Design Article
Comment
Rick DeMeis
Automotive Designline contacted the author of this feature about the above ...
High-voltage surge stoppers ensure reliability during power spikes
Alison Steer, Linear Technology Corporation
3/29/2012 3:58 PM EDT
Features and benefits
The LTC4366 and LT4363 share some common features:
Operating range
The LTC4366 operating range extends from 9 to 500+V, enabling extremely high voltage operation using a floating topology. The operational upper voltage is limited only by the availability of high valued resistors and MOSFET ratings. While the device cannot be used for cold crank applications, there are many automotive systems that do not need to be operational during ignition (i.e. infotainment, GPS, etc).
The LT4363 offers a wide operating range (4 to 80V) for continuous operation under cold crank conditions where the battery voltage can be as low as 4V. The surge stopper can also be used as a wide operating range Hot Swap™ controller, and can withstand overvoltage transients greater than 100V if a TVS diode and resistor are used to protect it from exceeding its 100V absolute maximum rating.
Regulated overvoltage protection protects valuable, safety critical electronics downstream from the device. The adjustable well-regulated output clamp voltage provides flexibility to control the clamped voltage level at the output while riding out the transient. For low-voltage applications, this capability eliminates the need for high-voltage rated components downstream, thus saving costs. The LT4363 also offers OV and UV comparator inputs which inhibit auto-retry if the input voltage is outside the range of these adjustable thresholds. Both the surge suppressors offer long cooldown periods between auto-retry. This helps reduce the power dissipated in the external pass FET during faults.
Adjustable fault timer
Both devices offer an adjustable fault timer which limits power dissipation on the pass FET. During a fault condition the surge stopper uses a current source to charge the capacitor on the TIMER pin, providing flexibility to use lower rated SOA MOSFETs.
Fault output indicator
The LT4363 offers a fault output to provide advance warning of impending power-off due to an overvoltage or overcurrent fault condition.
Overcurrent protection
The LT4363 features an adjustable current limit that protects against short circuits or excessive load current. Voltage drop is monitored across an external current sense resistor on the output to protect against overcurrent faults. During an overcurrent event, the GATE pin is regulated to limit the current through this resistor. Charging of the TIMER pin is accelerated with increasing voltage across the MOSFET. This turns the MOSFET off faster, because more power is dissipated during this condition.
Inrush current limiting eliminates current spikes propagating through the MOSFET to the output during power-up by controlling the GATE pin slew rate.
Reverse input protection to -60V
The LT4363 is designed to withstand reverse voltage of up to -60V without damage to itself or the load (using back-to-back FET). This eliminates the need for a blocking diode which causes extra power loss, generates heat, and reduces the available supply voltage range. During cold crank, the extra voltage drop is particularly undesirable.
Low shutdown current (<20 μA) prevents automobile battery from discharging when parked for long periods. Offers additional power savings for improved battery life in portable applications.
Gate sink current
Strong current pull-down (>150mA) on the GATE during a fault ensures fast response time.
-40 to +125C operating range
High temperature rating allows operation in automotive and industrial applications. Military plastic versions to -55C are available.
Target markets
Linear Technology’s surge stopper products are targeted at the automotive, industrial, and avionics markets because of their ability to provide high-voltage front-end protection in a very small package size.
LTC4366 applications include fuel cells, industrial and military systems, and high voltage DC distribution in servers.
LT4363 applications include all automotive, consumer, industrial, avionics, communications, and military applications that operate from a battery or a badly behaving supply.
Surge stopper characteristics
Alison Steer is product marketing manager, Mixed Signal Products, at Linear Technology Corporation.
The LTC4366 and LT4363 share some common features:
Operating range
The LTC4366 operating range extends from 9 to 500+V, enabling extremely high voltage operation using a floating topology. The operational upper voltage is limited only by the availability of high valued resistors and MOSFET ratings. While the device cannot be used for cold crank applications, there are many automotive systems that do not need to be operational during ignition (i.e. infotainment, GPS, etc).
The LT4363 offers a wide operating range (4 to 80V) for continuous operation under cold crank conditions where the battery voltage can be as low as 4V. The surge stopper can also be used as a wide operating range Hot Swap™ controller, and can withstand overvoltage transients greater than 100V if a TVS diode and resistor are used to protect it from exceeding its 100V absolute maximum rating.
Regulated overvoltage protection protects valuable, safety critical electronics downstream from the device. The adjustable well-regulated output clamp voltage provides flexibility to control the clamped voltage level at the output while riding out the transient. For low-voltage applications, this capability eliminates the need for high-voltage rated components downstream, thus saving costs. The LT4363 also offers OV and UV comparator inputs which inhibit auto-retry if the input voltage is outside the range of these adjustable thresholds. Both the surge suppressors offer long cooldown periods between auto-retry. This helps reduce the power dissipated in the external pass FET during faults.
Adjustable fault timer
Both devices offer an adjustable fault timer which limits power dissipation on the pass FET. During a fault condition the surge stopper uses a current source to charge the capacitor on the TIMER pin, providing flexibility to use lower rated SOA MOSFETs.
Fault output indicator
The LT4363 offers a fault output to provide advance warning of impending power-off due to an overvoltage or overcurrent fault condition.
Overcurrent protection
The LT4363 features an adjustable current limit that protects against short circuits or excessive load current. Voltage drop is monitored across an external current sense resistor on the output to protect against overcurrent faults. During an overcurrent event, the GATE pin is regulated to limit the current through this resistor. Charging of the TIMER pin is accelerated with increasing voltage across the MOSFET. This turns the MOSFET off faster, because more power is dissipated during this condition.
Inrush current limiting eliminates current spikes propagating through the MOSFET to the output during power-up by controlling the GATE pin slew rate.
Reverse input protection to -60V
The LT4363 is designed to withstand reverse voltage of up to -60V without damage to itself or the load (using back-to-back FET). This eliminates the need for a blocking diode which causes extra power loss, generates heat, and reduces the available supply voltage range. During cold crank, the extra voltage drop is particularly undesirable.
Low shutdown current (<20 μA) prevents automobile battery from discharging when parked for long periods. Offers additional power savings for improved battery life in portable applications.
Gate sink current
Strong current pull-down (>150mA) on the GATE during a fault ensures fast response time.
-40 to +125C operating range
High temperature rating allows operation in automotive and industrial applications. Military plastic versions to -55C are available.
Target markets
Linear Technology’s surge stopper products are targeted at the automotive, industrial, and avionics markets because of their ability to provide high-voltage front-end protection in a very small package size.
LTC4366 applications include fuel cells, industrial and military systems, and high voltage DC distribution in servers.
LT4363 applications include all automotive, consumer, industrial, avionics, communications, and military applications that operate from a battery or a badly behaving supply.
Surge stopper characteristics
Alison Steer is product marketing manager, Mixed Signal Products, at Linear Technology Corporation.
_____________
If you liked this article, go to the Automotive Designline home page for the latest in automotive electronics design, technology, trends, products, and news. Also, get a weekly highlights update delivered directly to your inbox by signing up for our weekly automotive electronics newsletter here. |
|
|
|
|
Navigate to related information
Rick DeMeis
4/6/2012 4:51 PM EDT
Automotive Designline contacted the author of this feature about the above postings. She and the company stand by the piece as written.
Sign in to Reply