LM3000 Datasheet, PDF (1/41 Pages) National Semiconductor (TI) – Dual Synchronous Emulated Current-Mode Controller

LM3000
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SNVS612B – JULY 2009 – REVISED APRIL 2013
LM3000 Dual Synchronous Emulated Current-Mode Controller
Check for Samples: LM3000
FEATURES
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•2 V_IN Range FROM 3.3V to 18.5V
• Output Voltage From 0.6V to 80% of V_IN
• Remote Differential Output Voltage Sensing
• 1% Accuracy at FB Pin
• Interleaved Operation Reduces Input
Capacitors
• Frequency Sync/Adjust From 200 kHz to 1.5
MHz
• Startup With Pre-Bias Load
• Independent Power Good, Enable, Soft-Start
and Track
• Programmable Current Limit Without External
Sense Resistor
• Hiccup Mode Short Circuit Protection
APPLICATIONS
• DC Power Distribution Systems
• Graphic Cards - GPU and Memory ICs
• FPGA, CPLD, and ASICs
• Embedded Processor
• 1.8V and 2.5V I/O Supplies
• Networking Equipment (Routers, Hubs)
DESCRIPTION
The LM3000 is a dual output synchronous buck
controller which is designed to convert input voltages
ranging from 3.3V to 18.5V down to output voltages
as low as 0.6V. The two outputs switch at a constant
programmable frequency of 200 kHz to 1.5 MHz, with
the second output 180 degrees out of phase from the
first to minimize the input filter requirements. The
switching frequency can also be phase locked to an
external frequency. A CLKOUT provides an external
clock 90 degrees out of phase with the main clock so
that a second chip can be run out of phase with the
main chip. The emulated current-mode control utilizes
bottom side FET sensing to provide fast transient
response and current limit without the need for
external current sense resistors or RC networks.
Separate Enable, Soft-Start and Track pins allow
each output to be controlled independently to provide
maximum flexibility in designing system power
sequencing.
The LM3000 has a full range of protection features
which include input under-voltage lock-out (UVLO),
power good (PGOOD) signals for each output, over-
voltage crowbar and hiccup mode during short circuit
events.
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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