The ISL6401 adjustable frequency, low power, pulse width
modulating (PWM) current mode controller is designed for a
wide range of DC/DC conversion applications including
boost, flyback, and isolated output configurations. The
device is optimized to provide a high performance, low-cost
solution for Ringing SLIC (RSLIC) ring and talk power
supplies. An integrated inverter allows for easy design of
negative voltage regulation circuits with a minimal amount of
external components. Internal soft-start minimizes start-up
stress without any external components. Peak current mode
control effectively handles Ring trip transients and provides
inherent overcurrent protection.
This advanced BiCMOS design features low operating
current, adjustable operating output frequency (50kHz to
600kHz), internal soft-start and a SYNC input that allows the
oscillator to be locked to an external clock for noise sensitive
applications. DC/DC conversion efficiency is optimized by
use of a low current sense voltage. A logic level shutdown
input is included, which reduces supply current to 55µA in
the shutdown mode.

Features
• Positive and Negative Output Regulation
• Starting Supply Current . . . . . . . . . . . . . . . . . 100µA (typ.)
• Quiescent Current . . . . . . . . . . . . . . . . . . . . . . 55µA (typ.)
• Output Frequency Range. . . . . . . . . . . . 50kHz to 600kHz
• External Clock Synchronization
• Fast Transient Response with Peak Current Mode Control
• Internal Soft-Start
• Drives N-Channel MOSFET
• Logic Level Shutdown
• Leading Edge Blanking
• 1% Tolerance Voltage Reference Over Line and
Temperature
• Pb-Free Available (RoHS Compliant)

Applications
• VoIP/VoDSL Ringer and Off-Hook Voltage Generators
• Multi-Output Flyback Supplies
• Cable and DSL Modems
• Set-Top Boxes
• Wireless Local Loops
• LMDH and FTTH Supplies
• Boost Regulators
• Routers