Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.COM

X  

AD7390AN Datasheet(PDF) 8 Page - Analog Devices

Part # AD7390AN
Description  3 Volt Serial-Input Micropower 10-Bit & 12-Bit DACs
Download  12 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  AD [Analog Devices]
Direct Link  http://www.analog.com
Logo AD - Analog Devices

AD7390AN Datasheet(HTML) 8 Page - Analog Devices

Back Button AD7390AN Datasheet HTML 4Page - Analog Devices AD7390AN Datasheet HTML 5Page - Analog Devices AD7390AN Datasheet HTML 6Page - Analog Devices AD7390AN Datasheet HTML 7Page - Analog Devices AD7390AN Datasheet HTML 8Page - Analog Devices AD7390AN Datasheet HTML 9Page - Analog Devices AD7390AN Datasheet HTML 10Page - Analog Devices AD7390AN Datasheet HTML 11Page - Analog Devices AD7390AN Datasheet HTML 12Page - Analog Devices  
Zoom Inzoom in Zoom Outzoom out
 8 / 12 page
background image
AD7390/AD7391
REV. 0
–8–
OPERATION
The AD7390 and AD7391 are a set of pin compatible, 12-bit/10-
bit digital-to-analog converters. These single-supply operation
devices consume less than 100 microamps of current while op-
erating from power supplies in the
2.7 V to
5.5 V range
making them ideal for battery operated applications. They con-
tain a voltage-switched, 12-bit/10-bit, laser-trimmed digital-to-
analog converter, rail-to-rail output op amps, serial-input
register, and a DAC register. The external reference input has
constant input resistance independent of the digital code setting
of the DAC. In addition, the reference input can be tied to the
same supply voltage as VDD resulting in a maximum output volt-
age span of 0 to VDD. The SPI compatible, serial-data interface
consists of a serial data input (SDI), clock (CLK), and load
(LD) pins. A CLR pin is available to reset the DAC register to
zero-scale. This function is useful for power-on reset or system
failure recovery to a known state.
D/A CONVERTER SECTION
The voltage switched R-2R DAC generates an output voltage
dependent on the external reference voltage connected to the
VREF pin according to the following equation:
Equation 1
VOUT = VREF
2N
D
where D is the decimal data word loaded into the DAC register,
and N is the number of bits of DAC resolution. In the case of
the 10-bit AD7391 using a 2.5 V reference, Equation 1
simplifies to:
Equation 2
VOUT = 2.5
1024
D
Using Equation 2 the nominal midscale voltage at VOUT is
1.25 V for D = 512; full-scale voltage is 2.497 volts. The LSB
step size is = 2.5
1/1024 = 0.0024 volts.
For the 12-bit AD7390 operating from a 5.0 V reference Equa-
tion 1 becomes:
Equation 3
VOUT = 5.0
4096
D
Using Equation 3 the AD7390 provides a nominal midscale
voltage of 2.5 V for D =2048, and a full-scale output of 4.998 V.
The LSB step size is = 5.0
1/4096 = 0.0012 volts.
AMPLIFIER SECTION
The internal DAC’s output is buffered by a low power con-
sumption precision amplifier. The op amp has a 60
µs typical
settling time to 0.1% of full scale. There are slight differences in
settling time for negative slewing signals versus positive. Also,
negative transition settling time to within the last 6 LSBs of zero
volts has an extended settling time. The rail-to-rail output stage
of this amplifier has been designed to provide precision perfor-
mance while operating near either power supply. Figure 21
shows an equivalent output schematic of the rail-to-rail ampli-
fier with its N-channel pull-down FETs that will pull an output
load directly to GND. The output sourcing current is provided
by a P-channel pull-up device that can source current to GND
terminated loads.
P-CH
N-CH
VDD
VOUT
AGND
Figure 21. Equivalent Analog Output Circuit
The rail-to-rail output stage provides
1 mA of output current.
The N-channel output pull-down MOSFET shown in Figure 21
has a 35
Ω ON resistance, which sets the sink current capability
near ground. In addition to resistive load driving capability, the
amplifier has also been carefully designed and characterized for
up to 100 pF capacitive load driving capability.
REFERENCE INPUT
The reference input terminal has a constant input-resistance in-
dependent of digital code which results in reduced glitches on
the external reference voltage source. The high 2 M
Ω input-
resistance minimizes power dissipation within the AD7390/
AD7391 D/A converters. The VREF input accepts input voltages
ranging from ground to the positive-supply voltage VDD. One of
the simplest applications which saves an external reference volt-
age source is connection of the VREF terminal to the positive
VDD supply. This connection results in a rail-to-rail voltage out-
put span maximizing the programmed range. The reference in-
put will accept ac signals as long as they are kept within the
supply voltage range, 0 < VREF IN < VDD. The reference
bandwidth and integral nonlinearity error performance are plot-
ted in the typical performance section, see Figures 18 and 19.
The ratiometric reference feature makes the AD7390/AD7391
an ideal companion to ratiometric analog-to-digital converters
such as the AD7896.
POWER SUPPLY
The very low power consumption of the AD7390/AD7391 is a di-
rect result of a circuit design optimizing the use of a CBCMOS
process. By using the low power characteristics of CMOS for the
logic, and the low noise, tight-matching of the complementary bi-
polar transistors, excellent analog accuracy is achieved. One ad-
vantage of the rail-to-rail output amplifiers used in the AD7390/
AD7391 is the wide range of usable supply voltage. The part is
fully specified and tested for operation from
2.7 V to
5.5 V.
POWER SUPPLY BYPASSING AND GROUNDING
Precision analog products, such as the AD7390/AD7391, re-
quire a well filtered power source. Since the AD7390/AD7391
operates from a single
3 V to
5 V supply, it seems conve-
nient to simply tap into the digital logic power supply. Unfortu-
nately, the logic supply is often a switch-mode design, which
generates noise in the 20 kHz to 1 MHz range. In addition, fast
logic gates can generate glitches hundred of millivolts in ampli-
tude due to wiring resistance and inductance. The power supply
noise generated thereby means that special care must be taken
to assure that the inherent precision of the DAC is maintained.
Good engineering judgment should be exercised when address-
ing the power supply grounding and bypassing of the AD7390.


Similar Part No. - AD7390AN

ManufacturerPart #DatasheetDescription
logo
Analog Devices
AD7390AN AD-AD7390AN Datasheet
203Kb / 12P
   3 V Serial-Input Micropower 10-Bit and 12-Bit DACs
REV. A
AD7390AN AD-AD7390AN Datasheet
203Kb / 12P
   3 V Serial-Input Micropower 10-Bit and 12-Bit DACs
REV. A
More results

Similar Description - AD7390AN

ManufacturerPart #DatasheetDescription
logo
Analog Devices
AD7391ANZ AD-AD7391ANZ Datasheet
203Kb / 12P
   3 V Serial-Input Micropower 10-Bit and 12-Bit DACs
REV. A
AD7390 AD-AD7390 Datasheet
203Kb / 12P
   3 V Serial-Input Micropower 10-Bit and 12-Bit DACs
REV. A
AD7391 AD-AD7391_15 Datasheet
203Kb / 12P
   3 V Serial-Input Micropower 10-Bit and 12-Bit DACs
REV. A
AD7390 AD-AD7390_15 Datasheet
203Kb / 12P
   3 V Serial-Input Micropower 10-Bit and 12-Bit DACs
REV. A
AD7392 AD-AD7392_15 Datasheet
458Kb / 20P
   3 V, Parallel Input Micropower 10-/12-Bit DACs
REV. C
AD7393 AD-AD7393_15 Datasheet
458Kb / 20P
   3 V, Parallel Input Micropower 10-/12-Bit DACs
REV. C
AD7392AR-REEL AD-AD7392AR-REEL Datasheet
458Kb / 20P
   3 V, Parallel Input Micropower 10-/12-Bit DACs
REV. C
AD7398BRZ-REEL7 AD-AD7398BRZ-REEL7 Datasheet
416Kb / 24P
   Quad, Serial-Input 12-Bit/10-Bit DACs
REV. C
AD7398 AD-AD7398_15 Datasheet
416Kb / 24P
   Quad, Serial-Input 12-Bit/10-Bit DACs
REV. C
AD7399 AD-AD7399_15 Datasheet
416Kb / 24P
   Quad, Serial-Input 12-Bit/10-Bit DACs
REV. C
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Link Exchange   |   Manufacturer List
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com