LTM8046MPYPBF View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTM8046MPYPBF' PDF : 20 Pages View PDF
Block Diagram
VIN
0.1µF
RUN
BIAS*
SS
FB
•
•
CURRENT
MODE
CONTROLLER
GND
*DO NOT ALLOW BIAS VOLTAGE TO EXCEED VIN
VOUT
1µF
VOUT–
8046 BD
LTM8046
Operation
The LTM8046 is a stand-alone isolated flyback switching
DC/DC µModule converter that can deliver over 700mA of
output current. This module provides a regulated output
voltage programmable via one external resistor from 1.8V
to 12V. The input voltage range of the LTM8046 is 3.1V
to 31V. Given that the LTM8046 is a flyback converter,
the output current depends upon the input and output
voltages, so make sure that the input voltage is high
enough to support the desired output voltage and load
current. The Typical Performance Characteristics section
gives several graphs of the maximum load versus VIN for
several output voltages.
A simplified block diagram is given. The LTM8046 contains
a current mode controller, power switching element, power
transformer, power Schottky diode, a modest amount of
input and output capacitance.
The LTM8046 has a galvanic primary to secondary isola-
tion rating of 2kVAC. This is verified by applying 3kVDC
between the primary to secondary for 1 second. Note
that the 2kVAC isolation is verified by a 3kVDC test. This
is because the 2kVAC waveform has a peak voltage 1.414
times higher than 2kV, or 2.83kVDC. For the LTM8046, at
least 3kVDC is applied. For further details please refer to
the Isolation and Working Voltage section.
An internal regulator provides power to the control cir-
cuitry. The bias regulator normally draws power from the
VIN pin, but if the BIAS pin is connected to an external
voltage higher than 3.1V, bias power will be drawn from
the external source, improving efficiency. VBIAS must not
exceed VIN. The RUN pin is used to turn on or off the
LTM8046, disconnecting the output and reducing the
input current to 1ÎĽA or less.
The LTM8046 is a variable frequency device. For a fixed
input and output voltage, the frequency decreases as
the load increases. For light loads, the current through
the internal transformer may be discontinuous, so that
frequency may appear to decrease. Note that a minimum
load is required to keep the output voltage in regulation.
Refer to the Typical Performance Characteristics section.
For more information www.linear.com/LTM8046
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