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FEATURES Dynamic Range 85.5 dB Resolution 1.5 dB Full ؎25 V Input Range Multiplying DAC Full Military Temperature Range –55؇ C to +125؇ C Low Distortion Low Power Consumption Latch Proof Operation (Schottky Diodes Not Required) Single 5 V to 15 V Supply APPLICATIONS Digitally Controlled AGC Systems Audio Attenuators Wide Dynamic Range A/D Converters Sonar Systems Function Generators
LOGDAC CMOS Logarithmic D/A Converter AD7118*
FUNCTIONAL DIAGRAM
PIN CONFIGURATION
GENERAL DESCRIPTION
The LOGDAC® AD7118 is a CMOS multiplying D/A converter which attenuates an analog input signal over the range 0 to –85.5 dB in 1.5 dB steps. The analog output is determined by a six-bit attenuation code applied to the digital inputs. Operating frequency range of the device is from dc to several hundred kHz. The device is manufactured using an advanced monolithic silicon gate thin-film on CMOS process and is packaged in a 14-pin dual-in-line package.
ORDERING INFORMATION
Model AD7118KN AD7118LN AD7118BQ AD7118CQ AD7118TQ2 AD7118UQ2
Temperature Range 0°C to +70°C 0°C to +70°C –25°C to +85°C –25°C to +85°C –55°C to +125°C –55°C to +125°C
Specified Accuracy Range 0 to 42 dB 0 to 48 dB 0 to 42 dB 0 to 48 dB 0 to 42 dB 0 to 48 dB
Package Option1 N-16 N-16 Q-16 Q-16 Q-16 Q-16
NOTES 1 N = Plastic DIP; Q = Cerdip. 2 To order MIL-STD-883, Class B processed parts, add /883B to part number.
*Protected by U.S. Patent No. 4521,764. LOGDAC is a registered trademark of Analog Devices, Inc.
REV. A
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.
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AD7118–SPECIFICATIONS
Parameter NOMINAL RESOLUTION ACCURACY RELATIVE TO VIN AD7118L/C/U 0 dB to –30 dB –31.5 dB to –42 dB –43.5 dB to –48 dB AD7118K/B/T 0 dB to –30 dB –31.5 dB to –42 dB MONOTONIC RANGE Nominal 1.5 dB Steps Nominal 3 dB Steps VIN INPUT RESISTANCE (PIN 12) RFB INPUT RESISTANCE (PIN 13) L/C/U Grade K/B/T Grade All Grades All Grades L/C/U Grade K/B/T Grade All Grades L/C/U Grade K/B/T Grade 1.5 ± 0.35 ± 0.7 ± 1.0 ± 0.5 ± 0.75
(VDD = +5 V or +15 V, VIN = –10 V dc, IOUT = AGND = DGND = 0 V, output amplifier AD544 except where noted)
Test Conditions/Comments
TA = +25؇C TA = TMIN, TMAX VDD = +5 V VDD = +15 V VDD = +5 V VDD = +15 V Units 1.5 1.5 1.5 dB
± 0.35 ± 0.5 ± 0.7 ± 0.5 ± 0.75
± 0.4 ± 0.8 ± 1.3 ± 0.5 ± 1.0
± 0.4 ± 0.7 ± 1.0 ± 0.5 ± 0.8 0 to –72 0 to –66 9 17 21 9.45 18 22 13.5 1.5 ± 10 – 15 2
dB max dB max dB max dB max dB max dB dB kΩ min kΩ max kΩ max kΩ min kΩ max kΩ max V min V max µA max V min V max mA max
Accuracy is measured using circuit of Figure 1 and includes any effects due to mismatch between RFB and the R-2R ladder circuit.
Monotonic Over Full 0 to –72 Code Range 0 to –66 Monotonic Over Full Code Range 9 17 21 9.45 18 22 3.0 0.8 ±1 5 – 0.5 9 17 21 9.45 18 22 13.5 1.5 ±1 – 15 1 9 17 21 9.45 18 22 3.0 0.8 ± 10 5 – 1
Digital Inputs 000000 to 110000 Digital Inputs 000000 to 101100
DIGITAL INPUTS Input High Voltage Requirements VIH Input Low Voltage Requirements VIL Input Leakage Current POWER SUPPLY VDD for Specified Accuracy IDD
Specifications subject to change without notice.
Digital Inputs = VDD
Digital Inputs = 0 V or VDD (See Figure 7)
AC PERFORMANCE CHARACTERISTICS
Parameter DC Supply Rejection, ∆Gain/∆VDD Propagation Delay Digital-to-Analog Glitch Impulse 0.01 1.8 225 0.005 0.4 1200
(VDD = +5 V or +15 V, VIN = –10 V except where stated, IOUT = AGND = DGND = 0 V, output amplifier AD544 except where noted)
These characteristics are included for design guidance only and are not subject to test.
TA = +25؇C TA = TMIN, TMAX VDD = +5 V VDD = +15 V VDD = +5 V VDD = +15 V Units 0.01 2.2 – 0.005 0.5 – dB per % max µs max nV secs typ ∆VDD = ± 10%, Input code = 100000 Full-Scale Change Measured with ADLH0032CG as output amplifier for input code transition 100000 to 000000. C1 of Figure 1 is 0 pF. Feedthrough is also determined by circuit layout VIN = 6 V rms per DIN 45403 Blatt 4 Includes AD544 amplifier noise
Output Capacitance (Pin 14) Input Capacitance Pin 12 and Pin 13 Feedthrough at 1 kHz L/C/U Grade K/B/T Grade Total Harmonic Distortion Intermodulation Distortion Output Noise Voltage Density Digital Input Capacitance
Specifications subject to change without notice.
100 7 –86 –80 –85 –79 70 7
100 7 –86 –80 –85 –79 70 7
100 7 –68 –63 –85 –79 70 7
100 7 –68 –63 –85 –79 70 7
pF max pF max dB max dB max dB typ dB typ nV/√Hz max pF max
Accuracy Specification for K/B/T Grade Devices at T A = +25°C
–2–
Accuracy Specification for L/C/U Grade Devices at T A = +25°C REV. A
Applications Information–AD7118
ABSOLUTE MAXIMUM RATINGS*
(TA = +25°C unless .