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Dual, High Voltage Current Shunt Monitor AD8213
FEATURES
4000 V HBM ESD High common-mode voltage range -2 V to +65 V operating -3 V to +68 V survival Buffered output voltage Wide operating temperature range 10-lead MSOP: -40C to +125C Excellent ac and dc performance 3 V/C typical offset drift -10 ppm/C typical gain drift 120 dB typical CMRR at dc
FUNCTIONAL BLOCK DIAGRAM
-IN2 +IN2 +IN1 -IN1
A2 PROPRIETARY OFFSET CIRCUITRY OUT2 G = +20
A1 PROPRIETARY OFFSET CIRCUITRY
V+
OUT1 G = +20
APPLICATIONS
High-side current sensing Motor controls Transmission controls Diesel injection controls Engine management Suspension controls Vehicle dynamic controls DC-to-DC converters
CF2
GND
CF1
Figure 1.
GENERAL DESCRIPTION
The AD8213 is a dual-channel, precision current sense amplifier. It features a set gain of 20 V/V, with a maximum 0.5% gain error over the entire temperature range. The buffered output voltage directly interfaces with any typical converter. Excellent commonmode rejection from -2 V to +65 V, is independent of the 5 V supply. The AD8213 performs unidirectional current measurements across a shunt resistor in a variety of industrial and automotive applications, such as motor control, solenoid control, or battery management. Special circuitry is devoted to output linearity being maintained throughout the input differential voltage range of 0 mV to 250 mV, regardless of the common-mode voltage present. The AD8213 also features additional pins that allow the user to low-pass filter the input signal before amplifying, via an external capacitor to ground. The AD8213 has an operating temperature range of -40C to +125C and is offered in a small 10-lead MSOP package.
Rev. 0
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. Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 (c)2007 Analog Devices, Inc. All rights reserved.
06639-001
AD8213
AD8213 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications....................................................................................... 1 Functional Block Diagram .............................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 4 ESD Caution.................................................................................. 4 Pin Configuration and Function Descriptions............................. 5 Typical Performance Characteristics ............................................. 6 Theory of Operation ...................................................................... 10 Application Notes ........................................................................... 11 Output Linearity......................................................................... 11 Low-Pass Filtering...................................................................... 11 Applications Information .............................................................. 12 High-Side Current Sense with a Low-Side Switch................. 12 High-Side Current Sensing ....................................................... 12 Low-Side Current Sensing ........................................................ 12 Bidirectional Current Sensing .................................................. 13 Outline Dimensions ....................................................................... 14 Ordering Guide .......................................................................... 14
REVISION HISTORY
5/07--Revision 0: Initial Version
Rev. 0 | Page 2 of 16
AD8213 SPECIFICATIONS
TOPR = operating temperature range, VS = 5 V, RL = 25 k (RL is the output load resistor), unless otherwise noted. Table 1.
Parameter GAIN Initial Accuracy Accuracy Over Temperature Gain vs. Temperature VOLTAGE OFFSET Offset Voltage (RTI) Over Temperature (RTI) Offset Drift INPUT Input Impedance Differential Common Mode Common-Mode Input Voltage Range Differential Input Voltage Range Common-Mode Rejection OUTPUT Output Voltage Range Low Output Voltage Range High Output Impedance FILTER RESISTOR DYNAMIC RESPONSE Small Signal -3 dB Bandwidth Slew Rate NOISE 0.1 Hz to 10 Hz, RTI Spectral Density, 1 kHz, RTI POWER SUPPLY Operating Range Quiescent Current Over Temperature Power Supply Rejection Ratio TEMPERATURE RANGE For Specified Performance
1
Min
AD8213 Typ Max 20 0.25
Unit V/V % % ppm/C mV mV V/C
Conditions
0
-10
0.5 -25 1 2.2 12
VO 0.1 V dc TOPR
25C TOPR TOPR
5 5 3.5 -2 100 80 0.1 250 120 90 0.05 4.95 2 20 500 4.5 2.7 7 70 4.5 2.5 76 -40 +125 5.5 3.75 +65
k M k V mV dB dB V V k kHz V/s V/s V p-p nV/Hz V mA dB C
V common mode > 5 V V common mode < 5 V Common mode continuous Differential input voltage TOPR, f = DC, VCM > 5 V (see Figure 5) TOPR, f = DC, VCM < 5 V (see Figure 5)
4.9 22
18
CF access to resistor for low-pass filter
COUT = 20 pF, no filter capacitor (CF) COUT = 20 pF, CF = 20 pF
VCM > 5 V, per amplifier 1 , total supply current for two channels
When the input common mode is less than 5 V, the supply current increases. This can be calculated by IS = -0.52(VCM) + 4.9 (see Figure 11).
Rev. 0 | Page 3 of 16
AD8213 ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Supply Voltage Continuous Input Voltage Reverse Supply Voltage HBM (Human Body Model) ESD Rating CDM (Charged Device Model) ESD Rating Operating Temperature Range Storage Temperature Range Output Short-Circuit Duration Rating 12.5 V -3 V to +68 V -0.3 V 4000 V 1000 V -40C to +125C -65C to +150C Indefinite
Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ESD CAUTION
Rev. 0 | Page 4 of 16
AD8213 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
1 2 10 9
-IN2 1 +IN2 2
10
-IN1 +IN1 V+ CF1
06639-003
3
8
GND 3 OUT2 4 CF2 5
AD8213
TOP VIEW (Not to Scale)
9 8 7 6
OUT1
4
7
Figure 3. Pin Configuration
06639-002
5
6
Figure 2. Metallization Diagram
Table 3. Pin Function Descriptions
Pin No. 1 2 3 4 5 6 7 8 9 10 Mnemonic -IN2 +IN2 GND OUT2 CF2 CF1 OUT1 V+ +IN1 -IN1 X -401 -401 -401 -394 -448 448 394 401 401 401 Y 677 510 -53 -500 -768 -768 -500 -61 510 677 Description Inverting input of the second channel. Noninverting input of the second channel. Ground. Output of the second channel. Low-pass filter pin for the second channel. Low-pass filter pin for the first channel. Output of the first channel. Supply. Noninverting input of the first channel. Inverting input of the first channel.
Rev. 0 | Page 5 of 16
AD8213 TYPICAL PERFORMANCE CHARACTERISTICS
0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 -0.7
06639-104
40 35 30 25 20 15 10 5 0 -5 -10 -15 -20 -25 -30 -35 100k 1M 10M
06639-008
GAIN (dB)
VOSI (mV)
-0.8 -40
-20
0
20
40
60
80
100
120
-40 10k
TEMPERATURE (C)
FREQUENCY (Hz)
Figure 4. Typical Offset Drift
130
10
Figure 7. Typical Small Signal Bandwidth (VOUT = 200 mV p-p)
OUTPUT ERROR (%) (% ERROR OF THE IDEAL OUTPUT VALUE)
120 110 100
COMMON-MODE VOLTAGE > 5V
9 8 7 6 5 4 3 2 1 0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 250 DIFFERENTIAL INPUT VOLTAGE (mV)
06639-013 06639-010
CMRR (dB)
90 COMMON-MODE VOLTAGE < 5V 80 70 60 50 10
100
1k
10k
100k
1M
FREQUENCY (Hz)
Figure 5. CMRR vs. Frequency
2500 2000 1500
GAIN ERROR (ppm)
06639-005
-1
Figure 8. Total Output Error vs. Differential Input Voltage
-475 -480 -485
1000 500 0 -500 -1000 -1500 -2000 -20 0 20 40 60 80 100 120
06639-102
INPUT BIAS CURRENT (nA)
-490 -495 -500 -505 -510 -515 -520 -525 -530 -535 0 25 50 75 -IN +IN
-2500 -40
100
125
150
175
200
225
250
TEMPERATURE (C)
DIFFERENTIAL INPUT VOLTAGE (mV)
Figure 6. Typical Gain Drift
Figure 9. Input Bias Current vs. Differential Input Voltage (VCM = 0 V) (Per Channel)
Rev. 0 | Page 6 of 16
AD8213
0.2 0
INPUT 100mV/DIV
INPUT BIAS CURRENT (mA)
-0.2
OUTPUT
-0.4 -0.6 -0.8 -1.0 -1.2 -5
1V/DIV, CF = 20pF
OUTPUT
1V/DIV, CF = 100pF
5
15
25
35
45
55
65
06639-011
INPUT COMMON-MODE VOLTAGE (V)
TIME (2s/DIV)
Figure 10. Input Bias Current vs. Common-Mode Voltage (Per Input)
7.0 6.5 6.0
Figure 13. Rise Time
200mV/DIV
SUPPLY CURRENT (mA)
5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5
06639-012
INPUT
2V/DIV, CF = 20pF
OUTPUT
-2
0
2
4
6
8
65
COMMON-MODE VOLTAGE (V)
TIME (1s/DIV)
Figure 11. Supply Current vs. Common-Mode Voltage
Figure 14. Differential Overload Recovery (Falling)
100mV/DIV INPUT 1V/DIV, CF = 20pF 200mV/DIV
INPUT
1V/DIV, CF = 100pF
OUTPUT
OUTPUT
OUTPUT
2V/DIV, CF = 20pF
06639-014
TIME (2s/DIV)
TIME (1s/DIV)
Figure 12. Fall Time
Figure 15. Differential Overload Recovery (Rising)
Rev. 0 | Page 7 of 16
06639-017
06639-016
1.0 -4
06639-015
AD8213
12
MAXIMUM OUTPUT SOURCE CURRENT (mA)
06639-105
2V/DIV
11 10 9 8 7 6 5 4 3 2 1 -20 0 20 40 60 80 100 120 140
06639-021
06639-024 06639-023
0.01/DIV
0 -40
TIME (5s/DIV)
TEMPERATURE (C)
Figure 16. Settling Time (Falling)
5.0 4.9 4.8
OUTPUT VOLTAGE RANGE (V)
Figure 19. Output Source Current vs. Temperature (Per Channel)
4.7 4.6 4.5 4.4 4.3 4.2 4.1 4.0 3.9 3.8 3.7 3.6 3.5
2V/DIV
0.01/DIV
06639-106
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 OUTPUT SOURCE CURRENT (mA)
TIME (5s/DIV)
Figure 17. Settling Time (Rising)
12 OUTPUT VOLTAGE RANGE FROM GND (V) -20 0 20 40 60 80 100 120 140
06639-020
Figure 20. Output Voltage Range vs. Output Source Current (Per Channel)
2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 1 2 3 4 5 6 7 8 9 10
MAXIMUM OUTPUT SINK CURRENT (mA)
11 10 9 8 7 6 5 4 3 2 1 0 -40
TEMPERATURE (C)
OUTPUT SINK CURRENT (mA)
Figure 18. Output Sink Current vs. Temperature (Per Channel)
Figure 21. Output Voltage Range from GND vs. Output Sink Current (Per Channel)
Rev. 0 | Page 8 of 16
AD8213
2100
1000
1800
TEMP = -40C TEMP = +25C TEMP = +125C
800
1500 1200 900 600
COUNT
400
200
300
06639-006
VOS (V/C)
-1.5
-1.0
-0.5
0 VOS (mV)
0.5
1.0
1.5
2.0
Figure 22. Offset Drift Distribution (V/C) (Temperature Range = -40C to +125C)
1400 1200 1000
COUNT
Figure 24. Offset Distribution (mV) (VCM = 6 V)
800 600 400 200 0
-24
-21
-18
-15
-12
-9
-6
-3
0
GAIN DRIFT (ppm/C)
Figure 23. Gain Drift Distribution (ppm/C) (Temperature Range = -40C to +125C)
06639-101
Rev. 0 | Page 9 of 16
06639-103
0 -15
COUNT -10 -5 0 5 10 15
600
0 -2.0
AD8213 THEORY OF OPERATION
In typical applications, the AD8213 amplifies a small differential input voltage generated by the load current flowing through a shunt resistor. The AD8213 rejects high common-mode voltages (up to 65 V) and provides a ground referenced, buffered output that interfaces with an analog-to-digital converter (ADC). Figure 25 shows a simplified schematic of the AD8213. The following explanation refers exclusively to Channel 1 of the AD8213, however, the same explanation applies to Channel 2. A load current flowing through the external shunt resistor produces a voltage at the input terminals of the AD8213. The input terminals are connected to Amplifier A1 by Resistor R1(1) and Resistor R1(2). The inverting terminal, which has very high input impedance is held to (VCM) - (ISHUNT x RSHUNT), since negligible current flows through Resistor R1(2). Amplifier A1 forces the noninverting input to the same potential. Therefore, the current that flows through Resistor R1(1), is equal to IIN1 = (ISHUNT1 x RSHUNT1)/R1(1)
ISHUNT2 RSHUNT2 IIN2 R2 (1) R2 (2) IIN1 R1 (1) R1 (2) ISHUNT1 RSHUNT1
This current (IIN1) is converted back to a voltage via ROUT1. The output buffer amplifier has a gain of 20 V/V, and offers excellent accuracy as the internal gain setting resistors are precision trimmed to within 0.01% matching. The resulting output voltage is equal to VOUT1 = (ISHUNT1 x RSHUNT1) x 20 Prior to the buffer amplifier, a precision-trimmed 20 k resistor is available to perform low-pass filtering of the input signal prior to the amplification stage. This means that the noise of the input signal is not amplified, but rejected, resulting in a more precise output signal that will directly interface with a converter. A capacitor from the CF1 pin to GND, will result in a low-pass filter with a corner frequency of
f -3dB = 1 2 (20000 )C FILTER
A2 PROPRIETARY OFFSET CIRCUITRY OUT2 = (ISHUNT2 x RSHUNT2 ) x 20 G = +20 20k ROUT2
A1 PROPRIETARY OFFSET CIRCUITRY 20k ROUT1 G = +20
V+
Q2
Q1
OUT1 = (ISHUNT1 x RSHUNT1 ) x 20
CF2
GND
CF1
Figure 25. Simplified Schematic
Rev. 0 | Page 10 of 16
06639-028
AD8213
AD8213 APPLICATION NOTES
OUTPUT LINEARITY
In all current sensing applications, and especially in automotive and industrial environments where the common-mode voltage can vary significantly, it is important that the current sensor maintain the specified output linearity, regardless of the input differential or common-mode voltage. The AD8213 contains specific circuitry on the input stage, which ensures that even when the differential input voltage is very small, and the common-mode voltage is also low (below the 5 V supply), the input to output linearity is maintained. Figure 26 displays the input differential voltage versus the corresponding output voltage at different common modes.
220 200 180 160 140
LOW-PASS FILTERING
In typical applications, such as motor and solenoid current sensing, filtering the differential input signal of the AD8213 could be beneficial in reducing differential common-mode noise as well as transients and current ripples flowing through the input shunt resistor. Typically, such a filter can be implemented by adding a resistor in series with each input and a capacitor directly between the input pins. However, the AD8213 features a filter pin available after the input stage, but before the final amplification stage. The user can connect a capacitor to ground, making a low-pass filter with the internal precisiontrimmed 20 k resistor. This means the no gain or CMRR errors are introduced by adding resistors at the input of the AD8213. Figure 27 shows the typical connection.
ISHUNT2 RSHUNT2 R2 (1)
VOUT @ VCM = 65V
ISHUNT1 RSHUNT1 R1 (1) R1 (2)
VOUT (mV)
120 100 80 60 40 20 0 1 2 3 4 5 6 7 8 9 10
06639-029
R2 (2)
VOUT @ VCM = 0V
A2 PROPRIETARY OFFSET CIRCUITRY 20k
A1 PROPRIETARY OFFSET CIRCUITRY 20k G = +20
V+
0
IDEAL VOUT
G = +20
VIN DIFFERENTIAL (mV)
AD8213
CF2 CAP2 GND CF1
06639-030
Figure 26. Gain Linearity Due to Differential and Common-Mode Voltage
The AD8213 provides a correct output voltage, regardless of the common mode, when the input differential is at least 2 mV. This is due to the voltage range of the output amplifier that can go as low as 33 mV typical. The specified minimum output amplifier voltage is 100 mV in order to provide sufficient guardbands. The ability of the AD8213 to work with very small differential inputs regardless of the common-mode voltage, allows for more dynamic range, accuracy, and flexibility in any current sensing application.
CAP1
Figure 27. Filter Capacitor Connections
The 3 dB frequency of this low-pass filter is calculated using the following formula:
f -3dB = 1 2 (20000 )C FILTER
It is recommended that in order to prevent output chatter due to noise potentially entering through the filter pin and coupling to the output, a capacitor is always placed from the filter pin to GND. This can be a 20 pF capacitor in cases when all of the bandwidth of the AD8213 is needed in the application.
Rev. 0 | Page 11 of 16
AD8213 APPLICATIONS INFORMATION
HIGH-SIDE CURRENT SENSE WITH A LOW-SIDE SWITCH
In such load control configurations, the PWM controlled switch is ground referenced. An inductive load (solenoid) is tied to a power supply. A resistive shunt is placed between the switch and the load (see Figure 28). An advantage of placing the shunt on the high side is that the entire current, including the recirculation current, can be measured, because the shunt remains in the loop when the switch is off. In addition, diagnostics can be enhanced because shorts to ground can be detected with the shunt on the high side. 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.
INDUCTIVE LOAD CLAMP DIODE BATTERY SHUNT
1 2 3 4 5
OVERCURRENT DETECTION (<100ns)
8 7 6 5
-IN VS
1
NC GND OUT
AD8214
+IN VREG NC
2 3 4
OVERCURRENT DETECTION (<100ns)
5
6
7
8
OUT GND NC
-IN VS
1
AD8214
NC VREG +IN
4 3 2
SHUNT
1
AD8213
-IN2 +IN2 GND OUT2 CF2 -IN1 10 +IN1 V+ OUT1 CF1
9 8 7 6 2 3 4
SHUNT
BATTERY
LOAD
5V
LOAD
SWITCH
5
SWITCH
AD8213
-IN2 +IN2 GND OUT2 CF2 -IN1 10 +IN1 V+ OUT1 CF1
9 8 7 6
INDUCTIVE LOAD CLAMP DIODE 5V SHUNT BATTERY
CAP2
CAP1
06639-032
Figure 29. Battery Referenced Shunt Resistor
SWITCH
CAP2
CAP1
SWITCH
06639-031
LOW-SIDE CURRENT SENSING
In systems where low-side current sensing is preferred, the AD8213 provides an integrated solution with great accuracy. Ground noise is rejected, CMRR is typical higher than 90 dB, and output linearity is not compromised, regardless of the input differential voltage.
INDUCTIVE LOAD CLAMP DIODE BATTERY SWITCH
1 2 3 4 5
Figure 28. Low-Side Switch
HIGH-SIDE CURRENT SENSING
In this configuration, the shunt resistor is referenced to the battery. High voltage will be present at the inputs of the current sense amplifier. In this mode, the recirculation current is again measured and shorts to ground can be detected. When the shunt is battery referenced the AD8213 produces a linear ground referenced analog output. An AD8214 can also be used to provide an overcurrent detection signal in as little as 100 ns. This feature will be useful in high current systems, where fast shutdown in overcurrent conditions is essential.
AD8213
-IN2 +IN2 GND OUT2 CF2 -IN1 10 +IN1 V+ OUT1 CF1
9 8 7 6
INDUCTIVE LOAD CLAMP DIODE 5V SWITCH BATTERY
SHUNT
SHUNT
06639-033
Figure 30. Ground Referenced Shunt Resistor
Rev. 0 | Page 12 of 16
BATTERY
AD8213
BIDIRECTIONAL CURRENT SENSING
The AD8213 can also be configured to sense current in both directions at the inputs. This configuration is useful in charge/ discharge applications. A typical connection diagram is shown in Figure 31. In this mode Channel 1 monitors ILOAD and Channel 2 monitors ICHARGE.
ICHARGE ILOAD BATTERY RSHUNT LOAD CHARGER
ICHARGE ILOAD RSHUNT +IN -IN LOAD CHARGER
BATTERY
V+
AD8210
0.1F VREF 1
AD8213
1 2 3 4 5
G = +20
OUTPUT
-IN2 +IN2 GND OUT2 CF2
-IN1 10 +IN1 V+ OUT1 CF1
9 8 7 6
5V
VREF 2 GND
06639-035 06639-034
CF2
CF1
Figure 32. AD8210 in Bidirectional Applications
Figure 31. Bidirectional Current Sensing
For applications requiring a bidirectional current measurement, an optimal solution could be to use a single channel device, which offers the same functionality as the previous circuit. The AD8210 is a single channel current sensor featuring bidirectional capability. The typical connection diagram for the AD8210 in bidirectional applications is shown in Figure 32.
Rev. 0 | Page 13 of 16
AD8213 OUTLINE DIMENSIONS
3.10 3.00 2.90 3.10 3.00 2.90 PIN 1 0.50 BSC 0.95 0.85 0.75 0.15 0.05 0.33 0.17 COPLANARITY 0.10 COMPLIANT TO JEDEC STANDARDS MO-187-BA 1.10 MAX 8 0 0.80 0.60 0.40
10 6
1
5
5.15 4.90 4.65
SEATING PLANE
0.23 0.08
Figure 33. 10-Lead Mini Small Outline Package [MSOP] (RM-10) Dimensions shown in millimeters
ORDERING GUIDE
Model AD8213YRMZ 1 AD8213YRMZ-RL1 AD8213YRMZ-RL71
1
Temperature Range -40C to +125C -40C to +125C -40C to +125C
Package Description 10-Lead MSOP 10-Lead MSOP, 13" Tape and Reel 10-Lead MSOP, 7" Tape and Reel
Package Option RM-10 RM-10 RM-10
Branding HOU HOU HOU
Z = RoHS Compliant Part.
Rev. 0 | Page 14 of 16
AD8213 NOTES
Rev. 0 | Page 15 of 16
AD8213 NOTES
(c)2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D06639-0-5/07(0)
Rev. 0 | Page 16 of 16

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