TO PROTECT electronic systems that must cope with high-voltage surges of short duration, such as load dump in automobiles, Linear Technology Corporation has released an overvoltage protection regulator with overcurrent protection and inrush current limiting. The LT4356 provides solid front-end protection for valuable, safety-critical downstream components. The wide input operating range of 4 V to 80 V enables continuous operation during cold crank conditions where the battery voltage can be as low as 4 V. With its high input voltage rating, the LT4356 can handle transient voltages of 100 V and higher, and provides reverse input protection to-30 V without damage to itself or the load. Consequently, the LT4356 lends itself well to automotive, industrial and avionics applications, as well as positive high-voltage distributed power hot swap systems.
Designed to replace complicated and bulky protection circuitry with a simple IC and FET solution, it provides a well-regulated output during an overvoltage transient, allowing continued operation through the event. The output voltage is adjustable with 2% accuracy over the operating temperature range of the device. According to the manufacturer, front-end protection permits the use of lower-cost dc-dc regulators downstream. During an overvoltage event, the LT4356 regulates the output to a user-defined voltage by controlling the gate of an external n-channel MOSFET. Inrush current limiting is achieved by controlling the voltage slew rate of the gate. The LT4356 monitors voltage drop across a current sense resistor at the input of the circuit to protect against overcurrent faults. For either an overvoltage or overcurrent fault condition, an integrated fault timer ensures safe shutdown of the MOSFET if the fault persists.
An auxiliary amplifier is provided for additional design flexibility. It may be used as a voltage-detection comparator or a low drop-out (LDO) linear regulator controller. The LT4356 is available in two options defined by the function of the shutdown pin. For the LT4356-1, shutdown of the IC reduces the quiescent current to 5 ¼A. For the LT4356-2, the auxiliary amplifier and internal reference remain active to ensure a keep-alive supply voltage for vital functions while the main system is shutdown. Quiescent current is reduced to 50 µA during shutdown. Specified over the full commercial, industrial and automotive temperature ranges, the LT4356 is offered in (4 mm × 3 mm) 12-pin DFN and 10-pin MSOP packages. Evaluation kits are available from the factory. Pricing for the automotive-grade part is $2.59, in 1,000-piece quantities.
Linear Technology Corporation
NVIS COMPLIANCE FOR LED-BACKLIT TFT LCDS >
Apollo Display Technologies has developed an innovative, more efficient and more cost-effective way to make LED-backlit TFT LCDs compatible with night-vision imaging systems (NVIS).
Apollo can furnish VGA and XGA resolution TFT LCDs backlit by LED rails that are addressable via the company's standard PRISMA II industrial controller board to switch back and forth between day and night mode. Eliminated are the cumbersome and expensive filters--large glass overlays bonded to the outside of the display — that have been previously used.
These LCDs can be used in the full range of NVIS applications, including displays in military aircraft cockpits, tanks, trucks, ground mobile applications, communications equipment, electronics and a broad range of other applications.
A key to Apollo's approach is its addressable LED rails. Apollo's LED rails have separate day and night mode functions built into them.
Two versions are available: NVIS A for upper-echelon applications and NVIS B for applications with less stringent requirements. Apollo has produced an 8.4-inch diagonal NVIS-compatible LCD, which will be scalable up to 15 inches diagonal. All LCDs are fully ROHS-compliant.
Apollo Display Technologies • (631) 580-4360 • www.apollodisplays.com
POWER DEVICES FOR ENGINE CONTROL
As alternatives to ASICs in engine control applications, Freescale Semiconductor has unleashed six SMARTMOS analog/power products. Tailored for high-current powertrain applications, it includes two output drivers, two signal monitoring and conditioning devices, and two H-bridges. These devices can be mixed and matched with 32-bit MPC55xx power architecture microcontrollers (MCUs), to support a variety of multicylinder engine control applications.
While the MC33800 is a 16-channel, multifunction output driver featuring eight low-side drivers, six FET pre-drivers and two constant current low-side drivers, the MC33810 low-side driver provides a programmable interface between the engine control MCU and the spark ignition and fuel injection functions of a gas engine. Called a “Swiss Army knife,” the MC33800 is designed to control relays, motors, solenoids, lamps, valves and heated exhaust gas oxygen sensors. The device is also suited for electronic power steering, four-wheel drive control, and industrial and commercial control systems requiring low-side drivers with diagnostic reporting and fault protection.
The MC33810 scales for various numbers of engine cylinders. The device integrates four low-side drivers and four PWM-capable pre-drivers that can be configured to drive fuel injectors, solenoids, external FETs or IGBTs. The MC33810 reduces the number of components in an engine control unit, reducing its size, cost and complexity.
On the signal monitoring and conditioning front, the MC33811 is a five-channel solenoid-monitoring device used to determine the correct operation of a solenoid. The device determines whether there is a problem with a solenoid opening and closing by monitoring the profile of the solenoid's current waveform.
Likewise, the MC33899 and MC33926 devices are monolithic H-bridge power ICs designed for electronic throttle control and low-voltage dc servo motor control applications.
These devices are supported by evaluation boards and a USB to SPI interface board. Per unit pricing for the devices, in 10,000-piece quantities, is: MC33800 16-channel output driver at $2.40; MC33810 eight-channel ignition and injector driver at $2.28; MC33811 five-channel solenoid monitor at $1.20; MC33899 programmable H-bridge motor driver at $3.29; MC33926 throttle control H-bridge at $2.03; and MC33975 22-channel multiple switch detection interface at $1.91.
RTD FOR HARSH ENVIRONMENTS
Measurement Specialties has a temperature sensor that is for use in harsh environments, the Ni1000SOT. This nickel thin-film resistance temperature detector is constructed for use in contact temperature sensing. It is compliant with former DIN 43760, which defines temperature profile and tolerance class for nickel-based temperature sensors. The Ni1000SOT sensor is qualified for demanding automotive applications.
The Ni1000SOT is manufactured by PVD-deposition on a silicon substrate. The thin-film structure is covered by a passivation layer for environmental protection and enhanced stability. The nickel elements are mounted on lead frames and encapsulated in SOT23 packages. Key features include resistance of 1000 V at 0 °C, min/max temperature range of -55 °C to +160 °C, good linearity between resistance and temperature, and large temperature coefficient of resistance (TCR) of 6178 ppm/K (measured at 0 °C, 100 °C), plus, low power consumption.
(937) 427-1231 ext 388