PWM rejection current sense amplifier for large commonmode transients 1 Benefits of designing with current sense amplifiers Discrete current sensing Op amp used for current sensing External gain setting resistors ID: 701753
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Slide1
INA240High-voltage, enhanced PWM rejection current sense amplifier for large common-mode transients
1Slide2
Benefits of designing with current sense amplifiers
Discrete
current sensing
Op amp used for current sensing
External gain setting resistors
Input range limited by supply voltage
Dedicated
current sense amplifierSlide3
INA240 FamilyWide common-mode : -4V to 80V Bi-directionalHigh AC CMRR: 93dB @ 50kHzEnhanced PWM rejectionHigh accuracyInput offset voltage: 25µV (Max) with 0.25µV/°C Max DriftGain error: ±0.20% (Max) with 2.5ppm/°C Max DriftAvailable gains: 20, 50, 100, 200V/V
Package: TSSOP-8AEC Q100 Option available in 1Q17
Motor control • Power supplies
Solenoid/valve Control
3
Large input range to integrate into increasing common-mode voltage applications
High accuracy minimizes system marginsHigh CMRR allows for direct in-line motor current sensingFeatures
BenefitsApplicationsHigh-voltage, enhanced PWM rejection current sense amplifier for large common-mode transients
INA240EVM gain options:20V/V, 50V/V, 100V/V, 200V/V
INA240EVM User’s GuideTINA-SPICE ModelTIDA-00913 GaN half-bridge with in-line motor current sensing using INA240Tools & Resources
3
Ex: In-line Motor Current Sensing
Ex: High-side DC-DC Current Sensing
V
CM
V
CM
V
OUT
V
OUT
Stable V
OUT
!
Large, high slew rate input V
CMSlide4
Enhanced PWM RejectionWhat is it?Active circuitry which monitors the input common-mode signals.If a fast transition is detected, will suppress the signal to minimize the “glitch” to be propagated through the device’s output.How do other solutions tackle this problem?
Competitive solutions typically utilize high-bandwidth amplifiers to settle the output as quickly as possible.Problem with this approach is it may incur added delay due to the settling time.
4
V
OUT
V
CM
What system-level benefit is there with Enhanced PWM Rejection?“Blanking time” is reduced substantially!
Can measure accurately at lower duty cycles!Slide5
Why is in-line motor sensing important?Why measure current in a motor?Fault protectionInput into motor control algorithmWhy measure current in-line vs. low-side?
Low-side is a proven approach with a large customer base and perceived to have a lower system cost, but has
difficulty
to
scaling to higher precision and lower driftLow-side creates a non-linear output signal that must be post-processed to extract the proportional base current information
In-line provides a faster response, higher precision, and the ability to have less drift over a wide temperature rangeIn-line reproduces a continuous proportional signal of the phase current which does not need further processing5Slide6
6TI solutions for 3-phase DC Motor Control
Current meas. options in 3-phase DC motor
TI 3-phase DC motor current measurement solutions
In-line Phase Current
Device
V
CM
Range
V
OS
V
OS
Drift
Gain
Gain Error
Gain Error Drift
Comment
INA240
–4V to +80V
25µV
0.25µV
/°C
20, 50, 100, 200
0.2%
2.5ppm
/°C
Enhanced PWM Rejection
Low-side Phase Current
Device
V
CM
Range
V
OS
V
OS
Drift
Gain
Gain Error
Gain Error Drift
Comment
INA303
0V to +36V
35µV
0.1µV/°C
20, 50, 100
0.10%
10ppm/°C
Integrated Window Comparator
High-side Motor Current Monitoring for Over-Current Protection
Device
V
CM
Range
V
OS
VOSDriftGainGain ErrorGain Error DriftCommentINA240–4V to +80V25µV0.25µV/°C20, 50, 100, 2000.2%2.5ppm/°CUltra-high PrecisionLMP8640HV–2V to +76V900µV2.6µV/°C20, 50, 1000.25%26.2ppm/°CHigh BandwidthINA200–16V to +80V2.5mV5µV/°C (typ)20, 50, 1001%-Over-currentLow-side Motor Current Monitoring for Over-Current ProtectionDeviceVCMRangeVOSVOSDriftGainGain ErrorGain Error DriftCommentINA199–0.3V to +26V150µV0.1µV/°C50, 100, 2001.40%10ppm/°CLow-cost Current Sense AmplifierINA3010V to +36V35µV0.1µV/°C20, 50, 1000.10%10ppm/°CIntegrated Fast ComparatorSlide7
7
TI 3-phase DC Motor Current Measurement Solutions
In-line Phase Current
Device
V
CM
Range
V
OS
V
OS
Drift
Gain
Gain Error
Gain Error Drift
Comment
INA240
–4V to +80V
25µV
0.25µV
/°C
20, 50, 100, 200
0.2%
2.5ppm
/°C
Enhanced PWM Rejection
Low-side Phase Current
Device
V
CM
Range
V
OS
V
OS
Drift
Gain
Gain Error
Gain Error Drift
Comment
INA303
0V to +36V
35µV
0.1µV/°C
20, 50, 100
0.10%
10ppm/°C
Integrated Window Comparator
High-side Motor Current Monitoring for Over-Current Protection
Device
V
CM
Range
V
OS
V
OSDriftGainGain ErrorGain Error DriftCommentINA240–4V to +80V25µV0.25µV/°C20, 50, 100, 2000.2%2.5ppm/°CUltra-high PrecisionLMP8640HV–2V to +76V900µV2.6µV/°C20, 50, 1000.25%26.2ppm/°CHigh BandwidthINA200–16V to +80V2.5mV5µV/°C (typ)20, 50, 1001%-Over-currentLow-side Motor Current Monitoring for Over-Current ProtectionDeviceVCMRangeVOSVOSDriftGainGain ErrorGain Error DriftCommentINA199–0.3V to +26V150µV0.1µV/°C50, 100, 2001.40%10ppm/°CLow-cost Current Sense AmplifierINA3010V to +36V35µV0.1µV/°C20, 50, 1000.10%10ppm/°CIntegrated Fast ComparatorTI solutions for 3-phase DC motor controlCurrent Meas. options in 3-phase DC Motor
System benefits gained from using INA240
Most accurate phase current representation with in-line phase current sensing
Algorithm optimization
Reduced blanking time
Possible elimination of galvanic isolation
Increased motor efficiencySlide8
8TI solutions for embedded DC-DC power
Current measurement in Embedded DC-DC
TI Solutions for Embedded DC-DC
8
System
Power
12VDC
Current Feedback
Sense
Resistor
High-side
current sensing
(system power)
High-side
current sensing (phase power)
Single-
ph
DC-DC
FETs
Load
Vout
Low-side current sensing
High-side Current Sensing (system power)
Device
V
CM
Range
V
OS
V
OS
Drift
Gain
Gain Error
Gain Error Drift
Comment
INA240
-4V
to
+80V
25µV
0.25µV
/°C
20, 50
,
100, 200
0.2%
2.5ppm
/°C
Ultra-high Precision
INA210
-0.3V
to
+26V
35µV
60µV
100µV0.1µV/°C50, 75, 100,200, 5000.9%10ppm/°CHighPerformanceINA3010V to +36V35µV0.1µV/°C20, 50, 1000.10%10ppm/°CFast ComparatorINA3020V to +36V35µV0.1µV/°C20, 50, 1000.10%10ppm/°COver/Under CurrentHigh-side Current Sensing (phase power)DeviceVCMRangeVOSVOSDriftGainGain ErrorGain Error DriftCommentINA240-4V to +80V25µV0.25µV/°C20, 50, 100, 2000.2%2.5ppm/°CPWM RejectionINA210-0.3V to +26V35µV60µV100µV
0.1µV/°C
50
,
75, 100,
200, 500
0.9%
10ppm/°C
High
Performance
LMP8645
-2V
to
+42V
1000µV
7µV
/°C
Adjustable
2%
140ppm
/°C
High
Bandwidth
Low-side
Current Sensing
Device
V
CM
Range
V
OS
V
OS
Drift
Gain
Gain Error
Gain Error Drift
Comment
INA210
-0.3V
to
+26V
35µV
60µV
100µV
0.1µV/°C
50
,
75, 100,
200, 500
0.9%
10ppm/°C
High
Performance
INA199
–0.3V to +26V
150µV
0.1µV/°C
50, 100, 200
1.40%
10ppm/°C
Low-cost
INA301
0V to +36V
35µV
0.1µV/°C
20, 50, 100
0.10%
10ppm/°C
Fast ComparatorINA3020V to +36V35µV0.1µV/°C20, 50, 1000.10%10ppm/°CWarning/ShutdownSlide9
9
TI Solutions for Embedded DC-DC
High-side Current Sensing (system power)
Device
V
CM
Range
V
OS
V
OS
Drift
Gain
Gain Error
Gain Error Drift
Comment
INA240
-4V
to
+80V
25µV
0.25µV
/°C
20, 50
,
100, 200
0.2%
2.5ppm
/°C
Ultra-high Precision
INA210
-0.3V
to
+26V
35µV
60µV
100µV
0.1µV/°C
50
,
75, 100,
200, 500
0.9%
10ppm/°C
High
Performance
INA301
0V to +36V
35µV
0.1µV/°C
20, 50, 100
0.10%
10ppm/°C
Fast
Comparator
INA302
0V to +36V35µV0.1µV/°C20, 50, 1000.10%10ppm/°COver/Under CurrentHigh-side Current Sensing (phase power)DeviceVCMRangeVOSVOSDriftGainGain ErrorGain Error DriftCommentINA240-4V to +80V25µV0.25µV/°C20, 50, 100, 2000.2%2.5ppm/°CPWM RejectionINA210-0.3V to +26V35µV60µV100µV0.1µV/°C50, 75, 100,200, 5000.9%10ppm/°CHighPerformanceLMP8645-2V to +42V1000µV7µV/°CAdjustable2%140ppm/°CHighBandwidthLow-side Current SensingDeviceVCMRangeVOSVOSDriftGainGain ErrorGain Error DriftCommentINA210-0.3V to +26V35µV60µV100µV0.1µV/°C50, 75, 100,200, 5000.9%
10ppm/°C
High
Performance
INA199
–0.3V to +26V
150µV
0.1µV/°C
50, 100, 200
1.40%
10ppm/°C
Low-cost
INA301
0V to +36V
35µV
0.1µV/°C
20, 50, 100
0.10%
10ppm/°C
Fast
Comparator
INA302
0V to +36V
35µV
0.1µV/°C
20, 50, 100
0.10%
10ppm/°C
Warning/
Shutdown
TI
solutions
for
embedded DC-DC power
Current measurement in Embedded DC-DC
9
System
Power
12VDC
Current Feedback
Sense
Resistor
High-side
current sensing
(system power)
High-side
current sensing (phase power)
Single-
ph
DC-DC
FETs
Load
Vout
Low-side current sensing
System benefits gained from using INA240
Part of the feedback control loop for DC-DC controllers
High accuracy current measurement
Enables smaller sense resistor value which lowers overall system power dissipationSlide10
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