The MAX5070/MAX5071 BiCMOS, high-performance,
current-mode PWM controllers have all the features
required for wide input voltage range isolated/nonisolated
power supplies. These controllers are used for low- and
high-power universal input voltage and telecom power
supplies.
The MAX5070/MAX5071 contain a fast comparator with
only 60ns typical delay from current sense to the output
for overcurrent protection. The MAX5070A/MAX5070B
have an integrated error amplifier with the output at
COMP. Soft-start is achieved by controlling the COMP
voltage rise using external components.
The frequency is adjustable from 20kHz to 1MHz with
an external resistor and capacitor. The timing capacitor
discharge current is trimmed allowing for programmable
dead time and maximum duty cycle for a given frequency.
The available saw-toothed waveform at RTCT
can be used for slope compensation when needed.
The MAX5071A/MAX5071B include a bidirectional synchronization
circuit allowing for multiple controllers to
run at the same frequency to avoid beat frequencies.
Synchronization is accomplished by simply connecting
the SYNC pins of all devices together. When synchronizing
with other devices, the MAX5071A/MAX5071B
with the highest frequency synchronizes the other
devices. Alternatively, the MAX5071A/MAX5071B can
be synchronized to an external clock with an opendrain
output stage running at a higher frequency.
The MAX5071C provides a clock output pulse
(ADV_CLK) that leads the driver output (OUT) by
110ns. The advanced clock signal is used to drive the
secondary-side synchronous rectifiers.
The MAX5070/MAX5071 are available in 8-pin µMAX®
and SO packages and operate over the automotive temperature
range of -40°C to +125°C.
Key Features
Applications/Uses
Pin-for-Pin Replacement for UC2842 (MAX5070A) and UC2844 (MAX5070B)
2A Drive Source and 1A Sink Capability
Up to 1MHz Switching Frequency Operation
Bidirectional Synchronization (MAX5071A/MAX5071B)
Advanced Output Drive for Secondary-Side Synchronous Rectification (MAX5071C)
Fast 60ns Cycle-by-Cycle Current Limit
Trimmed Oscillator Capacitor Discharge Current Sets Maximum Duty Cycle Accurately
Accurate 5% Start and Stop Voltage with 6V Hysteresis
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