
It’s good to reduce the power dissipated by the device. Using resistor connected in series to the input (the left figure) is a simple and economic method to reduce the device input-output differential voltage. Here’s the formula for calculating R:
R= [Vi min- (Vo+Vdrop)]/Io
Vdrop = minimum differential voltage between the input and the output of the [...]
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The TPS61160/1 is a boost converter that drives up to 10 LEDs in series with a 40-V rated integrated switch FET. To reduce output ripple, improve convertion efficiency, and allows for the use of small external component, the boost converter is very usefull. The default white LED current is set with the external sensor resistor [...]
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Simplicity, low cost and improved efficiency when compared with the alternative options are the reasons why the switchstart circuit has been widely adopted. Moreover, the 230V mains voltage is sufficiently higher than tube running voltage to let the use of the simple series impedance ballast in almost every case. Where the mains voltage is not [...]
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For the best advantage as a low noise high input impedance device, the preamp and tone control uses JFET. If the circuit reaches harmonic distortion levels of less than 0.05% with a S/N ratio of over 85 dB, all device parameters are non-critical. 18 dB of cut and boost is allowed by the tone controls. [...]
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On the circuit diagram, R1 is used to senses current flow of a power supply. We could use JFET as a buffer because Id=Is, therefore the power supply current flow is accurately reflected by the output monitor.
Here’s the circuit diagram:
[Source: National Semiconductor Application Note]
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To reach low channel ON resistance (<30 Ohm) and low OFF current leakage, 4-channel commutator uses the 2N4091. The DM7800 voltage translator is a monolithic device. This device give us +10V to -20V gate drive to the JFETs while at the same time giving DTL-TTL logic compatibility.
Here’s the circuit diagram:
[Source: National Semiconductor Application Note]
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