![]() or average (peak value) > 1 MHz Total power dissipation at Tmb = 25 ☌ > 1 MHz Storage temperature Operating junction temperature Ptot Tstg Tj IC ICM VCBOM VCEO VEBO RATINGS Limiting values in accordance with the Absolute Maximum System (IEC 134) Collector-base voltage (open emitter) peak value Collector-emitter voltage (open base) Emitter-base voltage (open collector) Collector current d.c. The device is entirely safe provided that the BeO disc is not damaged. PRODUCT SAFETY This device incorporates beryllium oxide, the dust of which is toxic. PINNING PIN 1 DESCRIPTION emitter base collector emitter performance in a common-emitter class-B circuit MODE OF OPERATION narrow band c.w. The transistor has a 6-lead flange envelope with a ceramic cap. gold metallization ensures excellent reliability. internal matching to achieve an optimum wideband capability and high power gain. FEATURES multi-base structure and emitter-ballasting resistors for an optimum temperature profile. The base-emitter junction would always be forward biased whatever you put at the microcontroller pin, bcoz of same reason stated above.ġ) Use an NPN transistor and common cathode displays.Ģ) Provide 5V supply to the displays if possible (preferred solution)ģ) Go for a two transistor circuit involving an NPN transistor as first stage switching the PNP in the second stageĤ) Use ULN2803 in between display and microcontoller, with supply voltage of 12V for ULN2803.DESCRIPTION N-P-N silicon planar epitaxial transistor in SOT-119 envelope primarily intended for use in mobile radio transmitters in the 470 MHz communications band. So they turn ON dim.Īgain, another problem you may face is that, you won't be able to turn off the transistor with the microcontroller. Effectively, the leds turn on at the difference voltage of 7V (12-5=7V). Now what you have done is that the common anode of the leds is connected to 12V and the cathodes(of leds which you wish to be OFF) to 5V. Since you are connecting the cathodes to a microcontroller, you put a logic high on those pins which corresponds to 5V. Now think about the segments you tried to turn OFF. You supply 0V at the cathode pins of the segments you need to turn ON, here the pins are: A,B,C,D & E. What you provide at the common anode through the transistor is 12V. You have used BC557 which is a PNP transistor, so I infer you have used common anode displays.Īssume you need to display '3'. ![]()
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