MAX15004, MAX15005: Flyback/boost/SEPIC Power-Supply Controllers

The MAX15004A/B/MAX15005A/B are high-performance, current-mode PWM controllers that operate over an automotive-grade input voltage range of 4.5V to 40V (load dump). If VCC is supplied by an external bias voltage, the input voltage can be reduced to 2.5V after startup. The controller integrates all the control blocks required to implement a fixed-frequency isolated/nonisolated power supply. Converters for common boost, flyback, forward, and SEPIC topologies can be easily designed around the MAX15004/MAX15005.

The current mode control architecture provides excellent line transient response and cycle-by-cycle current limiting while simplifying frequency compensation. Programmable slope compensation further simplifies design. The fast 60ns current limit response time and low 300mV current limit threshold make the controller suitable for high-efficiency, high-frequency DC-DC converters. The device includes an internal error amplifier and 1% accurate reference to facilitate the implementation of primary-regulated single-ended flyback converters or non-isolated converters.

The switching frequency can be set from 15kHz to 500kHz (1MHz for MAX15004A/B) by an external RC network. The MAX15004A/B/MAX15005A/B offer a SYNC input for synchronization to an external clock. The maximum duty cycle of the FET drivers for the MAX15004A/B is 50%. The maximum duty cycle of the MAX15005A/B can be set by selecting the appropriate combination of RT and CT.

The input supply start-up voltage is set by input undervoltage lockout (ON//OFF) and can be used to shut down the converter to reduce the total shutdown current to 10uA. Protection measures include periodic and hiccup current limiting, output overvoltage protection and thermal shutdown.

The MAX15004A/B/MAX15005A/B are available in space-saving 16-pin TSSOP and thermally enhanced 16-pin TSSOP-EP packages. All devices are specified over the -40°C to +125°C automotive temperature range.

Key Features

● Wide input voltage range: 4.5V to 40V

● Operating voltage as low as 2.5V (using bootstrap VCC bias)

● Current mode control

● Current limit threshold voltage as low as 300mV, with an accuracy of 5%

● Built-in error amplifier and 1% accurate reference

● Switching frequency can be programmed by RC with an accuracy of 4%

● Adjustable switching frequency range: 15kHz to 500kHz (1MHz for MAX15004A/B)

● External frequency synchronization

● Maximum duty cycle 50% (MAX15004) or adjustable (MAX15005)

● Programmable slope compensation

● 10uA shutdown current

● Cycle-by-cycle and hiccup current limiting protection

● Overvoltage and overtemperature shutdown protection

● Automotive temperature range from -40°C to +125°C

● 16-pin TSSOP or 16-pin thermally enhanced TSSOP-EP package

Typical working circuit

application

● Car

● Isolated flyback, forward, non-isolated SEPIC, boost converter

● Vacuum fluorescent display (VFD) power supply