Datasheet AD509 Datasheet (ANALOG DEVICES)

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- Page 12

.'

r. ANALOG

LIllI

DEVICES

FastSettlingIe UpAmp

HighSpeed,

. AD509 I

FEATURES
Fat Settting Time

~O.1'" in 5OOns mex

0.01% in 2.5ps max
High Slew Rate: 100V/1lS min'
Low 10': 25nA max

Guaranteed VOl Drift: 3OIlVrC mex
High CMRR: BOdBmin

Orive.5OOpF
Low Price

APPLICATIONS
01A and AID Converlion
Wideband Amplifi8n
MultiplexeR
Pul. AmplifieR

INVERTINGr2

OBSOLETE

PRODUCT DESCRIPTION
The ADS09j, ADS09K and ADS09S are monolithic
operational amplifiers specifically designed for applications

requiring fast settling times to high accuracy. Other compar-
able dynamic parameters include a small signal bandwidth of
2OMHz, slew rate of lOOV/JlS min and a full power response
of 150kHz min. The devices are internally compensated for
all closed loop gains greater than 3, and are compensated with
a single capacitor for lower gains.

The input characteristics of the AD.509 are consistent with

0.01 % accuracy over limited temperature ranges; offset current
is 2SnA max, offset voltage is 8mV max, nullable to' zero, and
offset voltage drift is limited to 30p.V/'C max. PSRR and
CMRR are typically 90dB.

The ADS09 is designed for use with high speed D/A or AID
conveners where the minimum conversion time is limited by
the amplifier setding time. If 0.01 % accuracy of conversion
is required. a conversion cannot be made in a shoner period
than the time required for the amplifier to settle to within

0.01 % of its final value,
All devices are supplied in the TO-99 package. The ADS09j

and ADS09K are specified for 0 to +70oC temperatUte range;
the ADS09S for operation from -SSoC to +12SoC.

PRODUCT HIGHLIGHTS

1. The ADS09 is internally compensated for all closed loop
gains above 3. and compensated with a single capacitor for
lower gains thus eliminating the c:laborate stabilizing tech-
niques required by other high speed IC op amps.

2. The ADSO9 will drive capaciti~ loads of SOOpF without
deterioration in settling time. Larger capacitive loads
can be driven by tailoring the compensation to minimize
settling time.

3. Common Mode Rejection, Gain and Noise are compatible
with a 0.01% accuracy device.

4. The ADSO9K and ADSO9S are 100% tested for minimum
slew rate and guaranteed to settle to 0.01% of its final

value in less than 2.Slls.

PIN CONFIGURATION

TO-99

FREQUENCY

COMPENSATION

INPUT

~

2.. T !.

TOPVIEW

v-

V+

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ANALOGDEVICES fAX-ON-DEMAND HOTLINE

- Page 13

AD509-SPECIFICATIONS(@ %25°&andVs= %15Vdeunlessoth8lWi~e specified)

,.

Model
OPEN LOOP GAIN

Vo = :t10V,RL2:2kO
TmiDtoT...,RL '" 2kO

OUTPUT CHARACTERISTICS

Voltage@RL = 2k.O,T....D[oT-

FREQUENCY RESPONSE

Unity<din Small Sipal
Full Power Response
SlewRate, UnityGain
SettlingTime

100.1%

100.01%

INPUT OFFSET VOLTAGE

InitialOffset

Input Offset Voltage TmiDto T...

Input Off8CIVoltageVI.Supply,

T.....toT...

INPUT BIASCURRENT

l'Di0ai

T...toT-

OBSOLETE

INPUT OFFSET CURRENT

Initial
T,,=minlOmax

INPUT IMPEDANCE

Differential

INPUT VOLTAGE RANGE

Differential
CommooMode
CommonModeRejection

INPUT NOISE VOLTAGE

f = 10Hz
f'" 100Hz
f=]OOIt}h

POWER SUPPLY

Rated Perfonnana:
Opcnting

QuicsceD[Current

TEMPERATURE RANGE

Opcnting. Rated Performanc:e
SIOtllF

NOTES
SpecifICationS subject to cbanae without DOrice,
AU miA and mu specuJCations are guarm>teed,
SpecifJCaDoaSshown ill boldface are tared on all 'prodUCtion units at fmal
dectric:aI tat. Results from t~ tests are used to calculate outgoing quality

Ie¥$.

MiD

7,500 15,000
5,000

:10 :t 12

1.2 J.6

80' 120

4()

74

:5

0 +70

-65 +150 -65

AD5O9J

Typ

20

200

1.0

5

125 250

20

100

: 15 : 15
: 10

90

100
30
19

:!:]5 ::!:15

4 '

Mas MiD

10,000 15,000
7,500

:10

l.5 2,0
80 120

10
14

2OCt

SOO

50 10

100

50 100 50 100

at 90

:20 ::5 :!:20 :!:5

0 +70

AD5O9K
Typ

:!:12

20

200

1.0 1.0

4

100

,dO

100
30
19

Max MiD

10,000
7,500

:tICI :!:12

1.5
100

8 4 8

11 11

100

200 100
400

25 10 25

50 50

80 90 dB

4 6

-55

+ 150 -65

AD509S
Typ

15.000

20

2.0
120

200 500

:!::i5
: 10 V

100
30 nV/Y'Hz
]9

:t 15

4 6

Max Uaita

.

2.5

100

200 nA
400 nA

:!:20

+ 125 .C
+ 150 .C

VN
VN

V

MHz
MHz

VI.,...

ms
,,"5

mV
mV

ILVN

nA
nA

MO

V

nV/Y'Hz

nVIY'Hz

V
V
mA

ORDERING GUIDE

Model

AD509JH ,
AD509KH

AD509SH

"H-O8A = TO-99 Style Metal Can. For outline information see Package

Information section.

Temperature Range
DoCto +70°C

DoCto +70°C

-55"C to +12S"C

-2-

Package Option*
H-o8A

H-o8A
H-o8A

ANALOGDEVICES fAX-ON-DEMAND HOTLINE - Page 1~

"

ApplyingtheAD509

APPLYING THE ADS09

MEASURING SETTLING TIME. Settling time is defined as

that period required for an amplifier output to swing from

0 volts to full scale, usually 10 voltS, and to settle to within

a specified percentage of tbe final output voltage. For high
accuracy systems, the accuracy requirement is normally
specified as either 0.1'.16(lo-bit accuracy) or 0.01'.16(12-bit
accuracy) of the 10 volt output level. The settling time
perioo is comprised of an initial propagation delay, an
additional time for the amplifier to slew to the vicinity of
10 volts, and a final time period to'recover from internal
saturation and other effects, and settle within the specified

error band. Because settling time depends on both .linear
and nonlinear factors, there is no simple approach to
predicting itSfinal value to different levels of accuracy, ]n
particular, extremely high slew rates do not assure a rapid
scnling time, since this is only one of many factors affecting
settling time. In most high speed. amplifiers, after the
amplifier has slewed to the vicinity of tbe final output
voltage, it must recover from internal saturation and then
allow any overshoot and ringing to damp out. These
definitions are illustrated in Figure 1.

OBSOLETE

E::~~{r!~~~!~~~:~=:===~--,--

The AD509K and AD509S are guaranteed to settle to 0.1%
in SOOnsand 0.01" in 2.S/JSwhen tested as shown in Figure 2.
There is no appreciable degradation in settling time when
the capacitive load is increa.scd to 500pF, as discussed below.
The settling time is computed by summing the output and the
input into a differential amplifier, which then drives a scope

Eo - AE

DEAO

TIME SLEWING RECOIIERYLINEAR SETTLING

j I

-SETTLING TIME To1:..:lE-1

~: x100%

OR .:!:

Figure 1. Settling Time

5f>f

fin

Figure 2. AD509 Settling Time Test Circuit

~

I

DECOUI'lING CAPACITORS
OMITTED fOR CLARITY

SCOI'£

display. The resultant waveform of (Eo - EIN) of a typical

ADS09 is shown in Figure 3. Note that the waveform crosses
the 1mV point representing 0.01 % ac~uracy in approximately

l.S/JS. The top trace represents the output signal; the bottom

trace represents the error signal.

OUTPUT

ERROR
SIGNAL

Figure 3. Settling Time of AD509

SETTLING TIME VS. Rf AND Ri. Settling time of an
amplifier is a function of the feedback and input resistors,

since they interact with the input capacitance of the amplifier.
When operating in the non-inverting mode, the source
impedance should be kept relatively low; e.g., Sill; in order
to insure optimum performance. The small feedback
capacitor (SpF) is used in the settling time test circuit in
parallel with tbe feedback resistor to reduce ringing. This
capacitor partially cancels the pole formed in the loop gain

response as a result of the feedback and input resistors, and
the input capacitance.

SETTLING TIME VS. CAPACIT]VE LOAD. The ADS09

will drive capacitive loads of SOOpFwithout appreciable

deterioration in settling time. Larger capacitive loads can be
dtiven by tailoring the compensation to minimize settling
time, Figure 4 shows the settling time of a typical ADS09,
compensated for unity gain witb a 1SpF capacitOr, with a
SOOpFcapacitive load on the output. Note that settling time

to 0.01 % is still under 2.01-15.

OIJTP\IT

ERROR
SIGNAL

Figure 4. AD509 with 500pF Capacitive Load

SUGGESTIONS FOR MINIMIZING SETTL]NG TIME. The
ADS09 has been designed to settle to 0.01 % accuracy in

1 to 2.S/JS. However, this amplifier is only a building block
in a circuit that also has a feedback network, input and output
connections, power supply connections, and a number of
external componentS. What has been painsta.kingly gained in

amplifier design can be lost without careful circuit design,

Some of the elements of a good high speed design are..........

CONNECTIONS. It is essential that care be taken in the.

signal and power ground circuits to avoid inducing or
generating extraneous voltages in the ground signal paths.

i

I

.0

II

.

-- t

,..

I ,

1/ i- no

11m'

T n.

I

,

....1--

m

i-

t

f1$

r-

-

-

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ANALOGDEVICES fAX-ON-DEMAND HOTLINE

AD509

- Page 15

"

The O.lIlF cetatnic power supply bypass capacitors are
considerably more important for the AD509 than for low
frequency general purpose amplifiers. Their main purpose
is to convert the distributed high frequency ground to a

'lumped singJe point (the V+ point). The V+ to V- O.lIlF

capacitor equalizes the supply grounds while the O.lIlF
capacitor from V+ to signal ground should be returned to
signal common. The signal common, which is bypassed to
pin 7, is defined as that point at which the input signal
source, tltc feedback network, and tbe retUrn side of the load
are joined to the power common,

Note that the diagram shows each individual capacitor
directly connected to the appropriate terminal (pin 7 [V+).

1M

TO SIGNAL
COMMON POINT

OUTPUT

30'

10M 100M

INVERTING

INPUT

_INVERTING

INPUT

OBSOLETE

Figunt 5. Configuration for Unity Gain Applications

DYNAMIC RESPONSE OF ADS09

120

,100

8' 10

..! 80

z'"

~:i <10

...

~ 20

II

-20
.0

100

.. 1011 1OOOt

FREQUENCY-II,

Figure 6. Open Loop Frequency and Phase Response

O.,..F

CEIlAMIe OISe

[n addition, it is suggested that all connections be sbort and
direct, and as physically dose to the case as possible, so that
the length of any conducting path shared by external
components will be minimized. .

COMPONENTS. Resistors are preferably metal fIlm types.

because they have less capacitance and stray inductance
than wirewound types, and are available with excellent
accuracies and temperatUre coefficients.

Diodes are hot carrier types for the very fastest-settling

applications, but lN914 types are suitable for more

routine uses.
Capacitors in critical locations are polystyrene, teflon, or

polycarbonate to minimize dielectric absorption.
CIRCUIT. For the fastest settling times, keep leads short,

orient components to minimize stray capacitance, keep
circuit impedance levels as low as consistent with the out-
put capabilities of the amplifier and the signal source,
reduce all extemalload capacitances to the absolute
minimum. Don't overlook sockets or printed circuit
board mounting as possible sources of dielectric absorption.
Avoid pole-zero mismatches in any feedback networks used
with the amplifier. Minimize noise pickup,

-20

.0 ..

100

101< IOOIt

FREQUENCY-H.

1M

10M

100M

Figure7. Open Loop Frequency Response for VariousCc's

THE ADS09 AS AN OUTPUT AMPLIFIER FOR FAST
CURRENT -OUTPUT D-TO-A CONVERTERS

Most fast integrated circuit digital to analog converters have
current outputs. That is, the digital input code is translated
to an output current proportional to the digital code. In
many applications, that output current isconverted to a volt-
age by connecting an operational amplifier in the current-to-

voltageconvc:;rsionmode. '

, The senling time of the combination depends on the settling

time of the DAC and the output amplifier. A good approxima-
tion is:

Is TOTAL =.JCt~DAC) 2 + ( ts AMP) 2

Some IC DACs settle to final output value in 100-500 nano-
seconds. Since most IC op amps require a longer time to settle

to :1:0.1%or :1:0.01%of final value, amplifier settling time can
dominate total settling time. And for a 12-bit DAC, one least
significant bit is only 0,024% of full-scale, so low drift and
high linearity and precision are also required of tbe output
amplifier.

Figure 8 shows the AD509K connected as an output amplifier
with the ADS65K, high speed 12-bit IC digital-to-analog con-
verter. The 10 picofarad capacitor, Cl, compensates for the
2SpF AD56S output capacitance. The voltage output of the

AD565K/ADS09K combination settles to :to.Ol% in one
microsecond. The low input voltage drift and high open loop

gain of the ADSO9K assures 12-bit accuracy over the operating
temperature range.

AD566K

SkU

~

Figure8. AD509 asan Output Amplifier for BFast Current-
Output D-tO-AConvert",

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