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ADR293GRU-REEL7
Datasheet (Analog Devices)
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Datasheet ADR293GRU-REEL7, ADR293GR-REEL7, ADR293GR-REEL, ADR293GR, ADR293FR-REEL7 Datasheet (Analog Devices)

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Page 1
Low Noise Micropower
a
5.0 V, Precision Voltage Reference

FEATURES

6.0 V to 15 V Supply Range Supply Current 15 A Max Low Noise 15 V p–p Typ (0.1 Hz to 10 Hz) High Output Current 5 mA Temperature Range 40C to 125C Pin Compatible with REF02/REF19x
APPLICATIONS Portable Instrumentation Precision Reference for 5 V Systems A/D and D/A Converter Reference Solar Powered Applications Loop-Current Powered Instruments
GENERAL DESCRIPTION
The ADR293 is a low noise, micropower precision voltage
®
reference that utilizes an XFET FET)
reference circuit. The new XFET architecture offers sig-
(eXtra implanted junction
nificant performance improvements over traditional bandgap and buried Zener-based references. Improvements include: one quarter the voltage noise output of bandgap references operating at the same current, very low and ultralinear temperature drift, low thermal hysteresis and excellent long-term stability.
The ADR293 is a series voltage reference providing stable and accurate output voltage from a 6.0 V supply. Quiescent current is only 15 µA max, making this device ideal for battery powered instrumentation. Three electrical grades are available offering initial output accuracy of ±3 mV, ±6 mV, and ± 10 mV. Tem­perature coefficients for the three grades are 8 ppm/°C, 15 ppm/°C and 25 ppm/°C max. Line regulation and load regulation are typically 30 ppm/V and 30 ppm/mA, maintaining the reference’s overall high performance.
The ADR293 is specified over the extended industrial tempera­ture range of –40°C to +125°C. This device is available in the 8-lead SOIC and 8-lead TSSOP packages.
ADR293
PIN CONFIGURATIONS
8-Lead Narrow Body SO
(R Suffix)
18
NC NC
ADR293
2
IN
TOP VIEW
(Not to Scale)
3
NC
GND
4
NC = NO CONNECT
8-Lead TSSOP
(RU Suffix)
18
NC NC
ADR293
2
IN
TOP VIEW
(Not to Scale)
3
NC
GND
4
NC = NO CONNECT
ADR29x Products
Output Initial Temperature Voltage Accuracy Coefficient
Device (V) (%) (ppm/C) Max
ADR290 2.048 (See ADR290/ADR291/ADR292 ADR291 2.500 Data Sheet) ADR292 4.096
ADR293 5.000 0.06, 0.12, 0.20 8, 15, 25
8
7
NC
7
6
6
OUT
5
5
NC
8
7
NC
7
6
6
OUT
5
5
NC
XFET 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.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 World Wide Web Site: http://www.analog.com Fax: 781/326-8703 © Analog Devices, Inc., 2001
Page 2
ADR293–SPECIFICATIONS
ELECTRICAL SPECIFICATIONS
(VS = 6.0 V, TA = 25C unless otherwise noted.)
Parameter Symbol Conditions Min Typ Max Unit
INITIAL ACCURACY
Output Voltage V
O
I
OUT
= 0 mA
“E” Grade 4.997 5.000 5.003 V
–3 +3 mV
0.06 %
“F” Grade 4.994 5.000 5.006 V
–6 +6 mV
0.12 %
“G” Grade 4.990 5.000 5.010 V
–10 +10 mV
0.20 %
LINE REGULATION
“E/F” Grades ∆V
O
/∆V
IN
6.0 V to 15 V, I
= 0 mA 30 100 ppm/V
OUT
“G” Grade 40 150 ppm/V
LOAD REGULATION
“E/F” Grades ∆V
/∆I
O
LOAD
VS = 6.0 V, 0 mA to 5 mA 30 100 ppm/mA
“G” Grade 40 150 ppm/mA
LONG-TERM STABILITY ∆V
NOISE VOLTAGE e
WIDEBAND NOISE DENSITY e
N
N
ELECTRICAL SPECIFICATIONS
O
(VS = 6.0 V, TA = –25C ≤ TA ≤ 85C unless otherwise noted.)
After 1000 hrs of Operation @ 125°C 50 ppm
0.1 Hz to 10 Hz 15 µV p-p at 1 kHz 640 nV/√Hz
Parameter Symbol Conditions Min Typ Max Unit
TEMPERATURE COEFFICIENT
“E” Grade TCV
O
I
= 0 mA 3 8 ppm/°C
OUT
“F” Grade 5 15 ppm/°C “G” Grade 10 25 ppm/°C
LINE REGULATION
“E/F” Grades ∆V
O
/∆V
IN
6.0 V to 15 V, I
= 0 mA 35 150 ppm/V
OUT
“G” Grade 50 200 ppm/V
LOAD REGULATION
“E/F” Grades ∆V
/∆I
O
LOAD
VS = 6.0 V, 0 mA to 5 mA 20 150 ppm/mA
“G” Grade 30 200 ppm/mA
(V
= 6.0 V, TA = –40C ≤ TA ≤ 125C unless otherwise noted.)
ELECTRICAL SPECIFICATIONS
S
Parameter Symbol Conditions Min Typ Max Unit
TEMPERATURE COEFFICIENT
“E” Grade TCV
O
I
= 0 mA 3 10 ppm/°C
OUT
“F” Grade 5 20 ppm/°C “G” Grade 10 30 ppm/°C
LINE REGULATION
“E/F” Grades ∆V
O
/∆V
IN
6.0 V to 15 V, I
= 0 mA 40 200 ppm/V
OUT
“G” Grade 70 250 ppm/V
LOAD REGULATION
“E/F” Grades ∆V
/∆I
O
LOAD
VS = 6.0 V, 0 mA to 5 mA 20 200 ppm/mA
“G” Grade 30 300 ppm/mA
SUPPLY CURRENT I
S
@ 25°C1115µA
15 20 µA
THERMAL HYSTERESIS V
O–HYS
SO-8 72 ppm TSSOP-8 157 ppm
Specifications subject to change without notice.
–2–
REV. A
Page 3
ADR293
WARNING!
ESD SENSITIVE DEVICE

ABSOLUTE MAXIMUM RATINGS

Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 V
Output Short-Circuit Duration to GND . . . . . . . . . . Indefinite
Storage Temperature Range
SO, RU Package . . . . . . . . . . . . . . . . . . . ⫺65°C to 150°C
Operating Temperature Range . . . . . . . . . . ⫺40°C to 125°C
1
Package Type JA*
JC
Unit
8-Lead SOIC (SO) 158 43 °C/W 8-Lead TSSOP (RU) 240 43 °C/W
*θJA is specified for worst-case conditions, i.e., θ
socket testing; in practice, θ
is specified for a device soldered in circuit board.
JA
is specified for device in
JA
Junction Temperature Range
SO, RU Package . . . . . . . . . . . . . . . . . . . ⫺65°C to 125°C
Lead Temperature (Soldering, 60 sec) . . . . . . . . . . . . . 300°C
NOTES
1
Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
2
Remove power before inserting or removing units from their sockets.

ORDERING GUIDE

Temperature Output Initial Coefficient Number of Voltage Accuracy Max Package Package Parts per
Model V % ppm/C Description Option Package
ADR293ER, ADR293ER-REEL7, ADR293ER-REEL 5.00 0.06 8 SOIC SO-8 98, 1000, 2500 ADR293FR, ADR293FR-REEL7, ADR293FR-REEL 5.00 0.12 15 SOIC SO-8 98, 1000, 2500 ADR293GR, ADR293GR-REEL7, ADR293GR-REEL 5.00 0.20 25 SOIC SO-8 98, 1000, 2500 ADR293GRU-REEL7, ADR293GRU-REEL 5.00 0.20 25 TSSOP RU-8 1000, 2500
CAUTION
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 ADR293 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.
REV. A
–3–
Page 4
ADR293
PARAMETER DEFINITION
Line Regulation, the change in output voltage due to a speci-
fied change in input voltage. It includes the effects of self-heating. Line regulation is expressed in either percent-per-volt, parts-per­million-per-volt, or microvolts-per-volt change in input voltage.
Load Regulation, the change in output voltage due to a specified change in load current. It includes the effects of self-heating. Load Regulation is expressed in either microvolts-per-milliam­pere, parts-per-million-per-milliampere, or ohms of dc output resistance.
Long-Term Stability, typical shift of output voltage of 25°C on a sample of parts subjected to high-temperature operating life test of 1000 hours at 125°C.
∆∆VVt–Vt
=
() ()
OO0 O1
Vt–Vt
() ()
where:
V V
V ppm =
[]
O
) = VO at 25°C at time 0.
O(t0
) = VO at 25°C after 1000 hours operation at 125°C.
O(t1
O0 O1
Vt
()
O0
× 10
6
NC = No Connect (There are in fact connections at NC pins which are reserved for manufacturing purposes. Users should not connect anything at NC pins.).
Temperature Coefficient, the change of output voltage over the operating temperature change and normalized by the output voltage at 25°C, expressed in ppm/°C. The equation follows:
TCV ppm C
[/]
O
°=
OO
VCTT
()
°×
25
O
()−()
21
6
×
10
VT VT
()−()
21
where:
V
(25°C) = VO at 25°C.
O
) = VO at temperature1.
V
O(T1
V
) = VO at temperature2.
O(T2
Thermal Hysteresis, is defined as the change of output voltage after the device is cycled through temperature from +25°C to –40°C to +85°C and back to +25°C. This is a typical value from a sample of parts put through such a cycle.
25
VVCV
V ppm
where:
V
(25°C) = VO at 25°C.
O
V
=VO (25°C) after temperature cycle at +25°C to
O_TC
=°
O HYS O O TC
__
O HYS
_
()–
VCV
=
[]
25
°
()–
OOTC
VC
()
O
25
_
°
6
10
×
–40°C to +85°C and back to +25°C.
–4–
REV. A
Page 5
Typical Performance Characteristics–ADR293
LOAD CURRENT – mA
0
0 5.0
DIFFERENTIAL VOLTAGEV
1.0 2.5 3.0
0.7
0.4
0.3
0.2
0.1
0.5 3.5
0.5
0.6
TA +125C
TA +25C
TA  –40C
1.5 2.0 4.0 4.5
5.006
3 TYPICAL PARTSVS 6.0V
5.004
5.002
5.000
4.998
OUTPUT VOLTAGE – V
4.996
4.994
TEMPERATURE – C
TPC 1. V
16
14
12
10
8
6
SUPPLY CURRENTA
4
2
0
vs. Temperature
OUT
TA +125C
TA +25C
TA  –40C
INPUT VOLTAGE – V
TPC 2. Supply Current vs. Input Voltage
100
VS 6.0V TO 15V
80
60
40
LINE REGULATION ppm/V
20
1251007550250–25–50
0
TEMPERATURE – C
1251007550250–25–50
TPC 4. Line Regulation vs. Temperature
100
VS 6.0V TO 9.0V
80
60
40
LINE REGULATION ppm/V
20
1614121086420
0
TEMPERATURE – C
I
OUT
0mA
1251007550250–25–50
TPC 5. Line Regulation vs. Temperature
16
VS 6.0V
14
12
10
SUPPLY CURRENT– A
8
REV. A
6
TEMPERATURE – C
TPC 3. Supply Current vs. Temperature
1251007550250–25–50
TPC 6. Minimum Input-Output Voltage Differential vs. Load Current
–5–
Page 6
ADR293
100
VS 6.0V
160
120
I
5mA
OUT
80
I
1mA
LOAD REGULATION ppm/mA
40
0
OUT
TEMPERATURE – C
TPC 7. Load Regulation vs. Temperature
2
1
FROM NOMINAL mV
V
OUT
2
3
0
1
TA  –40C
TA +125C
TA +25C
120
100
80
60
40
RIPPLE REJECTION dB
20
1251007550250–25–50
0
10 1000
FREQUENCY – Hz
VS 6.0V
100
TPC 10. Ripple Rejection vs. Frequency
50
VS  6.0V
IL 0mA
40
30
20
RIPPLE REJECTION dB
10
4
010
TPC 8.∆V
1200
1000
800
600
400
200
VOLTAGE NOISE DENSITY nV/ Hz
0
10 1000
SOURCING LOAD CURRENT – mA
from Nominal vs. Load Current
OUT
1
VIN 15V
TA  25C
100
FREQUENCY – Hz
TPC 9. Voltage Noise Density
0
10 10k
TPC 11. Output Impedance vs. Frequency
10V p-p
TPC 12. 0.1 Hz to 10 Hz Noise
100
FREQUENCY – Hz
1k
1s
–6–
REV. A
Page 7
ADR293
V
OUT
DEVIATION – ppm
18
16
0
–200 40–160
FREQUENCY
–120 –80 –40 0 24080 120 160 200
14
12
10
8
6
4
2
TEMPERATURE
+25C –40C
+85C +25C
IL 5mA
5V/DIV
2V/DIV
TPC 13. Turn-On Time
IL 5mA
5V/DIV
50s
IL 5mA
CL 1nF
1ms
TPC 16. Load Transient
IL 5mA CL 100nF
2V/DIV
TPC 14. Turn-Off Time
IL 5mA
TPC 15. Load Transient
REV. A
50s
1ms
1ms
TPC 17. Load Transient
TPC 18. Typical Hysteresis for ADR29x Product
–7–
Page 8
ADR293
THEORY OF OPERATION
The ADR293 uses a new reference generation technique known as XFET,
which yields a reference with low noise, low supply
current and very low thermal hysteresis.
The core of the XFET reference consists of two junction field­effect transistors one of which has an extra channel implant to raise its pinch-off voltage. By running the two JFETS at the same drain current, the difference in pinch-off voltage can be amplified and used to form a highly stable voltage reference. The intrinsic reference voltage is around 0.5 V with a negative temperature coefficient of about –120 ppm/K. This slope is essentially locked to the dielectric constant of silicon and can be closely compensated by adding a correction term generated in the same fashion as the proportional-to-temperature (PTAT) term used to compensate bandgap references. The big advan­tage over a bandgap reference is that the intrinsic temperature coefficient is some thirty times lower (therefore less correction is needed) and this results in much lower noise since most of the noise of a bandgap reference comes from the temperature com­pensation circuitry.
The simplified schematic below shows the basic topology of the ADR293. The temperature correction term is provided by a current source with value designed to be proportional to abso­lute temperature. The general equation is:
RR R
++
VV
=
∆
OUT P PTAT
123
R
IR
+
()()
1
3
where ∆VP is the difference in pinch-off voltage between the two FETs and I
is the positive temperature coefficient
PTAT
correction current.
The process used for the XFET reference also features vertical NPN and PNP transistors, the latter of which are used as output devices to provide a very low drop-out voltage.
V
IN
I
I
1
1
*
V
P
R1
R2
I
PTAT
V
OUT
Device Power Dissipation Considerations
The ADR293 is guaranteed to deliver load currents to 5 mA with an input voltage that ranges from 5.5 V to 15 V. When this device is used in applications with large input voltages, care should be exercised to avoid exceeding the published specifica­tions for maximum power dissipation or junction temperature that could result in premature device failure. The following formula should be used to calculate a device’s maximum junc­tion temperature or dissipation:
TT
−
A
J
P
=
D
θ
A
J
In this equation, TJ and TA are the junction and ambient tem­peratures, respectively, P
is the device package thermal resistance.
θ
JA
is the device power dissipation, and
D
Basic Voltage Reference Connections
References, in general, require a bypass capacitor connected from the V
pin to the GND pin. The circuit in Figure 2
OUT
illustrates the basic configuration for the ADR293. Note that the decoupling capacitors are not required for circuit stability.
NC
1
ADR293
2
NC
+
10F
0.1F
3
4
NC = NO CONNECT
8
7
6
5
NC
NC
OUTPUT
NC
0.1F
Figure 2. Basic Voltage Reference Configuration
Noise Performance
The noise generated by the ADR293 is typically less than 15 µV p-p over the 0.1 Hz to 10 Hz band. The noise measurement is made with a bandpass filter made of a 2-pole high-pass filter with a corner frequency at 0.1 Hz and a 2-pole low-pass filter with a corner frequency at 10 Hz.
Turn-On Time
Upon application of power (cold start), the time required for the output voltage to reach its final value within a specified error band is defined as the turn-on settling time. Two components normally associated with this are; the time for the active circuits to settle, and the time for the thermal gradients on the chip to stabilize. TPC 13 shows the typical turn-on time for the ADR293.
R3
*EXTRA CHANNEL IMPLANT
R1+R2+R3
=
V
OUT
V
R1
+ I
PTAT
P
GND
R3
Figure 1. Simplified Schematic
–8–
REV. A
Page 9
ADR293
APPLICATIONS A Negative Precision Reference without Precision Resistors
In many current-output CMOS DAC applications where the output signal voltage must be of the same polarity as the reference voltage, it is often required to reconfigure a current­switching DAC into a voltage-switching DAC through the use of a 1.25 V reference, an op amp and a pair of resistors. Using a current-switching DAC directly requires the need for an additional operational amplifier at the output to reinvert the signal. A negative voltage reference is then desirable from the point that an additional operational amplifier is not required for either reinversion (current-switching mode) or amplifica­tion (voltage-switching mode) of the DAC output voltage. In general, any positive voltage reference can be converted into a negative voltage reference through the use of an operational amplifier and a pair of matched resistors in an inverting configu­ration. The disadvantage to that approach is that the largest single source of error in the circuit is the relative matching of the resis­tors used.
The circuit illustrated in Figure 3 avoids the need for tightly matched resistors with the use of an active integrator circuit. In this circuit, the output of the voltage reference provides the input drive for the integrator. The integrator, to maintain circuit equilibrium, adjusts its output to establish the proper relation­ship between the reference’s V
and GND. One caveat with
OUT
this approach should be mentioned: although rail-to-rail output amplifiers work best in the application, these operational ampli­fiers require a finite amount (mV) of headroom when required to provide any load current. The choice for the circuit’s negative supply should take this issue into account.

A Precision Current Source

Many times in low power applications, the need arises for a preci­sion current source that can operate on low supply voltages. As shown in Figure 4, the ADR293 is configured as a precision current source. The circuit configuration illustrated is a floating current source with a grounded load. The reference’s output voltage is bootstrapped across R
, which sets the output current
SET
into the load. With this configuration, circuit precision is main­tained for load currents in the range from the reference’s supply current, typically 15 µA to approximately 5 mA.
V
IN
ADR293
V
OUT
R1
GND
1F
ADJUST
I
SY
R
SET
P1
I
OUT
R
L
Figure 4. A Precision Current Source
V
IN
ADR293
V
GND
OUT
100k 100k
1k
1F
1F
+5V
A
1
–5V
= 1/2 OP291,
A
1
1/2 OP295
–V
REF
Figure 3. A Negative Precision Voltage Reference Uses No Precision Resistors
REV. A
–9–
Page 10
ADR293
Kelvin Connections
In many portable instrumentation applications where PC board cost and area go hand-in-hand, circuit interconnects are very often of dimensionally minimum width. These narrow lines can cause large voltage drops if the voltage reference is required to provide load currents to various functions. In fact, a circuit’s interconnects can exhibit a typical line resistance of 0.45 mΩ/square (1 oz. Cu, for example). Force and sense connections also referred to as Kelvin connections, offer a convenient method of eliminating the effects of voltage drops in circuit wires. Load currents flowing through wiring resistance produce an error (V
ERROR
= R ⫻ IL ) at the load. However, the Kelvin connection of Figure 5 overcomes the problem by including the wiring resistance within the forcing loop of the op amp. Since the op amp senses the load voltage, op amp loop control forces the output to compensate for the wiring error and to produce the correct voltage at the load.
R
V
IN
ADR293
V
GND
OUT
1F
100k
LW
V
IN
A
1
+V
OUT
SENSE
R
LW
+V
OUT
FORCE
R
L

Voltage Regulator For Portable Equipment

The ADR293 is ideal for providing a stable, low cost and low power reference voltage in portable equipment power supplies. Figure 6 shows how the ADR293 can be used in a voltage regulator that not only has low output noise (as compared to switch mode design) and low power, but also a very fast recovery after current surges. Some precautions should be taken in the selection of the output capacitors. Too high an ESR (effective series resistance) could endanger the stability of the circuit. A solid tantalum capacitor, 16 V or higher, and an aluminum elec­trolytic capacitor, 10 V or higher, are recommended for C1 and C2, respectively. Also, the path from the ground side of C1 and C2 to the ground side of R1 should be kept as short as possible.
CHARGER
INPUT
LEAD-ACID
BATTERY
0.1F
R3
V
IN
510k
ADR293
6V
V
GND
OUT
402k
1%
C1 68F TANT
IRF9530
+
5V, 100mA
+
C2 1000F ELECT
OP-20
R1
R2
402k
1%
+
C00164–0–3/01 (A)
Figure 5. Advantage of Kelvin Connection
8-Lead Narrow Body SO
(SO-8)
0.1968 (5.00)
0.1890 (4.80)
0.1574 (4.00)
0.1497 (3.80)
PIN 1
0.0098 (0.25)
0.0040 (0.10)
SEATING
85
0.0500 (1.27)
PLANE
0.2440 (6.20)
0.2284 (5.80)
41
BSC
0.0192 (0.49)
0.0138 (0.35)
0.0688 (1.75)
0.0532 (1.35)
0.0098 (0.25)
0.0075 (0.19)
Figure 6. Voltage Regulator for Portable Equipment
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
0.0196 (0.50)
0.0099 (0.25)
8
0.0500 (1.27)
0
0.0160 (0.41)
45
PIN 1
0.006 (0.15)
0.002 (0.05)
SEATING
PLANE
0.122 (3.10)
0.114 (2.90)
8
5
41
0.0256 (0.65) BSC
0.0118 (0.30)
0.0075 (0.19)
8-Lead TSSOP
(RU-8)
0.177 (4.50)
0.169 (4.30)
0.256 (6.50)
0.246 (6.25)
0.0433 (1.10) MAX
0.0079 (0.20)
0.0035 (0.090)
8 0
0.028 (0.70)
0.020 (0.50)
PRINTED IN U.S.A.
–10–
REV. A
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