AD8200 ,High COmmon-Mode Voltage, Single Supply Difference AmplifierSpecifications subject to change without notice.–2– REV. AAD8200ABSOLUTE MAXIMUM RATINGS* PIN CONFI ..
AD8200YR , High Common-Mode Voltage, Single-Supply Difference Amplifier
AD8202YR ,High Common-Mode Voltage, Single-Supply Difference AmplifierGENERAL DESCRIPTION OUTPUTDIODE+IN NC +V OUTSThe AD8202 is a single-supply difference amplifier for ..
AD8202YRMZ ,High Common-Mode Voltage, Single-Supply Difference AmplifierSPECIFICATIONS—SINGLE SUPPLY TA = operating temperature range, VS = 5 V, unless otherwise noted. Ta ..
AD8205YR ,Single Supply 42V System Difference AmplifierGENERAL DESCRIPTION The AD8205 is a single-supply difference amplifier for amplify- Excellent dc pe ..
AD8205YRZ , Single-Supply 42 V System Difference Amplifier
ADP1829ACPZ-R7 , Dual, Interleaved, Step-Down DC-to-DC Controller with Tracking
ADP1877 ,Dual Output Synchronous Buck PWM ControllerFEATURES output voltage accuracy of ±0.85% from −40°C to +85°C and Input voltage range: 2.75 V to 1 ..
ADP1877ACPZ-R7 , Dual Output Synchronous Buck PWM Controller With Tracking
ADP1877ACPZ-R7 , Dual Output Synchronous Buck PWM Controller With Tracking
ADP190ACBZ-R7 , Logic Controlled, High-Side Power Switches
ADP195ACBZ-R7 , Logic Controlled, High-Side Power Switch with Reverse Current Blocking
AD8200
High COmmon-Mode Voltage, Single Supply Difference Amplifier
REV.A
High Common-Mode Voltage, Single-Supply
Difference Amplifier
FUNCTIONAL BLOCK DIAGRAM
SOIC (R) Package
DIE Form
FEATURES
High Common-Mode Voltage Range –2V to +24V
at a 5 V Supply Voltage
Operating Temperature Range
Die: –40�C to +150�C
8-Lead SOIC: –40�C to +125�C
Supply Voltage Range: 4.7 V to 12 V
Low-Pass Filter (One Pole or Two Pole)
EXCELLENT AC AND DC PERFORMANCE�6 �V/�C Typ Offset Drift
�10 ppm/�C Typ Gain Drift
80 dB CMRR Min DC to 10 kHz
PLATFORMS
Transmission Control
Diesel Injection Control
Engine Management
Adaptive Suspension Control
Vehicle Dynamics Control
GENERAL DESCRIPTIONThe AD8200 is a single-supply difference amplifier for amplifying
and low-pass filtering small differential voltages in the presence
of a large common-mode voltage. The input CMV range extends
from –2 V to +24 V at a typical supply voltage of 5V.
The AD8200 is offered in die and packaged form. Both package
options are specified over wide temperature ranges, making the
AD8200 well suited for use in many automotive platforms. The
SOIC package is specified over a temperature range of –40°C to
+125°C. The die is specified from –40°C to +150°C.
Figure 1.High-Line Current Sensor
Automotive platforms demand precision components for better
system control. The AD8200 provides excellent ac and dc per-
formance that keeps errors to a minimum in the user’s system.
Typical offset and gain drift in the SOIC package are 6 µV/°C
and 10 ppm/°C, respectively. The device also delivers a mini-
mum CMRR of 80 dB from dc to 10 kHz.
The AD8200 features an externally accessible 100kΩ resistor at
the output of the preamp A1, which can be used for low-pass
filter applications and for establishing gains other than 20.
Figure 2.Low-Line Current Sensor
+IN
–IN
OUT
GNDA1A2+VS
NC = NO CONNECT
AD8200–SPECIFICATIONS
SINGLE SUPPLYNOTESSource Imbalance < 2 Ω.The AD8200 preamplifier exceeds 80 dB CMRR at 10 kHz. However, since the signal is available only by way of a 100 kΩ resistor, even the small amounts of pin-
to-pin capacitance between Pins 1, 8 and 3, 4 may couple an input common-mode signal larger than the greatly attenuated preamplifier output. The effect of pin-to-
pin coupling may be neglected in all applications using filter capacitors at Node 3.
Specifications subject to change without notice.
(TA = 25�C, VS = 5 V, VCM = 0 V, RL = 10 k�, Pin 5 to ground, unless otherwise noted.)
ABSOLUTE MAXIMUM RATINGS*Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5 V
Transient Input Voltage (300 ms) . . . . . . . . . . . . . . . . . . 44 V
Continuous Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . 35 V
Reversed Supply Voltage Protection . . . . . . . . . . . . . . . 0.3 V
Operating Temperature . . . . . . . . . . . (Die) –40°C to +150°C
. . . . . . . . . (SOIC) –40°C to +125°C
Storage Temperature . . . . . . . . . . . . . . . . . . –65°C to +150°C
Output Short Circuit Duration . . . . . . . . . . . . . . . . Indefinite
Lead Temperature Range (Soldering 60 sec) . . . . . . . . 300°C
*Stresses beyond those listed under Absolute Maximum Ratings may cause
permanent damage to the device. This is a stress rating only; the functional
operation of the device at these or any other conditions above those indicated in
the operational sections of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
ORDERING GUIDE
PIN CONFIGURATION
CAUTIONESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000V readily
accumulate on the human body and test equipment and can discharge without detection. Although
the AD8200 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.
METALLIZATION PHOTOGRAPH
+IN
–IN1
GND
+VS
OUT54
TPC 1.Input Common-Mode Range vs. Supply
TPC 2.Output Voltage – VS vs. Supply
TPC 3.Output Voltage Swing vs. Load Resistance
AD8200–Typical Performance Characteristics
FREQUENCY – Hz
–201k
GAIN – dB
10k100k1M
–10TPC 4.Gain vs. Frequency
FREQUENCY – Hz
CMRR – dB10k1M
100100kTPC 5.Common-Mode Rejection vs. Frequency
FREQUENCY – Hz
PSRR – dB40
10010k1k100kTPC 6.Power Supply Rejection vs. Frequency
(TA = 25�C, VS = 5 V, VCM = 0 V, RL = 10 k�, unless otherwise noted.)
THEORY OF OPERATIONThe AD8200 consists of a preamp and buffer arranged as shown
in Figure 3. Like-named resistors have equal values.
The preamp incorporates a dynamic bridge (subtractor) circuit.
Identical networks (within the shaded areas), consisting of RA,
RB, RC, and RG, attenuate input signals applied to Pins 1 and 8.
Note that when equal amplitude signals are asserted at inputs 1
and 8, and the output of A1 is equal to the common potential
(i.e., zero), the two attenuators form a balanced-bridge network.
When the bridge is balanced, the differential input voltage at A1
and thus its output will be zero.
Any common-mode voltage applied to both inputs will keep the
bridge balanced and the A1 output at zero. Because the resistor
networks are carefully matched, the common-mode signal rejec-
tion approaches this ideal state.
However, if the signals applied to the inputs differ, the result is a
difference at the input to A1. A1 responds by adjusting its output
to drive RB, by way of RG, to adjust the voltage at its inverting
input until it matches the voltage at its noninverting input.
By attenuating voltages at Pins 1 and 8, the amplifier inputs are
held within the power supply range, even if Pin 1 and Pin 8 input
levels exceed the supply, or fall below common (ground.) The
input network also attenuates normal (differential) mode volt-
ages. RC and RG form an attenuator that scales A1 feedback,
forcing large output signals to balance relatively small differen-
tial inputs. The resistor ratios establish the preamp gain at 10.
Because the differential input signal is attenuated, and then
amplified to yield an overall gain of 10, the amplifier A1 oper-
ates at a higher noise gain, multiplying deficiencies such as input
offset voltage and noise with respect to Pins 1 and 8.
To minimize these errors while extending the common-mode
range, a dedicated feedback loop is employed to reduce the
range of common-mode voltage applied to A1, for a given over-
all range at the inputs. By offsetting the range of voltage applied
to the compensator, the input common-mode range is also offset
to include voltages more negative than the power supply. Ampli-
fier A3 detects the common-mode signal applied to A1 and
adjusts the voltage on the matched RCM resistors to reduce the
common-mode voltage range at the A1 inputs. By adjusting the
common voltage of these resistors, the common-mode input
range is extended while, at the same time, the normal mode
signal attenuation is reduced, leading to better performance
referred to input.
The output of the dynamic bridge taken from A1 is connected
to Pin 3 by way of a 100kΩ series resistor, provided for low-
pass filtering and gain adjustment. The resistors in the input
networks of the preamp and the buffer feedback resistors are
ratio-trimmed for high accuracy.
The output of the preamp drives a gain-of-two buffer-amplifier
A2, implemented with carefully matched feedback resistors RF.
The two-stage system architecture of the AD8200 enables the
user to incorporate a low-pass filter prior to the output buffer.
By separating the gain into two stages, a full-scale rail-to-rail
signal from the preamp can be filtered at Pin 3, and a half-scale
signal resulting from filtering can be restored to full scale by the
output buffer amp. The source resistance seen by the inverting
input of A2 is approximately 100kΩ, to minimize the effects of
A2’s input bias current. However, this current is quite small and
errors resulting from applications that mismatch the resistance
are correspondingly small.
APPLICATIONSThe AD8200 difference amplifier is intended for applications
where it is required to extract a small differential signal in the
presence of large common-mode voltages. The input resistance
is nominally 200kΩ, and the device can tolerate common-mode
voltages higher than the supply voltage and lower than ground.
The open collector output stage will source current to withinmV of ground.
TPC 7.Pulse Response
TEK RUN: 2.5MS/sAVERAGE
CH3100mVTPC 8.Settling Time
AD8200
CURRENT SENSING
High Line, High Current SensingBasic automotive applications making use of the large common-
mode range are shown in Figures 1 and 2. The capability of the
device to operate as an amplifier in primary battery supply cir-
cuits is shown in Figure 1; Figure 2 illustrates the ability of the
device to withstand voltages below system ground.
Low Current SensingThe AD8200 can also be used in low current sensing applica-
tions, such as a 4–20mA current loop shown in Figure 4. In
such applications, the relatively large shunt resistor can degrade
the common-mode rejection. Adding a resistor of equal value in
the low impedance side of the input corrects for this error.
Figure 4.4–20 mA Current Loop Receiver
GAIN ADJUSTMENTThe default gain of the preamplifier and buffer are ×10 and ×2,
respectively, resulting in a composite gain of ×20. With the
addition of external resistor(s) or trimmer(s), the gain may be
lowered, raised, or finely calibrated.
Gains Less than 20See Figure 5. Since the preamplifier has an output resistance of
100 kΩ, an external resistor connected from Pins 3 and 4 to
GND will decrease the gain by a factor REXT/(100 kΩ + REXT).
Figure 5.Adjusting for Gains Less than 20
The overall bandwidth is unaffected by changes in gain using
this method, although there may be a small offset voltage due to
the imbalance in source resistances at the input to the buffer. In
many cases this can be ignored, but if desired, can be nulled by
Gains Greater than 20Connecting a resistor from the output of the buffer amplifier to
its noninverting input, as shown in Figure 6, will increase the
gain. The gain is now multiplied by the factor REXT/(REXT –
100kΩ); for example, it is doubled for REXT = 200 kΩ. Overall
gains as high as 50 are achievable in this way. Note that the
accuracy of the gain becomes critically dependent on resistor
value at high gains. Also, the effective input offset voltage at
Pins 1 and 8 (about six times the actual offset of A1) limits the
part’s use in very high gain, dc-coupled applications.
Figure 6.Adjusting for Gains Greater than 20
GAIN TRIMFigure 7 shows a method for incremental gain trimming using
a trimpot and external resistor REXT.
The following approximation is useful for small gain ranges:
∆G ≈ (10 MΩ ÷ REXT) %
Thus, the adjustment range would be ±2% for REXT = 5 MΩ;
±10% for REXT = 1 MΩ, and so on.
Figure 7.Incremental Gain Trim
