MAX5400EKA [MAXIM]
Digital Potentiometer, 1 Func, 50000ohm, 2-wire Serial Control Interface, 256 Positions, BICMOS, PDSO8, SOT-23, 8 PIN;
| 型号： | MAX5400EKA |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Digital Potentiometer, 1 Func, 50000ohm, 2-wire Serial Control Interface, 256 Positions, BICMOS, PDSO8, SOT-23, 8 PIN 信息通信管理 光电二极管 转换器 电阻器 |
| 文件： | 总8页 (文件大小：195K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1848; Rev 0; 10/00
256-Tap SOT-PoT,
Low-Drift Digital Potentiometers in SOT23
General Description
Features
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.
♦ Miniature 8-Pin SOT23 (3mm x 3mm)
♦ 256 Tap Positions
♦ Ultra-Low 0.1µA Supply Current
♦ Single-Supply Operation: +2.7V to +5.5V
♦ Low Ratiometric Temperature Coefficient:
5ppm/°C
♦ Power-On Reset: Wiper Goes to Midscale
(Position 128)
♦ Glitchless Switching Between the Resistor Taps
♦ 3-Wire SPI™-Interface Compatible
♦ 50kΩ/100kΩ Resistor Values
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.
Ordering Information
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).
TEMP.
PIN-
PART
R (kΩ)
RANGE
PACKAGE
MAX5400EKA-T
MAX5401EKA-T
-40°C to +85°C
-40°C to +85°C
8-SOT23
8-SOT23
50
100
________________________Applications
SOT-PoT is a trademark of Maxim Integrated Products.
SPI is a trademark of Motorola, Inc.
Mechanical Potentiometer Replacement
Low-Drift PGAs
Pin Configuration appears at end of data sheet.
Adjustable Voltage References
Functional Diagram
V
DD
H
8
8
8-BIT
LATCH
W
DECODER
8-BIT
SHIFT
REGISTER
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
ABSOLUTE MAXIMUM RATINGS
DD
V
to GND............................................................. -0.3V to +6V
Continuous Power Dissipation (T = +70°C)
A
DIN, SCLK, CS to GND ............................................-0.3V to +6V
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
H, L, W to GND...........................................-0.3V to (V
Maximum Continuous Current into
+ 0.3V)
DD
Pins H, L, and W ........................................................... 1mA
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 T = +25°C, unless otherwise noted. Parameters are mea-
DD
H
DD
L
A
MIN
MAX A
sured at T = +25°C. Values over full temperature range are guaranteed by design.)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DC PERFORMANCE (Voltage Divider Mode)
Resolution
N
8
Bits
Integral Nonlinearity
(Notes 1, 2)
INL
1/2
1/2
LSB
Differential Nonlinearity
(Notes 1, 2)
DNL
LSB
End-to-End Resistor Tempco
Ratiometric Resistor Tempco
TC
50
5
ppm/°C
ppm/°C
R
MAX5400
MAX5401
MAX5400
MAX5401
-0.8
-0.4
+0.8
+0.4
Full-Scale Ratio Error
Zero-Scale Ratio Error
LSB
LSB
POWER SUPPLIES
Supply Voltage
V
2.7
8
5.5
5
V
DD
V
V
= 5V
0.7
0.1
µA
µA
DD
DD
Supply Current
I
CS = SCLK = DIN = V
DD
DD
= 2.7V
DC PERFORMANCE (Variable Resistor Mode)
Resolution
N
Bits
V
V
= 5V
= 3V
1
CC
CC
Integral Nonlinearity
(Notes 1, 3)
INL
LSB
MAX5400
MAX5401
1.5
1
V
V
= 5V
= 3V
1/2
1/2
CC
CC
Differential Nonlinearity
(Notes 1, 3)
DNL
LSB
DC PERFORMANCE (Resistor Characteristics)
Wiper Resistance (Note 4)
Wiper Capacitance
R
W
C
W
250
25
800
Ω
pF
MAX5401
MAX5400
75
100
50
125
End-to-End Resistance
R
kΩ
HL
37.5
62.5
2
_______________________________________________________________________________________
256-Tap SOT-PoT,
Low-Drift Digital Potentiometers in SOT23
ELECTRICAL CHARACTERISTICS (continued)
(V
= +5V, V = V , V = 0, T = T
to T
. Typical values are at T = +25°C, unless otherwise noted. Parameters are mea-
DD
H
DD
L
A
MIN
MAX A
sured at T = +25°C. Values over full temperature range are guaranteed by design.)
A
PARAMETER
DIGITAL INPUTS
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
✕
Input High Voltage
Input Low Voltage
Input High Voltage
Input Low Voltage
Input Leakage Current
Input Capacitance
V
V
V
V
V
= 5V
= 5V
= 3V
= 3V
0.7
V
DD
V
V
IH
CC
CC
CC
CC
✕
V
0.3
0.3
V
V
IL
DD
DD
✕
V
0.7
V
V
IH
DD
✕
V
V
IL
1.0
µA
pF
5.0
TIMING CHARACTERISTICS (Voltage Divider Mode)
MAX5400 (to 50% of final value, from code 0
to code 128)
300
600
Wiper Settling Time
t
ns
IL
MAX5401 (to 50% of final value, from code 0
to code 128)
TIMING CHARACTERISTICS (Digital) (Note 5)
SCLK Clock Period
t
100
40
ns
ns
ns
CP
CH
SCLK Pulse Width High
SCLK Pulse Width Low
t
t
40
CL
CS Fall to SCLK Rise Setup
Time
t
40
ns
CSS
SCLK Rise to CS Rise Hold Time
DIN Setup Time
t
0
40
0
ns
ns
ns
ns
ns
ns
CSH
t
DS
DIN Hold Time
t
DH
SCLK Rise to CS Fall Delay
CS Rise to SCLK Rise Hold
CS Pulse Width High
t
t
10
40
100
CS0
CS1
t
CSW
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 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
Typical Operating Characteristics
(T = +25°C, unless otherwise noted.)
A
END-TO-END RESISTANCE % CHANGE
vs. TEMPERATURE
W-to-L RESISTANCE vs. INPUT CODE
WIPER RESISTANCE vs. VOLTAGE
(100kΩ)
100
90
80
70
60
50
40
30
20
10
0
0.05
0.03
600
V
= 2.7V
DD
to 5.5V
500
100kΩ
50kΩ
0.01
V
DD
= +3V
400
300
200
100
0
-0.01
-0.03
-0.05
-0.07
-0.09
-0.11
V
= +5V
DD
-40 -30 -20 -10
0
10 20 30 40 50 60 70 80
0
1
2
3
4
5
0
32 64 96 128 160 192 224 256
INPUT CODE-DECIMAL
TEMPERATURE (°C)
WIPER VOLTAGE (V)
W-to-L RESISTANCE vs. INPUT CODE
VARIABLE RESISTOR DNL
vs. INPUT CODE (50kΩ)
VARIABLE RESISTOR INL vs. INPUT CODE
(50kΩ)
(50kΩ)
50
45
40
35
30
25
20
15
10
5
0.020
0.20
V
= 2.7V
DD
to 5.5V
0.15
0.10
0.015
0.010
0.005
0
0.05
0
-0.05
-0.10
-0.15
-0.20
-0.005
-0.010
-0.015
0
-0.020
0
32 64 96 128 160 192 224 256
INPUT CODE-DECIMAL
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 DNL
vs. INPUT CODE (100kΩ)
SUPPLY CURRENT
vs. TEMPERATURE
VARIABLE RESISTOR INL
vs. INPUT CODE (100kΩ)
0.20
1.0
0.8
0.020
0.015
0.010
0.005
0
0.15
0.10
0.05
V
= +5V
DD
0.6
0.4
0.2
0
-0.005
-0.010
-0.015
-0.05
-0.10
-0.15
-0.20
V
DD
= +3V
0
-1.020
-10
0
20
40 50 60 70 80
30
-40 -30 -20
10
0
32 64 96 128 160 192 224 256
INPUT CODE-DECIMAL
0
32 64 96 128 160 192 224 256
INPUT CODE-DECIMAL
TEMPERATURE (°C)
4
_______________________________________________________________________________________
256-Tap SOT-PoT,
Low-Drift Digital Potentiometers in SOT23
Typical Operating Characteristics (continued)
(T = +25°C, unless otherwise noted.)
A
TAP-to-TAP SWITCHING TRANSIENT
SUPPLY CURRENT vs.
INPUT LOGIC VOLTAGE
(FROM CODE 127 toc CODE 128)
MAX5400 Toc10
10
10mV/div
2.5V
1
0.1
V
W-L
V
DD
= +5V
5V/div
0
0.01
0.001
CS
V
= +3V
DD
0.0001
0
1
2
3
4
5
DIGITAL INPUT VOLTAGE (V)
VOLTAGE DIVIDER DNL
vs. INPUT CODE (50kΩ)
VOLTAGE DIVIDER INL
vs. INPUT CODE (50kΩ)
0.10
0.08
0.06
0.04
0.02
0
0.20
V
DD
= +2.7V to +5.5V
0.15
0.10
0.05
0
-0.02
-0.04
-0.06
-0.08
-0.10
-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
Pin Description
PIN
1
NAME
L
FUNCTION
Low Terminal of Resistor
Ground
2
GND
CS
3
Chip Select Input
Serial Data Input
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 SOT-PoT,
Low-Drift Digital Potentiometers in SOT23
POT REGISTER LOADED
CS
SCLK
8TH CLOCK PULSE
1ST CLOCK PULSE
DIN
D7
D6
D5
D4
D3
D2
D1
D0
LSB
MSB
TIME
Figure 2. Serial Interface Timing Diagram
CS
t
CSW
t
CS1
t
CSS
t
CSO
t
CL
t
CP
t
CSH
t
CH
SCLK
t
DS
t
DH
DIN
Figure 3. 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
50kΩ/255 or 196.1Ω for the MAX5400 and 100kΩ/255
or 392.2Ω for the MAX5401.
The MAX5400/MAX5401 feature power-on reset (POR)
circuitry that sets the wiper to the midscale position at
power-up by loading a binary value of 128 into the 8-bit
latch.
Detailed Description
The MAX5400/MAX5401 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 different tap points on the resistor string. The
MAX5400/MAX5401 uses a 3-wire serial data interface
to control the wiper tap position. This write-only inter-
face 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. The MSB is shifted in first as shown in
Figure 4. Note that if CS is not kept low during the entire
data stream, the data will be corrupted and the device
The MAX5400/MAX5401 can be used as a variable
resistor by connecting pin W to either pin H or pin L.
6
_______________________________________________________________________________________
256-Tap SOT-PoT,
Low-Drift Digital Potentiometers in SOT23
DATA WORD
B0 (D7)
B1 (D6)
B2 (D5)
B3 (D4)
B4 (D3)
B5 (D2)
B6 (D1)
B7 (D0)
(MSB)
FIRST
BIT IN
(LSB)
LAST
BIT IN
Figure 4. Serial Data Format
resistor configuration so that the gain of the circuit can
be digitally controlled.
Applications Information
The MAX5400/MAX5401 are intended for a variety of
circuits that require accurate, fine-tuning adjustable
resistance, such as adjustable voltage or adjustable
gain circuit configurations. The MAX5400/MAX5401 are
primarily used in either a potentiometer divider or a
variable resistor configuration.
Adjustable Voltage Reference
In Figure 7, the MAX5400/MAX5401 are shown with the
MAX6160 to make an adjustable voltage reference. In
this circuit, the H pin of the MAX5400/MAX5401 is con-
nected to the OUT pin of the MAX6160, the L pin of the
MAX5400/MAX5401 is connected to GND, and the W
pin of the MAX5400/MAX5401 is connected to the ADJ
pin of the MAX6160. The MAX5400/MAX5401 allow pre-
cise tuning of the voltage reference output. A low
5ppm/°C ratiometric tempco allows a very stable
adjustable voltage over temperature.
Adjustable Current-to-Voltage Converter
Figure 5 shows the MAX5400/MAX5401 being used
with a MAX4250 low-noise op amp to fine tune a cur-
rent-to-voltage converter. Pins H and W of the
MAX5400/MAX5401 are connected to the node
between R3 and R2 and pin L is connected to ground.
Adjustable Gain Amplifier
The MAX5400/MAX5401 are used again with the
MAX4250 to make a digitally adjustable gain circuit as
shown in Figure 6. The normal feedback resistor is
replaced with the MAX5400/MAX5401 in a variable
+5V
R3
V
S
+5V
V
O
R1
R2
V
O
MAX4250
R2
MAX4250
R1
V
/ I = R (1 + R / R )+ R
S 3 2 1 2
O
V / V = 1 + R / R
1
O
S
2
Figure 5. I to V Converter
Figure 6. Noninverting Amplifier
_______________________________________________________________________________________
7
256-Tap SOT-PoT,
Low-Drift Digital Potentiometers in SOT23
Chip Information
+5V
TRANSISTOR COUNT: 3769
TECHNOLOGY: BiCMOS
V
IN
V
O
REF
H
OUT
ADJ
MAX6160
W
GND
L
100kΩ
2
V
V
= 1.23V ×
= 1.23V ×
FOR MAX5401
FOR MAX5400
O
R (kΩ)
50kΩ
O
R (kΩ)
2
Figure 7. Adjustable Voltage Reference
Pin Configuration
TOP VIEW
L
GND
CS
1
2
3
4
8
7
6
5
H
W
MAX5400/
MAX5401
V
DD
DIN
SCLK
SOT23
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.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2000 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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