LM5642, LM5642X
www.ti.com
SNVS219K –JUNE 2003–REVISED APRIL 2013
LM5642/LM5642X High Voltage, Dual Synchronous Buck Converter with Oscillator
Synchronization
Check for Samples: LM5642, LM5642X
1
FEATURES
DESCRIPTION
The LM5642 series consists of two current mode
synchronous buck regulator controllers operating
180° out of phase with each other at a normal
switching frequency of 200kHz for the LM5642 and at
375kHz for the LM5642X.
2
•
Two Synchronous Buck Regulators
180° Out of Phase Operation
•
•
•
•
200 kHz Fixed Nominal Frequency: LM5642
375 kHz Fixed Nominal Frequency: LM5642X
Synchronizable Switching Frequency from 150
kHz to 250 kHz for the LM5642 and 200 kHz to
500 kHz for the LM5642X
Out of phase operation reduces the input RMS ripple
current, thereby significantly reducing the required
input capacitance. The switching frequency can be
synchronized to an external clock between 150 kHz
and 250 kHz for the LM5642 and between 200 kHz
and 500 kHz for the LM5642X. The two switching
regulator outputs can also be paralleled to operate as
a dual-phase, single output regulator.
•
•
•
•
4.5V to 36V Input Range
50 µA Shutdown Current
Adjustable Output from 1.3V to 90% of Vin
0.04% (Typical) Line and Load Regulation
Accuracy
The output of each channel can be independently
adjusted from 1.3V to 90% of Vin. An internal 5V rail
is also available externally for driving bootstrap
circuitry.
•
•
•
Current Mode Control with or without a Sense
Resistor
Independent Enable/Soft-start Pins Allow
Simple Sequential Startup Configuration.
Current-mode feedback control assures excellent line
and load regulation and wide loop bandwidth for
excellent response to fast load transients. Current is
sensed across either the Vds of the top FET or
across an external current-sense resistor connected
in series with the drain of the top FET.
Configurable for Single Output Parallel
Operation. (See Figure 4)
•
•
•
•
•
•
Adjustable Cycle-by-cycle Current Limit
Input Under-voltage Lockout
Output Over-voltage Latch Protection
Output Under-voltage Protection with Delay
Thermal Shutdown
The LM5642 features analog soft-start circuitry that is
independent of the output load and output
capacitance making the soft-start behavior more
predictable and controllable than traditional soft-start
circuits.
Self Discharge of Output Capacitors when the
Regulator is OFF
Over-voltage protection is available for both outputs.
A UV-Delay pin is also available to allow delayed shut
off time for the IC during an output under-voltage
event.
•
TSSOP and HTSSOP (Exposed PAD) Packages
APPLICATIONS
•
•
•
•
•
•
Embedded Computer Systems
Navigation Systems
Telecom Systems
Typical Application Circuit
V
IN
4.5V - 36V
Set-Top Boxes
UV_Delay
Vout1
1.3V-0.9VIN
WebPAD
SYNC
Point Of Load Power Architectures
LM5642/LM5642X
SS/ON1
SS/ON2
Vout2
1.3V-0.9VIN
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
2
All trademarks are the property of their respective owners.
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.
Copyright © 2003–2013, Texas Instruments Incorporated