SLVS074I January 1983 – July 2022 TL494
PRODUCTION DATA
Both high-gain error amplifiers receive their bias from the VI supply rail. This permits a common-mode input voltage range from –0.3 V to 2 V less than VI. Both amplifiers behave characteristically of a single-ended single-supply amplifier, in that each output is active high only. This allows each amplifier to pull up independently for a decreasing output pulse-width demand. With both outputs ORed together at the inverting input node of the PWM comparator, the amplifier demanding the minimum pulse out dominates. The amplifier outputs are biased low by a current sink to provide maximum pulse width out when both amplifiers are biased off.