LM39300(2011) Ver la hoja de datos (PDF) - HTC Korea
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LM39300 Datasheet PDF : 12 Pages
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3A Low-Voltage Low-Dropout Regulator LM39300/39301/39302
converting from 3.3V to 2.5V, the NPN-based regulators are already operating in dropout, with typical dropout
requirements of 1.2V or greater. To convert down to 2.5V without operating in dropout, NPN-based regulators
require an input voltage of 3.7V at the very least. The LM39300/1/2 regulator will provide excellent
performance with an input as low as 3.0V. This gives the PNP-based regulators a distinct advantage over
older, NPN-based linear regulator.
Error Flag
The LM39301 version features an error flag circuit which monitors the output voltage and signals an error
condition when the voltage drops 5% below the nominal output voltage. The error flag is an open-collector
output that can sink 10mA during a fault condition. Low output voltage can be caused by a number of
problems, including an over current fault (device in current limit) or low input voltage. The flag is inoperative
during over temperature shutdown.
Enable Input
The LM39301 version features an enable input for on/off control of the device. Its shutdown state draws “zero”
current (only microamperes of leakage). The enable input is TTL/ CMOS compatible for simple logic interface,
but can be connected to up to 20V. When enabled, it draws approximately 15A.
Adjustable Regulator Design
The LM39302 allows programming the output voltage any-where between 1.25V and the 16V maximum
operating rating of the family. Two resistors are used. Resistors can be quite large, up to 1MΩ, because of the
very high input impedance and low bias current of the sense comparator: The resistor values are calculated
by: R1=R2(Vout/1.250-1)
Where VO is desired output voltage. Figure 1 shows component definition. Applications with widely varying
load currents may scale the resistors to draw the minimum load current required for proper operation (see
below).
Figure 1. Adjustable Regulator with Resistors
Maximum Output Current Capability
The LM39300/1/2 can deliver a continuous current of 3A over the full operating junction temperature range.
However, the output current is limited by the restriction of power dissipation which differs from packages. A
heat sink may be required depending on the maximum power dissipation and maximum ambient temperature
of application. With respect to the applied package, the maximum output current of 3A may be still
undeliverable due to the restriction of the power dissipation of LM39300/1/2. Under all possible conditions, the
junction temperature must be within the range specified under operating conditions. The temperatures over
the device are given by:
TC = TA + PD X θCA / TJ = TC + PD X θJC / TJ = TA + PD X θJA
Feb. 2011 - Rev. 1.1
- 11 -
HTC
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