General Description
The MIC9131 is a current-mode PWM controller that efficiently converts –48V telecom voltages to logic levels. The MIC9131 features a high voltage start-up circuit that allows the device to be connected to input voltages as high as 180V. The high input voltage capability protects the MIC9131 from line transients that are common in telecom systems. The start-up circuitry also saves valuable board space and simplifies designs by integrating several external components.

Features
• Input voltages up to 180V
• Internal oscillator capable of > 2.5MHz operation
• Accurate 75% maximum duty cycle
• Synchronisation capability to 6MHz
• Current sense delay of 34ns
• Minimum pulse width of <25ns
• 90% efficiency
• 1.3mA quiescent current
• 1µA shutdown current
• Soft-start
• Resistor programmable current sense threshold
• Selectable soft-start retry
• 4Ω sink, 12Ω source output driver
• Programmable under-voltage lockout
• Constant-frequency PWM current-mode control
• 16-pin SOIC and 16-pin QSOP

Applications
• Telecom power supplies
• Line cards
• ISDN network terminators
• Micro- and pico-cell base stations
• Low power (< 100W) dc-dc converters
• DSL line cards