AD8842AR-REEL Analog Devices Inc, AD8842AR-REEL Datasheet

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AD8842AR-REEL

Manufacturer Part Number
AD8842AR-REEL
Description
IC DAC MULT 8BIT OCTAL 24-SOIC
Manufacturer
Analog Devices Inc
Series
TrimDAC®r
Datasheet

Specifications of AD8842AR-REEL

Rohs Status
RoHS non-compliant
Settling Time
2.9µs
Number Of Bits
8
Data Interface
Serial
Number Of Converters
8
Voltage Supply Source
Dual ±
Power Dissipation (max)
135mW
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
24-SOIC (7.5mm Width)
a
GENERAL DESCRIPTION
The AD8842 provides eight general purpose digitally controlled
voltage adjustment devices. The TrimDAC® capability allows
replacement of the mechanical trimmer function in new designs.
The AD8842 is ideal for ac or dc gain control of up to 50 kHz
bandwidth signals. The four-quadrant multiplying capability is
useful for signal inversion and modulation often found in video
vertical deflection circuitry.
Internally the AD8842 contains eight voltage output digital-to-
analog converters, each with separate voltage inputs. A new
current conveyor amplifier design performs the four-quadrant
multiplying function with a single amplifier at the output of the
current steering digital-to-analog converter. This approach of-
fers an improved constant input resistance performance versus
previous voltage switched DACs used in TrimDAC circuits,
eliminating the need for additional input buffer amplifiers.
Each DAC has its own DAC register that holds its output state.
These DAC registers are updated from an internal serial-to-
parallel shift register that is loaded from a standard 3-wire serial
input digital interface. Twelve data bits make up the data word
clocked into the serial input register. This data word is decoded
where the first 4 bits determine the address of the DAC register
to be loaded with the last 8 bits of data. A serial data output pin
at the opposite end of the serial register allows simple daisy
chaining in multiple DAC applications without additional exter-
nal decoding logic.
TrimDAC is a registered trademark of Analog Devices, Inc.
The current conveyor amplifier is a patented circuit belonging to Analog
Devices, Inc.
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
FEATURES
Low Cost
Replaces 8 Potentiometers
50 kHz 4-Quadrant Multiplying Bandwidth
Low Zero Output Error
Eight Individual Channels
3-Wire Serial Input
500 kHz Update Data Loading Rate
Midscale Preset, Zero Volts Out
APPLICATIONS
Automatic Adjustment
Trimmer Replacement
Vertical Deflection Amplitude Adjustment
Waveform Generation and Modulation
3 V Output Swing
The AD8842 consumes only 95 mW from 5 V power supplies.
For single 5 V supply applications consult the DAC-8841. The
AD8842 is pin compatible with the 1 MHz multiplying band-
width DAC8840. The AD8842 is available in 24-pin plastic
DIP and surface mount SOL-24 packages.
One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A.
Tel: 617/329-4700
Figure 2. Actual Current Conveyor Implementation of
Multiplying DAC Channel
Figure 1. Functional Circuit of One 4-Quadrant
Multiplying Channel
CLK
V
SDI
LD
DD
V
V
IN
Multiplying, CMOS TrimDAC
IN
8
4
GND
LOGIC
FUNCTIONAL BLOCK DIAGRAM
REGISTER
DECODED
ADDRESS
R
SERIAL
REF
8-Bit Octal, 4-Quadrant
8
DATA
256
D
SDO
(1- D)
256
R
V
8 X 8
R
DAC
IN
PR
R
G
R
E
S
T
E
S
I
V
R
IN
V
I1
I2
8
8
OUT
CURRENT CONVEYOR
= V
R
DAC A
DAC H
AMPLIFIER
IN
• (D/128 – 1)
AD8842
R
AD8842
Fax: 617/326-8703
= V
V
V
OUT
IN
G
G
SS
V
OUT
(D/128–1)
V
V
V
V
IN
OUT
IN
OUT
A
H
A
H

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AD8842AR-REEL Summary of contents

Page 1

FEATURES Low Cost Replaces 8 Potentiometers 50 kHz 4-Quadrant Multiplying Bandwidth Low Zero Output Error Eight Individual Channels 3-Wire Serial Input 500 kHz Update Data Loading Rate 3 V Output Swing Midscale Preset, Zero Volts Out APPLICATIONS Automatic Adjustment ...

Page 2

AD8842–SPECIFICATIONS ELECTRICAL CHARACTERISTICS Parameter Symbol STATIC ACCURACY—All Specifications Apply for DACs Resolution N Integral Nonlinearity Error INL Differential Nonlinearity DNL Full-Scale Gain Error G Output Offset V Output Offset Drift TCV VOLTAGE ...

Page 3

... CKLD LD LDCK LSB 1 LSB ERROR BAND 1 LSB Figure 3. Timing Diagram Model , V AD8842AN XIND AD8842AR DD SS *XIND = – +85 C. The AD8842 contains 2452 transistors Max– –3– AD8842 DAC REGISTER LOAD ORDERING GUIDE Temperature Package Range* Description 24-Pin 300mil P-DIP N-24 ...

Page 4

AD8842 PIN DESCRIPTION Pin Mnemonic Description DAC C Output OUT DAC B Output OUT DAC A Output OUT DAC B Reference Input DAC A ...

Page 5

LAST LSB DATA CLK *Data shifted into the SDI pin appears twelve clocks later at the SDO pin. REV. 0 ...

Page 6

AD8842–Typical Performance Characteristics +1/2 DACs SUPERIMPOSED 0 – – +3V IN +1/2 0 DACs SUPERIMPOSED –1/2 ...

Page 7

Figure 13. Pulse Response—Upper Trace V Lower Trace V @2 V/Div OUT 100 100 50mV 2V Figure 14. Worst ...

Page 8

AD8842 2V 100 Figure 19. 10 kHz Sawtooth Waveform, Upper Trace V , Lower Trace V IN –3dB FREQUENCY 300 200 100 0 –100 –200 500 mVp-p INPUT AMPLITUDE –300 –400 ...

Page 9

CIRCUIT OPERATION The AD8842 is a general purpose 8-channel signal- level adjustment device designed to replace potentiometers used in the three-terminal connection mode. Eight independent channels of programmable signal level control are available in this 24-pin package ...

Page 10

AD8842 ADJUSTING SIGNAL LEVELS The four-quadrant multiplication operation of the AD8842 is shown in Figure 27. For dc operation the equation describing the relationship between V , digital inputs and (D) = (D/128-1) V ...

Page 11

CLOCK DATA ADDRESSS CODED DECODE PACKAGE ADDRESS • • • ANALOG CONNECTIONS OMITTED FOR CLARITY Figure 31. Addressing Multiple AD8842 Packages There is some digital feedthrough from the digital input pins. Operating the clock only when the DAC ...

Page 12

AD8842 PIN 1 0.210 (5.33) MAX 0.160 (4.06) 0.115 (2.92) 0.022 (0.558) 0.014 (0.356) PIN 1 0.0118 (0.30) 0.0040 (0.10) OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 24-Pin Narrow Body Plastic DIP Package 13 24 0.280 (7.11) 0.240 (6.10) ...

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