Datenblatt-pdf.com


AD8208 Schematic ( PDF Datasheet ) - Analog Devices

Teilenummer AD8208
Beschreibung Precision Difference Amplifier
Hersteller Analog Devices
Logo Analog Devices Logo 




Gesamt 20 Seiten
AD8208 Datasheet, Funktion
Data Sheet
FEATURES
Qualified for automotive applications
EMI filters included
High common-mode voltage range
−2 V to +45 V operating
−24 V to +80 V survival
Buffered output voltage
Gain = 20 V/V
Low-pass filter (1-pole or 2-pole)
Wide operating temperature range
−40°C to +125°C for WB grade
−40°C to +150°C for WH grade
Excellent ac and dc performance
±1 mV voltage offset
−5 ppm/°C typical gain drift
80 dB CMRR minimum dc to 10 kHz
APPLICATIONS
High-side current sensing
Motor controls
Solenoid controls
Power management
Low-side current sensing
Diagnostic protection
GENERAL DESCRIPTION
The AD8208 is a single-supply difference amplifier ideal for
amplifying and low-pass filtering small differential voltages in the
presence of a large common-mode voltage. The input common-
mode voltage range extends from −2 V to +45 V at a single +5 V
supply. The AD8208 is qualified for automotive applications. The
amplifier offers enhanced input overvoltage and ESD protection,
and includes EMI filtering.
High Voltage,
Precision Difference Amplifier
AD8208
FUNCTIONAL BLOCK DIAGRAM
VS A1 A2
EMI
FILTER
+IN
EMI
FILTER
–IN
EMI
FILTER
+
G = 10
AD8208
+
G=2
OUT
GND
Figure 1.
Automotive applications demand robust, precision components for
improved system control. The AD8208 provides excellent ac and
dc performance, minimizing errors in the application. Typical
offset and gain drift in both the SOIC and MSOP packages are
less than 5 µV/°C and 10 ppm/°C, respectively. The device also
delivers a minimum CMRR of 80 dB from dc to 10 kHz.
The AD8208 features an externally accessible 100 kΩ resistor at
the output of the preamplifier (A1), which can be used for low-
pass filtering and for establishing gains other than 20.
Rev. C
Document Feedback
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 that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©2010–2013 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com






AD8208 Datasheet, Funktion
AD8208
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
–IN 1
GND 2
A1 3
A2 4
AD8208
TOP VIEW
(Not to Scale)
8 +IN
7 NC
6 VS
5 OUT
NC = NO CONNECT
Figure 2. Pin Configuration
Table 3. Pin Function Descriptions
Coordinates
Pin No. Mnemonic X
Y
1 −IN
−322 +563
2 GND
−321 +208
3 A1
−321 −51
4 A2
−321 −214
5 OUT
+321 −388
6 VS
+322 +363
7 NC
8 +IN
+322 +561
Description
Inverting Input
Ground
Preamplifier (A1) Output
Buffer (A2) Input
Buffer (A2) Output
Supply
No Connect
Noninverting Input
Data Sheet
18
26
3
4
5
Figure 3. Metallization Photograph
Rev. C | Page 6 of 20

6 Page









AD8208 pdf, datenblatt
AD8208
Data Sheet
APPLICATIONS INFORMATION
HIGH-SIDE CURRENT SENSING
WITH A LOW-SIDE SWITCH
In load control configurations for high-side current sensing with a
low-side switch, the PWM-controlled switch is ground referenced.
An inductive load (solenoid) connects to a power supply/battery.
A resistive shunt is placed between the switch and the load (see
Figure 25). An advantage of placing the shunt on the high side
is that the entire current, including the recirculation current, is
monitored because the shunt remains in the loop when the switch
is off. In addition, shorts to ground can be detected with the shunt
on the high side, enhancing the diagnostics of the control loop. In
this circuit configuration, when the switch is closed, the common-
mode voltage moves down to near the negative rail. When the
switch is opened, the voltage reversal across the inductive load
causes the common-mode voltage to be held one diode drop
above the battery by the clamp diode.
5V
CLAMP
DIODE
INDUCTIVE
LOAD
BATTERY
+
SHUNT
+IN NC VS OUT
OUTPUT
AD8208
SWITCH
–IN GND A1 A2
CF
NC = NO CONNECT
Figure 25. Low-Side Switch
In cases where a high-side switch is used for PWM control of the
load current in an application, the AD8208 can be used as shown
in Figure 26. The recirculation current through the freewheeling
diode (clamp diode) is monitored through the shunt resistor. In
this configuration, the common-mode voltage in the application
drops below GND when the FET is switched off. The AD8208
operates down to −2 V, providing an accurate current measurement.
5V
BATTERY
+
SWITCH
SHUNT
+IN NC VS OUT
OUTPUT
AD8208
CLAMP
DIODE
INDUCTIVE
LOAD
–IN GND A1 A2
CF
NC = NO CONNECT
Figure 26. High-Side Switch
HIGH-RAIL CURRENT SENSING
In the high-rail current-sensing configuration, the shunt resistor is
referenced to the battery. High voltage is present at the inputs of
the current-sense amplifier. When the shunt is battery referenced,
the AD8208 produces a linear ground-referenced analog output.
Additionally, the AD8214 can be used to provide an overcurrent
detection signal in as little as 100 ns (see Figure 27). This feature is
useful in high current systems where fast shutdown in overcurrent
conditions is essential.
OVERCURRENT
DETECTION (<100ns)
5678
OUT GND NC –IN
AD8214
NC VREG +IN VS
4321
–IN
1
GND
2
A1
3
A2
4
CF
AD8208
+IN
8
7 NC 5V
6 VS
OUT
5
CLAMP
DIODE
SHUNT
INDUCTIVE
LOAD
+
BATTERY
SWITCH
Figure 27. Battery-Referenced Shunt Resistor
LOW-SIDE CURRENT SENSING
In systems where low-side current sensing is preferable, the
AD8208 provides a simple, high accuracy, integrated solution. In
this configuration, the AD8208 rejects ground noise and offers
high input to output linearity, regardless of the differential input
voltage.
INDUCTIVE
LOAD
CLAMP
DIODE
SWITCH
BATTERY
SHUNT
5V
+IN NC VS OUT
OUTPUT
AD8208
–IN GND A1 A2
CF
NC = NO CONNECT
Figure 28. Ground-Referenced Shunt Resistor
Rev. C | Page 12 of 20

12 Page





SeitenGesamt 20 Seiten
PDF Download[ AD8208 Schematic.PDF ]

Link teilen




Besondere Datenblatt

TeilenummerBeschreibungHersteller
AD820FET Input Op AmpAnalog Devices
Analog Devices
AD8200High Common-Mode Voltage/ Single Supply Difference AmplifierAnalog Devices
Analog Devices
AD8202Single-Supply Difference AmplifierAnalog Devices
Analog Devices
AD8203Single-Supply Difference AmplifierAnalog Devices
Analog Devices
AD8205Single-Supply 42 V System Difference AmplifierAnalog Devices
Analog Devices

TeilenummerBeschreibungHersteller
CD40175BC

Hex D-Type Flip-Flop / Quad D-Type Flip-Flop.

Fairchild Semiconductor
Fairchild Semiconductor
KTD1146

EPITAXIAL PLANAR NPN TRANSISTOR.

KEC
KEC


www.Datenblatt-PDF.com       |      2020       |      Kontakt     |      Suche