Abstract: A method and circuit for producing an output current is provided. The method and circuit adds two currents with opposing temperature coefficients to produce such output current. A first one of the two currents, I.sub.1, is a scaled copy of current produced in a temperature compensated bandgap reference circuit. A second one of the two currents, I.sub.2, is derived from a temperature stable voltage produced by the bandgap circuit divided by a positive temperature coefficient resistance. The added currents, I.sub.1 +I.sub.2, provide the output current. The circuit includes a first circuit for producing: (i) a reference current having a positive temperature coefficient; and (ii) an output voltage at an output node substantially insensitive to variations in supply voltage and temperature over a predetermined range. The current source includes a second circuit connected to the output node for producing a first current derived from the bandgap reference current.

Abstract: Power-on detection circuitry with almost instantaneous response to a power-off condition includes a network of several transistors (30, 32, 38, 40) and a resistor (34). When a supply voltage (+VCC) used with the circuitry is first turned on, the network produces at an output (terminal 52) a short pulse which is subsequently used to generate a power-on (PWRON) signal (line 24) to reset or initialize circuit elements termed "latches" (14). The latches (14) in turn provide operating information to other (main) circuits (16). A reverse coupled diode-connected transistor (30) is provided to shunt to ground charge stored in parasitic capacitance (36) at an input (terminal 50) when power is interrupted, such as by a sudden negative voltage transient. This shunting action of the diode-connected transistor (30) virtually instantly brings the voltage at the input down almost to zero so that whenever power comes back on another short pulse at the output is sure to be generated.