TI DRV421 Drv421 integrated magnetic fluxgate sensor for closed-loop current sensing Datasheet

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DRV421
SBOS704A – MAY 2015 – REVISED JULY 2015
DRV421 Integrated Magnetic Fluxgate Sensor for Closed-Loop Current Sensing
1 Features
3 Description
•
The DRV421 is designed for magnetic closed-loop
current sensing solutions, enabling isolated, precise
dc- and ac-current measurements. This device
provides both, a proprietary integrated fluxgate
sensor, and the required analog signal conditioning,
thus minimizing component count and cost. The low
offset and drift of the fluxgate sensor, along with an
optimized front-end circuit results in unrivaled
measurement precision.
1
•
•
•
•
•
•
•
High-Precision Integrated Fluxgate Sensor
– Offset and Drift: ±8 µT max, ±5 nT/°C typ
Extended Current Measurement Range
– H-Bridge Output Drive: ±250 mA typ at 5 V
Precision Shunt Sense Amplifier
– Offset and Drift (max): ±75 µV, ±2 µV/°C
– Gain Error and Drift (max): ±0.3%, ±5 ppm/°C
Precision Reference
– Accuracy and Drift (max): ±2%, ±50 ppm/°C
– Pin-Selectable Voltage: 2.5 V or 1.65 V
– Selectable Ratiometric Mode: VDD/2
Magnetic Core Degaussing Feature
Diagnostic Features: Overrange and Error Flags
Supply Voltage Range: 3.0 V to 5.5 V
Fully Specified Over the Extended Industrial
Temperature Range of –40°C to +125°C
The DRV421 provides all the necessary circuit blocks
to drive the current-sensing feedback loop. The
sensor front-end circuit is followed by a filter that can
be configured to work with a wide range of magnetic
cores. The integrated 250-mA H-Bridge drives the
compensation coil, while doubling the current
measurement range, compared to conventional
single-ended drive methods. The device also
provides a precision voltage reference and shunt
sense amplifier to generate and drive the analog
output signal.
Device Information
2 Applications
•
•
•
PART NUMBER
Closed-Loop DC- and AC-Current Sensor
Modules
Leakage Current Sensors
Industrial Monitoring and Control Systems
DRV421
PACKAGE
WQFN (20)
(1)
BODY SIZE (NOM)
4.00 mm × 4.00 mm
(1) For all available packages, see the package option addendum
at the end of the datasheet.
Typical Application
optional
3.3 V or 5 V
magnetic
core
RSHUNT
DRV421
Fluxgate Sensor Front-End
DRV421
H-Bridge
Driver
Fluxgate
Sensor
Shunt
Sense
Amplifier
Integrator
and
Filter
compensation
coil
return current
conductor
(optional)
ADC
primary
current
conductor
Device Control and Degaussing
Reference
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
DRV421
SBOS704A – MAY 2015 – REVISED JULY 2015
www.ti.com
Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
6.6
4
4
4
4
5
7
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description ............................................ 16
7.1
7.2
7.3
7.4
Overview .................................................................
Functional Block Diagram .......................................
Feature Description.................................................
Device Functional Modes........................................
16
16
17
26
8
Application and Implementation ........................ 27
8.1 Application Information............................................ 27
8.2 Typical Application ................................................. 29
9
Power-Supply Recommendations...................... 34
9.1 Power-Supply Decoupling....................................... 34
9.2 Power-On Start Up and Brownout .......................... 34
9.3 Power Dissipation ................................................... 34
10 Layout................................................................... 35
10.1 Layout Guidelines ................................................. 35
10.2 Layout Example .................................................... 36
11 Device and Documentation Support ................. 37
11.1
11.2
11.3
11.4
11.5
Documentation Support .......................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
37
37
37
37
37
12 Mechanical, Packaging, and Orderable
Information ........................................................... 37
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Original (May 2015) to Revision A
•
2
Page
Changed from product preview to production data ................................................................................................................ 1
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SBOS704A – MAY 2015 – REVISED JULY 2015
5 Pin Configuration and Functions
GSEL1
ER
DEMAG
GND
GND
20
19
18
17
16
RTJ Package
20-Pin QFN
Top View
GSEL0
1
15
OR
RSEL1
2
14
AINN
RSEL0
3
13
AINP
REFOUT
4
12
ICOMP1
REFIN
5
11
ICOMP2
6
7
8
9
10
VOUT
GND
VDD
VDD
GND
(Thermal Pad)
Pin Functions
PIN
NAME
NO.
I/O
DESCRIPTION
AINN
14
I
Inverting input of shunt sense amplifier
AINP
13
I
Noninverting input of shunt sense amplifier
DEMAG
18
I
Degauss control input
ER
19
O
Error flag; open-drain, active low output
Ground reference
GND
7, 10, 16, 17
—
GSEL0
1
I
Gain and bandwidth selection input 0
GSEL1
20
I
Gain and bandwidth selection input 1
ICOMP1
12
O
Output 1 of compensation coil driver
ICOMP2
11
O
Output 2 of compensation coil driver
OR
15
O
Shunt sense amplifier overrange indicator; open-drain, active-low output
REFIN
5
I
Common-mode reference input for the shunt sense amplifier
REFOUT
4
O
Voltage reference output
RSEL0
3
I
Voltage reference mode selection input 0
RSEL1
2
I
Voltage reference mode selection input 1
8, 9
—
Supply voltage, 3.0 V to 5.5 V. Decouple both pins using 1-µF ceramic capacitors placed as
close as possible to the device. See the Power-Supply Decoupling and Layout sections for
further details.
6
O
Shunt sense amplifier output
—
Connect thermal pad to GND
VDD
VOUT
PowerPAD™
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)
(1)
Supply voltage (VDD to GND)
Voltage
Input voltage, except pins AINP and AINN
(2)
Shunt sense amplifier inputs (pins AINP and AINN)
(3)
Pins ICOMP1 and ICOMP2 (short circuit current ISC)
Current
(1)
(2)
(3)
(4)
MAX
UNIT
7
V
GND – 0.5
VDD + 0.5
V
GND – 6.0
VDD + 6.0
V
–300
300
mA
pins AINP and AINN
–5
5
mA
All remaining pins
–25
25
mA
Junction, TJ max
–50
150
°C
Storage, Tstg
–65
150
°C
Shunt sense amplifier inputs
Temperature
(4)
MIN
–0.3
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
Input terminals are diode-clamped to the power-supply rails. Input signals that can swing more than 0.5 V beyond the supply rails must
be current limited, except for the shunt sense amplifier input pins.
These inputs are not diode-clamped to the power supply rails.
Power-limited; observe maximum junction temperature.
6.2 ESD Ratings
VALUE
Electrostatic
discharge
V(ESD)
(1)
(2)
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001
(1)
±2000
Charged-device model (CDM), per JEDEC specification JESD22-C101 (2)
±1000
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
NOM
MAX
VDD
Supply voltage
3.0
5.0
5.5
UNIT
V
TA
Specified ambient temperature range
–40
125
°C
6.4 Thermal Information
SBOS704
THERMAL METRIC
(1)
RTJ (QFN)
UNITS
20 PINS
RθJA
Junction-to-ambient thermal resistance
34.1
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
33.1
°C/W
RθJB
Junction-to-board thermal resistance
11.0
°C/W
ψJT
Junction-to-top characterization parameter
0.3
°C/W
ψJB
Junction-to-board characterization parameter
11.0
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
2.1
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
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6.5 Electrical Characteristics
All minimum and maximum specifications at TA = +25°C, VDD = 3.0 V to 5.5 V, and ICOMP1 = ICOMP2 = 0 mA (unless otherwise
noted). Typical values are at VDD = 5.0 V.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
–8
±2
8
UNIT
FLUXGATE SENSOR FRONT-END
Offset
AOL
(1)
No magnetic field
No magnetic field
Noise
f = 0.1 Hz to 10 Hz
17
nTrms
Noise density
f = 1 kHz
1.5
nT/√Hz
VICOMP
±5
nT/°C
Saturation trip level for pin ER
1.7
mT
DC open-loop gain
16
V/µT
GSEL[1:0] = 00, at 3.8 kHz,
integration-to-flatband corner frequency
8.5
V/mT
GSEL[1:0] = 01, at 3.8 kHz,
integration-to-flatband corner frequency
38
V/mT
GSEL[1:0] = 10, at 1.9 kHz,
integration-to-flatband corner frequency
25
V/mT
GSEL[1:0] = 11, at 1.9 kHz,
integration-to-flatband corner frequency
70
V/mT
AC open-loop gain
IICOMP
µT
Offset drift
Peak current at pins ICOMP1 and
ICOMP2
Voltage swing at pins ICOMP1 and
ICOMP2
VICOMP1 – VICOMP2 = 4.2 VPP,VDD = 5 V,
TA = –40°C to +125°C
210
250
mA
VICOMP1 – VICOMP2 = 2.5 VPP, VDD = 3.3 V,
TA = –40°C to +125°C
125
150
mA
20-Ω load, VDD = 5 V, TA = –40°C to +125°C
4.2
VPP
20-Ω load, VDD = 3.3 V, TA = –40°C to +125°C
2.5
VPP
Common-mode output voltage at pins
ICOMP1 and ICOMP2
VREFOUT
V
SHUNT SENSE AMPLIFIER
VOO
Output offset voltage
VAINP = VAINN = VREFIN, VDD = 3.0 V
Output offset voltage drift
CMRR
Common-mode rejection ratio, RTO
PSRRAMP
Power-supply rejection ratio, RTO
VIC
Common-mode input voltage range
ZIND
Differential input impedance
ZIC
Common-mode input impedance
G
Gain, VOUT / (VAINP – VAINN)
EG
Gain error
(2)
VCM = −1 V to VDD + 1 V, VREFIN = VDD / 2
VDD = 3.0 V to 5.5 V, VCM = VREFIN
±0.01
0.075
–2
±0.4
2
µV/°C
–250
±50
250
µV/V
–50
±4
50
µV/V
–1
VDD + 1
V
kΩ
16.5
20
23.5
40
50
60
kΩ
V/V
–0.3%
±0.02%
0.3%
–5
±1
5
ppm/°C
Linearity error
RL = 1 kΩ
12
Voltage output swing from negative rail
(OR pin trip level)
VDD = 5.5 V, IVOUT = 2.5 mA
48
85
mV
VDD = 3.0 V, IVOUT = 2.5 mA
56
100
mV
Voltage output swing from positive rail
(OR pin trip level)
VDD = 5.5 V, IVOUT = –2.5 mA
VDD – 85
VDD – 48
mV
VDD = 3.0 V, IVOUT = –2.5 mA
VDD – 100
VDD – 56
mV
VOUT connected to GND
–18
mA
VOUT connected to VDD
20
mA
2.5 to 3.5
µs
Short-circuit current
Signal overrange indication delay (OR pin) VIN = 1-V step
BW–3dB
Bandwidth
SR
Slew rate
Settling time, large-signal
ΔV = ± 2 V to 1% accuracy, no external filter
Settling time, small-signal
ΔV = ± 0.4 V to 0.01% accuracy
en
Output voltage noise density, RTO
f = 1 kHz, compensation loop disabled
VREFIN
Input voltage range at pin REFIN
TA = –40°C to +125°C
(1)
(2)
mV
4
Gain error drift
ISC
–0.075
ppm
2
MHz
6.5
V/µs
0.9
µs
8
µs
170
GND
nV/√Hz
VDD
V
Fluxgate sensor front-end offset can be reduced using the feature.
Parameter value referred to output (RTO).
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Electrical Characteristics (continued)
All minimum and maximum specifications at TA = +25°C, VDD = 3.0 V to 5.5 V, and ICOMP1 = ICOMP2 = 0 mA (unless otherwise
noted). Typical values are at VDD = 5.0 V.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
V
VOLTAGE REFERENCE
VREFOUT
Reference output voltage at pin REFOUT
PSRRREF
2.45
2.5
2.55
RSEL[1:0] = 01, no load
1.6
1.65
1.7
V
RSEL[1:0] = 1x, no load
45
50
55
% of VDD
Reference output voltage drift
RSEL[1:0] = 00, 01
–50
±10
50
ppm/°C
Voltage divider gain error drift
RSEL[1:0] = 1x
–50
±10
50
ppm/°C
Power-supply rejection ratio
RSEL[1:0] = 00, 01
–300
±15
300
µV/V
RSEL[1:0] = 0x, load to GND or VDD,
ΔILOAD = 0 mA to 5 mA, TA = –40°C to +125°C
0.15
0.35
mV/mA
RSEL[1:0] = 1x, load to GND or VDD,
ΔILOAD = 0 mA to 5 mA, TA = –40°C to +125°C
0.3
0.8
mV/mA
Load regulation
ISC
RSEL[1:0] = 00, no load
Short-circuit current
REFOUT connected to VDD
20
mA
REFOUT connected to GND
–18
mA
DIGITAL INPUTS/OUTPUTS
Logic Inputs (CMOS)
VIH
High-level input voltage
TA = –40°C to +125°C
0.7 × VDD
VDD + 0.3
VIL
Low-level input voltage
TA = –40°C to +125°C
–0.3
0.3 × VDD
Input leakage current
0.01
V
V
µA
Logic Outputs (Open-Drain)
VOH
High-level output voltage
VOL
Low-level output voltage
Set by external pull-up resistor
V
4-mA sink
0.3
V
IICOMP1 = IICOMP2 = 0 mA, 3.0 V ≤ VDD ≤ 3.6 V,
TA = –40°C to +125°C
6.5
9
mA
IICOMP1 = IICOMP2 = 0 mA, 4.5 V ≤ VDD ≤ 5.5 V,
TA = –40°C to +125°C
8.1
11
mA
POWER SUPPLY
IQ
VRST
6
Quiescent current
Power-on reset threshold
2.4
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6.6 Typical Characteristics
50
40
40
D001
Offset (PT)
8
7
6
5
4
3
2
1
0
-1
Figure 2. Fluxgate Sensor Front-End Offset Histogram
4
3
3
2
2
1
1
Offset (PT)
Offset (PT)
Figure 1. Fluxgate Sensor Front-End Offset Histogram
0
-1
-1
-2
-3
-3
-4
5
-4
-40
5.5
Device 1
Device 2
Device 3
0
-2
4
4.5
Supply Voltage (V)
-2
VDD = 3.3 V
4
3.5
D002
Offset (PT)
VDD = 5 V
3
-3
-8
8
7
6
5
4
3
2
1
0
-1
-2
-3
-4
0
-5
0
-6
10
-7
10
-4
20
-5
20
30
-6
30
-7
Devices (%)
50
-8
Devices (%)
at VDD = 5 V and TA = +25°C (unless otherwise noted)
-25
-10
D003
Figure 3. Fluxgate Sensor Front-End Offset vs Supply
Voltage
5
20 35 50 65
Temperature (°C)
80
95
110 125
D004
Figure 4. Fluxgate Sensor Front-End Offset vs Temperature
100
50
Noise Density (nT/—Hz)
Devices (%)
40
30
20
10
1
10
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
35
40
45
50
0
Offset Drift (nT/qC)
0.1
0.0001
D005
Figure 5. Fluxgate Sensor Front-End Offset Drift Histogram
0.001
0.01
0.1
1
Noise Frequency (kHz)
10
100
D006
Figure 6. Fluxgate Sensor Front-End Noise Density vs Noise
Frequency
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Typical Characteristics (continued)
60
60
50
50
40
40
D007
40
35
30
25
20
15
10
-5
-10
2.1
2
1.9
1.8
0
1.7
0
1.6
10
1.5
10
1.4
20
1.3
20
Saturation Trip Level (mT)
D008
DC Open-Loop Gain (V/PT)
Figure 7. Fluxgate Sensor Saturation (ER Pin) Trip Level
Histogram
Figure 8. Fluxgate Sensor Front-End DC Open-Loop Gain
Histogram
50
160
AC Open-Loop Gain (dB)
30
20
10
0
-40
GSEL[1:0]=00
GSEL[1:0]=01
GSEL[1:0]=10
GSEL[1:0]=11
140
40
DC Open-Loop Gain (V/PT)
30
5
30
0
Devices (%)
Devices (%)
at VDD = 5 V and TA = +25°C (unless otherwise noted)
120
100
80
60
-25
-10
5
20 35 50 65
Temperature (°C)
80
95
40
0.001
110 125
0.01
D009
Figure 9. Fluxgate Sensor Front-End DC Open-Loop Gain vs
Temperature
0.1
1
Frequency (kHz)
10
100
D010
Figure 10. Fluxgate Sensor Front-End AC Open-Loop Gain
vs Frequency
5
0
VDD = 5 V
VDD = 3.3 V
-1
Voltage Swing (VPP)
Voltage Swing (VPP)
4
3
2
1
-2
-3
-4
VDD = 5 V
VDD = 3.3 V
0
-250 -225 -200 -175 -150 -125 -100 -75
Negative Peak Current (mA)
-5
-50
-25
0
Figure 11. Voltage Swing at ICOMPx Pins vs Negative Peak
Current
8
0
25
D011
50
75 100 125 150 175
Positive Peak Current (mA)
200
225
250
D012
Figure 12. Voltage Swing at ICOMPx Pins vs Positive Peak
Current
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Typical Characteristics (continued)
at VDD = 5 V and TA = +25°C (unless otherwise noted)
0
5
VDD = 5 V
VDD = 3.3 V
4
Voltage Swing (VPP)
Voltage Swing (VPP)
-1
-2
-3
-4
3
2
1
VDD = 5 V
VDD = 3.3 V
20 35 50 65
Temperature (°C)
80
95
0
-40
110 125
-25
-10
5
D013
20 35 50 65
Temperature (°C)
RLOAD = 20 Ω
60
60
50
50
D015
50
40
-50
50
40
30
20
0
10
0
0
10
-10
10
-20
20
-30
20
30
30
-20
30
-40
D014
40
-30
40
-40
Devices (%)
70
-50
Devices (%)
110 125
Figure 14. Positive Voltage Swing at ICOMPx Pins vs
Temperature
70
Output Offset (PV)
D015
D016
Output Offset (PV)
VDD = 5 V
VDD = 3.3 V
Figure 15. Shunt Sense Amplifier Offset Histogram
Figure 16. Shunt Sense Amplifier Offset Histogram
75
75
Device 1
Device 2
Device 3
50
Output Offset (PV)
50
Output Offset (PV)
95
RLOAD = 20 Ω
Figure 13. Negative Voltage Swing at ICOMPx Pins vs
Temperature
25
0
-25
25
0
-25
-50
-50
-75
-40
80
20
5
10
-10
0
-25
-10
-5
-40
-75
-25
-10
5
20 35 50 65
Temperature (°C)
80
95
110 125
3
D017
Figure 17. Shunt Sense Amplifier Offset vs Temperature
3.5
4
4.5
Supply Voltage (V)
5
5.5
D018
Figure 18. Shunt Sense Amplifier Offset vs Supply Voltage
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Typical Characteristics (continued)
at VDD = 5 V and TA = +25°C (unless otherwise noted)
100
Common-Mode Rejection Ratio (dB)
50
Devices (%)
40
30
20
10
-250
-225
-200
-175
-150
-125
-100
-75
-50
-25
0
25
50
75
100
125
150
175
200
225
250
0
Common-Mode Rejection Ratio (PV/V)
60
40
20
0
0.01
0.1
D019
1
10
100
Input Signal Frequency (kHz)
1000
D020
Figure 20. Shunt Sense Amplifier Common-Mode Rejection
Ratio vs Input Signal Frequency
Figure 19. Shunt Sense Amplifier Common-Mode Rejection
Ratio Histogram
70
Power-Supply Rejection Ratio (dB)
100
60
50
Devices (%)
80
40
30
20
10
60
40
20
0
0.01
50
40
30
20
10
0
-10
-20
-30
-40
-50
0
80
0.1
1
10
Ripple Frequency (kHz)
D001
D021
Power-Supply Rejection Ratio (PV/V)
100
1000
D022
Figure 22. Shunt Sense Amplifier Power-Supply Rejection
Ratio vs Ripple Frequency
Figure 21. Shunt Sense Amplifier Power-Supply Rejection
Ratio Histogram
100
51
50.8
AINP Input Impedance (k:)
Devices (%)
80
60
40
20
50.6
50.4
50.2
50
49.8
49.6
49.4
49.2
AINP Input Impedance (k:)
49
-40
60
58
56
54
52
50
48
46
44
42
40
0
Figure 23. Shunt Sense Amplifier AINP Input Impedance
Histogram
10
-25
D023
-10
5
20 35 50 65
Temperature (°C)
80
95
110 125
D024
Figure 24. Shunt Sense Amplifier AINP Input Impedance vs
Temperature
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Typical Characteristics (continued)
at VDD = 5 V and TA = +25°C (unless otherwise noted)
50
11
10.8
10.6
AINN Input Impedance (k:)
Devices (%)
40
30
20
10
10.4
10.2
10
9.8
9.6
9.4
9.2
9
-40
12
11.5
11.75
11
11.25
10.5
10.75
10
10.25
9.5
9.75
9
9.25
8.5
8.75
8
8.25
0
-25
-10
5
D025
20 35 50 65
Temperature (°C)
80
95
110 125
D026
AINN Input Impedance (k:)
Figure 26. Shunt Sense Amplifier AINN Input Impedance vs
Temperature
Figure 25. Shunt Sense Amplifier AINN Input Impedance
Histogram
100
0.3
0.25
0.2
80
0.1
Gain Error (%)
Devices (%)
0.15
60
40
0.05
0
-0.05
-0.1
-0.15
20
-0.2
-0.25
-0.3
-40
0.1
0.08
0.06
0.04
0.02
0
-0.02
-0.04
-0.06
-0.08
-0.1
0
-25
-10
D027
5
20 35 50 65
Temperature (°C)
80
95
110 125
D028
Gain Error (%)
Figure 27. Shunt Sense Amplifier Gain Error Histogram
Figure 28. Shunt Sense Amplifier Gain Error vs Temperature
20
40
35
Linearity Error (ppm)
Gain (dB)
15
10
5
30
25
20
15
10
5
0
0.01
0
0.1
1
10
100
Input Signal Frequency (kHz)
1000
10000
3
D029
Figure 29. Shunt Sense Amplifier Gain vs Frequency
3.5
4
4.5
Supply Voltage (V)
5
5.5
D030
Figure 30. Shunt Sense Amplifier Linearity vs Supply
Voltage
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Typical Characteristics (continued)
at VDD = 5 V and TA = +25°C (unless otherwise noted)
0.5
VDD = 5.5 V
VDD = 3.0 V
Voltage Difference to VDD or GND (V)
Voltage Difference to VDD or GND (V)
0.5
0.4
0.3
0.2
0.1
0
0
1
2
3
4
5
6
7
Output Current (mA)
8
9
VDD = 5.5 V
VDD = 3.0 V
0.4
0.3
0.2
0.1
0
-40
10
Figure 31. OR Pin Trip Level vs Output Current
3.75
30
Short-Circuit Current (mA)
4
Trip Delay (Ps)
3.5
3.25
3
2.75
2.5
5
20 35 50 65
Temperature (°C)
80
95
110 125
D032
VOUT to GND
VOUT to VDD
20
10
0
-10
-20
-30
2.25
-25
-10
5
20 35 50 65
Temperature (°C)
80
95
-40
-40
110 125
-25
-10
5
20 35 50 65
Temperature (°C)
D033
Figure 33. OR Pin Trip Delay vs Temperature
80
95
110 125
D034
Figure 34. Shunt Sense Amplifier Output Short-Circuit
Current vs Temperature
40
0.25
VOUT to GND
VOUT to VDD
30
0.2
0.15
20
0.1
10
Voltage (V)
Short-Circuit Current (mA)
-10
Figure 32. OR Pin Trip Level vs Temperature
40
2
-40
-25
D031
0
-10
0.05
0
-0.05
-0.1
-20
-0.15
-30
VOUT
VIN
-0.2
-40
3
3.5
4
4.5
Supply Voltage (V)
5
5.5
-0.25
-2.5
D035
0
2.5
5
7.5
10
Time (Ps)
12.5
15
17.5
D048
Rising Edge
Figure 35. Shunt Sense Amplifier Output Short-Circuit
Current vs Supply Voltage
12
Figure 36. Shunt Sense Amplifier Small-Signal Settling Time
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Typical Characteristics (continued)
at VDD = 5 V and TA = +25°C (unless otherwise noted)
0.25
1.25
VOUT
VIN
0.2
1
0.15
0.75
0.5
Voltage (V)
Voltage (V)
0.1
0.05
0
-0.05
0.25
0
-0.25
-0.1
-0.5
-0.15
-0.75
-0.2
-1
-0.25
-2.5
0
2.5
5
7.5
10
Time (Ps)
12.5
15
VOUT
VIN
-1.25
-0.5
17.5
0
0.5
D049
Falling Edge
2.5
D050
5
VOUT
VIN
1
0.75
3
0.5
2
0.25
0
-0.25
1
0
-1
-0.5
-2
-0.75
-3
-1
-4
0
0.5
1
Time (Ps)
1.5
2
VIN
VOUT
4
Voltage (V)
Voltage (V)
2
Figure 38. Shunt Sense Amplifier Large-Signal Settling Time
1.25
-5
-0.1
2.5
D051
-0.075 -0.05 -0.025
0
0.025
Time (ms)
Falling Edge
0.05
0.075
0.1
D036
VDD = 5 V
Figure 39. Shunt Sense Amplifier Large-Signal Settling Time
Figure 40. Shunt Sense Amplifier Overload Recovery
Response
5
10000
Output Voltage Noise Density (nV/—Hz)
VIN
VOUT
4
3
2
Voltage (V)
1.5
Rising Edge
Figure 37. Shunt Sense Amplifier Small-Signal Settling Time
-1.25
-0.5
1
Time (Ps)
1
0
-1
-2
-3
-4
-5
-0.1
-0.075 -0.05 -0.025
0
0.025
Time (ms)
0.05
0.075
0.1
1000
100
10
10
D037
100
1000
10000
Noise Frequency (Hz)
100000
D038
VDD = 3.3 V
Figure 41. Shunt Sense Amplifier Overload Recovery
Response
Figure 42. Shunt Sense Amplifier Output Voltage Noise
Density vs Noise Frequency
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Typical Characteristics (continued)
at VDD = 5 V and TA = +25°C (unless otherwise noted)
50
2.55
Device 1
Device 2
Device 3
2.54
2.53
Reference Voltage (V)
Devices (%)
40
30
20
2.52
2.51
2.5
2.49
2.48
10
2.47
2.46
2.505
2.504
2.503
2.502
2.501
2.5
2.499
2.498
2.497
2.496
2.495
0
2.45
-40
-25
-10
D039
5
20 35 50 65
Temperature (°C)
80
95
110 125
D040
Reference Voltge (V)
Figure 44. Reference Voltage vs Temperature
Figure 43. Reference Voltage Histogram
30
3
2.6
Reference Voltage (V)
Devices (%)
25
20
15
10
2.4
2.2
2
1.8
5
1.6
0
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
14
16
18
20
1.4
3
3.5
D041
Reference Voltage Drift (ppm/qC)
4
4.5
Supply Voltage (V)
5
5.5
D042
Figure 46. Reference Voltage vs Supply Voltage
Figure 45. Reference Voltage Drift Histogram
50
3
RSEL[1:0] = 00
RESL[1:0] = 01
RSEL[1:0] = 1x
2.8
40
2.6
2.4
Devices (%)
Reference Voltage (V)
RSEL[1:0] = 00
RSEL[1:0] = 01
2.8
2.2
2
30
20
1.8
10
1.6
0
-4
-3
-2
-1
0
1
2
Referene Current (mA)
3
4
5
D043
-300
-270
-240
-210
-180
-150
-120
-90
-60
-30
0
30
60
90
120
150
180
210
240
270
300
1.4
-5
D044
Power-Supply Rejection Ratio (PV/V)
Figure 47. Reference Voltage vs Reference Output Current
14
Figure 48. Reference Voltage Power-Supply Rejection Ratio
Histogram
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Typical Characteristics (continued)
at VDD = 5 V and TA = +25°C (unless otherwise noted)
100
10
VDD = 3 V
VDD = 5.5 V
9.5
Quiescent Current (mA)
Devices (%)
80
60
40
20
9
8.5
8
7.5
7
6.5
6
5.5
0.3
0.35
0.2
0.25
0.15
0.1
0
0.05
-0.1
-0.05
-0.2
-0.15
-0.25
-0.3
-0.35
0
5
-40
-25
-10
D045
5
20 35 50 65
Temperature (°C)
80
95
110 125
D046
Load Regulation (mV/mA)
Figure 49. Reference Voltage Load Regulation Histogram
Figure 50. Quiescent Current vs Temperature
Reset Threshold (V)
2.55
2.45
2.35
2.25
-40
-25
-10
5
20 35 50 65
Temperature (°C)
80
95
110 125
D047
Figure 51. Power-On Reset Threshold vs Temperature
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7 Detailed Description
7.1 Overview
The DRV421 is a fully-integrated, magnetic fluxgate sensor, with the necessary sensor conditioning and
compensation circuitry for closed-loop current sensors. The device is inserted into an air gap of an external
ferromagnetic toroid core to sense the magnetic field. A compensation coil wrapped around the magnetic core
generates a magnetic field opposite to the one generated by the current flow to be measured.
At dc and low-frequencies, the magnetic field induced by the current in the primary conductor generates a flux in
the magnetic core. The fluxgate sensor detects the flux in the DRV421. The device filters the sensor output to
provide loop stability. The filter output connects to the built-in H-bridge driver that drives an opposing current
through the external compensation coil. The compensation coil generates an opposite magnetic field that brings
the original magnetic flux in the core back to zero.
At higher frequencies, the inductive coupling between the primary conductor and compensation coil directly
drives a current through the compensation coil.
The compensation current is proportional to the primary current (IPRIMARY), with a value that is calculated using
Equation 1:
IICOMP = IPRIMARY / NWINDING
where
•
NWINDING = the number of windings of the compensation coil
(1)
This compensation current generates a voltage drop across a small external shunt resistor, RSHUNT. An
integrated difference amplifier with a fixed gain of 4 V/V measures this voltage and generates an output voltage
that is referenced to REFIN and proportional to the primary current. The Functional Block Diagram shows the
DRV421 used as a closed-loop current sensor, for both single-ended and differential primary currents.
7.2 Functional Block Diagram
RSHUNT
compensation
coil
magnetic
core
VDD GND
ICOMP1
DRV421
DRV421
AINN
VOUT
Fluxgate
H-Bridge
Sensor Integrator and Filter Driver
Device Control and Degaussing
16
AINP
Shunt
Sense
Amplifier
Fluxgate Sensor Front-End
return current
conductor
(optional)
ICOMP2
primary
current
conductor
OR
ER
DEMAG GSEL0 GSEL1
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REFIN
1.65 V or 2.5 V
Voltage Reference
REFOUT
RSEL0 RSEL1
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7.3 Feature Description
7.3.1 Fluxgate Sensor
The fluxgate sensor of the DRV421 is uniquely suited for closed-loop current sensors due to high sensitivity, low
noise, and low offset. The fluxgate principle relies on repeatedly driving the sensor in and out of saturation;
therefore, the sensor is free of any significant magnetic hysteresis. The feedback loop accurately drives the
magnetic flux inside the core to zero.
The DRV421 package is free of any ferromagnetic materials in order to prevent magnetization by external fields
and to obtain accurate and hysteresis-free operation. Select nonmagnetizable materials for the printed circuit
board (PCB) and passive components in the direct vicinity of the DRV421; see the Layout Guidelines section for
more details.
Figure 52 shows the orientation of the fluxgate sensor and the direction of magnetic sensitivity inside of the
package. This orientation is marked by a straight line on top of the package.
D421
TI Date
Code
Figure 52. Orientation and Magnetic Sensitivity Direction of the Integrated Fluxgate Sensor
7.3.2 Integrator-Filter Function and Compensation Loop Stability
The DRV421 and the magnetic core are components of the system feedback loop that compensates the
magnetic flux generated by the primary current. Therefore, the loop properties and stability depend on both
components. Four key parameters determine the stability and effective loop gain at high frequencies:
GSEL[1:0]
Filter gain setting pins of the DRV421
GCORE
Open-loop, current-to-field transfer of the magnetic core
Amount of magnetic field generated by 1 A of uncompensated primary current (unit is T/A).
NWINDING
Number of compensation coil windings
L
Compensation coil inductance
A minimum inductance of 100 mH is required for stability. Higher inductance improves
overload current robustness (see the Overload Detection and Control section).
To properly select the filter gain of the DRV421, combine these three parameters into a modified gain factor
(GMOD) using Equation 2:
GCORE u NWINDING
GMOD
(2)
L
The effective loop gain is proportional to the current-to-field transfer of the magnetic core (larger field means
larger gain) and number of compensation coil windings (larger number of windings means larger compensation
field for a given input current). The compensation coil inductance adds a low-frequency pole to the system, thus
a larger inductance reduces the effective loop gain at higher frequencies. A more detailed review of system loop
stability is provided in application report SLOA224, Designing with the DRV421: Control Loop Stability.
For stable operation with a wide range of magnetic cores, the DRV421 features an adjustable loop filter
controlled with pins GSEL1 and GSEL0. Table 1 shows the different filter settings and the related core
properties. For standard closed-loop current transducer modules with medium inductance and small shunt
resistor value, use gain setting 10. Gain setting 01 features a higher integrator-filter crossover frequency of 3.8
kHz, and is recommended for fault-current sensors with a large shunt resistor and medium inductance.
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Feature Description (continued)
Table 1. DRV421 Loop Gain Filter Settings and Relation to Magnetic Core Parameters
COMPENSATION LOOP PROPERTIES
AC OPEN-LOOP GAIN
RANGE OF
MODIFIED GAIN
FACTOR GMOD
RANGE OF COMPENSATION
COIL INDUCTANCE L
(NWINDING = 1000
and GCORE = 0.6 mT/A)
3.8 kHz
8.5
3 < GMOD < 12
100 mH < L < 200 mH
1
3.8 kHz
38
1 < GMOD < 3
200 mH < L < 600 mH
0
1.9 kHz
25
1 < GMOD <3
200 mH < L < 600 mH
1
1.9 kHz
70
0.3 < GMOD < 1
600 mH < L < 2 H
GSEL1
GSEL0
INTEGRATOR CORNER
FREQUENCY
0
0
0
1
1
Table 1 gives an initial gain-setting recommendation based on a simulation model of a generic magnetic core.
Secondary magnetic effects, such as eddy current losses and core hysteresis, can lead to different optimal
settings. Therefore, make sure to verify the correct gain setting by measuring the response of the current sensor
to an input current step at compensation driver output pins ICOMP1 and ICOMP2. Examples of measurement
results with a magnetic core of 300 mH, 1000 compensation coil windings, and different DRV421 gain settings
are shown in Figure 53 to Figure 56.
ICOMP1
ICOMP1
ICOMP2
ICOMP2
VOUT
ER
VOUT
Figure 53. Settling of ICOMP1 and ICOMP2
with GSEL[1:0] = 00
Figure 54. Settling of ICOMP1 and ICOMP2
with GSEL[1:0] = 01
ICOMP1
ICOMP1
ICOMP2
ICOMP2
VOUT
ER
VOUT
Figure 55. Settling of ICOMP1 and ICOMP2
with GSEL[1:0] = 10
ER
ER
Figure 56. Settling of ICOMP1 and ICOMP2
with GSEL[1:0] = 11
These measurement examples show a stable response for both GSEL[1:0] = 10 and 11 settings. However,
inductive coupling between the primary current and compensation coil makes it difficult to measure highfrequency instability. Therefore, use the lowest gain setting that yields a stable response; in this case, use gain
setting 10.
18
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7.3.3 H-Bridge Driver for Compensation Coil
The H-bridge compensation coil driver provides the current for the compensation coil at pins ICOMP1 and
ICOMP2. A fully-differential driver stage maximizes the driving voltage that is needed to overcome the wire
resistance and inductance of the coil with a single 3.3-V or 5-V supply. The low impedance of the H-bridge driver
outputs over a wide frequency range provides a smooth transition between the compensation frequency range of
the integrator-filter stage and the high-frequency range of the primary current that directly couples into the
compensation coil according to the winding ratio (transformer effect).
The common-mode voltage of the H-bridge driver outputs is set by the RSEL pins (see the Voltage Reference
section). Thus, the common-mode voltage of the shunt sense amplifier is matched if the internal reference is
used.
The two compensation driver outputs are protected and accept inductive energy. However, for high-current
sensors, add external protection diodes (see the Protection Recommendations section).
Consider the polarity of the compensation coil connection to the output of the H-bridge driver. If the polarity is
incorrect, the H-bridge output drives to the power supply rails, even at low primary-current levels. In this case,
interchange the connection of pins ICOMP1 and ICOMP2 to the compensation coil.
7.3.4 Shunt Sense Amplifier
The compensation coil current creates a voltage drop across the external shunt resistor, RSHUNT. The internal
differential amplifier senses this voltage drop. This differential amplifier offers wide bandwidth and a high slew
rate for fast current sensors. Excellent dc stability and accuracy result from an autozero technique. The voltage
gain is 4 V/V, set by precisely-matched and thermally-stable internal resistors.
Both AINN and AINP differential amplifier inputs are connected to the shunt resistor. This resistor, in series with
the internal 10-kΩ resistor, affects the overall gain and causes an additional gain error; this gain error is often
negligible. However, if a common-mode rejection of 70 dB is desired, the match of both divider ratios must be
higher than 1/3000. Therefore, for best common-mode rejection performance, place a dummy shunt resistor (R5)
with a value higher than the shunt resistor in series with the REFIN pin to restore matching of both resistor
dividers, as shown in Figure 57.
DRV421
AINN
R1
10 k R2
40 k _
RSHUNT
Shunt Sense
Amplifier
VOUT
RF
500 ADC
CF
10 nF
+
Compensation
Coil
AINP
R3
10 k optional
R4
40 k REFIN
REFIN (compensated)
R5
(Dummy Shunt)
ICOMP2
ICOMP1
Figure 57. Internal Difference Amplifier with Example of a Decoupling Filter
For an overall gain of 4 V/V, calculate the value of R5 using Equation 3:
R 4 + R5
R
4= 2 =
R1
RSHUNT + R3
where:
•
•
R2 / R1 = R4 / R3 = 4
R5 = RSHUNT × 4
(3)
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If the input signal is large, the amplifier output drives close to the supply rails. The amplifier output is able to drive
the input of a successive approximation register (SAR) analog-to-digital converter (ADC). For best performance,
add an RC low-pass filter stage between the shunt sense amplifier output and the ADC input. This filter limits the
noise bandwidth and decouples the high-frequency sampling noise of the ADC input from the amplifier output.
For filter resistor RF and filter capacitor CF values, refer to the specific converter recommendations in the
respective product data sheet.
The shunt sense amplifier output drives 100 pF directly and shows 50% overshoot with a 1-nF capacitance. Filter
resistor RF extends the capacitive load range. Note that with an RF of only 20 Ω, the load capacitor must be
either less than 1 nF or more than 33 nF to avoid overshoot; with an RF of 50 Ω, this transient area is avoided.
Reference input REFIN is the common-mode voltage node for output signal VOUT. Use the internal voltage
reference of the DRV421 by connecting the REFIN pin to reference output REFOUT. To avoid mismatch errors,
use the same reference voltage for REFIN and the ADC. Alternatively, use an ADC with a pseudodifferential
input, with the positive input of the ADC connected to the VOUT and the negative input connected to REFIN of
the DRV421.
7.3.5 Overrange Comparator
High peak current across the shunt resistor can generate a voltage drop that overloads the shunt sense amplifier
input. The open-drain, active-low output overrange pin (OR) indicates an overvoltage condition of the amplifier.
The output of this flag is suppressed for 3 μs, preventing unwanted triggering from transients and noise. This pin
returns to high as soon as the overload condition is removed; an external pull-up resistor is required to return the
OR pin to high.
This OR output can be used as a window comparator to actively shut off circuits in the system. The value of the
shunt resistor defines the operating window for the current, and sets the ratio between the nominal signal and the
trip level of the overrange comparator. The trip level (IMAX) of this window comparator is calculated using
Equation 4:
IMAX = Input Voltage Swing / RSHUNT
where
•
Input Voltage Swing = Output Voltage Swing / Gain
(4)
For example, with a 5-V supply, the output voltage swing is approximately ±2.45 V (load and supply voltagedependent).
The gain of 4 V/V enables an input voltage swing of ±0.6125 V.
The resulting trip level is IMAX = 0.6125 V / RSHUNT.
See Figure 32 and Figure 33 in the Typical Characteristics section for details.
Common window comparators use a preset level to detect an overrange condition. The DRV421 internally
detects an overrange condition as soon as the amplifier exceeds the linear operating range, not just at a preset
voltage level. Therefore, the error is reliably indicated in faults such as output-short, low-load, or low-supply
conditions. This configuration is a safety improvement if compared to a standard voltage-level comparator.
The internal resistance of the compensation coil may prevent high compensation current flow because of Hbridge driver overload; therefore, the shunt sense amplifier might not overload. However, a fast rate of change of
the primary current transmitted through transformer effect safely triggers the overload flag.
20
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7.3.6 Voltage Reference
The internal precision voltage reference circuit offers low drift performance at the REFOUT output pin and is
used for internal biasing. The reference output is intended to be the common-mode voltage of the output (VOUT
pin) to provide a bipolar signal swing. This low-impedance output tolerates sink and source currents of ±5 mA.
However, fast load transients can generate ringing on this line. A small series resistor of a few ohms improves
the response, particularly for capacitive loads equal to or greater than 1 μF.
Adjust the value of the voltage reference output to the power supply of the DRV421 using mode selection pins
RSEL0 and RSEL1, as shown in Table 2.
Table 2. Reference Output Voltage Selection
MODE
RSEL1
RSEL0
VREFOUT = 2.5 V
0
0
Use with sensor module supply of 5 V
DESCRIPTION
VREFOUT = 1.65 V
0
1
Use with sensor module supply of 3.3 V
Ratiometric output
1
x
Provides output centered on VDD / 2
In ratiometric output mode, an internal resistor divider divides the power supply voltage by a factor of two.
For current sensor modules with a reference input pin, the DRV421 also allows overwriting the internal reference
with an external reference voltage, VEXT, as shown in Figure 58. If there is a significant difference between the
external and the internal voltage, resistor R5 limits the current flow from the internal reference. In this case, the
internal reference sources current IREFOUT shown in Equation 5:
VREFOUT VEXT
IREFOUT
600
(5)
Current Sense Module
DRV421
AINN
VDD
VDD
VOUT
VOUT
_
RSHUNT
Shunt Sense
Amplifier
+
Compensation
Coil
REFIN
AINP
Internal
Voltage
Reference
ICOMP2
R5
(Dummy Shunt)
REFOUT
REFIN
R6
600 GND
External
Voltage
Reference
GND
ICOMP1
Figure 58. DRV421 with External Reference
The example of 600 Ω for R6 was chosen for illustration purposes; different values are possible. If no external
reference is connected, R6 has little impact on the common-mode rejection of the shunt sense amplifier;
therefore, use a resistor value that is as small as possible.
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7.3.7 Overload Detection and Control
Magnetic fluxgate sensors have a very high sensitivity and allow detection of small magnetic fields. These
sensors are ideally suited for use in closed-loop current modules appllications because the high sensitivity makes
sure that the field inside the core gap is accurately driven to zero. However, for large fields, the fluxgate
saturates and causes the output to return to zero, as shown in Figure 59.
V
Fluxgate
sensor
saturated
Fluxgate
sensor
saturated
-1 mT
B
1 mT
Normal
operation
area
Figure 59. Typical Fluxgate Sensor Response to Magnetic Fields
In normal operation, the feedback loop keeps the magnetic field close to zero. However, large overload currents
that exceed the measurement range (for example, short-circuit currents) saturates the fluxgate. The behavior is
illustrated in Figure 60, where the compensation current, magnetic field in the core, and fluxgate output are
shown for the case of a 1000-A primary current step.
Primary Current
Compensation Current
1000 A
1A
0A
0A
t
t
Magnetic Field in the Core
Fluxgate Sensor Output
Saturation Detection Level
1.7 mT
0 mT
t
t
Figure 60. Closed-Loop Current Sensor Response to an Overloaded Step Current
22
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Use the inverse of Equation 1 to calculate the current measurement range. For example, if the compensation coil
has 1000 windings, the maximum measurement range is 210 A at a 5-V supply (210-mA minimum compensation
driver capability × 1000 windings). The inductive coupling between primary current and compensation coil initially
provides a correct compensation current. However, over time, the compensation current drops to 210 mA and
the field inside the core increases beyond the measurement range of the fluxgate. Thus, the sensor output
returns to zero because of saturation.
This zero output causes unpredictable behavior in the analog control loop. For example, as a result of an invalid
fluxgate output, the H-bridge drives the wrong compensation current and generates a large magnetic field
through the compensation coil. This magnetic field keeps the fluxgate in saturation and leads to system lockup.
This unpredicatable behavior exists for any fluxgate-based current sensor.
For proper handling of overload currents, the DRV421 features a two-step overload detection and control
function. Firstly, the polarity of the last four fluxgate sensor outputs exceeding a threshold value of approximately
13 µT are internally stored. Secondly, the DRV421 features an additional circuitry that verifies every 4 µs whether
the fluxgate is saturated. If saturation is detected, digital circuitry overrides the fluxgate output and provides a
high output according to the polarity detected during the last valid sensor output. As a result, the H-brigde drives
the outputs to the supply rails, making sure that the magnetic field returns to within the fluxgate range as soon as
the current returns to within the measurement range. After this happens, the fluxgate is no longer saturated, and
normal analog feedback loop operation resumes. During fluxgate saturation, the error pin is pulled low to signal
that the current exceeds the measurement range (see the Error Flag section).
For correct operation of this overload control feature, at least 10 µs are required between the time the field
exceeds the polarity detection threshold (13 µT) and the saturation trip level (1.7 mT). Initially, fast primary
current steps are inductively coupled to the compensation coil (transformer effect); therefore, the primary current
rise time is not limited. Instead, the rise time is determined by the compensation coil inductance; a larger
inductance leads to a slower compensation current decrease. The minimum required inductance is 100 mH; for
optimal robustness, use 300 mH (see the Magnetic Core Design section for detailed requirements).
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7.3.8 Magnetic Core Demagnetization
Ferromagnetic cores can have a significant remanence (residual magnetism in the absence of any currents).
This core magnetization is caused by strong external magnetic fields, overcurrent conditions in the system, or if a
significant primary current flows while the sensor is not powered. This remaining magnetic field is
indistinguishable from an actual primary current, and creates a magnetic offset error. This magnetic offset error
limits the precision and the dynamic range of the current sensor, and is independent of the fluxgate sensor frontend offset specified in this data sheet.
To reduce errors caused by core magnetization, the DRV421 features a unique closed-loop demagnetization
feature. Conventional open-loop demagnetization techniques rely on driving a fixed ac waveform through the
compensation coil. Instead, the DRV421 demagnetization feature first measures the magnetic offset using its
integrated fluxgate sensor, and then drives a controlled ac waveform to reduce the measured magnetization.
This method results in significantly better results. Moreover, any fluxgate offset is part of the closed-loop
demagnetization measurement, and therefore removed along with core magnetization, leaving only fluxgate
offset drift over temperature as an error source.
Start the demagnetization feature on demand by pulling the DEMAG pin high for at least 25 µs. This process
starts a 500-ms demagnetization cycle. During this time, the error pin (ER) is pulled low to indicate that the
output is not valid. When DEMAG is high during power up, the demagnetization cycle initiates immediately after
the supply voltage crosses the power-up threshold. Hold DEMAG low to avoid this cycle during start up. To abort
the demagnetization cycle, pull DEMAG low for longer than 25 µs. Figure 61 shows the ICOMPx output behavior
during a demagnetization sequence. Figure 62 shows the reduced error due to core demagnetization.
1000 mA
6
VDD
VOUT
VICOMP1
VICOMP2
5
Error Current Level
before Demagnetization
Voltage (V)
4
100 mA
3
Repeatable Error Current
Level after Demagnetization
2
10 mA
1
0
-0.1
0
0.1
0.2
0.3
Time (ms)
0.4
0.5
-8
0.6
1 mA
D052
Figure 61. Demagnetization Sequence
Figure 62. Impact of Demagnetization on Error Current
During a demagnetization cycle, the primary current must be zero because the resulting magnetic field cannot be
distinguished from the remanence of the core. A demagnetization cycle in the presence of primary current (or
any other sources of magnetic field) leads to residual errors because the demagnetization feature attempts to
reduce the primary-generated field to zero, but significantly magnetizes the core instead of demagnetizing the
core. If a primary current is present that is large enough to saturate the fluxgate sensor during start up, the
DRV421 skips demagnetization (regardless of the level on the DEMAG pin), and the search function starts
instead (see the Search Function section for more details).
To reduce effects from the earth's magnetic field, degauss in the same orientation as nominal operation of the
system.
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7.3.9 Search Function
Closed-loop current sensors usually require primary current to be applied only after the sensor is powered up.
This requirement allows the feedback loop to start from zero current operation; the magnetic core is maintained
at zero flux at all times, thus preventing magnetization. Moreover, the DRV421 integrated fluxgate has a limited
measurement range of 1.7 mT. As a result, the presence of a significant primary current at power up saturates
the fluxgate, and the system feedback loop does not work; similar to the presence of an overload current (see
the Overload Detection and Control section).
The DRV421 search function allows for a power up in presence of primary dc current. If the fluxgate is saturated
at power up, the digital logic of the DRV421 connects ICOMP1 to VDD and COMP2 to GND for 30 ms. Because
of the compensation coil inductance, the compensation current slowly increases during this time, and depending
on the primary current polarity, may at some point compensate the primary current. In this case, the fluxgate
sensor desaturates and normal operation initiates. If the fluxgate sensor is still saturated after 30 ms, the voltage
polarity on ICOMPx pins is inverted (ICOMP1 = GND, ICOMP2 = VDD) and the process repeats for opposite
primary current polarity. If the fluxgate remains saturated after 60 ms, the error state persists and the error pin
ER remains active low. Figure 63 shows a search sequence starting with the wrong polarity.
VDD
Search Function
with Wrong Polarity
Inverted
Polarity
VICOMP1
VICOMP2
Normal
Operation
VER
Figure 63. Search Sequence Starting with Wrong Polarity
The search funciton cannot be used for primary ac currents. Moreover, the presence of primary current before
the sensor is powered up may lead to core magnetization, and thus offset shift. Therefore, for robust operation,
do not power up in the presence of primary currents.
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7.3.10 Error Flag
The DRV421 features an error output (ER pin) that is activated under multiple conditions. The error flag is active
when the output voltage is not proportional to the primary current; during a power fail or brownout; during a
demagnetization cycle; or when the magnetic field on the fluxgate is greater than 1.7 mT (saturation of the
fluxgate). Saturation is usually caused by either the consequence of an overload current (see the Overload
Detection and Control section) or due to a power up in the presence of a primary current (see the Search
Function section).
The error flag resets as soon as the error condition is no longer present and the circuit has returned to normal
operation. The error flag is an open-drain logic output. Connect the error flag to the overrange flag for a wiredOR; for proper operation, use an external pull-up resistor. The following conditions result in error flag activation
(ER asserts low):
1. For 80 µs after power-up
2. If a supply-voltage brownout condition (VDD < 2.4 V) lasts for more than 20 µs
3. If the sensed magnetic field is > 1.7 mT because:
– Overload control is active
– Search function is active
4. Demagnetization cycle is active (see the Magnetic Core Demagnetization section)
7.4 Device Functional Modes
The DRV421 has a single functional mode and is operational when the power-supply voltage is greater than 3 V.
The maximum power supply voltage for the DRV421 is 5.5 V.
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8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
8.1.1 Magnetic Core Design
The high sensitivity, low offset, and low noise of the DRV421 fluxgate sensor enable a high-performance closedloop current sensor module. For good module performance, an appropriate magnetic core design is required.
Table 3 lists the DRV421 and magnetic core specifications with relation to the overall current module
specifications.
Table 3. Current-Sensor Module Performance versus DRV421 Specifications and Magnetic Core
Performance
CURRENT SENSOR MODULE
PARAMETER
PERFORMANCE DETERMINED BY:
Offset and offset drift
DRV421 fluxgate sensor front-end: offset and offset drift
Offset on start-up and after
overload condition
Magnetic core: magnetization (see the Magnetic Core Demagnetization section)
Noise
DRV421 fluxgate sensor front-end: noise
Linearity error
DRV421 fluxgate sensor front-end: AC open-loop gain
Gain error
Magnetic core: Permeability, geometry, and actual number of compensation coil windings
Measurement range
1) DRV421 fluxgate sensor front-end: H-bridge peak current
2) Compensation coil: number of windings and resistance
3) Value of the external shunt resistor
Neighbor-current rejection
(crosstalk)
Magnetic core: permeability, sensor gap design, and magnetic shielding
Bandwidth and gain flatness
1) DRV421 fluxgate sensor front-end: AC open-loop gain setting
2) Magnetic core: high-frequency behavior of the core and inductance of the compensation coil
3) Value of the external shunt resistor
Common-mode current rejection
(for fault current sensors)
Magnetic core: permeability, actual position of the primary current conductors, and magnetic shielding
For further details, see also application report SLOA223, Designing with the DRV421: Closed Loop Current
Sensor Specifications.
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Application Information (continued)
8.1.2 Protection Recommendations
Inputs AINP and AINN require external protection to limit the voltage swing to within 6 V beyond both supply
rails. Driver outputs ICOMP1 and ICOMP2 handle high-current pulses protected by internal clamp circuits to the
supply voltage. If large magnitude overcurrents are expected, connect external Schottky diodes to the supply
rails to protect the DRV421 from damage.
CAUTION
Large overcurrents may drive the power supply above the normal operating voltage.
Route large overcurrent pulses away from the device using diodes connected to the
supply, as shown in the Typical Application on the front page. To prevent these pulses
from driving up the supply voltage, and prevent damage to the DRV421 and other
components in the circuit, use an additional supply clamp, as shown in Figure 64. All
other pins offer standard protection; see the Absolute Maximum Ratings.
VDD
Figure 64. Additonal Supply Clamp for the DRV421
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8.2 Typical Application
8.2.1 Closed-Loop Current Sensing Module
Closed-loop current sensor modules measure currents over a wide frequency range, including dc currents. These
sensor modules offer a contact-free sensing method and excellent galvanic isolation performance, combined with
high resolution, accuracy, and reliability. The DRV421 is designed for use in this kind of application.
At dc and in low-frequency range, the magnetic field induced by the primary current is sensed by the DRV421
fluxgate sensor. The sensed signal is filtered by the DRV421 and the internal H-bridge driver generates a
proportional compensation current. The compensation current flows through the compensation coil, and
generates a magnetic field. This magnetic field drives the original magnetic flux in the core back to zero. The
value of this magnetic field is increased by the number of compensation coil windings. Therefore, use Equation 1
to calculate the required compensation current for a given primary current.
At higher frequencies, the magnetic field induced by the primary current directly couples into the compensation
coil and generates a current. The low impedance of the H-bridge driver does not influence the value of this
current. Also in this case, the value of the compensation current is the value of the primary current divided by the
number of compensation coil windings.
Closed-Loop Current Module
VDD
optional
magnetic
core
ICOMP1
ICOMP2
AINP
AINN
RSHUNT
VDD
VDD
compensation
coil
ADC
GPIO0
GPIO1
GPIO2
GND
DRV421
GND
DRV421
GSEL0
GSEL1
RSEL0
RSEL1
MCU
VOUT
REFIN
REFOUT
DEMAG
OR
ER
R2
R1
primary
current
conductor
C1
VDD
C2
Figure 65. Closed-Loop Current Sensing Module
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Typical Application (continued)
8.2.1.1 Design Requirements
A closed-loop current sensing module contains the DRV421, the magnetic core with a compensation coil, and a
shunt resistor. To increase the robustness of the module to high primary current peaks, use additional protection
diodes. See application report SLOA223, Designing with the DRV421: Closed Loop Current Sensor
Specifications, for additional information on the magnetic core and compensation coil design. The DRV421
output voltage is calculated as described in Equation 6:
VOUT
§ NPRIM ·
IPRIM u ¨
¸ u RSHUNT u G
© NWINDING ¹
where:
•
•
•
•
•
IPRIM = primary current value
NPRIM = the number of windings of the primary current conductor
NWINDING = the number of windings of the compensation coil
RSHUNT = shunt resistor value
G = shunt sense amplifier gain; default value is 4
(6)
8.2.1.2 Detailed Design Procedure
The compensation current creates a voltage drop across the shunt resistor. The maximum shunt resistor value is
limited by supply voltage VDD, the compensation current range, and the resistance of the compensation coil, as
described in Equation 7:
VICOMP(MIN)
RSHUNT RCOIL d
IICOMP
(7)
The voltage drop across the shunt resistor is sensed by the DRV421 shunt sense amplifier with a gain of four.
For proper operation, keep the resulting output voltage at VOUT pin within the voltage output swing range
specified in the Electrical Characteristics.
8.2.1.3 Application Curves
Current Error referred to Primary Current (%)
1.06
Normalized Gain (dB)
1.04
1.02
1
0.98
0.96
0.94
1
10
100
1000
Frequency (Hz)
10000
100000
0.02
0.01
0
-0.01
-0.02
-0.03
0.0001
D053
Figure 66. Gain Flatness of a DRV421-Based Closed-Loop
Current Sensing Module
30
0.03
0.001
0.01
0.1
1
Primary Current (A)
10
100
D054
Figure 67. Current Error of a DRV421-Based Closed-Loop
Current Sensing Module
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Typical Application (continued)
8.2.2 Differential Closed-Loop Current Sensing Module
The differential closed-loop current sensing module measures the difference between two or more currents.
Typical end-applications for such modules are leakage or residual current sensors. The high sensitivity of the
fluxgate sensor and the low temperature drift make the DRV421 a suitable choice for this type of modules. The
principle operation is the same as that of the closed-loop current module described in the Closed-Loop Current
Sensing Module section. The compensation current corresponds to the current difference between the primary
conductors.
Differential Closed-Loop Current Module
VDD
optional
magnetic
core
ICOMP1
ICOMP2
AINP
AINN
RSHUNT
VDD
VDD
compensation
coil
VOUT
REFIN
REFOUT
DEMAG
OR
ER
ADC
GPIO0
GPIO1
GPIO2
GND
DRV421
GND
DRV421
GSEL0
GSEL1
RSEL0
RSEL1
MCU
R1
return
current
conductor
primary
current
conductor
C1
C2
R2
VDD
Figure 68. Differential Closed-Loop Current Sensing Module
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Typical Application (continued)
8.2.2.1 Design Requirements
As with the previous application, the compensation current creates a voltage drop across the shunt resistor. The
maximum shunt resistor value is limited by supply voltage VDD, the compensation current range, and the
resistance of the compensation coil, as shown in Equation 7.
However, in applications that sense leakage or residual currents, the difference between the primary currents is
zero in normal operation. In fault condition only, there is a small difference current that is sensed in order to shut
down the system to prevent damage to the device or the user. In this case, the compensation current is also very
low, usually only in the range of few mA. Therefore, use a higher shunt resistor value in this case to support high
sensitivity on system level. Consider the impact of shunt resistor value on gain and gain flatness as decribed in
application report SLOA223, Designing with the DRV421: Closed Loop Current Sensor Specifications.
8.2.2.2 Detailed Design Procedure
For differential current sensing modules with a large shunt resistor and medium compensation coil inductance,
use the gain setting that features the higher cross-over frequency of 3.8 kHz: GSEL[1:0] = 01.
Current Error referred to Primary Current (%)
8.2.2.3 Application Curves
0.03
0.02
0.01
0
-0.01
-0.02
-0.03
0.0001
0.001
0.01
Primary Current (A)
0.1
1
D055
Figure 69. Current Error of a DRV421-Based Differential Closed-Loop Current Sensing Module
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Typical Application (continued)
8.2.3 Using the DRV421 in ±15-V Sensor Applications
The DRV421 is designed for 3.3-V or 5-V nominal operation. To support a wider module current range, the
device is also used in ±15-V application, as shown in Figure 70. In this application, an external regulator
generates the 5-V supply for the DRV421. An additional external ±15-V power driver stage drives the
compensation coil. These techniques allow the design of exceptionally precise and stable ±15-V current-sense
modules.
+15 V
LDO
5V
VDD
ICOMP1
Fluxgate
Sensor
H-Bridge
Driver
ICOMP2
External
Driver
Compensation
Coil
DRV421
GND
RSHUNT
-15 V
Figure 70. ±15-V Current-Sense Modules
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9 Power-Supply Recommendations
9.1 Power-Supply Decoupling
Decouple both VDD pins of the DRV421 with 1-uF X7R-type ceramic capacitors to the adjacent GND pin as
shown in Figure 71. For best performance, place both decoupling capacitors as close to the related power-supply
pins as possible. Connect these capacitors to the power-supply source in a way that allows the current to flow
through the pads of the decoupling capacitors.
9.2 Power-On Start Up and Brownout
Power-on is detected when the supply voltage exceeds 2.4 V at VDD pin. At this point, DRV421 initiates
following start-up sequence:
1. Digital logic starts up and waits for 26 μs for the supply to settle.
2. Fluxgate sensor powers up.
3. If fluxgate sensor saturation is detected, search function starts as described in the Search Function section.
4. If DEMAG pin is set high, demagnetization cycle starts as described in the Magnetic Core Demagnetization
section.
5. The compensation loop is active after the demagnetization cycle, or 80 μs after the supply voltage exceeds
2.4 V.
During this startup sequence, the ICOMP1 and ICOMP2 outputs are pulled low to prevent undesired signals on
the compensation coil, and the ER pin is asserted low.
The DRV421 tests for low supply voltages with a brownout voltage level of 2.4 V. Use a power-supply source
capable of supporting large current pulses driven by the DRV421, and low ESR bypass capacitors for stable
supply voltage in the system. A supply drop below 2.4-V that lasts longer than 20 μs generates a power-on reset;
the device ignores shorter voltage drops. A voltage drop on the VDD pin to below 1.8 V immediately initiates a
power-on reset. After the power supply returns to 2.4 V, the device initiates a start-up cycle, as described at the
beginning of this section.
9.3 Power Dissipation
The thermally-enhanced, PowerPAD, QFN package reduces the thermal impedance from junction to case. This
package has a downset lead frame on which the die is mounted. The lead frame has an exposed thermal pad
(PowerPAD) on the underside of the package, and provides a good thermal path for the heat dissipation.
The power dissipation on both linear outputs ICOMP1 and ICOMP2 is calculated with Equation 8:
PD(ICOMP) = IICOMP × (VICOMP – VSUPPLY)
where
•
VSUPPLY = voltage potential closer to VICOMP, VDD, or GND
(8)
CAUTION
Output short-circuit conditions are particularly critical for the H-bridge driver output pins
ICOMP1 and ICOMP2. The full supply voltage occurs across the conducting transistor
and the current is only limited by the current density limitation of the FET; permanent
damage can occur. The DRV421 does not feature temperature protection or thermal
shut-down.
9.3.1 Thermal Pad
Packages with an exposed thermal pad are specifically designed to provide excellent power dissipation, but
board layout greatly influences the overall heat dissipation. Technical details are described in application report
SLMA002, PowerPad Thermally Enhanced Package, available for download at www.ti.com.
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10 Layout
10.1 Layout Guidelines
The DRV421 unique, integrated fluxgate has a very high sensitivity to magnetic fields in order to enable design of
a closed-loop current sensor with best-in-class precision and linearity. Observe proper PCB layout techniques
because any current-conducting wire in the direct vicinity of the DRV421 generates a magnetic field that may
distort measurements. Common passive components and some PCB plating materials contain ferromagnetic
materials that are magnetizable. For best performance, use the following layout guidelines:
• Route current conducting wires in pairs: route a wire with an incoming supply current next to, or on top of its
return current path. The opposite magnetic field polarity of these connection cancel each other. To facilitate
this layout approach, the DRV421 positive and negative supply pins are located next to each other.
• Route the compensation coil connections close to each other as a pair to reduce coupling effects.
• Route currents parallel to the fluxgate sensor sensitivity axis as shown in Figure 71. As a result, magnetic
fields are perpendicular to the fluxgate sensitivity, and have limited impact.
• Vertical current flow (for example, through vias) generates a field in the fluxgate-sensitive direction. Minimize
the number of vias in vincinity of the DRV421.
• Place all passive components (for example, decoupling capacitors and the shunt resistor) outside of the
portion of the PCB that is inserted into the magnetic core gap. Use nonmagnetic components to prevent
magnetizing effects.
• Do not use PCB trace finishes using nickel-gold plating because of the potential for magnetization.
• Connect all GND pins to a local ground plane.
Ferrite beads in series to the power-supply connection reduce interaction with other circuits powered from the
same supply voltage source. However, to prevent influence of the magnetic fields if ferrite beads are used, do
not place them next to the DRV421.
The reference output (REFOUT pin) refers to GND. Use a low-impedance and star-type connection to reduce the
driver current and the fluxgate sensor current modulating the voltage drop on the ground track. The REFOUT
and VOUT outputs are able to drive some capacitive load, but avoid large direct capacitive loading because of
increased internal pulse currents. Given the wide bandwidth of the shunt sense amplifier, isolate large capacitive
loads with a small series resistor.
Solder the exposed PowerPAD, on the bottom of the package to the ground layer because the PowerPAD is
internally connected to the substrate that must be connected to the most-negative potential.
Figure 71 shows a generic layout example that highlights the placement of components that are critical to the
DRV421 performance. For specific layout examples, see SLOU409, DRV421EVM Users Guide, and TIDUA92,
TIPD196 Design Guide.
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10.2 Layout Example
Keep this area free of components
creating magnetic fields.
1206
ICOMP2
GND
REFIN
X7R
0603
ICOMP1
VDD
REFOUT
1 µF
AINP
VDD
RSEL0
X7R
0603
AINN
GND
RSEL1
1 µF
OR
VOUT
GSEL0
RSHUNT
GND
GND
DEMAG
ER
GSEL1
Fluxgate sensor sensitivity axis
To
Compensation
Coil
LEGEND
Top Layer:
Copper Pour and Traces
Via to Ground Plane
Via to Supply Plane
To ADC
Figure 71. Generic Layout Example (Top View)
36
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Copyright © 2015, Texas Instruments Incorporated
Product Folder Links: DRV421
DRV421
www.ti.com
SBOS704A – MAY 2015 – REVISED JULY 2015
11 Device and Documentation Support
11.1 Documentation Support
11.1.1 Related Documentation
• DRV421EVM Users Guide, SLOU409
• TIPD196 Design Guide, TIDUA92
• Designing with the DRV421: Closed Loop Current Sensor Specifications, SLOA223
• Designing with the DRV421: Control Loop Stability, SLOA224
11.2 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.3 Trademarks
PowerPAD, E2E are trademarks of Texas Instruments.
All other trademarks are the property of their respective owners.
11.4 Electrostatic Discharge Caution
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
11.5 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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Copyright © 2015, Texas Instruments Incorporated
Product Folder Links: DRV421
37
PACKAGE OPTION ADDENDUM
www.ti.com
29-Jul-2015
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
DRV421RTJR
ACTIVE
QFN
RTJ
20
3000
Green (RoHS
& no Sb/Br)
CU
Level-3-260C-168 HR
-40 to 125
----->
DRV421
DRV421RTJT
ACTIVE
QFN
RTJ
20
250
Green (RoHS
& no Sb/Br)
CU
Level-3-260C-168 HR
-40 to 125
----->
DRV421
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3)
MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4)
There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5)
Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6)
Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
29-Jul-2015
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
28-Jul-2015
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
B0
(mm)
K0
(mm)
P1
(mm)
W
Pin1
(mm) Quadrant
DRV421RTJR
QFN
RTJ
20
3000
330.0
12.4
4.25
4.25
1.15
8.0
12.0
Q2
DRV421RTJT
QFN
RTJ
20
250
180.0
12.4
4.25
4.25
1.15
8.0
12.0
Q2
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
28-Jul-2015
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
DRV421RTJR
QFN
RTJ
20
3000
367.0
367.0
35.0
DRV421RTJT
QFN
RTJ
20
250
210.0
185.0
35.0
Pack Materials-Page 2
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