The MAX1973/MAX1974 are constant-frequency 1.4MHz pulse-width-modulated (PWM) current-mode step-down regulators. The output voltage can be set as low as 0.75V using an external voltage-divider, or it can be set to preset outputs of 1V, 1.5V (MAX1974), 1.8V, or 2.5V (MAX1973) without requiring external resistors. The MAX1973 also includes a voltage-margining feature that offsets the output voltage up or down 4% to facilitate board-level production testing.
A fixed 1.4MHz operating frequency ensures operation outside the DSL frequency band, provides fast transient response, and allows the use of small external components. Only 4.7µF input and output ceramic capacitors are needed for 1A applications. Forced PWM operation ensures a constant switching frequency over all load conditions.
Output voltage accuracy is ±1% over load, line, and temperature operating ranges. The MAX1973 features voltage margining; the MAX1974 provides a POK output to indicate when the output has reached 90% of its nominal regulation voltage. Both devices are available in small 10-pin µMAX® packages.
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