Low voltage current source/start-up circuit

Details Low voltage current source/start-up circuit Low voltage current source/start-up circuit

1988-03-28

1989-06-06

Salce, Patrick R.

Electricity: power supply or regulation systems

Self-regulating

Using a three or more terminal semiconductive device as the...

323316, G05F 320

Patent

active

048374962

ABSTRACT:
A start-up circuit/current source includes a first current path including serially connected first field effect transistor, first resistor, first bipolar transistor, and second resistor. A second current path includes a second field effect transistor, a second bipolar transistor, and a third resistor. The base electrodes of the first and second bipolar transistors are interconnected, and the base and collector of the second bipolar transistor are shorted together. A first current source includes a bipolar transistor serially connected through the third resistor, the base of the third bipolar transistor connected to the first current path. A second current source can be provided including a fourth bipolar transistor serially connected with a fourth resistor and with the base of the fourth transistor connected to a common terminal of the first resistor and first bipolar transistor. The two field effect transistors can be replaced by two equal resistors or by a single field effect transistor serially connected with a two-collector PNP bipolar transistor which provides the equal currents for the two current paths. The current source is independent of supply voltage and the magnitude of the currents in the two current paths so long as the currents are equal. Accordingly, the circuit is independent of poorly-controlled currents in field effect transistors so long as the currents are equal.

REFERENCES:
patent: 3835410 (1974-09-01), Wittlinger
patent: 3930172 (1975-12-01), Dobkin
patent: 4308496 (1981-12-01), Nagano
patent: 4352057 (1982-09-01), Okada et al.
patent: 4370608 (1983-01-01), Nagano et al.
patent: 4399399 (1983-08-01), Joseph
patent: 4525682 (1985-06-01), Lai et al.
patent: 4563632 (1986-01-01), Palara et al.
patent: 4574233 (1986-03-01), Taylor
patent: 4578633 (1986-03-01), Aoki
patent: 4733161 (1988-03-01), Kuwahara

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