LTM8046 데이터 시트보기 (PDF) - Linear Technology
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LTM8046 Datasheet PDF : 20 Pages
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LTM8046
Pin Functions
VIN (Bank 1): VIN supplies current to the LTM8046’s
internal regulator and to the integrated power switch.
These pins must be locally bypassed with an external,
low ESR capacitor.
GND (Bank 2): This is the primary side local ground of
the LTM8046 primary. In most applications, the bulk of
the heat flow out of the LTM8046 is through the GND and
VOUT– pads, so the printed circuit design has a large impact
on the thermal performance of the part. See the PCB Layout
and Thermal Considerations sections for more details.
VOUT– (Bank 3): VOUT– is the return for VOUT. VOUT and
VOUT– comprise the isolated output of the LTM8046. In
most applications, the bulk of the heat flow out of the
LTM8046 is through the GND and VOUT– pads, so the
printed circuit design has a large impact on the thermal
performance of the part. See the PCB Layout and Thermal
Considerations sections for more details. Apply an external
capacitor between VOUT and VOUT–.
VOUT (Bank 4): VOUT and VOUT– comprise the isolated
output of the LTM8046 flyback stage. Apply an external
capacitor between VOUT and VOUT–. Do not allow VOUT– to
exceed VOUT.
RUN (Pin L3): A resistive divider connected to VIN and this
pin programs the minimum voltage at which the LTM8046
will operate. Below 1.24V, the LTM8046 does not deliver
power to the secondary. Above 1.24V, power will be de-
livered to the secondary and 8µA will be fed into the SS
pin. When RUN is less than 1.24V, the pin draws 2.5µA,
allowing for a programmable hysteresis. Do not allow a
negative voltage (relative to GND) on this pin.
BIAS (Pin L4): This pin supplies the power necessary to
operate the LTM8046. It must be locally bypassed with
a low ESR capacitor of at least 1μF. Do not allow this pin
voltage to rise above VIN.
SS (Pin L5): Place a soft-start capacitor here to limit inrush
current and the output voltage ramp rate. Do not allow a
negative voltage (relative to GND) on this pin.
FB (Pin L6): Apply a resistor from this pin to GND to set
the output voltage, using the recommended value given
in Table 1. If Table 1 does not list the desired VOUT value,
the equation
( ) RFB = 31.6 VOUT –0.84 kΩ
may be used to approximate the value. To the seasoned
designer, this exponential equation may seem unusual.
The equation is exponential due to non-linear current
sources that are used to temperature compensate the
output regulation.
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For more information www.linear.com/LTM8046
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