ch7 protect high side drivers
TRANSCRIPT
![Page 1: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/1.jpg)
Bridging Theory in PracticeTransferring Technical Knowledgeto Practical Applications
![Page 2: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/2.jpg)
Protected High Side Drivers
![Page 3: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/3.jpg)
Protected High Side DriversOvervoltage
ProtectionPower Stage
TemperatureSensor
CurrentControl
ChargePump
OvervoltageLogic
ESDProtection
OvervoltageProtection
Logic
Power OutputStage
![Page 4: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/4.jpg)
Intended Audience:• Electrical engineers with a knowledge of simple electrical circuits• An understanding of MOSFETs and high side drivers is assumed
Topics Covered:• What is a PROFET?• What type of protection does a PROFET have?• What type of diagnostics does a PROFET have?• How does a PROFET impact system EMI?• How is a PROFET circuit implemented?• PROFET Selection Questions
Expected Time: • Approximately 90 Minutes
Protected High Side Drivers
![Page 5: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/5.jpg)
Protected High Side Drivers
• Introduction to PROFETs
• PROFET Protection Features
• PROFET Diagnostic Features
• EMI/EMC Considerations
• System Implementation
• Frequently Asked Questions
![Page 6: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/6.jpg)
D
S
G
N-ChannelMOSFET
( Enhancement) (
MOSFET Metal Oxide Semiconductor Field Effect Transistor
VGS
VSG
n+
p+
n+
p+
n+
n-
GateSource Source
Drain
P-ChannelMOSFET
(Enhancement)
MOSFET Review
G
D
S
GS
D
![Page 7: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/7.jpg)
MOSFETRegions of Operation
• A positive (for N-Channel) or negative (for P-Channel) VGS produces a conducting channel between the Drain and Source
• The MOSFET is then able to operate in two regions:– 1) Linear region: The MOSFET behaves like a resistance.– 2) Saturation region: The MOSFET behaves like a current source.
VGS > 0V
N-ChannelMOSFET(NMOS)
IDS
VDS
VG
S i
ncr
ease
s
VDS = VGS-VT
![Page 8: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/8.jpg)
High Side Drive (HSD) Configuration
14V
Load
MOSFETSwitch
The switch is on the “HIGH”side of the load
To turn on the HSD, the MOSFETgate is pulled high
14V
But, the maximum voltage at theMOSFET source is VG - VT
VS ~ 13V
The low value of VGS translatesinto a small ILOAD (saturation region)
ILOAD
VGS ~ 1V
![Page 9: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/9.jpg)
High Side Drive (HSD)Configuration
14V
Load
MOSFETSwitch
The switch is on the “HIGH”side of the load
To turn on the HSD, the MOSFETgate is pulled high
26V
The source voltage is now approximately Vsupply
VS ~ 14V
If the MOSFET gate is pulled toa higher voltage…
The high value of VGS translatesinto a large value of ILOAD
(linear region)
ILOAD
VGS ~ 14V
![Page 10: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/10.jpg)
PROFETs = PROtected FETs
PROFET
MOSFETDiagnostics
Short CircuitProtection
IntegratedCharge Pump
OverVoltage
Protection
Current Limit
OverTemperature
Protection
ReverseBattery
Protection
![Page 11: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/11.jpg)
Voltage Controlled PROFET Block DiagramVoltage Controlled
IN
![Page 12: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/12.jpg)
Current Controlled PROFET Block DiagramCurrent Controlled
IN
IIN
Current Controlled PROFET Block DiagramCurrent Controlled
![Page 13: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/13.jpg)
Introduction to PROFETs
• Introduction to PROFETs
• PROFET Protection Features
• PROFET Diagnostic Features
• EMI/EMC Considerations
• System Implementation
• Frequently Asked Questions
![Page 14: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/14.jpg)
Rugged vs. ProtectedRugged
• MOSFETs• Achieved through
process & manufacturing technology
• Protection Not Built in
Protected • PROFETs• Achieved through design and
utilization of more advanced integrated circuit technologies
• Available CMOS, DMOS and Bipolar devices allow for the integration of ESD protection, active clamping, current limit, temperature sensing, etc.
• Protection Built in
Protected • PROFETs• Achieved through design and
utilization of more advanced integrated circuit technologies
• Available CMOS, DMOS and Bipolar devices allow for the integration of ESD protection, active clamping, current limit, temperature sensing, etc.
• Protection Built in
Protected • PROFETs• Achieved through design and
utilization of more advanced integrated circuit technologies
• Available CMOS, DMOS and Bipolar devices allow for the integration of ESD protection, active clamping, current limit, temperature sensing, etc.
• Protection Built in
![Page 15: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/15.jpg)
PROtected FET (PROFET)Protection Features• Electrostatic Discharge (ESD) Protection• Overvoltage / Load Dump Protection• Overvoltage Shutdown Protection and Restart• Undervoltage Shutdown Protection and Restart• Reverse Battery Protection• Reversave™ Battery Protection• Inductive and Overvoltage Output Clamp Protection• Thermal Shutdown Protection• Current Limit Protection• Short Circuit Shutdown Protection• Inversave™ Inverse Current Protection• Loss of Ground Protection• Loss of Supply Voltage Protection
![Page 16: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/16.jpg)
Block Diagram Including Protection Features
![Page 17: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/17.jpg)
ESD Protection
![Page 18: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/18.jpg)
Overvoltage Protection
VAZ
![Page 19: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/19.jpg)
Overvoltage Shutdown Protection and Restart
![Page 20: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/20.jpg)
Undervoltage Shutdown Protection and Restart
![Page 21: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/21.jpg)
Load Dump Protection
• The rated load dump voltage is a function of the generator impedance (RG) and the load resistance (RL)
• As RG and RL increase, less energy is dissipated in the PROFET, and the maximum allowable load dump voltage increases
![Page 22: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/22.jpg)
4) The over temperature protection is not active during reverse current operation!
The PROFET will requires a 150 resistor in the GND connection to limit the reverse supply current.
Reverse Battery Protection
![Page 23: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/23.jpg)
4) The temperature protection is not active during reverse current operation!
Reverse Battery Protection
The reverse load current through the intrinsic drain- source diode has to be limited by the connected load. Power dissipation is higher compared to normal operating conditions due to the voltage drop across the drain-source diode.
![Page 24: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/24.jpg)
4) The temperature protection is not active during reverse current operation!
Reverse Battery Protection
PROFETs with ReverSaveTM
protection overcome thisproblem…
![Page 25: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/25.jpg)
Rbb
ReverSave™ Reverse Battery Protection
In PROFETs with ReverSaveTM protection, the MOSFET is turned on by the voltage drop across the resistor Rbb.
With the MOSFET conductingthe reverse load current (instead of the intrinsic diode), the power dissipation is greatly reduced under reverse batteryconditions.
![Page 26: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/26.jpg)
Inductive and Overvoltage Output Clamp Protection
![Page 27: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/27.jpg)
Thermal Shutdown Protection
A B C D E
InputVoltage
LoadCurrent
JunctionTemperature
F
![Page 28: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/28.jpg)
Current Limit Protection
IL(SCr)
IL(SCp)
![Page 29: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/29.jpg)
Short CircuitShutdown Protection
VON(SC)
![Page 30: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/30.jpg)
Short CircuitShutdown Protection
![Page 31: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/31.jpg)
Inversave™ Inverse Current Protection
Devices with Inversave™ can be operatedin inverse current mode.
When the device is off, only the intrinsic diode conducts with high power dissipation.
When device on, MOSFET turns on forlower power dissipation.
![Page 32: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/32.jpg)
Loss of Ground Protection• With Loss of Ground Protection, Vbb, VIN, and VST are still
referenced to ground through the output• This ensures the device will be safely shut off if the ground pin
is opened
![Page 33: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/33.jpg)
Loss of Supply Voltage Protection• All PROFETs are protected against a loss of supply voltage for
non-inductive loads• Most PROFETs are also protected against a loss of supply
voltage for inductive loads by handling the recirculation current through the GND pin
I
VOUT goes negative
![Page 34: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/34.jpg)
Introduction to PROFETs
• Introduction to PROFETs
• PROFET Protection Features
• PROFET Diagnostic Features
• EMI/EMC Considerations
• System Implementation
• Frequently Asked Questions
![Page 35: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/35.jpg)
PROFET Diagnostic Feedback Digital vs. Analog
ISTATUS
GND
STATUS
![Page 36: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/36.jpg)
Digital Diagnostic Feedback• The type of fault is determined by a diagnostic truth table
Normal Operation
Short Circuit to GND
Short Circuit to Vbb
Overcurrent
Overtemperature
Open Load
Input
L
H
L
H
L
H
L
H
L
H
LH
Output
L
H
L
L
H
H
L
H
L
L
HH
Status
L
L
L
H
H
L
L
L
L
H
HL
14V
Load
PROFET
Input
StatusOutput
![Page 37: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/37.jpg)
Analog Diagnostic Feedback• The type of fault is determined by a diagnostic truth
table AND a sense ratio parameter14V
Load
PROFET
Input
IIS
OutputRIS
Normal
Operation
Overcurrent
Short Circuit
to Ground
Overtemperature
Short Circuit
to Vbb
Open Load
Input
Current
L
H
L
H
L
H
L
H
L
H
L
H
Output
Voltage
L
H
L
H
L
L
L
L
H
H
Z
H
Current
IIS
IIS(LL)
nominal
IIS(LL)
IIS,FAULT
IIS(LL)
IIS,FAULT
IIS(LL)
IIS,FAULT
IIS(LL)
< nominal
IIS(LL)
IIS(LH)
![Page 38: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/38.jpg)
Analog Load Current FeedbackVia IIS Current
• Under normal operation, IIS is proportional to the output current
• KILIS = IL / IIS ~ 10,000
• For example:IL = 25A
IIS ~ 2.5mA
![Page 39: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/39.jpg)
IIS Current Sense Ratio• The accuracy of IIS improves with increasing output current
KILIS
(IL / IIS)
![Page 40: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/40.jpg)
IIS Current Sense Ratio
• The accuracy of IIS improves with increasing output current
Less Accurate
More Accurate
![Page 41: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/41.jpg)
Status Signal Settling Time
• The Status signal is not valid during a settling time after turn-on, turn-off, or after change of load current
• This is true of PROFETs with analog or digital diagnostic feedback
![Page 42: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/42.jpg)
Open Load DetectionThree Different PROFET strategies
• Open load detection via Sense pin on HiC (High Current) PROFETs and some PROFETs
• Open load detection while PROFET is turned on (for some PROFETS---mostly older types)
• Open load detection while PROFET is turned off (for most PROFETs---mainly newer types)
![Page 43: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/43.jpg)
Open Load Detection – Via Sense Pin
Under an open load condition,the PROFET will maintain IIS below 1A (maximum).
CurrentSense
![Page 44: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/44.jpg)
Open Load Detection – PROFET On
An open load is detected if the PROFET is on and the voltage across the MOSFET is
VON < RdsonIL(OL)
![Page 45: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/45.jpg)
Open Load Detection - PROFET Off
Using an external resistor, an open load is identified if the PROFET is turned off and VOUT > 3.2V (typ.)
![Page 46: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/46.jpg)
Introduction to PROFETs
• Introduction to PROFETs
• PROFET Protection Features
• PROFET Diagnostic Features
• EMI/EMC Considerations
• System Implementation
• Frequently Asked Questions
![Page 47: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/47.jpg)
MOSFET High Side Drive
• Recall, the gate of the N-Channel MOSFET must be at a voltage higher than the transistor’s source to turn the MOSFET on:
• With VSUPPLY being the highest voltage in the system, where does VGATE come from?
14V
Load
MOSFETSwitch
26V
VS ~ 14V
ILOAD
VGS ~ 12V
![Page 48: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/48.jpg)
Charge Pump Gate Voltage• A charge pump is used to raise (pump) the gate
voltage to an acceptable level to turn on the MOSFET
Switch B
Switch A
DADB
CACB
VSUPPLY
VOUT
![Page 49: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/49.jpg)
Charge Pump Gate Voltage
• Initially, Switch A is closed, and CA is charged to VSUPPLY - VDA
Switch B
Switch A
DADB
CACB
VOUT
VSUPPLY = 14V
~13V
![Page 50: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/50.jpg)
Charge Pump Gate Voltage
• Next, Switch B is closed, and current flows from CA, through DB to charge CB
Switch B
Switch A
DADB
CACB
VOUT
VSUPPLY = 14V
~13V
![Page 51: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/51.jpg)
Charge Pump Gate Voltage
• But, CA acts like a battery in series with VSUPPLY
Switch B
Switch A
DADB
CACB
VOUT
ReverseBiased
VSUPPLY = 14V
~13V
~27V
~26V
![Page 52: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/52.jpg)
• Now, the High Side Drive MOSFET can be turned on
• The turning on and off of Switch A and Switch B, however, leads to a new problem….
MOSFET High Side Drive
14V
Load
MOSFETSwitch
26V
VS ~ 14V
ILOAD
VGS ~ 12V
![Page 53: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/53.jpg)
Charge Pump Electromagnetic Interference (EMI)
Frequency (MHz)
0
20
40
60
80
100
120
0.1 1 10 100 1000
LW
M
KW
UKW
dBV
0
20
40
60
80
100
120
1.0 10 1000.1
Charge pumpscan cause harmonic
emissions
![Page 54: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/54.jpg)
0
20
40
60
80
100
120
LW
MW
KW
UKW
Frequency (MHz)
dBV
0
20
40
60
80
100
120
1.0 10 1000.1
Newer, improved design reduces emissions
20 - 30 dB
PROFET’s Improved Charge Pump Reduces (EMI)
![Page 55: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/55.jpg)
0
20
40
60
80
100
120
0.1 1 10 100 1000
Frequency [MHz]
dBµV
BTS 736 L2ESG1
ESG2ESG3ESG4
ESG5 (DB)BMW
LW
M
KW
UKW
0
20
40
60
80
100
120
0.1 1 10 100 1000
Frequency [MHz]
dBµV
BTS 736 L2
ESG1ESG2ESG3ESG4
ESG5 (DB)BMW
LW
M
KW
UKW
Filter solutions may be required for the charge pump
Vbb
IN
OUT
GND150
GND
load
BTS736
CEMI
Vbb
IN
OUT
GND
load
BTS736
CEMI
Filtering - RC 150/4.7nF Filtering - C= 2µF
Continuous charge pump emissionContinuous charge pump emission
![Page 56: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/56.jpg)
EMI/EMC Emissions due to PWM Operation• One source of EMI/EMC emissions is the internal charge pump as
shown on previous slides
• The other source of emissions can be PWM operation
• During PWM operation the slew rate and shape of the output voltage and current waveforms cause an increase in the emission spectra
• For slow switching applications (most Profets used at 100Hz) this results in an increase of the emission spectra below approximately 1Mhz.
![Page 57: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/57.jpg)
Benefits of Edge Shaping• Edge shaping allows to reduce emission levels while maintaining a
slew rate which still allows for permissible power loss levels
Slew rate
control
Slew control only
Theoretical ideal
100%
90%
10%
0%
Edge shaping
Edge shaping
Turn off edge shaping
![Page 58: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/58.jpg)
Hi-Current Profet---EMC improvements• BTS650-Original Hi-current design with slew rate control only.• BTS6510-Same as BTS650 with longer switching times• BTS443P-Second generation with edge shaping for current turn off• BTS6143/44-Third generation with edge shaping for current turn on and offOperating point: Vs=13.5V, ILoad =5A, fs = 100Hz, resistive load
Emission Spectra:
Ten
denc
y
0
10
20
30
40
50
60
70
80
90
100
110
120
0.1 1 10 100 1000
f / MHz
dB
µV
BTS650
BTS6510
BTS443
BTS6144P
Noise
Class 1 P
Class 2 P
Class 3 P
Class 4 P
Class 5 P
BMW
Device: BTS650 / BTS6510 / . BTS443 / BTS6144P0 / . BTS6144PLoad: 60W BulbO-Mode: PWM 100HzDetector: Peak
BTS 650 vs. BTS6510 vs. BTS 443 vs. BTS6144
![Page 59: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/59.jpg)
Introduction to PROFETs
• Introduction to PROFETs
• PROFET Protection Features
• PROFET Diagnostic Features
• EMI/EMC Considerations
• System Implementation
• Frequently Asked Questions
![Page 60: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/60.jpg)
Overvoltage Protection of Logic Functional Block
• RGND required to limit current through DAZ
• RST required to protect microcontroller input pin
• RIN may be required to protect microcontroller output pin
RST
RINVAZ
RGND
![Page 61: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/61.jpg)
Reverse Battery Protection• RGND required to limit current through logic zener diode
• RST required to protect microcontroller input pin
• RIN may be required to protect microcontroller output pin
• RL must limit current through power inverse diode
RST
RGND
RIN
RL
![Page 62: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/62.jpg)
Reverse battery—Power Dissipation• Power dissipation during reverse battery can be higher than
normal operation due to conduction of load current through the FET body diode
• For example:– 3A load with 100mohm Fet in normal mode gives 0.9W– 3A load thru body diode in reverse battery gives 2.1W (3A*0.7V)
• The discrepancy between normal mode dissipation and reverse battery dissipation becomes worse as load current becomes higher
• Care must be take to control this dissipation to safe levels since over temperature protection is not active during reverse battery.
• This leads us to a feature where the MOSFET channel can be turned on during reverse battery operation---ReverSave
![Page 63: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/63.jpg)
ReverSave™ Reverse Battery Protection Circuitry
• About 100mA of current must flow through the Rbb (from the IN or STATUS pins) to turn on the MOSFET in inverse mode
• Currents above 100mA in Rbb may create excessive power dissipation. Add RIN to limit
current below 100mA
![Page 64: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/64.jpg)
IS Pin Overvoltage Protection• Overvoltage conditions greater than 67V (typ) can cause the IS pin to
exceed 5V - damaging a microcontroller input pin• The IS pin can be clamped by an external diode if necessary
![Page 65: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/65.jpg)
Introduction to PROFETs
• Introduction to PROFETs
• PROFET Protection Features
• PROFET Diagnostic Features
• EMI/EMC Considerations
• System Implementation
• Frequently Asked Questions
![Page 66: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/66.jpg)
PROFET Selection: Customer Questions
• How many channels?• What is the load current?• Is the load capacitive and what is the inrush current?• Is the load inductive and the inductance and/or energy during turn-off?• Will load be on/off or PWM? What is PWM frequency?• What is ambient temperature?• What type of package - surface mount or through-hole?• If surface mount, how much copper area for Vbb / tab connection?
• If through-hole, what type of heatsink will be provided for package?• What diagnostics are needed?• What application extremes will the device / system be subjected to
(reverse battery, load dump, overvoltage etc.)?
![Page 67: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/67.jpg)
What Is the Load Current?• What is the maximum load current?• When does the maximum occur?• What is the typical load current?
• Alternative Question: What is the load resistance?
• Alternative Question: If the load is a lamp, what is it’s wattage?
• Recall, the load current is fundamental in determining an appropriate PROFET Rdson value
![Page 68: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/68.jpg)
500mA
5.5A
Is the Load Capacitive?What Is the In-rush Current?
• Recall, the in rush current for lamps and RC networks may be an order of magnitude higher than the steady state current
![Page 69: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/69.jpg)
What Is Load Inductance or Energy During Turn-Off?
• FETs are rated for the max absorbable energy when turning off inductive loads
![Page 70: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/70.jpg)
Will the Load Be On/Off or PWM? What is PWM frequency?
• PROFETs are often used in applications where the load is pulse width modulated – especially lighting applications
![Page 71: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/71.jpg)
PWM Definitions• Frequency-(frequency domain) What is the rate of repetition of
a waveform?• Duty cycle-(Time domain) What is the amount of time spent on
with respect to the amount of time spent off?
T0 T1 T2 T3 T4
I0
I1
Period
Ton Toff
Frequency= 1/Period
Duty Cycle = Ton/(Ton+Toff)
Period = Ton + Toff
![Page 72: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/72.jpg)
What Is the Ambient Temperature?• Minimum ambient temperatures is usually -40C
• Maximum ambient temperature ranges from 85C to 125C for most applications:
85C for most non-powertrain applications105C for some in-dashboard applications125C for most powertrain applications
![Page 73: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/73.jpg)
What Type of Package?Surface Mount or Through-hole?• Many applications require all surface mount
components
• Surface mount components typically only have excess copper board space heatsinks
• Through-hole components can have large heatsinks for improved power dissipation
![Page 74: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/74.jpg)
If Surface Mount - How Much Board Area Is Available for Heatsinks?
• Engineers must trade-off the cost and size of the heatsink vs. the Rdson (and hence, the cost) of the PROFET
![Page 75: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/75.jpg)
Introduction to PROFETs
• Introduction to PROFETs
• PROFET Protection Features
• PROFET Diagnostic Features
• EMI/EMC Considerations
• System Implementation
• Frequently Asked Questions
![Page 76: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/76.jpg)
Introduction to PROFETsOvervoltage
ProtectionPower Stage
TemperatureSensor
CurrentControl
ChargePump
OvervoltageLogic
ESDProtection
OvervoltageProtection
Logic
Power OutputStage
![Page 77: Ch7 Protect High Side Drivers](https://reader036.vdocuments.site/reader036/viewer/2022081400/553282684a7959394b8b4669/html5/thumbnails/77.jpg)
Thank You!www.btipnow.com