AD8400 Analog Devices, AD8400 Datasheet

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AD8400

Manufacturer Part Number
AD8400
Description
Single-channel Digital Potentiometer
Manufacturer
Analog Devices
Datasheet

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a
GENERAL DESCRIPTION
The AD8400/AD8402/AD8403 provide a single, dual or quad
channel, 256 position digitally controlled variable resistor (VR) device.
These devices perform the same electronic adjustment function as
a potentiometer or variable resistor. The AD8400 contains a single
variable resistor in the compact SO-8 package. The AD8402 contains
two independent variable resistors in space-saving SO-14 surface-
mount packages. The AD8403 contains four independent variable
resistors in 24-lead PDIP, SOIC, and TSSOP packages. Each part
contains a fixed resistor with a wiper contact that taps the fixed
resistor value at a point determined by a digital code loaded into the
controlling serial input register. The resistance between the wiper and
either endpoint of the fixed resistor varies linearly with respect to the
digital code transferred into the VR latch. Each variable resistor
offers a completely programmable value of resistance, between the A
terminal and the wiper or the B terminal and the wiper. The fixed
A to B terminal resistance of 1 kΩ, 10 kΩ, 50 kΩ, or 100 kΩ has a ±1%
channel-to-channel matching tolerance with a nominal temperature
coefficient of 500 ppm/°C. A unique switching circuit minimizes the
high glitch inherent in traditional switched resistor designs avoiding
any make-before-break or break-before-make operation.
Each VR has its own VR latch that holds its programmed resistance
value. These VR latches are updated from an SPI compatible serial-
to-parallel shift register that is loaded from a standard 3-wire
serial-input digital interface. Ten data bits make up the data word
clocked into the serial input register. The data word is decoded where
the first two bits determine the address of the VR latch to be loaded,
the last eight bits are data. A serial data output pin at the opposite end
of the serial register allows simple daisy-chaining in multiple VR
applications without additional external decoding logic.
The reset (RS) pin forces the wiper to the midscale position by
loading 80
H
into the VR latch. The SHDN pin forces the resistor
to an end-to-end open circuit condition on the A terminal and
shorts the wiper to the B terminal, achieving a microwatt power
shutdown state. When SHDN is returned to logic high, the
previous latch settings put the wiper in the same resistance
setting prior to shutdown. The digital interface is still active in
shutdown so that code changes can be made that will produce
new wiper positions when the device is taken out of shutdown.
The AD8400 is available in both the SO-8 surface-mount and the
8-lead plastic DIP package.
The AD8402 is available in both surface mount (SO-14) and
14-lead plastic DIP packages, while the AD8403 is available in a
narrow body 24-lead plastic DIP and a 24-lead surface-mount
package. The AD8402/AD8403 are also offered in the 1.1 mm thin
TSSOP-14/TSSOP-24 packages for PCMCIA applications. All
parts are guaranteed to operate over the extended industrial tem-
perature range of –40°C to +125°C.
DGND
CLK
V
SDI
CS
DD
100
75
50
25
0
AD8400/AD8402/AD8403
0
AD8403
FUNCTIONAL BLOCK DIAGRAM
Digital Potentiometers
R
WA
D
SELECT
A1, A0
CK Q RS
SERIAL
LATCH
64
10-BIT
DAC
SDO
2
1
2
3
4
CODE – Decimal
8
1-/2-/4-Channel
128
LATCH
LATCH
CK RS
LATCH
CK RS
LATCH
CK RS
CK RS
8-BIT
8-BIT
8-BIT
8-BIT
RS
8
8
8
8
192
RDAC1
RDAC2
RDAC3
RDAC4
SHDN
SHDN
SHDN
SHDN
SHDN
R
WB
A1
W1
B1
AGND1
A2
W2
B2
AGND2
A3
W3
B3
AGND3
A4
W4
B4
AGND4
255

Related parts for AD8400

AD8400 Summary of contents

Page 1

... The digital interface is still active in shutdown so that code changes can be made that will produce new wiper positions when the device is taken out of shutdown. The AD8400 is available in both the SO-8 surface-mount and the 8-lead plastic DIP package. The AD8402 is available in both surface mount (SO-14) and ...

Page 2

... AD8400/AD8402/AD8403–SPECIFICATIONS ELECTRICAL CHARACTERISTICS–10 k VERSION Parameter DC CHARACTERISTICS RHEOSTAT MODE (Specifications Apply to All VRs) 2 Resistor Differential NL 2 Resistor Nonlinearity 3 Nominal Resistance Resistance Tempco Wiper Resistance Nominal Resistance Match DC CHARACTERISTICS POTENTIOMETER DIVIDER Specifications Apply to All VRs Resolution 4 Integral Nonlinearity 4 Differential Nonlinearity Voltage Divider Tempco ...

Page 3

... _50K R NWB kΩ kHz _100K R NWB AD8400/AD8402/AD8403 ≤ +125 C unless otherwise noted Min Typ Max ± 1/4 –1 +1 ± 1/2 – 100 130 500 53 100 = 25°C ...

Page 4

... AD8400/AD8402/AD8403–SPECIFICATIONS ELECTRICAL CHARACTERISTICS–1 k VERSION Parameter DC CHARACTERISTICS RHEOSTAT MODE Specifications Apply to All VRs 2 Resistor Differential NL 2 Resistor Nonlinearity 3 Nominal Resistance Resistance Tempco Wiper Resistance Nominal Resistance Match DC CHARACTERISTICS POTENTIOMETER DIVIDER Specifications Apply to All VRs Resolution 4 Integral Nonlinearity 4 Differential Nonlinearity Voltage Divider Temperature Coefficent ...

Page 5

... OUT) CLK OUT OUT ERROR BAND DD AD8400/AD8402/AD8403 ≤ +125 C unless otherwise noted Min Typ Max (10 and timed from a voltage level ...

Page 6

... ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the AD8400/AD8402/AD8403 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality ...

Page 7

... AD8402AN1 2 AD8402AR1 2 AD8402ARU1 2 AD8402ARU1-REEL 2 AD8403AN1 4 AD8403AR1 4 AD8403ARU1 4 AD8403ARU1-REEL 4 NOTES N = Plastic DIP Small Outline Thin Shrink SO The AD8400, AD8402, and AD8403 contain 720 transistors. ORDERING GUIDE End-to-End Temperature Package Range ( C) Description AB 10 –40 to +125 PDIP-8 10 –40 to +125 SO-8 10 –40 to +125 PDIP-14 10 – ...

Page 8

... Positive power supply, specified for operation DD at both 3 V and Wiper RDAC #1, Addr = Terminal A RDAC # Terminal B RDAC #1 All AGNDs must be connected to DGND. AD8400 PIN FUNCTION DESCRIPTIONS Pin Name GND CLK 4 SDI B1 ...

Page 9

... Typical Performance Characteristics–AD8400/AD8402/AD8403 10k 128 160 192 224 256 CODE – Decimal 1205 UNITS 40.0 42.5 45.0 47.5 50.0 52.5 55.0 57.5 60.0 62.5 65.0 WIPER RESISTANCE – Ω 184 UNITS ...

Page 10

... AD8400/AD8402/AD8403 700 600 T = –40 C/+ CONNECT A 500 R MEASURED WB 400 300 200 100 0 –100 128 160 192 224 256 CODE – Decimal ∆ ∆ 0.75 CODE = 0. 158 UNITS AVG + 2 SIGMA 0.25 AVG 0 –0.25 AVG – 2 SIGMA –0.50 – ...

Page 11

... B A 200 10k 100k 1M 10M FREQUENCY – Hz 100 –55 –35 – 105 125 TEMPERATURE – C AD8400/AD8402/AD8403 + p CODE = 10pF 4V SEE TEST CIRCUIT 4 0 100 1k 10k 100k FREQUENCY – ...

Page 12

... AD8400/AD8402/AD8403 TEST CIRCUITS DUT 1LSB = V+/256 CONNECT DUT DUT 1V/R W NOMINAL WHERE AND PSRR (dB) = 20LOG PSS (%/%) = ––––––– ...

Page 13

... The single-channel AD8400 requires The dual- channel AD8402 requires settings can be changed one at a time in random sequence. The serial clock running at 10 MHz makes it possible to load all four VRs in under 4 µs (10 × 4 × 100 ns) for the AD8403. The exact timing requirements are shown in Figures 2a, 2b, and 2c ...

Page 14

... Terminal B to the wiper. See TPC 9 for a plot of potentiometer tempco performance versus code setting. DIGITAL INTERFACING The AD8400/AD8402/AD8403 contain a standard SPI compat- ible three-wire serial input control interface. The three inputs are clock (CLK), CS and serial data input (SDI). The positive- edge sensitive CLK input requires clean transitions to avoid clocking incorrect data into the serial input register ...

Page 15

... ESD protection allows for mixed power supply applications where 5 V CMOS logic can be used to drive an AD8400, AD8402, or AD8403 operating from power sup- ply. The analog pins A, B, and W are protected with a 20 Ω series resistor and parallel Zener (see Figure 7b). ...

Page 16

... Test Circuits 1 and 2 (see page 11). Certain boundary conditions must be satisfied for proper AD8400/ AD8402/AD8403 operation. First, all analog signals must remain within the range used to operate the single-supply DD AD8400/AD8402/AD8403 products ...

Page 17

... P –20 –40 –60 – 0.01 F LOW PASS RDAC3 A4 –20 BAND- PASS –40 HIGH- –60 PASS –80 20 AD8400/AD8402/AD8403 –0.16 20.0000 k A 100 1k 10k 100k 200k FREQUENCY – Hz –19.01 2.00000 k A 100 1k 10k 100k 200k FREQUENCY – Hz ...

Page 18

... AD8400/AD8402/AD8403 0.210 (5.33) OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 8-Lead Plastic DIP (N-8) 0.430 (10.92) 0.348 (8.84 0.280 (7.11) 0.240 (6.10 0.325 (8.25) PIN 1 0.100 (2.54) 0.300 (7.62) BSC 0.060 (1.52) 0.210 0.015 (0.38) (5.33) MAX 0.130 (3.30) 0.160 (4.06) MIN 0.115 (2.93) 0.015 (0.381) 0.022 (0.558) 0.070 (1.77) SEATING 0.008 (0.204) PLANE 0.014 (0.356) ...

Page 19

... PIN 1 0.060 (1.52) 0.015 (0.38) 0.210 (5.33) 0.150 MAX (3.81) 0.200 (5.05) MIN 0.125 (3.18) 0.100 0.022 (0.558) 0.070 (1.77) SEATING (2.54) PLANE 0.014 (0.356) 0.045 (1.15) BSC AD8400/AD8402/AD8403 0.0196 (0.50) 45 0.0099 (0.25 0.0500 (1.27) 0.0160 (0.41 0.028 (0.70) 0.020 (0.50) 0.325 (8.25) 0.300 (7.62) 0.195 (4.95) 0.115 (2.93) 0.015 (0.381) 0.008 (0.204) ...

Page 20

... AD8400/AD8402/AD8403 PIN 1 0.0118 (0.30) 0.0040 (0.10) PIN 1 0.006 (0.15) 0.002 (0.05) SEATING PLANE Revision History Location Data Sheet changed from REV REV. C. Addition of new Figure Edits to SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Edits to ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Edits to TPCs 1, 8, 12, 16, 20, 24 Edits to PROGRAMMING THE VARIABLE RESISTOR section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 OUTLINE DIMENSIONS (continued) Dimensions shown in inches and (mm) ...

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