatile, SPI, Low-Voltage Linear
Taper Digital Potentiometer
13
register to be written. A RST will also deassert shutdown
mode and return the wiper to midscale (0x80). This
command does not affect the charge-pump status.
SD_L_ZERO Command
Moves wiper to zero-scale position (0x00) and opens the
L terminal. The wiper register remains unaltered. Writes
cannot be made to the wiper register while shutdown
mode is engaged. Clearing shutdown mode will return
the wiper to the position contained in the wiper register
and close the L terminal. A RST will also deassert
shutdown mode and return the wiper to midscale (0x80).
This command does not affect the charge-pump status.
SD_L_MID Command
Moves wiper to midscale position (0x80) and opens the
L terminal. The wiper register remains unaltered. Writes
cannot be made to the wiper register while shutdown
mode is engaged. Clearing shutdown mode will return
the wiper to the position contained in the wiper register
and close the L terminal. A RST will also deassert
shutdown mode and return the wiper to midscale (0x80).
This command does not affect the charge-pump status.
SD_L_FULL Command
Moves wiper to full-scale position (0xFF) and opens the
L terminal. The wiper register remains unaltered. Writes
cannot be made to the wiper register while shutdown
mode is engaged. Clearing shutdown mode will return
the wiper to the position contained in the wiper register
and close the L terminal. A RST will also deassert
shutdown mode and return the wiper to midscale (0x80).
This command does not affect the charge-pump status.
SD_W Command
Opens the W terminal keeping the internal tap position
the same as the wiper register. Writes cannot be made
to the wiper registers while shutdown mode is engaged.
Clearing shutdown mode will return the wiper to the
position contained in the wiper register and close W
terminal. A RST will also deassert shutdown mode and
return the wiper to midscale (0x80). This command does
not affect the charge-pump status.
QP_ON Command
Enables the onboard charge pump to allow low-supply
voltage operation. This is the power-on default condition.
Low supply voltage is 1.7V.
QP_OFF Command
Disables the on-board charge pump and places device
in low power mode. Low supply voltage is limited to 2.6V.
RST Command
Returns device to power-on default conditions. Resets
the wiper register to midscale (0x80), enables charge
pump, and deasserts any shutdown modes.
MAX5394
Single, 256-Tap Volatile, SPI, Low-Voltage Linear
Taper Digital Potentiometer
14
Ordering Information
Note: All devices operate over the -40°C to +125°C temperature range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Chip Information
PROCESS: BiCMOS
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maxim-ic.com/packages. Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
PART PIN-PACKAGE INTERFACE TAPS END-TO-END
RESISTANCE (kI)
MAX5394LATA+T 8 TDFN-EP* SPI 256 10
MAX5394MATA+T 8 TDFN-EP* SPI 256 50
MAX5394NATA+T 8 TDFN-EP* SPI 256 100
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
8 TDFN-EP T822+2 21-0168 90-0065
MAX5394
Single, 256-Tap Volatile, SPI, Low-Voltage Linear
Taper Digital Potentiometer
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. The parametric values (min and max limits) shown in the Electrical
Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated Products, Inc. 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 15
© 2012 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 7/12 Initial release —
