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FN6799.4
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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ISL9440B, ISL9440C
Triple Step-Down PWM and Single Linear
Controller with Programmable Soft-Start
The ISL9440B and ISL9440C are quad-output synchronous
buck controllers that integrate three PWM controllers and one
low drop-out linear regulator controller, which are full featured
and designed to provide multi-rail power for use in products
such as cable and satellite set-top boxes, VoIP gateways,
cable modems, and other home connectivity products as well
as a variety of industrial and general purpose applications.
Each output is adjustable down to 0.8V. The PWMs are
synchronized at 180° out-of-phase thus, reducing the RMS
input current and ripple voltage.
The ISL9440B and ISL9440C offer programmable soft-start,
independent enable inputs for ease of supply rail
sequencing, and integrated UV/OV/OC/OT protections in a
space conscious 5mmx5mm QFN package. An early
warning function is offered to output a logic signal to warn
the system to back up data when input voltage falls below a
certain level.
The ISL9440B and ISL9440C utilize internal loop
compensation to keep minimum peripheral components for
compact design and a low total solution cost. These devices
are implemented with current mode control with feed-forward
to cover various applications even with fixed internal
compensations.
Table 1 shows the difference in terms of ISL944xx family
features.
Features
• Three Integrated Synchronous Buck PWM Controllers
- Internal Bootstrap Diodes
- Internal Compensation
• Independent Control for each Regulator and
Programmable Output Voltages; Independent
Enable/Shutdown/Soft-start
• Fixed Switching Frequency: 300kHz(B), 600kHz(C)
• Adaptive Shoot-Through Protection on all Synchronous
Buck Controllers
• Pre-biased Output Start-up Capability
• Out-of-Phase Switching to Reduce Input Capacitance
(0°/180°/0°)
• No External Current Sense Resistor
- Uses Lower MOSFET’s r
DS(ON)
• Current Mode Controller with Voltage Feed-Forward
• Complete Protection
- Overcurrent, Overvoltage, Undervoltage Lockout,
Over-Temperature
• Cycle-by-Cycle Current Limiting
• Wide Input Voltage Range
- Input Rail Powers VIN Pin: 5.6V to 24V
- Input Rail Powers VCC_5V Pin (VIN tied to VCC_5V, for
5V input applications): 4.5V to 5.6V
• Early Warning on Input Voltage Failure
• Integrated Reset Function
• Pb-Free (RoHS Compliant)
Applications
• Satellite and Cable Set-Top Boxes
• Cable Modems
• VoX Gateway Devices
• NAS/SAN Devices
• ATX Power Supply
Related Literature
• Technical Brief TB389 “PCB Land Pattern Design and
Surface Mount Guidelines for QFN (MLFP) Packages”
TABLE 1.
PART
NUMBER
EARLY
WARNING
SWITCHING
FREQUENCY
(kHz)
SOFT-STARTING
TIME (ms)
ISL9440 Yes 300 1.7
ISL9440A Yes 600 1.7
ISL9441 No 300 1.7
ISL9440B Yes 300 Programmable
ISL9440C
(No longer
available or
supported)
Yes 600 Programmable
Data Sheet February 18, 2016
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