MAX5402EUA+T [MAXIM]
Digital Potentiometer, 1 Func, 10000ohm, 2-wire Serial Control Interface, 256 Positions, BICMOS, PDSO8, MICRO MAX PACKAGE-8;
| 型号： | MAX5402EUA+T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Digital Potentiometer, 1 Func, 10000ohm, 2-wire Serial Control Interface, 256 Positions, BICMOS, PDSO8, MICRO MAX PACKAGE-8 信息通信管理 光电二极管 转换器 电阻器 |
| 文件： | 总9页 (文件大小：208K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1896; Rev 0; 1/01
256-Tap, µPoT, Low-Drift,
Digital Potentiometer
General Description
Features
o Small Footprint, 8-Pin µMAX Package
o Ultra-Low 100nA Supply Current
o +2.7V to +5.5V Single-Supply Operation
o 256 Tap Positions
The MAX5402 µPoT™ digital potentiometer is a 256-tap
variable resistor with 10k 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.
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
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).
(Position 128)
o Glitchless Switching Between the Resistor Taps
o 3-Wire SPI™-Interface Compatible
o 10k Resistor Value
Ordering Information
________________________Applications
Mechanical Potentiometer Replacement
TEMP.
PIN-
PACKAGE
PART
R (k )
RANGE
Low-Drift PGAs
Adjustable Voltage References
MAX5402EUA
-40 C to +85 C
8 µMAX
10
µPoT is a trademark of Maxim Integrated Products.
SPI is a trademark of Motorola, Inc.
Functional Diagram
Pin Configuration
V
DD
TOP VIEW
H
W
L
R
R
256
8
8
8-BIT
LATCH
L
GND
CS
1
2
3
4
8
7
6
5
H
DECODE
8-BIT
SHIFT
REGISTER
W
DIN
MAX5402
V
DD
MAX5402
DIN
SCLK
SCLK
CS
POR
CLOCK
LOGIC
MAX
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
ABSOLUTE MAXIMUM RATINGS
DD
DIN, SCLK, CS to GND ............................................-0.3V to +6V
H, L, W to GND.............................................-0.3V to (V + 0.3)
Maximum Continuous Current into Pins H, L, and W ...........1mA
V
to GND..............................................................-0.3V to +6V
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
DD
Continuous Power Dissipation (T = +70°C)
A
8-Pin µMAX (derate 4.1mW/°C above +70°C) ............330mW
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
= +5V, V = V , V = 0, T = T
to T
. Typical values are at V = +5V, T = +25°C, unless otherwise noted.)
DD A
DD
H
DD
L
A
MIN
MAX
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DC PERFORMANCE (Voltage-Divider Mode)
Resolution
N
8
Bits
Integral Nonlinearity (Notes 1, 2)
INL
1/2
1
LSB
Differential Nonlinearity
(Notes 1, 2)
DNL
LSB
End-to-End Resistor Tempco
Ratiometric Resistor Tempco
Full-Scale Error
TC
35
5
ppm/°C
ppm/°C
LSB
R
-6
+6
Zero-Scale Error
LSB
DC PERFORMANCE (Variable-Resistor Mode)
Resolution
N
8
Bits
LSB
LSB
LSB
LSB
V
V
V
V
= +5V
= +3V
= +5V
= +3V
1
DD
DD
DD
DD
Integral Nonlinearity
(Notes 1, 3)
INL
3
1/2
1/2
Differential Nonlinearity
(Notes 1, 3)
DNL
DC PERFORMANCE (Resistor Characteristics)
V
V
= +5V
= +3V
275
DD
DD
Wiper Resistance (Note 4)
R
Ω
W
550
Wiper Capacitance
End-to-End Resistance
DIGITAL INPUTS
C
46
10
pF
W
R
7.5
12.5
kΩ
HL
Input High Voltage
Input Low Voltage
Input Leakage Current
Input Capacitance
V
0.7 ✕ V
V
V
IH
DD
V
0.3 ✕ V
DD
IL
1.0
µA
pF
5
TIMING CHARACTERISTICS (ANALOG)
Wiper-Settling Time
TIMING CHARACTERISTICS (DIGITAL) (Note 5) (Figure 2)
t
To 50% of final value from code 0 to code 128
100
ns
S
SCLK Clock Period
t
100
40
ns
ns
CP
CH
SCLK Pulse Width High
t
2
_______________________________________________________________________________________
256-Tap, µPoT, Low-Drift,
Digital Potentiometer
ELECTRICAL CHARACTERISTICS (continued)
(V
= +5V, V = V , V = 0, T = T
to T
. Typical values are at V
= +5V, T = +25°C, unless otherwise noted.)
DD A
DD
H
DD
L
A
MIN
MAX
PARAMETER
SCLK Pulse Width Low
SYMBOL
CONDITIONS
MIN
40
40
0
TYP
MAX
UNITS
ns
t
CL
CS Fall to SCLK Rise Setup Time
SCLK Rise to CS Rise Hold Time
DIN Setup Time
t
ns
CSS
CSH
t
ns
t
40
0
ns
DS
DH
DIN Hold Time
t
ns
SCLK Rise to CS Fall Delay
CS Rise to SCLK Rise Hold
CS Pulse Width High
t
t
10
40
100
ns
CS0
CS1
ns
t
ns
CSW
POWER SUPPLIES
Supply Voltage
V
2.7
5.5
5
V
DD
V
V
= +5V
0.8
0.1
µA
µA
DD
DD
CS = SCLK =
DIN = V
Supply Current
I
DD
DD
= +2.7V
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
and L = 0. The wiper
DD
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 = +3V and 400µA at V = +5V.
DD
DD
Note 4: The wiper resistance is the worst value measured, injecting a current, I = V /R into terminal W.
W
DD HL
Note 5: Digital timing is guaranteed by design.
________________________________________________________________________________________
3
256-Tap, µPoT, Low-Drift,
Digital Potentiometer
Typical Operating Characteristics
(T = +25°C, unless otherwise noted.)
A
END-TO-END RESISTANCE % CHANGE
vs. TEMPERATURE
WIPER RESISTANCE
vs. WIPER VOLTAGE
0.10
0.05
300
275
250
225
200
175
150
125
100
V
DD
= +3V
0.00
-0.05
-0.10
-0.15
V
DD
= +5V
-0.20
-40-30 -20 -10 0 10 20 30 40 50 60 70 80 90
0
1
2
3
4
5
TEMPERATURE (°C)
WIPER VOLTAGE (V)
VARIABLE RESISTOR DNL
RESISTANCE vs. INPUT CODE
vs. INPUT CODE
10
9
8
7
6
5
4
3
2
1
0
0.25
0.20
0.15
0.10
0.05
0.00
-0.05
-0.10
-0.15
-0.20
0
32 64 96 128 160 192 224 256
INPUT CODE (DECIMAL)
0
32 64 96 128 160 192 224 256
INPUT CODE (DECIMAL)
VARIABLE RESISTOR INL
vs. INPUT CODE
VOLTAGE-DIVIDER DNL vs. INPUT CODE
0.08
0.06
0.3
0.2
0.04
0.1
0.02
0.0
0.00
-0.1
-0.2
-0.3
-0.4
-0.02
-0.04
-0.06
-0.08
0
32 64 96 128 160 192 224 256
INPUT CODE (DECIMAL)
0
32 64 96 128 160 192 224 256
INPUT CODE (DECIMAL)
4
_______________________________________________________________________________________
256-Tap, µPoT, Low-Drift,
Digital Potentiometer
Typical Operating Characteristics (continued)
(T = +25°C, unless otherwise noted.)
A
VOLTAGE-DIVIDER INL vs. INPUT CODE
SUPPLY CURRENT vs. TEMPERATURE
0.20
0.15
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0.10
V
DD
= +5V
0.05
0.00
-0.05
-0.10
-0.15
-0.20
V
DD
= +3V
0
32 64 96 128 160 192 224 256
-40-30 -20 -10
0
10 20 30 40 50 60 70 80
INPUT CODE (DECIMAL)
TEMPERATURE (°C)
TAP-TO-TAP SWITCHING TRANSIENT
INPUT LOGIC VOLTAGE
MAX5402 toc09
10
1
+2.51V
+2.49V
V
W-L
0.1
0.01
V
DD
= +5V
+5V
0
CS
0.001
V
DD
= +3V
3
0.0001
0
1
2
4
5
200ns/div
(CODE 127 TO 128)
DIGITAL INPUT VOLTAGE (V)
Pin Description
PIN
1
NAME
L
FUNCTION
Low Terminal of Resistor
2
GND
CS
Ground
3
Chip Select Input
Serial Data Input
Serial Clock Input
4
DIN
SCLK
5
6
V
Power Supply. Bypass with a 0.1µF capacitor to GND.
Wiper Terminal
DD
7
W
H
8
High Terminal of Resistor
________________________________________________________________________________________
5
256-Tap, µPoT, Low-Drift,
Digital Potentiometer
POT REGISTER LOADED
CS
SCLK
8TH CLOCK PULSE
1ST CLOCK PULSE
DIN
D7
D6
D5
D4
D3
D2
D1
D0
LSB
MSB
TIME
Figure 1. Serial Interface Timing Diagram
CS
t
CSW
t
CS1
t
CSS
t
CSO
t
CH
t
CP
t
CSH
t
CL
SCLK
DIN
t
DS
t
DH
Figure 2. Detailed Serial Interface Timing Diagram
will need to be reloaded. After all 8 data bits have been
loaded into the shift register, they are latched into the
decoder once CS is taken high. The decoder switches
the potentiometer wiper to the tap position that corre-
sponds to the 8-bit input data. Each resistor cell is
10k /255 or 39.2 for the MAX5402.
Detailed Description
The MAX5402 consists of 255 fixed resistors in series
between pins H and L. The potentiometer wiper (pin W)
can be programmed to access any one of the 256 dif-
ferent tap points on the resistor string. The MAX5402
has an SPI-compatible 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 8-bit
serial shift register on the rising edge of each SCLK
pulse (Figure 1). The MSB is shifted in first, as shown in
Figure 3. Note that if CS is not kept low during the entire
data stream, the data will be corrupted and the device
The MAX5402 features POR circuitry. This sets the
wiper to the midscale position at power-up by loading a
binary value of 128 into the 8-bit latch. The MAX5402
can be used as a variable resistor by connecting pin W
to either pin H or L.
6
_______________________________________________________________________________________
256-Tap, µPoT, Low-Drift,
Digital Potentiometer
Data Word
B0 (D7)
B1 (D6)
B2 (D5)
B3 (D4)
B4 (D3)
B5 (D2)
B6 (D1)
B7 (D0)
(MSB)
(LSB)
First Bit In
Last Bit In
Figure 3. Serial Data Format
Applications Information
The MAX5402 is intended for a variety of circuits where
accurate, fine-tuned adjustable resistance is required,
such as in adjustable voltage or adjustable gain circuit
configurations. The MAX5402 is used in either a poten-
tiometer divider or a variable resistor configuration.
R3
H
+5V
MAX5402
R2
R1
W
Adjustable Current to Voltage Converter
Figure 4 shows the MAX5402 used with a MAX4250
low-noise op amp to precisely tune a current-to-voltage
converter. Pins H and W of the MAX5402 are connect-
ed to the node between R3 and R2, and pin L is con-
nected to ground.
L
V
O
MAX4250
Adjustable Gain Amplifier
The MAX5402 is used again with the MAX4250 to make
a digitally adjustable gain circuit as shown in Figure 5.
The normal feedback resistor is replaced with the
MAX5402 in a variable resistor configuration, so that
the gain of the circuit can be digitally controlled.
V
/ I = R (1 + R / R ) + R
O
S
3
2
1
2
Figure 4. I to V Converter
Adjustable Voltage Reference
In Figure 6, the MAX5402 is shown with the MAX6160
to make an adjustable voltage reference. In this circuit,
the H pin of the MAX5402 is connected to the OUT pin
of the MAX6160, the L pin of the MAX5402 is connect-
ed to GND, and the W pin of the MAX5402 is connect-
ed to the ADJ pin of the MAX6160. The MAX5402
allows precise tuning of the voltage reference output. A
low 5ppm/°C ratiometric tempco allows a very stable
adjustable voltage overtemperature.
+5V
V
S
V
O
MAX4250
R2
L
H
MAX5402
R1
W
V / V = 1 + R / R
1
O
S
2
Figure 5. Noninverting Amplifier
________________________________________________________________________________________
7
256-Tap, µPoT, Low-Drift,
Digital Potentiometer
Chip Information
+5V
VIN
TRANSISTOR COUNT: 3475
PROCESS: BiCMOS
V REF
O
OUT
ADJ
H
MAX6160
W
MAX5402
GND
L
✕
1.23V 255
C
V
O
=
WHERE C IS THE DECIMAL EQUIVALENT
WRITTEN CODE.
Figure 6. Adjustable Voltage Reference
8
_______________________________________________________________________________________
256-Tap, µPoT, Low-Drift,
Digital Potentiometer
Package Information
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9
© 2001 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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