Wide Input Range Dual PWM Controller
with DDR Option
The ISL6539 dual PWM controller delivers high efficiency and
tight regulation from two voltage regulating synchronous buck
DC/DC converters. It was designed especially for DDR DRAM,
SDRAM, graphic chipset applications, and system regulators in
high performance applications.
Voltage-feed-forward ramp modulation, current mode
control, and internal feedback compensation provide fast
response to input voltage and output load transients. Input
current ripple is minimized by channel-to-channel PWM
phase shift of 0°, 90°, or 180° (determined by input voltage
and status of the DDR pin).
The ISL6539 can control two independent output voltages
adjustable from 0.9V to 5.5V or, by activating the DDR pin,
transform into a complete DDR memory power supply
solution. In DDR mode, CH2 output voltage VTT tracks CH1
output voltage VDDQ. CH2 output can both source and sink
current, an essential power supply feature for DDR memory.
The reference voltage VREF required by DDR memory is
generated as well.
In dual power supply applications the ISL6539 monitors the
output voltage of both CH1 and CH2. An independent
PGOOD (power good) signal is asserted for each channel
after the soft-start sequence has completed, and the output
voltage is within PGOOD window. In DDR mode CH1
generates the only PGOOD signal.
Built-in overvoltage protection prevents the output from going
above 115% of the set point by holding the lower MOSFET on
and the upper MOSFET off. When the output voltage decays
below the overvoltage threshold, normal operation
automatically resumes. Once the soft-start sequence has
completed, undervoltage protection latches the offending
channel off if the output drops below 75% of its set point value
for the dual switcher. Adjustable overcurrent protection (OCP)
monitors the voltage drop across the rDS(ON) of the lower
MOSFET. If more precise current-sensing is required, an
external current sense resistor may be used.
• Provides regulated output voltage in the range 0.9V–5.5V
• Complete DDR memory power solution with VTT tracks
VDDQ/2 and VDDQ/2 buffered reference output
• Supports both DDR-I and DDR2 memory
• Lossless rDS(ON) current-sense sensing
• Excellent dynamic response with voltage feed-forward and
current mode control accommodating wide range LC filter
• Dual mode operation–operates directly from a 5.0-15V
input or 3.3V/5V system rail
• Undervoltage lock-out on VCC pin
• Power-good, overcurrent, overvoltage, undervoltage
protection for both channels
• Synchronized 300kHz PWM operation in PWM mode
• Pb-Free Available
• Single and Dual Channel DDR Memory Power Systems
• Graphics cards - GPU and memory supplies
• Supplies for Servers, Motherboards, FPGAs
• ASIC power supplies
• Embedded processor and I/O supplies
• DSP supplies
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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