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highpowerZONE Products for the week of October 6, 2008
Fairchild Semiconductor Says…
FAN7387: High-Voltage Gate Driver Simplifies Ballast, SMPS and Half-Bridge Inverter Applications
Industry’s Only HVIC with External Pin for Dead-Time Control
Fairchild Semiconductor provides designers with another high performance, design-flexible and low power solution for ballast, SMPS and half-bridge inverter designs with its self-oscillating, high-voltage gate driver. The FAN7387 is the industry’s only high-voltage gate driver (HVIC) with an external pin for dead-time control, providing engineers with excellent design flexibility. This HVIC is designed with an innovative noise canceling technique and features high-side driver operation with negative Vs swings up to -9.8V. This feature protects the IC from negative noise and makes it more noise immune. Alternate solutions must use an additional diode to achieve this same robust protection.
All of Fairchild’s HVICs, including the FAN7387, offer significant power savings due to their low quiescent current (220µA) resulting in low power consumption in standby mode. This HVIC also provides stable performance through its low temperature dependency and excellent system reliability over a wide range of operating conditions.
EN-Genius Says…
The neat thing about this FAN7387 from Fairchild is the flexibility it delivers to a variety of circuit applications. You can literally use it as a tool box for that SMPS you need to put together in a hurry, or use a pair of them as a full-bridge converter, or use the dead-time control pin feature for a fluorescent lamp or HID ballast. In each case the power delivered can be scaled by your choice of the external MOSFETs.
The dead-time control is, I believe, unique and can be implemented with a feedback from a resistive divider across the map load.
The part has undervoltage lockout, shutdown (using the same pin as the dead-time control), and some noise cancellation. The synchronization can be performed either externally or by using the internal clock and frequency divider – the frequency of which can be controlled externally with a set resistor and capacitor.
The maximum high-side offset voltage can be 600 V, with the floating supply voltage 14 V higher. The supply voltage (low-side voltage in Fairchild parlance) for the IC is between 11 V and 14 V with a typical quiescent current of 220 µA.
The extreme values for setting the on-chip clock are for the resistor to be a minimum of 2 kΩ and for the capacitor to be a minimum of 100 pF. With 40 kΩ and 330 pF the nominal frequency is 20 kHz; with 1 kΩ and 1 nF it is 250 kHz.
I always like parts where the applications can be scaled. The FAN7387 is one of those parts that when you have used it once you will come back to it time and time again for your succeeding jobs at differing power levels. It will be a huge money maker and is priced to attract attention.
The FAN7387 is in production in Pb-free DIP-8 and SOP-8, priced at $1.20 in 100-piece lots.
Data Sheet
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